/*
 * VIM - Vi IMproved	by Bram Moolenaar
 *
 * Do ":help uganda"  in Vim to read copying and usage conditions.
 * Do ":help credits" in Vim to see a list of people who contributed.
 * See README.txt for an overview of the Vim source code.
 */

/*
 * message.c: functions for displaying messages on the command line
 */

#include <assert.h>
#include <errno.h>
#include <inttypes.h>
#include <stdbool.h>
#include <stdarg.h>
#include <string.h>
#include <math.h>

#include "nvim/vim.h"
#include "nvim/ascii.h"
#include "nvim/message.h"
#include "nvim/charset.h"
#include "nvim/eval.h"
#include "nvim/ex_eval.h"
#include "nvim/ex_docmd.h"
#include "nvim/fileio.h"
#include "nvim/func_attr.h"
#include "nvim/getchar.h"
#include "nvim/mbyte.h"
#include "nvim/memory.h"
#include "nvim/misc1.h"
#include "nvim/misc2.h"
#include "nvim/keymap.h"
#include "nvim/garray.h"
#include "nvim/ops.h"
#include "nvim/option.h"
#include "nvim/normal.h"
#include "nvim/screen.h"
#include "nvim/strings.h"
#include "nvim/ui.h"
#include "nvim/mouse.h"
#include "nvim/os/os.h"
#include "nvim/os/input.h"
#include "nvim/os/time.h"

/*
 * To be able to scroll back at the "more" and "hit-enter" prompts we need to
 * store the displayed text and remember where screen lines start.
 */
typedef struct msgchunk_S msgchunk_T;
struct msgchunk_S {
  msgchunk_T  *sb_next;
  msgchunk_T  *sb_prev;
  char sb_eol;                  /* TRUE when line ends after this text */
  int sb_msg_col;               /* column in which text starts */
  int sb_attr;                  /* text attributes */
  char_u sb_text[1];            /* text to be displayed, actually longer */
};

/* Magic chars used in confirm dialog strings */
#define DLG_BUTTON_SEP  '\n'
#define DLG_HOTKEY_CHAR '&'

static int confirm_msg_used = FALSE;            /* displaying confirm_msg */
#ifdef INCLUDE_GENERATED_DECLARATIONS
# include "message.c.generated.h"
#endif
static char_u   *confirm_msg = NULL;            /* ":confirm" message */
static char_u   *confirm_msg_tail;              /* tail of confirm_msg */

struct msg_hist {
  struct msg_hist     *next;
  char_u              *msg;
  int attr;
};

static struct msg_hist *first_msg_hist = NULL;
static struct msg_hist *last_msg_hist = NULL;
static int msg_hist_len = 0;

static FILE *verbose_fd = NULL;
static int verbose_did_open = FALSE;

/*
 * When writing messages to the screen, there are many different situations.
 * A number of variables is used to remember the current state:
 * msg_didany	    TRUE when messages were written since the last time the
 *		    user reacted to a prompt.
 *		    Reset: After hitting a key for the hit-return prompt,
 *		    hitting <CR> for the command line or input().
 *		    Set: When any message is written to the screen.
 * msg_didout	    TRUE when something was written to the current line.
 *		    Reset: When advancing to the next line, when the current
 *		    text can be overwritten.
 *		    Set: When any message is written to the screen.
 * msg_nowait	    No extra delay for the last drawn message.
 *		    Used in normal_cmd() before the mode message is drawn.
 * emsg_on_display  There was an error message recently.  Indicates that there
 *		    should be a delay before redrawing.
 * msg_scroll	    The next message should not overwrite the current one.
 * msg_scrolled	    How many lines the screen has been scrolled (because of
 *		    messages).  Used in update_screen() to scroll the screen
 *		    back.  Incremented each time the screen scrolls a line.
 * msg_scrolled_ign  TRUE when msg_scrolled is non-zero and msg_puts_attr()
 *		    writes something without scrolling should not make
 *		    need_wait_return to be set.  This is a hack to make ":ts"
 *		    work without an extra prompt.
 * lines_left	    Number of lines available for messages before the
 *		    more-prompt is to be given.  -1 when not set.
 * need_wait_return TRUE when the hit-return prompt is needed.
 *		    Reset: After giving the hit-return prompt, when the user
 *		    has answered some other prompt.
 *		    Set: When the ruler or typeahead display is overwritten,
 *		    scrolling the screen for some message.
 * keep_msg	    Message to be displayed after redrawing the screen, in
 *		    main_loop().
 *		    This is an allocated string or NULL when not used.
 */

/*
 * msg(s) - displays the string 's' on the status line
 * When terminal not initialized (yet) mch_errmsg(..) is used.
 * return TRUE if wait_return not called
 */
int msg(char_u *s)
{
  return msg_attr_keep(s, 0, FALSE);
}

/*
 * Like msg() but keep it silent when 'verbosefile' is set.
 */
int verb_msg(char_u *s)
{
  int n;

  verbose_enter();
  n = msg_attr_keep(s, 0, FALSE);
  verbose_leave();

  return n;
}

int msg_attr(char_u *s, int attr) FUNC_ATTR_NONNULL_ARG(1)
{
  return msg_attr_keep(s, attr, FALSE);
}

int
msg_attr_keep (
    char_u *s,
    int attr,
    int keep                   /* TRUE: set keep_msg if it doesn't scroll */
)
  FUNC_ATTR_NONNULL_ARG(1)
{
  static int entered = 0;
  int retval;
  char_u      *buf = NULL;

  if (attr == 0)
    set_vim_var_string(VV_STATUSMSG, s, -1);

  /*
   * It is possible that displaying a messages causes a problem (e.g.,
   * when redrawing the window), which causes another message, etc..	To
   * break this loop, limit the recursiveness to 3 levels.
   */
  if (entered >= 3)
    return TRUE;
  ++entered;

  /* Add message to history (unless it's a repeated kept message or a
   * truncated message) */
  if (s != keep_msg
      || (*s != '<'
          && last_msg_hist != NULL
          && last_msg_hist->msg != NULL
          && STRCMP(s, last_msg_hist->msg)))
    add_msg_hist(s, -1, attr);

  /* When displaying keep_msg, don't let msg_start() free it, caller must do
   * that. */
  if (s == keep_msg)
    keep_msg = NULL;

  /* Truncate the message if needed. */
  msg_start();
  buf = msg_strtrunc(s, FALSE);
  if (buf != NULL)
    s = buf;

  msg_outtrans_attr(s, attr);
  msg_clr_eos();
  retval = msg_end();

  if (keep && retval && vim_strsize(s) < (int)(Rows - cmdline_row - 1)
      * Columns + sc_col)
    set_keep_msg(s, 0);

  xfree(buf);
  --entered;
  return retval;
}

/*
 * Truncate a string such that it can be printed without causing a scroll.
 * Returns an allocated string or NULL when no truncating is done.
 */
char_u *
msg_strtrunc (
    char_u *s,
    int force                  /* always truncate */
)
{
  char_u      *buf = NULL;
  int len;
  int room;

  /* May truncate message to avoid a hit-return prompt */
  if ((!msg_scroll && !need_wait_return && shortmess(SHM_TRUNCALL)
       && !exmode_active && msg_silent == 0) || force) {
    len = vim_strsize(s);
    if (msg_scrolled != 0)
      /* Use all the columns. */
      room = (int)(Rows - msg_row) * Columns - 1;
    else
      /* Use up to 'showcmd' column. */
      room = (int)(Rows - msg_row - 1) * Columns + sc_col - 1;
    if (len > room && room > 0) {
      if (enc_utf8)
        /* may have up to 18 bytes per cell (6 per char, up to two
         * composing chars) */
        len = (room + 2) * 18;
      else if (enc_dbcs == DBCS_JPNU)
        /* may have up to 2 bytes per cell for euc-jp */
        len = (room + 2) * 2;
      else
        len = room + 2;
      buf = xmalloc(len);
      trunc_string(s, buf, room, len);
    }
  }
  return buf;
}

/*
 * Truncate a string "s" to "buf" with cell width "room".
 * "s" and "buf" may be equal.
 */
void trunc_string(char_u *s, char_u *buf, int room, int buflen)
{
  int half;
  int len;
  int e;
  int i;
  int n;

  room -= 3;
  half = room / 2;
  len = 0;

  /* First part: Start of the string. */
  for (e = 0; len < half && e < buflen; ++e) {
    if (s[e] == NUL) {
      /* text fits without truncating! */
      buf[e] = NUL;
      return;
    }
    n = ptr2cells(s + e);
    if (len + n >= half)
      break;
    len += n;
    buf[e] = s[e];
    if (has_mbyte)
      for (n = (*mb_ptr2len)(s + e); --n > 0; ) {
        if (++e == buflen)
          break;
        buf[e] = s[e];
      }
  }

  /* Last part: End of the string. */
  i = e;
  if (enc_dbcs != 0) {
    /* For DBCS going backwards in a string is slow, but
     * computing the cell width isn't too slow: go forward
     * until the rest fits. */
    n = vim_strsize(s + i);
    while (len + n > room) {
      n -= ptr2cells(s + i);
      i += (*mb_ptr2len)(s + i);
    }
  } else if (enc_utf8) {
    /* For UTF-8 we can go backwards easily. */
    half = i = (int)STRLEN(s);
    for (;; ) {
      do
        half = half - (*mb_head_off)(s, s + half - 1) - 1;
      while (utf_iscomposing(utf_ptr2char(s + half)) && half > 0);
      n = ptr2cells(s + half);
      if (len + n > room)
        break;
      len += n;
      i = half;
    }
  } else {
    for (i = (int)STRLEN(s); len + (n = ptr2cells(s + i - 1)) <= room; --i)
      len += n;
  }

  /* Set the middle and copy the last part. */
  if (e + 3 < buflen) {
    memmove(buf + e, "...", (size_t)3);
    len = (int)STRLEN(s + i) + 1;
    if (len >= buflen - e - 3)
      len = buflen - e - 3 - 1;
    memmove(buf + e + 3, s + i, len);
    buf[e + 3 + len - 1] = NUL;
  } else {
    buf[e - 1] = NUL;      /* make sure it is truncated */
  }
}

/*
 * Note: Caller of smgs() and smsg_attr() must check the resulting string is
 * shorter than IOSIZE!!!
 */

int smsg(char *s, ...)
{
  va_list arglist;

  va_start(arglist, s);
  vim_vsnprintf((char *)IObuff, IOSIZE, s, arglist, NULL);
  va_end(arglist);
  return msg(IObuff);
}

int smsg_attr(int attr, char *s, ...)
{
  va_list arglist;

  va_start(arglist, s);
  vim_vsnprintf((char *)IObuff, IOSIZE, s, arglist, NULL);
  va_end(arglist);
  return msg_attr(IObuff, attr);
}

/*
 * Remember the last sourcing name/lnum used in an error message, so that it
 * isn't printed each time when it didn't change.
 */
static int last_sourcing_lnum = 0;
static char_u   *last_sourcing_name = NULL;

/*
 * Reset the last used sourcing name/lnum.  Makes sure it is displayed again
 * for the next error message;
 */
void reset_last_sourcing(void)
{
  xfree(last_sourcing_name);
  last_sourcing_name = NULL;
  last_sourcing_lnum = 0;
}

/*
 * Return TRUE if "sourcing_name" differs from "last_sourcing_name".
 */
static int other_sourcing_name(void)
{
  if (sourcing_name != NULL) {
    if (last_sourcing_name != NULL)
      return STRCMP(sourcing_name, last_sourcing_name) != 0;
    return TRUE;
  }
  return FALSE;
}

/*
 * Get the message about the source, as used for an error message.
 * Returns an allocated string with room for one more character.
 * Returns NULL when no message is to be given.
 */
static char_u *get_emsg_source(void)
{
  char_u      *Buf, *p;

  if (sourcing_name != NULL && other_sourcing_name()) {
    p = (char_u *)_("Error detected while processing %s:");
    Buf = xmalloc(STRLEN(sourcing_name) + STRLEN(p));
    sprintf((char *)Buf, (char *)p, sourcing_name);
    return Buf;
  }
  return NULL;
}

/*
 * Get the message about the source lnum, as used for an error message.
 * Returns an allocated string with room for one more character.
 * Returns NULL when no message is to be given.
 */
static char_u *get_emsg_lnum(void)
{
  char_u      *Buf, *p;

  /* lnum is 0 when executing a command from the command line
   * argument, we don't want a line number then */
  if (sourcing_name != NULL
      && (other_sourcing_name() || sourcing_lnum != last_sourcing_lnum)
      && sourcing_lnum != 0) {
    p = (char_u *)_("line %4ld:");
    Buf = xmalloc(STRLEN(p) + 20);
    sprintf((char *)Buf, (char *)p, (long)sourcing_lnum);
    return Buf;
  }
  return NULL;
}

/*
 * Display name and line number for the source of an error.
 * Remember the file name and line number, so that for the next error the info
 * is only displayed if it changed.
 */
void msg_source(int attr)
{
  char_u      *p;

  ++no_wait_return;
  p = get_emsg_source();
  if (p != NULL) {
    msg_attr(p, attr);
    xfree(p);
  }
  p = get_emsg_lnum();
  if (p != NULL) {
    msg_attr(p, hl_attr(HLF_N));
    xfree(p);
    last_sourcing_lnum = sourcing_lnum;      /* only once for each line */
  }

  /* remember the last sourcing name printed, also when it's empty */
  if (sourcing_name == NULL || other_sourcing_name()) {
    xfree(last_sourcing_name);
    if (sourcing_name == NULL)
      last_sourcing_name = NULL;
    else
      last_sourcing_name = vim_strsave(sourcing_name);
  }
  --no_wait_return;
}

/*
 * Return TRUE if not giving error messages right now:
 * If "emsg_off" is set: no error messages at the moment.
 * If "msg" is in 'debug': do error message but without side effects.
 * If "emsg_skip" is set: never do error messages.
 */
int emsg_not_now(void)
{
  if ((emsg_off > 0 && vim_strchr(p_debug, 'm') == NULL
       && vim_strchr(p_debug, 't') == NULL)
      || emsg_skip > 0
      )
    return TRUE;
  return FALSE;
}

/*
 * emsg() - display an error message
 *
 * Rings the bell, if appropriate, and calls message() to do the real work
 * When terminal not initialized (yet) mch_errmsg(..) is used.
 *
 * return TRUE if wait_return not called
 */
int emsg(char_u *s)
{
  int attr;
  char_u      *p;
  int ignore = FALSE;
  int severe;

  /* Skip this if not giving error messages at the moment. */
  if (emsg_not_now())
    return TRUE;

  called_emsg = TRUE;
  ex_exitval = 1;

  /*
   * If "emsg_severe" is TRUE: When an error exception is to be thrown,
   * prefer this message over previous messages for the same command.
   */
  severe = emsg_severe;
  emsg_severe = FALSE;

  if (!emsg_off || vim_strchr(p_debug, 't') != NULL) {
    /*
     * Cause a throw of an error exception if appropriate.  Don't display
     * the error message in this case.  (If no matching catch clause will
     * be found, the message will be displayed later on.)  "ignore" is set
     * when the message should be ignored completely (used for the
     * interrupt message).
     */
    if (cause_errthrow(s, severe, &ignore) == TRUE) {
      if (!ignore)
        did_emsg = TRUE;
      return TRUE;
    }

    /* set "v:errmsg", also when using ":silent! cmd" */
    set_vim_var_string(VV_ERRMSG, s, -1);

    /*
     * When using ":silent! cmd" ignore error messages.
     * But do write it to the redirection file.
     */
    if (emsg_silent != 0) {
      msg_start();
      p = get_emsg_source();
      if (p != NULL) {
        STRCAT(p, "\n");
        redir_write(p, -1);
        xfree(p);
      }
      p = get_emsg_lnum();
      if (p != NULL) {
        STRCAT(p, "\n");
        redir_write(p, -1);
        xfree(p);
      }
      redir_write(s, -1);
      return TRUE;
    }

    /* Reset msg_silent, an error causes messages to be switched back on. */
    msg_silent = 0;
    cmd_silent = FALSE;

    if (global_busy)                    /* break :global command */
      ++global_busy;

    if (p_eb)
      beep_flush();                     /* also includes flush_buffers() */
    else
      flush_buffers(FALSE);             /* flush internal buffers */
    did_emsg = TRUE;                    /* flag for DoOneCmd() */
  }

  emsg_on_display = TRUE;       /* remember there is an error message */
  ++msg_scroll;                 /* don't overwrite a previous message */
  attr = hl_attr(HLF_E);        /* set highlight mode for error messages */
  if (msg_scrolled != 0)
    need_wait_return = TRUE;        /* needed in case emsg() is called after
                                     * wait_return has reset need_wait_return
                                     * and a redraw is expected because
                                     * msg_scrolled is non-zero */

  /*
   * Display name and line number for the source of the error.
   */
  msg_source(attr);

  /*
   * Display the error message itself.
   */
  msg_nowait = FALSE;                   /* wait for this msg */
  return msg_attr(s, attr);
}

/*
 * Print an error message with one "%s" and one string argument.
 */
int emsg2(char_u *s, char_u *a1)
{
  return emsg3(s, a1, NULL);
}

void emsg_invreg(int name)
{
  EMSG2(_("E354: Invalid register name: '%s'"), transchar(name));
}

/// Print an error message with one or two "%s" and one or two string arguments.
int emsg3(char_u *s, char_u *a1, char_u *a2)
{
  if (emsg_not_now()) {
    return TRUE;                // no error messages at the moment
  }

  vim_snprintf((char *)IObuff, IOSIZE, (char *)s, a1, a2);
  return emsg(IObuff);
}

/// Print an error message with one "%" PRId64 and one (int64_t) argument.
int emsgn(char_u *s, int64_t n)
{
  if (emsg_not_now()) {
    return TRUE;                // no error messages at the moment
  }

  vim_snprintf((char *)IObuff, IOSIZE, (char *)s, n);
  return emsg(IObuff);
}

/// Print an error message with one "%" PRIu64 and one (uint64_t) argument.
int emsgu(char_u *s, uint64_t n)
{
  if (emsg_not_now()) {
    return TRUE;                // no error messages at the moment
  }

  vim_snprintf((char *)IObuff, IOSIZE, (char *)s, n);
  return emsg(IObuff);
}

/*
 * Like msg(), but truncate to a single line if p_shm contains 't', or when
 * "force" is TRUE.  This truncates in another way as for normal messages.
 * Careful: The string may be changed by msg_may_trunc()!
 * Returns a pointer to the printed message, if wait_return() not called.
 */
char_u *msg_trunc_attr(char_u *s, int force, int attr)
{
  int n;

  /* Add message to history before truncating */
  add_msg_hist(s, -1, attr);

  s = msg_may_trunc(force, s);

  msg_hist_off = TRUE;
  n = msg_attr(s, attr);
  msg_hist_off = FALSE;

  if (n)
    return s;
  return NULL;
}

/*
 * Check if message "s" should be truncated at the start (for filenames).
 * Return a pointer to where the truncated message starts.
 * Note: May change the message by replacing a character with '<'.
 */
char_u *msg_may_trunc(int force, char_u *s)
{
  int n;
  int room;

  room = (int)(Rows - cmdline_row - 1) * Columns + sc_col - 1;
  if ((force || (shortmess(SHM_TRUNC) && !exmode_active))
      && (n = (int)STRLEN(s) - room) > 0) {
    if (has_mbyte) {
      int size = vim_strsize(s);

      /* There may be room anyway when there are multibyte chars. */
      if (size <= room)
        return s;

      for (n = 0; size >= room; ) {
        size -= (*mb_ptr2cells)(s + n);
        n += (*mb_ptr2len)(s + n);
      }
      --n;
    }
    s += n;
    *s = '<';
  }
  return s;
}

static void
add_msg_hist (
    char_u *s,
    int len,                        /* -1 for undetermined length */
    int attr
)
{
  if (msg_hist_off || msg_silent != 0)
    return;

  /* Don't let the message history get too big */
  while (msg_hist_len > MAX_MSG_HIST_LEN)
    (void)delete_first_msg();

  /* allocate an entry and add the message at the end of the history */
  struct msg_hist *p = xmalloc(sizeof(struct msg_hist));
  if (len < 0)
    len = (int)STRLEN(s);
  /* remove leading and trailing newlines */
  while (len > 0 && *s == '\n') {
    ++s;
    --len;
  }
  while (len > 0 && s[len - 1] == '\n')
    --len;
  p->msg = vim_strnsave(s, len);
  p->next = NULL;
  p->attr = attr;
  if (last_msg_hist != NULL)
    last_msg_hist->next = p;
  last_msg_hist = p;
  if (first_msg_hist == NULL)
    first_msg_hist = last_msg_hist;
  ++msg_hist_len;
}

/*
 * Delete the first (oldest) message from the history.
 * Returns FAIL if there are no messages.
 */
int delete_first_msg(void)
{
  struct msg_hist *p;

  if (msg_hist_len <= 0)
    return FAIL;
  p = first_msg_hist;
  first_msg_hist = p->next;
  if (first_msg_hist == NULL) {  /* history is becoming empty */
    assert(msg_hist_len == 1);
    last_msg_hist = NULL;
  }
  xfree(p->msg);
  xfree(p);
  --msg_hist_len;
  return OK;
}

/*
 * ":messages" command.
 */
void ex_messages(exarg_T *eap)
{
  struct msg_hist *p;
  const char      *s;

  msg_hist_off = TRUE;

  s = os_getenv("LANG");
  if (s)
    msg_attr((char_u *)
        _("Messages maintainer: Bram Moolenaar <Bram@vim.org>"),
        hl_attr(HLF_T));

  for (p = first_msg_hist; p != NULL && !got_int; p = p->next)
    if (p->msg != NULL)
      msg_attr(p->msg, p->attr);

  msg_hist_off = FALSE;
}

/*
 * Call this after prompting the user.  This will avoid a hit-return message
 * and a delay.
 */
void msg_end_prompt(void)
{
  need_wait_return = FALSE;
  emsg_on_display = FALSE;
  cmdline_row = msg_row;
  msg_col = 0;
  msg_clr_eos();
  lines_left = -1;
}

/*
 * wait for the user to hit a key (normally a return)
 * if 'redraw' is TRUE, clear and redraw the screen
 * if 'redraw' is FALSE, just redraw the screen
 * if 'redraw' is -1, don't redraw at all
 */
void wait_return(int redraw)
{
  int c;
  int oldState;
  int tmpState;
  int had_got_int;
  int save_Recording;
  FILE        *save_scriptout;

  if (redraw == TRUE)
    must_redraw = CLEAR;

  /* If using ":silent cmd", don't wait for a return.  Also don't set
   * need_wait_return to do it later. */
  if (msg_silent != 0)
    return;

  /*
   * When inside vgetc(), we can't wait for a typed character at all.
   * With the global command (and some others) we only need one return at
   * the end. Adjust cmdline_row to avoid the next message overwriting the
   * last one.
   */
  if (vgetc_busy > 0)
    return;
  need_wait_return = TRUE;
  if (no_wait_return) {
    if (!exmode_active)
      cmdline_row = msg_row;
    return;
  }

  redir_off = TRUE;             /* don't redirect this message */
  oldState = State;
  if (quit_more) {
    c = CAR;                    /* just pretend CR was hit */
    quit_more = FALSE;
    got_int = FALSE;
  } else if (exmode_active) {
    MSG_PUTS(" ");              /* make sure the cursor is on the right line */
    c = CAR;                    /* no need for a return in ex mode */
    got_int = FALSE;
  } else {
    /* Make sure the hit-return prompt is on screen when 'guioptions' was
     * just changed. */
    screenalloc(false);

    State = HITRETURN;
    setmouse();
    /* Avoid the sequence that the user types ":" at the hit-return prompt
     * to start an Ex command, but the file-changed dialog gets in the
     * way. */
    if (need_check_timestamps)
      check_timestamps(FALSE);

    hit_return_msg();

    do {
      /* Remember "got_int", if it is set vgetc() probably returns a
       * CTRL-C, but we need to loop then. */
      had_got_int = got_int;

      /* Don't do mappings here, we put the character back in the
       * typeahead buffer. */
      ++no_mapping;
      ++allow_keys;

      /* Temporarily disable Recording. If Recording is active, the
       * character will be recorded later, since it will be added to the
       * typebuf after the loop */
      save_Recording = Recording;
      save_scriptout = scriptout;
      Recording = FALSE;
      scriptout = NULL;
      c = safe_vgetc();
      if (had_got_int && !global_busy)
        got_int = FALSE;
      --no_mapping;
      --allow_keys;
      Recording = save_Recording;
      scriptout = save_scriptout;


      /*
       * Allow scrolling back in the messages.
       * Also accept scroll-down commands when messages fill the screen,
       * to avoid that typing one 'j' too many makes the messages
       * disappear.
       */
      if (p_more) {
        if (c == 'b' || c == 'k' || c == 'u' || c == 'g'
            || c == K_UP || c == K_PAGEUP) {
          if (msg_scrolled > Rows)
            /* scroll back to show older messages */
            do_more_prompt(c);
          else {
            msg_didout = FALSE;
            c = K_IGNORE;
            msg_col =
              cmdmsg_rl ? Columns - 1 :
              0;
          }
          if (quit_more) {
            c = CAR;                            /* just pretend CR was hit */
            quit_more = FALSE;
            got_int = FALSE;
          } else if (c != K_IGNORE) {
            c = K_IGNORE;
            hit_return_msg();
          }
        } else if (msg_scrolled > Rows - 2
                   && (c == 'j' || c == 'd' || c == 'f'
                       || c == K_DOWN || c == K_PAGEDOWN))
          c = K_IGNORE;
      }
    } while ((had_got_int && c == Ctrl_C)
             || c == K_IGNORE
             || c == K_LEFTDRAG   || c == K_LEFTRELEASE
             || c == K_MIDDLEDRAG || c == K_MIDDLERELEASE
             || c == K_RIGHTDRAG  || c == K_RIGHTRELEASE
             || c == K_MOUSELEFT  || c == K_MOUSERIGHT
             || c == K_MOUSEDOWN  || c == K_MOUSEUP
             || (!mouse_has(MOUSE_RETURN)
                 && mouse_row < msg_row
                 && (c == K_LEFTMOUSE
                     || c == K_MIDDLEMOUSE
                     || c == K_RIGHTMOUSE
                     || c == K_X1MOUSE
                     || c == K_X2MOUSE))
             );
    os_breakcheck();
    /*
     * Avoid that the mouse-up event causes visual mode to start.
     */
    if (c == K_LEFTMOUSE || c == K_MIDDLEMOUSE || c == K_RIGHTMOUSE
        || c == K_X1MOUSE || c == K_X2MOUSE)
      (void)jump_to_mouse(MOUSE_SETPOS, NULL, 0);
    else if (vim_strchr((char_u *)"\r\n ", c) == NULL && c != Ctrl_C) {
      /* Put the character back in the typeahead buffer.  Don't use the
       * stuff buffer, because lmaps wouldn't work. */
      ins_char_typebuf(c);
      do_redraw = TRUE;             /* need a redraw even though there is
                                       typeahead */
    }
  }
  redir_off = FALSE;

  /*
   * If the user hits ':', '?' or '/' we get a command line from the next
   * line.
   */
  if (c == ':' || c == '?' || c == '/') {
    if (!exmode_active)
      cmdline_row = msg_row;
    skip_redraw = TRUE;             /* skip redraw once */
    do_redraw = FALSE;
  }

  /*
   * If the window size changed set_shellsize() will redraw the screen.
   * Otherwise the screen is only redrawn if 'redraw' is set and no ':'
   * typed.
   */
  tmpState = State;
  State = oldState;                 /* restore State before set_shellsize */
  setmouse();
  msg_check();
  need_wait_return = FALSE;
  did_wait_return = TRUE;
  emsg_on_display = FALSE;      /* can delete error message now */
  lines_left = -1;              /* reset lines_left at next msg_start() */
  reset_last_sourcing();
  if (keep_msg != NULL && vim_strsize(keep_msg) >=
      (Rows - cmdline_row - 1) * Columns + sc_col) {
    xfree(keep_msg);
    keep_msg = NULL;                /* don't redisplay message, it's too long */
  }

  if (tmpState == SETWSIZE) {       /* got resize event while in vgetc() */
    ui_refresh();
  } else if (!skip_redraw
             && (redraw == TRUE || (msg_scrolled != 0 && redraw != -1))) {
    redraw_later(VALID);
  }
}

/*
 * Write the hit-return prompt.
 */
static void hit_return_msg(void)
{
  int save_p_more = p_more;

  p_more = FALSE;       /* don't want see this message when scrolling back */
  if (msg_didout)       /* start on a new line */
    msg_putchar('\n');
  if (got_int)
    MSG_PUTS(_("Interrupt: "));

  MSG_PUTS_ATTR(_("Press ENTER or type command to continue"), hl_attr(HLF_R));
  if (!msg_use_printf())
    msg_clr_eos();
  p_more = save_p_more;
}

/*
 * Set "keep_msg" to "s".  Free the old value and check for NULL pointer.
 */
void set_keep_msg(char_u *s, int attr)
{
  xfree(keep_msg);
  if (s != NULL && msg_silent == 0)
    keep_msg = vim_strsave(s);
  else
    keep_msg = NULL;
  keep_msg_more = FALSE;
  keep_msg_attr = attr;
}

/*
 * Prepare for outputting characters in the command line.
 */
void msg_start(void)
{
  int did_return = FALSE;

  if (!msg_silent) {
    xfree(keep_msg);
    keep_msg = NULL;                    /* don't display old message now */
  }

  if (need_clr_eos) {
    /* Halfway an ":echo" command and getting an (error) message: clear
     * any text from the command. */
    need_clr_eos = FALSE;
    msg_clr_eos();
  }

  if (!msg_scroll && full_screen) {     /* overwrite last message */
    msg_row = cmdline_row;
    msg_col =
      cmdmsg_rl ? Columns - 1 :
      0;
  } else if (msg_didout) {                /* start message on next line */
    msg_putchar('\n');
    did_return = TRUE;
    if (exmode_active != EXMODE_NORMAL)
      cmdline_row = msg_row;
  }
  if (!msg_didany || lines_left < 0)
    msg_starthere();
  if (msg_silent == 0) {
    msg_didout = FALSE;                     /* no output on current line yet */
  }

  /* when redirecting, may need to start a new line. */
  if (!did_return)
    redir_write((char_u *)"\n", -1);
}

/*
 * Note that the current msg position is where messages start.
 */
void msg_starthere(void)
{
  lines_left = cmdline_row;
  msg_didany = FALSE;
}

void msg_putchar(int c)
{
  msg_putchar_attr(c, 0);
}

void msg_putchar_attr(int c, int attr)
{
  char_u buf[MB_MAXBYTES + 1];

  if (IS_SPECIAL(c)) {
    buf[0] = K_SPECIAL;
    buf[1] = K_SECOND(c);
    buf[2] = K_THIRD(c);
    buf[3] = NUL;
  } else {
    buf[(*mb_char2bytes)(c, buf)] = NUL;
  }
  msg_puts_attr(buf, attr);
}

void msg_outnum(long n)
{
  char_u buf[20];

  sprintf((char *)buf, "%" PRId64, (int64_t)n);
  msg_puts(buf);
}

void msg_home_replace(char_u *fname)
{
  msg_home_replace_attr(fname, 0);
}

void msg_home_replace_hl(char_u *fname)
{
  msg_home_replace_attr(fname, hl_attr(HLF_D));
}

static void msg_home_replace_attr(char_u *fname, int attr)
{
  char_u      *name;

  name = home_replace_save(NULL, fname);
  msg_outtrans_attr(name, attr);
  xfree(name);
}

/*
 * Output 'len' characters in 'str' (including NULs) with translation
 * if 'len' is -1, output upto a NUL character.
 * Use attributes 'attr'.
 * Return the number of characters it takes on the screen.
 */
int msg_outtrans(char_u *str)
{
  return msg_outtrans_attr(str, 0);
}

int msg_outtrans_attr(char_u *str, int attr)
{
  return msg_outtrans_len_attr(str, (int)STRLEN(str), attr);
}

int msg_outtrans_len(char_u *str, int len)
{
  return msg_outtrans_len_attr(str, len, 0);
}

/*
 * Output one character at "p".  Return pointer to the next character.
 * Handles multi-byte characters.
 */
char_u *msg_outtrans_one(char_u *p, int attr)
{
  int l;

  if (has_mbyte && (l = (*mb_ptr2len)(p)) > 1) {
    msg_outtrans_len_attr(p, l, attr);
    return p + l;
  }
  msg_puts_attr(transchar_byte(*p), attr);
  return p + 1;
}

int msg_outtrans_len_attr(char_u *msgstr, int len, int attr)
{
  int retval = 0;
  char_u      *str = msgstr;
  char_u      *plain_start = msgstr;
  char_u      *s;
  int mb_l;
  int c;

  /* if MSG_HIST flag set, add message to history */
  if (attr & MSG_HIST) {
    add_msg_hist(str, len, attr);
    attr &= ~MSG_HIST;
  }

  /* If the string starts with a composing character first draw a space on
   * which the composing char can be drawn. */
  if (enc_utf8 && utf_iscomposing(utf_ptr2char(msgstr)))
    msg_puts_attr((char_u *)" ", attr);

  /*
   * Go over the string.  Special characters are translated and printed.
   * Normal characters are printed several at a time.
   */
  while (--len >= 0) {
    if (enc_utf8)
      /* Don't include composing chars after the end. */
      mb_l = utfc_ptr2len_len(str, len + 1);
    else if (has_mbyte)
      mb_l = (*mb_ptr2len)(str);
    else
      mb_l = 1;
    if (has_mbyte && mb_l > 1) {
      c = (*mb_ptr2char)(str);
      if (vim_isprintc(c))
        /* printable multi-byte char: count the cells. */
        retval += (*mb_ptr2cells)(str);
      else {
        /* unprintable multi-byte char: print the printable chars so
         * far and the translation of the unprintable char. */
        if (str > plain_start)
          msg_puts_attr_len(plain_start, (int)(str - plain_start),
              attr);
        plain_start = str + mb_l;
        msg_puts_attr(transchar(c), attr == 0 ? hl_attr(HLF_8) : attr);
        retval += char2cells(c);
      }
      len -= mb_l - 1;
      str += mb_l;
    } else {
      s = transchar_byte(*str);
      if (s[1] != NUL) {
        /* unprintable char: print the printable chars so far and the
         * translation of the unprintable char. */
        if (str > plain_start)
          msg_puts_attr_len(plain_start, (int)(str - plain_start),
              attr);
        plain_start = str + 1;
        msg_puts_attr(s, attr == 0 ? hl_attr(HLF_8) : attr);
        retval += (int)STRLEN(s);
      } else
        ++retval;
      ++str;
    }
  }

  if (str > plain_start)
    /* print the printable chars at the end */
    msg_puts_attr_len(plain_start, (int)(str - plain_start), attr);

  return retval;
}

void msg_make(char_u *arg)
{
  int i;
  static char_u *str = (char_u *)"eeffoc", *rs = (char_u *)"Plon#dqg#vxjduB";

  arg = skipwhite(arg);
  for (i = 5; *arg && i >= 0; --i)
    if (*arg++ != str[i])
      break;
  if (i < 0) {
    msg_putchar('\n');
    for (i = 0; rs[i]; ++i)
      msg_putchar(rs[i] - 3);
  }
}

/*
 * Output the string 'str' upto a NUL character.
 * Return the number of characters it takes on the screen.
 *
 * If K_SPECIAL is encountered, then it is taken in conjunction with the
 * following character and shown as <F1>, <S-Up> etc.  Any other character
 * which is not printable shown in <> form.
 * If 'from' is TRUE (lhs of a mapping), a space is shown as <Space>.
 * If a character is displayed in one of these special ways, is also
 * highlighted (its highlight name is '8' in the p_hl variable).
 * Otherwise characters are not highlighted.
 * This function is used to show mappings, where we want to see how to type
 * the character/string -- webb
 */
int
msg_outtrans_special (
    char_u *strstart,
    int from               /* TRUE for lhs of a mapping */
)
{
  char_u      *str = strstart;
  int retval = 0;
  char_u      *string;
  int attr;
  int len;

  attr = hl_attr(HLF_8);
  while (*str != NUL) {
    /* Leading and trailing spaces need to be displayed in <> form. */
    if ((str == strstart || str[1] == NUL) && *str == ' ') {
      string = (char_u *)"<Space>";
      ++str;
    } else
      string = str2special(&str, from);
    len = vim_strsize(string);
    /* Highlight special keys */
    msg_puts_attr(string, len > 1
        && (*mb_ptr2len)(string) <= 1
        ? attr : 0);
    retval += len;
  }
  return retval;
}

/*
 * Return the lhs or rhs of a mapping, with the key codes turned into printable
 * strings, in an allocated string.
 */
char_u *
str2special_save (
    char_u *str,
    int is_lhs          /* TRUE for lhs, FALSE for rhs */
)
{
  garray_T ga;
  char_u      *p = str;

  ga_init(&ga, 1, 40);
  while (*p != NUL)
    ga_concat(&ga, str2special(&p, is_lhs));
  ga_append(&ga, NUL);
  return (char_u *)ga.ga_data;
}

/*
 * Return the printable string for the key codes at "*sp".
 * Used for translating the lhs or rhs of a mapping to printable chars.
 * Advances "sp" to the next code.
 */
char_u *
str2special (
    char_u **sp,
    int from               /* TRUE for lhs of mapping */
)
{
  int c;
  static char_u buf[7];
  char_u              *str = *sp;
  int modifiers = 0;
  int special = FALSE;

  if (has_mbyte) {
    char_u  *p;

    /* Try to un-escape a multi-byte character.  Return the un-escaped
     * string if it is a multi-byte character. */
    p = mb_unescape(sp);
    if (p != NULL)
      return p;
  }

  c = *str;
  if (c == K_SPECIAL && str[1] != NUL && str[2] != NUL) {
    if (str[1] == KS_MODIFIER) {
      modifiers = str[2];
      str += 3;
      c = *str;
    }
    if (c == K_SPECIAL && str[1] != NUL && str[2] != NUL) {
      c = TO_SPECIAL(str[1], str[2]);
      str += 2;
      if (c == KS_ZERO)         /* display <Nul> as ^@ or <Nul> */
        c = NUL;
    }
    if (IS_SPECIAL(c) || modifiers)     /* special key */
      special = TRUE;
  }

  if (has_mbyte && !IS_SPECIAL(c)) {
    int len = (*mb_ptr2len)(str);

    /* For multi-byte characters check for an illegal byte. */
    if (has_mbyte && MB_BYTE2LEN(*str) > len) {
      transchar_nonprint(buf, c);
      *sp = str + 1;
      return buf;
    }
    /* Since 'special' is TRUE the multi-byte character 'c' will be
     * processed by get_special_key_name() */
    c = (*mb_ptr2char)(str);
    *sp = str + len;
  } else
    *sp = str + 1;

  /* Make unprintable characters in <> form, also <M-Space> and <Tab>.
   * Use <Space> only for lhs of a mapping. */
  if (special || char2cells(c) > 1 || (from && c == ' '))
    return get_special_key_name(c, modifiers);
  buf[0] = c;
  buf[1] = NUL;
  return buf;
}

/*
 * Translate a key sequence into special key names.
 */
void str2specialbuf(char_u *sp, char_u *buf, int len)
{
  char_u      *s;

  *buf = NUL;
  while (*sp) {
    s = str2special(&sp, FALSE);
    if ((int)(STRLEN(s) + STRLEN(buf)) < len)
      STRCAT(buf, s);
  }
}

/*
 * print line for :print or :list command
 */
void msg_prt_line(char_u *s, int list)
{
  int c;
  int col = 0;
  int n_extra = 0;
  int c_extra = 0;
  char_u      *p_extra = NULL;              /* init to make SASC shut up */
  int n;
  int attr = 0;
  char_u      *trail = NULL;
  int l;
  char_u buf[MB_MAXBYTES + 1];

  if (curwin->w_p_list)
    list = TRUE;

  /* find start of trailing whitespace */
  if (list && lcs_trail) {
    trail = s + STRLEN(s);
    while (trail > s && ascii_iswhite(trail[-1]))
      --trail;
  }

  /* output a space for an empty line, otherwise the line will be
   * overwritten */
  if (*s == NUL && !(list && lcs_eol != NUL))
    msg_putchar(' ');

  while (!got_int) {
    if (n_extra > 0) {
      --n_extra;
      if (c_extra)
        c = c_extra;
      else
        c = *p_extra++;
    } else if (has_mbyte && (l = (*mb_ptr2len)(s)) > 1) {
      col += (*mb_ptr2cells)(s);
      if (lcs_nbsp != NUL && list && mb_ptr2char(s) == 160) {
        mb_char2bytes(lcs_nbsp, buf);
        buf[(*mb_ptr2len)(buf)] = NUL;
      } else {
        memmove(buf, s, (size_t)l);
        buf[l] = NUL;
      }
      msg_puts(buf);
      s += l;
      continue;
    } else {
      attr = 0;
      c = *s++;
      if (c == TAB && (!list || lcs_tab1)) {
        /* tab amount depends on current column */
        n_extra = curbuf->b_p_ts - col % curbuf->b_p_ts - 1;
        if (!list) {
          c = ' ';
          c_extra = ' ';
        } else {
          c = lcs_tab1;
          c_extra = lcs_tab2;
          attr = hl_attr(HLF_8);
        }
      } else if (c == 160 && list && lcs_nbsp != NUL) {
        c = lcs_nbsp;
        attr = hl_attr(HLF_8);
      } else if (c == NUL && list && lcs_eol != NUL) {
        p_extra = (char_u *)"";
        c_extra = NUL;
        n_extra = 1;
        c = lcs_eol;
        attr = hl_attr(HLF_AT);
        --s;
      } else if (c != NUL && (n = byte2cells(c)) > 1) {
        n_extra = n - 1;
        p_extra = transchar_byte(c);
        c_extra = NUL;
        c = *p_extra++;
        /* Use special coloring to be able to distinguish <hex> from
         * the same in plain text. */
        attr = hl_attr(HLF_8);
      } else if (c == ' ' && trail != NULL && s > trail) {
        c = lcs_trail;
        attr = hl_attr(HLF_8);
      } else if (c == ' ' && list && lcs_space != NUL) {
        c = lcs_space;
        attr = hl_attr(HLF_8);
      }
    }

    if (c == NUL)
      break;

    msg_putchar_attr(c, attr);
    col++;
  }
  msg_clr_eos();
}

/*
 * Use screen_puts() to output one multi-byte character.
 * Return the pointer "s" advanced to the next character.
 */
static char_u *screen_puts_mbyte(char_u *s, int l, int attr)
{
  int cw;

  msg_didout = TRUE;            /* remember that line is not empty */
  cw = (*mb_ptr2cells)(s);
  if (cw > 1 && (
        cmdmsg_rl ? msg_col <= 1 :
        msg_col == Columns - 1)) {
    /* Doesn't fit, print a highlighted '>' to fill it up. */
    msg_screen_putchar('>', hl_attr(HLF_AT));
    return s;
  }

  screen_puts_len(s, l, msg_row, msg_col, attr);
  if (cmdmsg_rl) {
    msg_col -= cw;
    if (msg_col == 0) {
      msg_col = Columns;
      ++msg_row;
    }
  } else {
    msg_col += cw;
    if (msg_col >= Columns) {
      msg_col = 0;
      ++msg_row;
    }
  }
  return s + l;
}

/*
 * Output a string to the screen at position msg_row, msg_col.
 * Update msg_row and msg_col for the next message.
 */
void msg_puts(char_u *s)
{
  msg_puts_attr(s, 0);
}

void msg_puts_title(char_u *s)
{
  msg_puts_attr(s, hl_attr(HLF_T));
}

/*
 * Show a message in such a way that it always fits in the line.  Cut out a
 * part in the middle and replace it with "..." when necessary.
 * Does not handle multi-byte characters!
 */
void msg_puts_long_attr(char_u *longstr, int attr)
{
  msg_puts_long_len_attr(longstr, (int)STRLEN(longstr), attr);
}

void msg_puts_long_len_attr(char_u *longstr, int len, int attr)
{
  int slen = len;
  int room;

  room = Columns - msg_col;
  if (len > room && room >= 20) {
    slen = (room - 3) / 2;
    msg_outtrans_len_attr(longstr, slen, attr);
    msg_puts_attr((char_u *)"...", hl_attr(HLF_8));
  }
  msg_outtrans_len_attr(longstr + len - slen, slen, attr);
}

/*
 * Basic function for writing a message with highlight attributes.
 */
void msg_puts_attr(char_u *s, int attr)
{
  msg_puts_attr_len(s, -1, attr);
}

/*
 * Like msg_puts_attr(), but with a maximum length "maxlen" (in bytes).
 * When "maxlen" is -1 there is no maximum length.
 * When "maxlen" is >= 0 the message is not put in the history.
 */
static void msg_puts_attr_len(char_u *str, int maxlen, int attr)
{
  /*
   * If redirection is on, also write to the redirection file.
   */
  redir_write(str, maxlen);

  /*
   * Don't print anything when using ":silent cmd".
   */
  if (msg_silent != 0)
    return;

  /* if MSG_HIST flag set, add message to history */
  if ((attr & MSG_HIST) && maxlen < 0) {
    add_msg_hist(str, -1, attr);
    attr &= ~MSG_HIST;
  }

  /*
   * When writing something to the screen after it has scrolled, requires a
   * wait-return prompt later.  Needed when scrolling, resetting
   * need_wait_return after some prompt, and then outputting something
   * without scrolling
   */
  if (msg_scrolled != 0 && !msg_scrolled_ign)
    need_wait_return = TRUE;
  msg_didany = TRUE;            /* remember that something was outputted */

  /*
   * If there is no valid screen, use fprintf so we can see error messages.
   * If termcap is not active, we may be writing in an alternate console
   * window, cursor positioning may not work correctly (window size may be
   * different, e.g. for Win32 console) or we just don't know where the
   * cursor is.
   */
  if (msg_use_printf())
    msg_puts_printf(str, maxlen);
  else
    msg_puts_display(str, maxlen, attr, FALSE);
}

/*
 * The display part of msg_puts_attr_len().
 * May be called recursively to display scroll-back text.
 */
static void msg_puts_display(char_u *str, int maxlen, int attr, int recurse)
{
  char_u      *s = str;
  char_u      *t_s = str;       /* string from "t_s" to "s" is still todo */
  int t_col = 0;                /* screen cells todo, 0 when "t_s" not used */
  int l;
  int cw;
  char_u      *sb_str = str;
  int sb_col = msg_col;
  int wrap;
  int did_last_char;

  did_wait_return = FALSE;
  while ((maxlen < 0 || (int)(s - str) < maxlen) && *s != NUL) {
    /*
     * We are at the end of the screen line when:
     * - When outputting a newline.
     * - When outputting a character in the last column.
     */
    if (!recurse && msg_row >= Rows - 1 && (*s == '\n' || (
                                              cmdmsg_rl
                                              ? (
                                                msg_col <= 1
                                                || (*s == TAB && msg_col <= 7)
                                                || (has_mbyte &&
                                                    (*mb_ptr2cells)(s) > 1 &&
                                                    msg_col <= 2)
                                                )
                                              :
                                              (msg_col + t_col >= Columns - 1
                                               || (*s == TAB && msg_col +
                                                   t_col >= ((Columns - 1) & ~7))
                                               || (has_mbyte &&
                                                   (*mb_ptr2cells)(s) > 1
                                                   && msg_col + t_col >=
                                                   Columns - 2)
                                              )))) {
      /*
       * The screen is scrolled up when at the last row (some terminals
       * scroll automatically, some don't.  To avoid problems we scroll
       * ourselves).
       */
      if (t_col > 0)
        /* output postponed text */
        t_puts(&t_col, t_s, s, attr);

      /* When no more prompt and no more room, truncate here */
      if (msg_no_more && lines_left == 0)
        break;

      /* Scroll the screen up one line. */
      msg_scroll_up();

      msg_row = Rows - 2;
      if (msg_col >= Columns)           /* can happen after screen resize */
        msg_col = Columns - 1;

      /* Display char in last column before showing more-prompt. */
      if (*s >= ' '
          && !cmdmsg_rl
          ) {
        if (has_mbyte) {
          if (enc_utf8 && maxlen >= 0)
            /* avoid including composing chars after the end */
            l = utfc_ptr2len_len(s, (int)((str + maxlen) - s));
          else
            l = (*mb_ptr2len)(s);
          s = screen_puts_mbyte(s, l, attr);
        } else
          msg_screen_putchar(*s++, attr);
        did_last_char = TRUE;
      } else
        did_last_char = FALSE;

      if (p_more)
        /* store text for scrolling back */
        store_sb_text(&sb_str, s, attr, &sb_col, TRUE);

      inc_msg_scrolled();
      need_wait_return = TRUE;       /* may need wait_return in main() */
      if (must_redraw < VALID)
        must_redraw = VALID;
      redraw_cmdline = TRUE;
      if (cmdline_row > 0 && !exmode_active)
        --cmdline_row;

      /*
       * If screen is completely filled and 'more' is set then wait
       * for a character.
       */
      if (lines_left > 0)
        --lines_left;
      if (p_more && lines_left == 0 && State != HITRETURN
          && !msg_no_more && !exmode_active) {
        if (do_more_prompt(NUL))
          s = confirm_msg_tail;
        if (quit_more)
          return;
      }

      /* When we displayed a char in last column need to check if there
       * is still more. */
      if (did_last_char)
        continue;
    }

    wrap = *s == '\n'
           || msg_col + t_col >= Columns
           || (has_mbyte && (*mb_ptr2cells)(s) > 1
               && msg_col + t_col >= Columns - 1)
    ;
    if (t_col > 0 && (wrap || *s == '\r' || *s == '\b'
                      || *s == '\t' || *s == BELL))
      /* output any postponed text */
      t_puts(&t_col, t_s, s, attr);

    if (wrap && p_more && !recurse)
      /* store text for scrolling back */
      store_sb_text(&sb_str, s, attr, &sb_col, TRUE);

    if (*s == '\n') {               /* go to next line */
      msg_didout = FALSE;           /* remember that line is empty */
      if (cmdmsg_rl)
        msg_col = Columns - 1;
      else
        msg_col = 0;
      if (++msg_row >= Rows)        /* safety check */
        msg_row = Rows - 1;
    } else if (*s == '\r') {      /* go to column 0 */
      msg_col = 0;
    } else if (*s == '\b') {      /* go to previous char */
      if (msg_col)
        --msg_col;
    } else if (*s == TAB) {       /* translate Tab into spaces */
      do
        msg_screen_putchar(' ', attr);
      while (msg_col & 7);
    } else if (*s == BELL)          /* beep (from ":sh") */
      vim_beep();
    else {
      if (has_mbyte) {
        cw = (*mb_ptr2cells)(s);
        if (enc_utf8 && maxlen >= 0)
          /* avoid including composing chars after the end */
          l = utfc_ptr2len_len(s, (int)((str + maxlen) - s));
        else
          l = (*mb_ptr2len)(s);
      } else {
        cw = 1;
        l = 1;
      }
      /* When drawing from right to left or when a double-wide character
       * doesn't fit, draw a single character here.  Otherwise collect
       * characters and draw them all at once later. */
      if (
        cmdmsg_rl
        ||
        (cw > 1 && msg_col + t_col >= Columns - 1)
        ) {
        if (l > 1)
          s = screen_puts_mbyte(s, l, attr) - 1;
        else
          msg_screen_putchar(*s, attr);
      } else {
        /* postpone this character until later */
        if (t_col == 0)
          t_s = s;
        t_col += cw;
        s += l - 1;
      }
    }
    ++s;
  }

  /* output any postponed text */
  if (t_col > 0)
    t_puts(&t_col, t_s, s, attr);
  if (p_more && !recurse)
    store_sb_text(&sb_str, s, attr, &sb_col, FALSE);

  msg_check();
}

/*
 * Scroll the screen up one line for displaying the next message line.
 */
static void msg_scroll_up(void)
{
  /* scrolling up always works */
  screen_del_lines(0, 0, 1, (int)Rows, NULL);
}

/*
 * Increment "msg_scrolled".
 */
static void inc_msg_scrolled(void)
{
  if (*get_vim_var_str(VV_SCROLLSTART) == NUL) {
    char_u      *p = sourcing_name;
    char_u      *tofree = NULL;
    int len;

    /* v:scrollstart is empty, set it to the script/function name and line
     * number */
    if (p == NULL)
      p = (char_u *)_("Unknown");
    else {
      len = (int)STRLEN(p) + 40;
      tofree = xmalloc(len);
      vim_snprintf((char *)tofree, len, _("%s line %" PRId64),
          p, (int64_t)sourcing_lnum);
      p = tofree;
    }
    set_vim_var_string(VV_SCROLLSTART, p, -1);
    xfree(tofree);
  }
  ++msg_scrolled;
}

static msgchunk_T *last_msgchunk = NULL; /* last displayed text */


static int do_clear_sb_text = FALSE;    /* clear text on next msg */

/*
 * Store part of a printed message for displaying when scrolling back.
 */
static void
store_sb_text (
    char_u **sb_str,           /* start of string */
    char_u *s,                 /* just after string */
    int attr,
    int *sb_col,
    int finish                     /* line ends */
)
{
  msgchunk_T  *mp;

  if (do_clear_sb_text) {
    clear_sb_text();
    do_clear_sb_text = FALSE;
  }

  if (s > *sb_str) {
    mp = xmalloc((sizeof(msgchunk_T) + (s - *sb_str)));
    mp->sb_eol = finish;
    mp->sb_msg_col = *sb_col;
    mp->sb_attr = attr;
    memcpy(mp->sb_text, *sb_str, s - *sb_str);
    mp->sb_text[s - *sb_str] = NUL;

    if (last_msgchunk == NULL) {
      last_msgchunk = mp;
      mp->sb_prev = NULL;
    } else {
      mp->sb_prev = last_msgchunk;
      last_msgchunk->sb_next = mp;
      last_msgchunk = mp;
    }
    mp->sb_next = NULL;
  } else if (finish && last_msgchunk != NULL)
    last_msgchunk->sb_eol = TRUE;

  *sb_str = s;
  *sb_col = 0;
}

/*
 * Finished showing messages, clear the scroll-back text on the next message.
 */
void may_clear_sb_text(void)
{
  do_clear_sb_text = TRUE;
}

/*
 * Clear any text remembered for scrolling back.
 * Called when redrawing the screen.
 */
void clear_sb_text(void)
{
  msgchunk_T  *mp;

  while (last_msgchunk != NULL) {
    mp = last_msgchunk->sb_prev;
    xfree(last_msgchunk);
    last_msgchunk = mp;
  }
}

/*
 * "g<" command.
 */
void show_sb_text(void)
{
  msgchunk_T  *mp;

  /* Only show something if there is more than one line, otherwise it looks
   * weird, typing a command without output results in one line. */
  mp = msg_sb_start(last_msgchunk);
  if (mp == NULL || mp->sb_prev == NULL)
    vim_beep();
  else {
    do_more_prompt('G');
    wait_return(FALSE);
  }
}

/*
 * Move to the start of screen line in already displayed text.
 */
static msgchunk_T *msg_sb_start(msgchunk_T *mps)
{
  msgchunk_T *mp = mps;

  while (mp != NULL && mp->sb_prev != NULL && !mp->sb_prev->sb_eol)
    mp = mp->sb_prev;
  return mp;
}

/*
 * Mark the last message chunk as finishing the line.
 */
void msg_sb_eol(void)
{
  if (last_msgchunk != NULL)
    last_msgchunk->sb_eol = TRUE;
}

/*
 * Display a screen line from previously displayed text at row "row".
 * Returns a pointer to the text for the next line (can be NULL).
 */
static msgchunk_T *disp_sb_line(int row, msgchunk_T *smp)
{
  msgchunk_T  *mp = smp;
  char_u      *p;

  for (;; ) {
    msg_row = row;
    msg_col = mp->sb_msg_col;
    p = mp->sb_text;
    if (*p == '\n')         /* don't display the line break */
      ++p;
    msg_puts_display(p, -1, mp->sb_attr, TRUE);
    if (mp->sb_eol || mp->sb_next == NULL)
      break;
    mp = mp->sb_next;
  }
  return mp->sb_next;
}

/*
 * Output any postponed text for msg_puts_attr_len().
 */
static void t_puts(int *t_col, char_u *t_s, char_u *s, int attr)
{
  /* output postponed text */
  msg_didout = TRUE;            /* remember that line is not empty */
  screen_puts_len(t_s, (int)(s - t_s), msg_row, msg_col, attr);
  msg_col += *t_col;
  *t_col = 0;
  /* If the string starts with a composing character don't increment the
   * column position for it. */
  if (enc_utf8 && utf_iscomposing(utf_ptr2char(t_s)))
    --msg_col;
  if (msg_col >= Columns) {
    msg_col = 0;
    ++msg_row;
  }
}

// Returns TRUE when messages should be printed to stdout/stderr, which
// happens when no UIs are attached and nvim is not being embedded
int msg_use_printf(void)
{
  return !embedded_mode && !ui_active();
}

/*
 * Print a message when there is no valid screen.
 */
static void msg_puts_printf(char_u *str, int maxlen)
{
  char_u      *s = str;
  char_u buf[4];
  char_u      *p;

  while (*s != NUL && (maxlen < 0 || (int)(s - str) < maxlen)) {
    if (!(silent_mode && p_verbose == 0)) {
      /* NL --> CR NL translation (for Unix, not for "--version") */
      /* NL --> CR translation (for Mac) */
      p = &buf[0];
      if (*s == '\n' && !info_message)
        *p++ = '\r';
      *p++ = *s;
      *p = '\0';
      if (info_message)         /* informative message, not an error */
        mch_msg((char *)buf);
      else
        mch_errmsg((char *)buf);
    }

    /* primitive way to compute the current column */
    if (cmdmsg_rl) {
      if (*s == '\r' || *s == '\n')
        msg_col = Columns - 1;
      else
        --msg_col;
    } else {
      if (*s == '\r' || *s == '\n')
        msg_col = 0;
      else
        ++msg_col;
    }
    ++s;
  }
  msg_didout = TRUE;        /* assume that line is not empty */

}

/*
 * Show the more-prompt and handle the user response.
 * This takes care of scrolling back and displaying previously displayed text.
 * When at hit-enter prompt "typed_char" is the already typed character,
 * otherwise it's NUL.
 * Returns TRUE when jumping ahead to "confirm_msg_tail".
 */
static int do_more_prompt(int typed_char)
{
  int used_typed_char = typed_char;
  int oldState = State;
  int c;
  int retval = FALSE;
  int toscroll;
  msgchunk_T  *mp_last = NULL;
  msgchunk_T  *mp;
  int i;

  if (typed_char == 'G') {
    /* "g<": Find first line on the last page. */
    mp_last = msg_sb_start(last_msgchunk);
    for (i = 0; i < Rows - 2 && mp_last != NULL
         && mp_last->sb_prev != NULL; ++i)
      mp_last = msg_sb_start(mp_last->sb_prev);
  }

  State = ASKMORE;
  setmouse();
  if (typed_char == NUL)
    msg_moremsg(FALSE);
  for (;; ) {
    /*
     * Get a typed character directly from the user.
     */
    if (used_typed_char != NUL) {
      c = used_typed_char;              /* was typed at hit-enter prompt */
      used_typed_char = NUL;
    } else
      c = get_keystroke();


    toscroll = 0;
    switch (c) {
    case BS:                    /* scroll one line back */
    case K_BS:
    case 'k':
    case K_UP:
      toscroll = -1;
      break;

    case CAR:                   /* one extra line */
    case NL:
    case 'j':
    case K_DOWN:
      toscroll = 1;
      break;

    case 'u':                   /* Up half a page */
      toscroll = -(Rows / 2);
      break;

    case 'd':                   /* Down half a page */
      toscroll = Rows / 2;
      break;

    case 'b':                   /* one page back */
    case K_PAGEUP:
      toscroll = -(Rows - 1);
      break;

    case ' ':                   /* one extra page */
    case 'f':
    case K_PAGEDOWN:
    case K_LEFTMOUSE:
      toscroll = Rows - 1;
      break;

    case 'g':                   /* all the way back to the start */
      toscroll = -999999;
      break;

    case 'G':                   /* all the way to the end */
      toscroll = 999999;
      lines_left = 999999;
      break;

    case ':':                   /* start new command line */
      if (!confirm_msg_used) {
        /* Since got_int is set all typeahead will be flushed, but we
         * want to keep this ':', remember that in a special way. */
        typeahead_noflush(':');
        cmdline_row = Rows - 1;                 /* put ':' on this line */
        skip_redraw = TRUE;                     /* skip redraw once */
        need_wait_return = FALSE;               /* don't wait in main() */
      }
    /*FALLTHROUGH*/
    case 'q':                   /* quit */
    case Ctrl_C:
    case ESC:
      if (confirm_msg_used) {
        /* Jump to the choices of the dialog. */
        retval = TRUE;
      } else {
        got_int = TRUE;
        quit_more = TRUE;
      }
      /* When there is some more output (wrapping line) display that
       * without another prompt. */
      lines_left = Rows - 1;
      break;

    default:                    /* no valid response */
      msg_moremsg(TRUE);
      continue;
    }

    if (toscroll != 0) {
      if (toscroll < 0) {
        /* go to start of last line */
        if (mp_last == NULL)
          mp = msg_sb_start(last_msgchunk);
        else if (mp_last->sb_prev != NULL)
          mp = msg_sb_start(mp_last->sb_prev);
        else
          mp = NULL;

        /* go to start of line at top of the screen */
        for (i = 0; i < Rows - 2 && mp != NULL && mp->sb_prev != NULL;
             ++i)
          mp = msg_sb_start(mp->sb_prev);

        if (mp != NULL && mp->sb_prev != NULL) {
          /* Find line to be displayed at top. */
          for (i = 0; i > toscroll; --i) {
            if (mp == NULL || mp->sb_prev == NULL)
              break;
            mp = msg_sb_start(mp->sb_prev);
            if (mp_last == NULL)
              mp_last = msg_sb_start(last_msgchunk);
            else
              mp_last = msg_sb_start(mp_last->sb_prev);
          }

          if (toscroll == -1 && screen_ins_lines(0, 0, 1,
                  (int)Rows, NULL) == OK) {
            /* display line at top */
            (void)disp_sb_line(0, mp);
          } else {
            /* redisplay all lines */
            screenclear();
            for (i = 0; mp != NULL && i < Rows - 1; ++i) {
              mp = disp_sb_line(i, mp);
              ++msg_scrolled;
            }
          }
          toscroll = 0;
        }
      } else {
        /* First display any text that we scrolled back. */
        while (toscroll > 0 && mp_last != NULL) {
          /* scroll up, display line at bottom */
          msg_scroll_up();
          inc_msg_scrolled();
          screen_fill((int)Rows - 2, (int)Rows - 1, 0,
              (int)Columns, ' ', ' ', 0);
          mp_last = disp_sb_line((int)Rows - 2, mp_last);
          --toscroll;
        }
      }

      if (toscroll <= 0) {
        /* displayed the requested text, more prompt again */
        screen_fill((int)Rows - 1, (int)Rows, 0,
            (int)Columns, ' ', ' ', 0);
        msg_moremsg(FALSE);
        continue;
      }

      /* display more text, return to caller */
      lines_left = toscroll;
    }

    break;
  }

  /* clear the --more-- message */
  screen_fill((int)Rows - 1, (int)Rows, 0, (int)Columns, ' ', ' ', 0);
  State = oldState;
  setmouse();
  if (quit_more) {
    msg_row = Rows - 1;
    msg_col = 0;
  } else if (cmdmsg_rl)
    msg_col = Columns - 1;

  return retval;
}

#if defined(USE_MCH_ERRMSG)

#ifdef mch_errmsg
# undef mch_errmsg
#endif
#ifdef mch_msg
# undef mch_msg
#endif

/*
 * Give an error message.  To be used when the screen hasn't been initialized
 * yet.  When stderr can't be used, collect error messages until the GUI has
 * started and they can be displayed in a message box.
 */
void mch_errmsg(char *str)
{
  int len;

#if (defined(UNIX) || defined(FEAT_GUI)) && !defined(ALWAYS_USE_GUI)
  /* On Unix use stderr if it's a tty.
   * When not going to start the GUI also use stderr.
   * On Mac, when started from Finder, stderr is the console. */
  if (
# ifdef UNIX
    isatty(2)
# endif
    ) {
    fprintf(stderr, "%s", str);
    return;
  }
#endif

  /* avoid a delay for a message that isn't there */
  emsg_on_display = FALSE;

  len = (int)STRLEN(str) + 1;
  if (error_ga.ga_data == NULL) {
    ga_set_growsize(&error_ga, 80);
    error_ga.ga_itemsize = 1;
  }
  ga_grow(&error_ga, len);
  memmove((char_u *)error_ga.ga_data + error_ga.ga_len,
      (char_u *)str, len);
#ifdef UNIX
  /* remove CR characters, they are displayed */
  {
    char_u      *p;

    p = (char_u *)error_ga.ga_data + error_ga.ga_len;
    for (;; ) {
      p = vim_strchr(p, '\r');
      if (p == NULL)
        break;
      *p = ' ';
    }
  }
#endif
  --len;              /* don't count the NUL at the end */
  error_ga.ga_len += len;
}

/*
 * Give a message.  To be used when the screen hasn't been initialized yet.
 * When there is no tty, collect messages until the GUI has started and they
 * can be displayed in a message box.
 */
void mch_msg(char *str)
{
#if (defined(UNIX) || defined(FEAT_GUI)) && !defined(ALWAYS_USE_GUI)
  /* On Unix use stdout if we have a tty.  This allows "vim -h | more" and
   * uses mch_errmsg() when started from the desktop.
   * When not going to start the GUI also use stdout.
   * On Mac, when started from Finder, stderr is the console. */
  if (
#  ifdef UNIX
    isatty(2)
#  endif
    ) {
    printf("%s", str);
    return;
  }
# endif
  mch_errmsg(str);
}
#endif /* USE_MCH_ERRMSG */

/*
 * Put a character on the screen at the current message position and advance
 * to the next position.  Only for printable ASCII!
 */
static void msg_screen_putchar(int c, int attr)
{
  msg_didout = TRUE;            /* remember that line is not empty */
  screen_putchar(c, msg_row, msg_col, attr);
  if (cmdmsg_rl) {
    if (--msg_col == 0) {
      msg_col = Columns;
      ++msg_row;
    }
  } else {
    if (++msg_col >= Columns) {
      msg_col = 0;
      ++msg_row;
    }
  }
}

void msg_moremsg(int full)
{
  int attr;
  char_u      *s = (char_u *)_("-- More --");

  attr = hl_attr(HLF_M);
  screen_puts(s, (int)Rows - 1, 0, attr);
  if (full)
    screen_puts((char_u *)
        _(" SPACE/d/j: screen/page/line down, b/u/k: up, q: quit "),
        (int)Rows - 1, vim_strsize(s), attr);
}

/*
 * Repeat the message for the current mode: ASKMORE, EXTERNCMD, CONFIRM or
 * exmode_active.
 */
void repeat_message(void)
{
  if (State == ASKMORE) {
    msg_moremsg(TRUE);          /* display --more-- message again */
    msg_row = Rows - 1;
  } else if (State == CONFIRM) {
    display_confirm_msg();      /* display ":confirm" message again */
    msg_row = Rows - 1;
  } else if (State == EXTERNCMD) {
    ui_cursor_goto(msg_row, msg_col);     /* put cursor back */
  } else if (State == HITRETURN || State == SETWSIZE) {
    if (msg_row == Rows - 1) {
      /* Avoid drawing the "hit-enter" prompt below the previous one,
       * overwrite it.  Esp. useful when regaining focus and a
       * FocusGained autocmd exists but didn't draw anything. */
      msg_didout = FALSE;
      msg_col = 0;
      msg_clr_eos();
    }
    hit_return_msg();
    msg_row = Rows - 1;
  }
}

/*
 * Clear from current message position to end of screen.
 * Skip this when ":silent" was used, no need to clear for redirection.
 */
void msg_clr_eos(void)
{
  if (msg_silent == 0)
    msg_clr_eos_force();
}

/*
 * Clear from current message position to end of screen.
 * Note: msg_col is not updated, so we remember the end of the message
 * for msg_check().
 */
void msg_clr_eos_force(void)
{
  if (cmdmsg_rl) {
    screen_fill(msg_row, msg_row + 1, 0, msg_col + 1, ' ', ' ', 0);
    screen_fill(msg_row + 1, (int)Rows, 0, (int)Columns, ' ', ' ', 0);
  } else {
    screen_fill(msg_row, msg_row + 1, msg_col, (int)Columns, ' ', ' ', 0);
    screen_fill(msg_row + 1, (int)Rows, 0, (int)Columns, ' ', ' ', 0);
  }
}

/*
 * Clear the command line.
 */
void msg_clr_cmdline(void)
{
  msg_row = cmdline_row;
  msg_col = 0;
  msg_clr_eos_force();
}

/*
 * end putting a message on the screen
 * call wait_return if the message does not fit in the available space
 * return TRUE if wait_return not called.
 */
int msg_end(void)
{
  /*
   * If the string is larger than the window,
   * or the ruler option is set and we run into it,
   * we have to redraw the window.
   * Do not do this if we are abandoning the file or editing the command line.
   */
  if (!exiting && need_wait_return && !(State & CMDLINE)) {
    wait_return(FALSE);
    return FALSE;
  }
  ui_flush();
  return TRUE;
}

/*
 * If the written message runs into the shown command or ruler, we have to
 * wait for hit-return and redraw the window later.
 */
void msg_check(void)
{
  if (msg_row == Rows - 1 && msg_col >= sc_col) {
    need_wait_return = TRUE;
    redraw_cmdline = TRUE;
  }
}

/*
 * May write a string to the redirection file.
 * When "maxlen" is -1 write the whole string, otherwise up to "maxlen" bytes.
 */
static void redir_write(char_u *str, int maxlen)
{
  char_u      *s = str;
  static int cur_col = 0;

  /* Don't do anything for displaying prompts and the like. */
  if (redir_off)
    return;

  /* If 'verbosefile' is set prepare for writing in that file. */
  if (*p_vfile != NUL && verbose_fd == NULL)
    verbose_open();

  if (redirecting()) {
    /* If the string doesn't start with CR or NL, go to msg_col */
    if (*s != '\n' && *s != '\r') {
      while (cur_col < msg_col) {
        if (redir_reg)
          write_reg_contents(redir_reg, (char_u *)" ", -1, TRUE);
        else if (redir_vname)
          var_redir_str((char_u *)" ", -1);
        else if (redir_fd != NULL)
          fputs(" ", redir_fd);
        if (verbose_fd != NULL)
          fputs(" ", verbose_fd);
        ++cur_col;
      }
    }

    if (redir_reg)
      write_reg_contents(redir_reg, s, maxlen, TRUE);
    if (redir_vname)
      var_redir_str(s, maxlen);

    /* Write and adjust the current column. */
    while (*s != NUL && (maxlen < 0 || (int)(s - str) < maxlen)) {
      if (!redir_reg && !redir_vname)
        if (redir_fd != NULL)
          putc(*s, redir_fd);
      if (verbose_fd != NULL)
        putc(*s, verbose_fd);
      if (*s == '\r' || *s == '\n')
        cur_col = 0;
      else if (*s == '\t')
        cur_col += (8 - cur_col % 8);
      else
        ++cur_col;
      ++s;
    }

    if (msg_silent != 0)        /* should update msg_col */
      msg_col = cur_col;
  }
}

int redirecting(void)
{
  return redir_fd != NULL || *p_vfile != NUL
         || redir_reg || redir_vname
  ;
}

/*
 * Before giving verbose message.
 * Must always be called paired with verbose_leave()!
 */
void verbose_enter(void)
{
  if (*p_vfile != NUL)
    ++msg_silent;
}

/*
 * After giving verbose message.
 * Must always be called paired with verbose_enter()!
 */
void verbose_leave(void)
{
  if (*p_vfile != NUL)
    if (--msg_silent < 0)
      msg_silent = 0;
}

/*
 * Like verbose_enter() and set msg_scroll when displaying the message.
 */
void verbose_enter_scroll(void)
{
  if (*p_vfile != NUL)
    ++msg_silent;
  else
    /* always scroll up, don't overwrite */
    msg_scroll = TRUE;
}

/*
 * Like verbose_leave() and set cmdline_row when displaying the message.
 */
void verbose_leave_scroll(void)
{
  if (*p_vfile != NUL) {
    if (--msg_silent < 0)
      msg_silent = 0;
  } else
    cmdline_row = msg_row;
}

/*
 * Called when 'verbosefile' is set: stop writing to the file.
 */
void verbose_stop(void)
{
  if (verbose_fd != NULL) {
    fclose(verbose_fd);
    verbose_fd = NULL;
  }
  verbose_did_open = FALSE;
}

/*
 * Open the file 'verbosefile'.
 * Return FAIL or OK.
 */
int verbose_open(void)
{
  if (verbose_fd == NULL && !verbose_did_open) {
    /* Only give the error message once. */
    verbose_did_open = TRUE;

    verbose_fd = mch_fopen((char *)p_vfile, "a");
    if (verbose_fd == NULL) {
      EMSG2(_(e_notopen), p_vfile);
      return FAIL;
    }
  }
  return OK;
}

/*
 * Give a warning message (for searching).
 * Use 'w' highlighting and may repeat the message after redrawing
 */
void give_warning(char_u *message, bool hl) FUNC_ATTR_NONNULL_ARG(1)
{
  /* Don't do this for ":silent". */
  if (msg_silent != 0)
    return;

  /* Don't want a hit-enter prompt here. */
  ++no_wait_return;

  set_vim_var_string(VV_WARNINGMSG, message, -1);
  xfree(keep_msg);
  keep_msg = NULL;
  if (hl)
    keep_msg_attr = hl_attr(HLF_W);
  else
    keep_msg_attr = 0;
  if (msg_attr(message, keep_msg_attr) && msg_scrolled == 0)
    set_keep_msg(message, keep_msg_attr);
  msg_didout = FALSE;       /* overwrite this message */
  msg_nowait = TRUE;        /* don't wait for this message */
  msg_col = 0;

  --no_wait_return;
}

/*
 * Advance msg cursor to column "col".
 */
void msg_advance(int col)
{
  if (msg_silent != 0) {        /* nothing to advance to */
    msg_col = col;              /* for redirection, may fill it up later */
    return;
  }
  if (col >= Columns)           /* not enough room */
    col = Columns - 1;
  if (cmdmsg_rl)
    while (msg_col > Columns - col)
      msg_putchar(' ');
  else
    while (msg_col < col)
      msg_putchar(' ');
}

/*
 * Used for "confirm()" function, and the :confirm command prefix.
 * Versions which haven't got flexible dialogs yet, and console
 * versions, get this generic handler which uses the command line.
 *
 * type  = one of:
 *	   VIM_QUESTION, VIM_INFO, VIM_WARNING, VIM_ERROR or VIM_GENERIC
 * title = title string (can be NULL for default)
 * (neither used in console dialogs at the moment)
 *
 * Format of the "buttons" string:
 * "Button1Name\nButton2Name\nButton3Name"
 * The first button should normally be the default/accept
 * The second button should be the 'Cancel' button
 * Other buttons- use your imagination!
 * A '&' in a button name becomes a shortcut, so each '&' should be before a
 * different letter.
 */
int
do_dialog (
    int type,
    char_u *title,
    char_u *message,
    char_u *buttons,
    int dfltbutton,
    char_u *textfield,          /* IObuff for inputdialog(), NULL
                                           otherwise */
    int ex_cmd                 /* when TRUE pressing : accepts default and starts
                               Ex command */
)
{
  int oldState;
  int retval = 0;
  char_u      *hotkeys;
  int c;
  int i;

  /* Don't output anything in silent mode ("ex -s") */
  if (silent_mode)
    return dfltbutton;       /* return default option */


  oldState = State;
  State = CONFIRM;
  setmouse();

  /*
   * Since we wait for a keypress, don't make the
   * user press RETURN as well afterwards.
   */
  ++no_wait_return;
  hotkeys = msg_show_console_dialog(message, buttons, dfltbutton);

  for (;; ) {
    /* Get a typed character directly from the user. */
    c = get_keystroke();
    switch (c) {
    case CAR:                 /* User accepts default option */
    case NL:
      retval = dfltbutton;
      break;
    case Ctrl_C:              /* User aborts/cancels */
    case ESC:
      retval = 0;
      break;
    default:                  /* Could be a hotkey? */
      if (c < 0) {            /* special keys are ignored here */
        continue;
      }
      if (c == ':' && ex_cmd) {
        retval = dfltbutton;
        ins_char_typebuf(':');
        break;
      }

      /* Make the character lowercase, as chars in "hotkeys" are. */
      c = vim_tolower(c);
      retval = 1;
      for (i = 0; hotkeys[i]; ++i) {
        if (has_mbyte) {
          if ((*mb_ptr2char)(hotkeys + i) == c)
            break;
          i += (*mb_ptr2len)(hotkeys + i) - 1;
        } else if (hotkeys[i] == c)
          break;
        ++retval;
      }
      if (hotkeys[i])
        break;
      /* No hotkey match, so keep waiting */
      continue;
    }
    break;
  }

  xfree(hotkeys);

  State = oldState;
  setmouse();
  --no_wait_return;
  msg_end_prompt();

  return retval;
}


/*
 * Copy one character from "*from" to "*to", taking care of multi-byte
 * characters.  Return the length of the character in bytes.
 */
static int
copy_char (
    char_u *from,
    char_u *to,
    int lowercase                  /* make character lower case */
)
{
  int len;
  int c;

  if (has_mbyte) {
    if (lowercase) {
      c = vim_tolower((*mb_ptr2char)(from));
      return (*mb_char2bytes)(c, to);
    } else {
      len = (*mb_ptr2len)(from);
      memmove(to, from, (size_t)len);
      return len;
    }
  } else {
    if (lowercase)
      *to = (char_u)TOLOWER_LOC(*from);
    else
      *to = *from;
    return 1;
  }
}

#define HAS_HOTKEY_LEN 30
#define HOTK_LEN (has_mbyte ? MB_MAXBYTES : 1)

/// Allocates memory for dialog string & for storing hotkeys
///
/// Finds the size of memory required for the confirm_msg & for storing hotkeys
/// and then allocates the memory for them.
/// has_hotkey array is also filled-up.
///
/// @param message Message which will be part of the confirm_msg
/// @param buttons String containing button names
/// @param[out] has_hotkey An element in this array is set to true if
///                        corresponding button has a hotkey
///
/// @return Pointer to memory allocated for storing hotkeys
static char_u * console_dialog_alloc(const char_u *message,
                                     char_u *buttons,
                                     bool has_hotkey[])
{
  int lenhotkey = HOTK_LEN;  // count first button
  has_hotkey[0] = false;

  // Compute the size of memory to allocate.
  int len = 0;
  int idx = 0;
  char_u *r = buttons;
  while (*r) {
    if (*r == DLG_BUTTON_SEP) {
      len += 3;                         // '\n' -> ', '; 'x' -> '(x)'
      lenhotkey += HOTK_LEN;            // each button needs a hotkey
      if (idx < HAS_HOTKEY_LEN - 1) {
        has_hotkey[++idx] = false;
      }
    } else if (*r == DLG_HOTKEY_CHAR) {
      r++;
      len++;                    // '&a' -> '[a]'
      if (idx < HAS_HOTKEY_LEN - 1) {
        has_hotkey[idx] = true;
      }
    }

    // Advance to the next character
    mb_ptr_adv(r);
  }

  len += (int)(STRLEN(message)
                + 2                          // for the NL's
                + STRLEN(buttons)
                + 3);                        // for the ": " and NUL
  lenhotkey++;                               // for the NUL

  // If no hotkey is specified, first char is used.
  if (!has_hotkey[0]) {
    len += 2;                                // "x" -> "[x]"
  }


  // Now allocate space for the strings
  xfree(confirm_msg);
  confirm_msg = xmalloc(len);
  *confirm_msg = NUL;

  return xmalloc(lenhotkey);
}

/*
 * Format the dialog string, and display it at the bottom of
 * the screen. Return a string of hotkey chars (if defined) for
 * each 'button'. If a button has no hotkey defined, the first character of
 * the button is used.
 * The hotkeys can be multi-byte characters, but without combining chars.
 *
 * Returns an allocated string with hotkeys.
 */
static char_u *msg_show_console_dialog(char_u *message, char_u *buttons, int dfltbutton)
  FUNC_ATTR_NONNULL_RET
{
  bool has_hotkey[HAS_HOTKEY_LEN] = {false};
  char_u *hotk = console_dialog_alloc(message, buttons, has_hotkey);

  copy_hotkeys_and_msg(message, buttons, dfltbutton, has_hotkey, hotk);

  display_confirm_msg();
  return hotk;
}

/// Copies hotkeys & dialog message into the memory allocated for it
///
/// @param message Message which will be part of the confirm_msg
/// @param buttons String containing button names
/// @param default_button_idx Number of default button
/// @param has_hotkey An element in this array is true if corresponding button
///                   has a hotkey
/// @param[out] hotkeys_ptr Pointer to the memory location where hotkeys will be copied
static void copy_hotkeys_and_msg(const char_u *message, char_u *buttons,
                                 int default_button_idx, const bool has_hotkey[],
                                 char_u *hotkeys_ptr)
{
  *confirm_msg = '\n';
  STRCPY(confirm_msg + 1, message);

  char_u *msgp = confirm_msg + 1 + STRLEN(message);

  // Define first default hotkey. Keep the hotkey string NUL
  // terminated to avoid reading past the end.
  hotkeys_ptr[copy_char(buttons, hotkeys_ptr, TRUE)] = NUL;

  // Remember where the choices start, displaying starts here when
  // "hotkeys_ptr" typed at the more prompt.
  confirm_msg_tail = msgp;
  *msgp++ = '\n';

  bool first_hotkey = false;  // Is the first char of button a hotkey
  if (!has_hotkey[0]) {
    first_hotkey = true;     // If no hotkey is specified, first char is used
  }

  int idx = 0;
  char_u *r = buttons;
  while (*r) {
    if (*r == DLG_BUTTON_SEP) {
      *msgp++ = ',';
      *msgp++ = ' ';                    // '\n' -> ', '

      // Advance to next hotkey and set default hotkey
      hotkeys_ptr += (has_mbyte) ? STRLEN(hotkeys_ptr): 1;
      hotkeys_ptr[copy_char(r + 1, hotkeys_ptr, TRUE)] = NUL;

      if (default_button_idx) {
        default_button_idx--;
      }

      // If no hotkey is specified, first char is used.
      if (idx < HAS_HOTKEY_LEN - 1 && !has_hotkey[++idx]) {
        first_hotkey = true;
      }

    } else if (*r == DLG_HOTKEY_CHAR || first_hotkey) {
      if (*r == DLG_HOTKEY_CHAR) {
        ++r;
      }

      first_hotkey = false;
      if (*r == DLG_HOTKEY_CHAR) {                 // '&&a' -> '&a'
        *msgp++ = *r;
      } else {
        // '&a' -> '[a]'
        *msgp++ = (default_button_idx == 1) ? '[' : '(';
        msgp += copy_char(r, msgp, FALSE);
        *msgp++ = (default_button_idx == 1) ? ']' : ')';

        // redefine hotkey
        hotkeys_ptr[copy_char(r, hotkeys_ptr, TRUE)] = NUL;
      }
    } else {
      // everything else copy literally
      msgp += copy_char(r, msgp, FALSE);
    }

    // advance to the next character
    mb_ptr_adv(r);
  }

  *msgp++ = ':';
  *msgp++ = ' ';
  *msgp = NUL;
}

/*
 * Display the ":confirm" message.  Also called when screen resized.
 */
void display_confirm_msg(void)
{
  /* avoid that 'q' at the more prompt truncates the message here */
  ++confirm_msg_used;
  if (confirm_msg != NULL)
    msg_puts_attr(confirm_msg, hl_attr(HLF_M));
  --confirm_msg_used;
}

int vim_dialog_yesno(int type, char_u *title, char_u *message, int dflt)
{
  if (do_dialog(type,
          title == NULL ? (char_u *)_("Question") : title,
          message,
          (char_u *)_("&Yes\n&No"), dflt, NULL, FALSE) == 1)
    return VIM_YES;
  return VIM_NO;
}

int vim_dialog_yesnocancel(int type, char_u *title, char_u *message, int dflt)
{
  switch (do_dialog(type,
              title == NULL ? (char_u *)_("Question") : title,
              message,
              (char_u *)_("&Yes\n&No\n&Cancel"), dflt, NULL, FALSE)) {
  case 1: return VIM_YES;
  case 2: return VIM_NO;
  }
  return VIM_CANCEL;
}

int vim_dialog_yesnoallcancel(int type, char_u *title, char_u *message, int dflt)
{
  switch (do_dialog(type,
              title == NULL ? (char_u *)"Question" : title,
              message,
              (char_u *)_("&Yes\n&No\nSave &All\n&Discard All\n&Cancel"),
              dflt, NULL, FALSE)) {
  case 1: return VIM_YES;
  case 2: return VIM_NO;
  case 3: return VIM_ALL;
  case 4: return VIM_DISCARDALL;
  }
  return VIM_CANCEL;
}



static char *e_printf = N_("E766: Insufficient arguments for printf()");

/*
 * Get number argument from "idxp" entry in "tvs".  First entry is 1.
 */
static long tv_nr(typval_T *tvs, int *idxp)
{
  int idx = *idxp - 1;
  long n = 0;
  int err = FALSE;

  if (tvs[idx].v_type == VAR_UNKNOWN)
    EMSG(_(e_printf));
  else {
    ++*idxp;
    n = get_tv_number_chk(&tvs[idx], &err);
    if (err)
      n = 0;
  }
  return n;
}

/*
 * Get string argument from "idxp" entry in "tvs".  First entry is 1.
 * Returns NULL for an error.
 */
static char *tv_str(typval_T *tvs, int *idxp)
{
  int idx = *idxp - 1;
  char        *s = NULL;

  if (tvs[idx].v_type == VAR_UNKNOWN)
    EMSG(_(e_printf));
  else {
    ++*idxp;
    s = (char *)get_tv_string_chk(&tvs[idx]);
  }
  return s;
}

/*
 * Get float argument from "idxp" entry in "tvs".  First entry is 1.
 */
static double tv_float(typval_T *tvs, int *idxp)
{
  int idx = *idxp - 1;
  double f = 0;

  if (tvs[idx].v_type == VAR_UNKNOWN)
    EMSG(_(e_printf));
  else {
    ++*idxp;
    if (tvs[idx].v_type == VAR_FLOAT)
      f = tvs[idx].vval.v_float;
    else if (tvs[idx].v_type == VAR_NUMBER)
      f = tvs[idx].vval.v_number;
    else
      EMSG(_("E807: Expected Float argument for printf()"));
  }
  return f;
}

/*
 * This code was included to provide a portable vsnprintf() and snprintf().
 * Some systems may provide their own, but we always use this one for
 * consistency.
 *
 * This code is based on snprintf.c - a portable implementation of snprintf
 * by Mark Martinec <mark.martinec@ijs.si>, Version 2.2, 2000-10-06.
 * Included with permission.  It was heavily modified to fit in Vim.
 * The original code, including useful comments, can be found here:
 *	http://www.ijs.si/software/snprintf/
 *
 * This snprintf() only supports the following conversion specifiers:
 * s, c, d, u, o, x, X, p  (and synonyms: i, D, U, O - see below)
 * with flags: '-', '+', ' ', '0' and '#'.
 * An asterisk is supported for field width as well as precision.
 *
 * Limited support for floating point was added: 'f', 'e', 'E', 'g', 'G'.
 *
 * Length modifiers 'h' (short int) and 'l' (long int) are supported.
 * 'll' (long long int) is not supported.
 *
 * The locale is not used, the string is used as a byte string.  This is only
 * relevant for double-byte encodings where the second byte may be '%'.
 *
 * It is permitted for "str_m" to be zero, and it is permitted to specify NULL
 * pointer for resulting string argument if "str_m" is zero (as per ISO C99).
 *
 * The return value is the number of characters which would be generated
 * for the given input, excluding the trailing NUL. If this value
 * is greater or equal to "str_m", not all characters from the result
 * have been stored in str, output bytes beyond the ("str_m"-1) -th character
 * are discarded. If "str_m" is greater than zero it is guaranteed
 * the resulting string will be NUL-terminated.
 */

/*
 * When va_list is not supported we only define vim_snprintf().
 *
 * vim_vsnprintf() can be invoked with either "va_list" or a list of
 * "typval_T".  When the latter is not used it must be NULL.
 */

/* Like vim_vsnprintf() but append to the string. */
int vim_snprintf_add(char *str, size_t str_m, char *fmt, ...)
{
  va_list ap;
  int str_l;
  size_t len = STRLEN(str);
  size_t space;

  if (str_m <= len)
    space = 0;
  else
    space = str_m - len;
  va_start(ap, fmt);
  str_l = vim_vsnprintf(str + len, space, fmt, ap, NULL);
  va_end(ap);
  return str_l;
}

int vim_snprintf(char *str, size_t str_m, char *fmt, ...)
{
  va_list ap;
  int str_l;

  va_start(ap, fmt);
  str_l = vim_vsnprintf(str, str_m, fmt, ap, NULL);
  va_end(ap);
  return str_l;
}

int vim_vsnprintf(char *str, size_t str_m, char *fmt, va_list ap, typval_T *tvs)
{
  size_t str_l = 0;
  bool str_avail = str_l < str_m;
  char *p = fmt;
  int arg_idx = 1;

  if (!p)
    p = "";
  while (*p) {
    if (*p != '%') {
      // copy up to the next '%' or NUL without any changes
      size_t n = (size_t)(xstrchrnul(p + 1, '%') - p);
      if (str_avail) {
        size_t avail = str_m - str_l;
        memmove(str + str_l, p, MIN(n, avail));
        str_avail = n < avail;
      }
      p += n;
      assert(n <= SIZE_MAX - str_l);
      str_l += n;
    } else {
      size_t min_field_width = 0, precision = 0;
      int zero_padding = 0, precision_specified = 0, justify_left = 0;
      int alternate_form = 0, force_sign = 0;

      // if both ' ' and '+' flags appear, ' ' flag should be ignored
      int space_for_positive = 1;

      // allowed values: \0, h, l, 2 (for ll), z, L
      char length_modifier = '\0';

      // temporary buffer for simple numeric->string conversion
# define TMP_LEN 350    // 1e308 seems reasonable as the maximum printable
      char tmp[TMP_LEN];

      // string address in case of string argument
      char *str_arg;

      // natural field width of arg without padding and sign
      size_t str_arg_l;

      // unsigned char argument value (only defined for c conversion);
      // standard explicitly states the char argument for the c
      // conversion is unsigned
      unsigned char uchar_arg;

      // number of zeros to be inserted for numeric conversions as
      // required by the precision or minimal field width
      size_t number_of_zeros_to_pad = 0;

      // index into tmp where zero padding is to be inserted
      size_t zero_padding_insertion_ind = 0;

      // current conversion specifier character
      char fmt_spec = '\0';

      str_arg = NULL;
      p++;  // skip '%'

      // parse flags
      while (*p == '0' || *p == '-' || *p == '+' || *p == ' '
             || *p == '#' || *p == '\'') {
        switch (*p) {
          case '0': zero_padding = 1; break;
          case '-': justify_left = 1; break;
                    // if both '0' and '-' flags appear, '0' should be ignored
          case '+': force_sign = 1; space_for_positive = 0; break;
          case ' ': force_sign = 1; break;
                    // if both ' ' and '+' flags appear, ' ' should be ignored
          case '#': alternate_form = 1; break;
          case '\'': break;
        }
        p++;
      }

      // parse field width
      if (*p == '*') {
        p++;
        int j = tvs ? tv_nr(tvs, &arg_idx) : va_arg(ap, int);
        if (j >= 0)
          min_field_width = j;
        else {
          min_field_width = -j;
          justify_left = 1;
        }
      } else if (ascii_isdigit((int)(*p))) {
        // size_t could be wider than unsigned int; make sure we treat
        // argument like common implementations do
        unsigned int uj = *p++ - '0';

        while (ascii_isdigit((int)(*p)))
          uj = 10 * uj + (unsigned int)(*p++ - '0');
        min_field_width = uj;
      }

      // parse precision
      if (*p == '.') {
        p++;
        precision_specified = 1;
        if (*p == '*') {
          int j = tvs ? tv_nr(tvs, &arg_idx) : va_arg(ap, int);
          p++;
          if (j >= 0)
            precision = j;
          else {
            precision_specified = 0;
            precision = 0;
          }
        } else if (ascii_isdigit((int)(*p))) {
          // size_t could be wider than unsigned int; make sure we
          // treat argument like common implementations do
          unsigned int uj = *p++ - '0';

          while (ascii_isdigit((int)(*p)))
            uj = 10 * uj + (unsigned int)(*p++ - '0');
          precision = uj;
        }
      }

      // parse 'h', 'l', 'll' and 'z' length modifiers
      if (*p == 'h' || *p == 'l' || *p == 'z') {
        length_modifier = *p;
        p++;
        if (length_modifier == 'l' && *p == 'l') { // ll, encoded as 2
          length_modifier = '2';
          p++;
        }
      }

      fmt_spec = *p;

      // common synonyms
      switch (fmt_spec) {
        case 'i': fmt_spec = 'd'; break;
        case 'D': fmt_spec = 'd'; length_modifier = 'l'; break;
        case 'U': fmt_spec = 'u'; length_modifier = 'l'; break;
        case 'O': fmt_spec = 'o'; length_modifier = 'l'; break;
        case 'F': fmt_spec = 'f'; break;
        default: break;
      }

      // get parameter value, do initial processing
      switch (fmt_spec) {
      // '%' and 'c' behave similar to 's' regarding flags and field widths
      case '%': case 'c': case 's': case 'S':
        str_arg_l = 1;
        switch (fmt_spec) {
        case '%':
          str_arg = p;
          break;

        case 'c': {
          int j = tvs ? tv_nr(tvs, &arg_idx) : va_arg(ap, int);
          // standard demands unsigned char
          uchar_arg = (unsigned char)j;
          str_arg = (char *)&uchar_arg;
          break;
        }

        case 's':
        case 'S':
          str_arg = tvs ? tv_str(tvs, &arg_idx) : va_arg(ap, char *);
          if (!str_arg) {
            str_arg = "[NULL]";
            str_arg_l = 6;
          }
          // make sure not to address string beyond the specified precision
          else if (!precision_specified)
            str_arg_l = strlen(str_arg);
          // truncate string if necessary as requested by precision
          else if (precision == 0)
            str_arg_l = 0;
          else {
            // memchr on HP does not like n > 2^31
            // TODO(elmart): check if this still holds / is relevant
            str_arg_l = (size_t)((char *)xmemscan(str_arg,
                                                  NUL,
                                                  MIN(precision, 0x7fffffff))
                                 - str_arg);
          }
          if (fmt_spec == 'S') {
            if (min_field_width != 0)
              min_field_width += strlen(str_arg)
                                 - mb_string2cells((char_u *) str_arg);
            if (precision) {
              char_u *p1 = (char_u *)str_arg;
              for (size_t i = 0; i < precision && *p1; i++)
                p1 += mb_ptr2len(p1);
              str_arg_l = precision = p1 - (char_u *)str_arg;
            }
          }
          break;

        default:
          break;
        }
        break;

      case 'd': case 'u': case 'o': case 'x': case 'X': case 'p': {
        // u, o, x, X and p conversion specifiers imply the value is unsigned;
        // d implies a signed value

        // 0 if numeric argument is zero (or if pointer is NULL for 'p'),
        // +1 if greater than zero (or non NULL for 'p'),
        // -1 if negative (unsigned argument is never negative)
        int arg_sign = 0;

        // only defined for length modifier h, or for no length modifiers
        int int_arg = 0;
        unsigned int uint_arg = 0;

        // only defined for length modifier l
        long int long_arg = 0;
        unsigned long int ulong_arg = 0;

        // only defined for length modifier ll
        long long int long_long_arg = 0;
        unsigned long long int ulong_long_arg = 0;

        // only defined for length modifier z
        size_t size_t_arg = 0;

        // only defined for p conversion
        void *ptr_arg = NULL;

        if (fmt_spec == 'p') {
          length_modifier = '\0';
          ptr_arg = tvs ? (void *)tv_str(tvs, &arg_idx) : va_arg(ap, void *);
          if (ptr_arg)
            arg_sign = 1;
        } else if (fmt_spec == 'd') {
          // signed
          switch (length_modifier) {
          case '\0':
          case 'h':
            // char and short arguments are passed as int
            int_arg = tvs ? tv_nr(tvs, &arg_idx) : va_arg(ap, int);
            if (int_arg > 0)
              arg_sign =  1;
            else if (int_arg < 0)
              arg_sign = -1;
            break;
          case 'l':
            long_arg = tvs ? tv_nr(tvs, &arg_idx) : va_arg(ap, long int);
            if (long_arg > 0)
              arg_sign =  1;
            else if (long_arg < 0)
              arg_sign = -1;
            break;
          case '2':
            long_long_arg = tvs ? tv_nr(tvs, &arg_idx)
                                : va_arg(ap, long long int);
            if (long_long_arg > 0)
              arg_sign =  1;
            else if (long_long_arg < 0)
              arg_sign = -1;
            break;
          }
        } else {
          // unsigned
          switch (length_modifier) {
          case '\0':
          case 'h':
            uint_arg = tvs ? (unsigned)tv_nr(tvs, &arg_idx)
                           : va_arg(ap, unsigned int);
            if (uint_arg != 0)
              arg_sign = 1;
            break;
          case 'l':
            ulong_arg = tvs ? (unsigned long)tv_nr(tvs, &arg_idx)
                            : va_arg(ap, unsigned long int);
            if (ulong_arg != 0)
              arg_sign = 1;
            break;
          case '2':
            ulong_long_arg = tvs ? (unsigned long long)tv_nr(tvs, &arg_idx)
                                 : va_arg(ap, unsigned long long int);
            if (ulong_long_arg) arg_sign = 1;
            break;
          case 'z':
            size_t_arg = tvs ? (size_t)tv_nr(tvs, &arg_idx)
                             : va_arg(ap, size_t);
            if (size_t_arg) arg_sign = 1;
            break;
          }
        }

        str_arg = tmp;
        str_arg_l = 0;

        // For d, i, u, o, x, and X conversions, if precision is specified,
        // '0' flag should be ignored. This is so with Solaris 2.6, Digital UNIX
        // 4.0, HPUX 10, Linux, FreeBSD, NetBSD; but not with Perl.
        if (precision_specified)
          zero_padding = 0;

        if (fmt_spec == 'd') {
          if (force_sign && arg_sign >= 0)
            tmp[str_arg_l++] = space_for_positive ? ' ' : '+';
          // leave negative numbers for sprintf to handle, to
          // avoid handling tricky cases like (short int)-32768
        } else if (alternate_form) {
          if (arg_sign != 0 && (fmt_spec == 'x' || fmt_spec == 'X') ) {
            tmp[str_arg_l++] = '0';
            tmp[str_arg_l++] = fmt_spec;
          }
          // alternate form should have no effect for p * conversion, but ...
        }

        zero_padding_insertion_ind = str_arg_l;
        if (!precision_specified)
          precision = 1;  // default precision is 1
        if (precision == 0 && arg_sign == 0) {
          // when zero value is formatted with an explicit precision 0,
          // resulting formatted string is empty (d, i, u, o, x, X, p)
        } else {
          char f[5];
          int f_l = 0;

          // construct a simple format string for sprintf
          f[f_l++] = '%';
          if (!length_modifier)
            ;
          else if (length_modifier == '2') {
            f[f_l++] = 'l';
            f[f_l++] = 'l';
          } else
            f[f_l++] = length_modifier;
          f[f_l++] = fmt_spec;
          f[f_l++] = '\0';

          if (fmt_spec == 'p')
            str_arg_l += sprintf(tmp + str_arg_l, f, ptr_arg);
          else if (fmt_spec == 'd') {
            // signed
            switch (length_modifier) {
            case '\0':
            case 'h': str_arg_l += sprintf(tmp + str_arg_l, f, int_arg);
                      break;
            case 'l': str_arg_l += sprintf(tmp + str_arg_l, f, long_arg);
                      break;
            case '2': str_arg_l += sprintf(tmp + str_arg_l, f, long_long_arg);
                      break;
            }
          } else {
            // unsigned
            switch (length_modifier) {
            case '\0':
            case 'h': str_arg_l += sprintf(tmp + str_arg_l, f, uint_arg);
                      break;
            case 'l': str_arg_l += sprintf(tmp + str_arg_l, f, ulong_arg);
                      break;
            case '2': str_arg_l += sprintf(tmp + str_arg_l, f, ulong_long_arg);
                      break;
            case 'z': str_arg_l += sprintf(tmp + str_arg_l, f, size_t_arg);
                      break;
            }
          }

          // include the optional minus sign and possible "0x" in the region
          // before the zero padding insertion point
          if (zero_padding_insertion_ind < str_arg_l
              && tmp[zero_padding_insertion_ind] == '-')
            zero_padding_insertion_ind++;
          if (zero_padding_insertion_ind + 1 < str_arg_l
              && tmp[zero_padding_insertion_ind]   == '0'
              && (tmp[zero_padding_insertion_ind + 1] == 'x'
                  || tmp[zero_padding_insertion_ind + 1] == 'X'))
            zero_padding_insertion_ind += 2;
        }

        {
          size_t num_of_digits = str_arg_l - zero_padding_insertion_ind;

          if (alternate_form && fmt_spec == 'o'
              // unless zero is already the first character
              && !(zero_padding_insertion_ind < str_arg_l
                   && tmp[zero_padding_insertion_ind] == '0')) {
            // assure leading zero for alternate-form octal numbers
            if (!precision_specified
                || precision < num_of_digits + 1) {
              // precision is increased to force the first character to be zero,
              // except if a zero value is formatted with an explicit precision
              // of zero
              precision = num_of_digits + 1;
            }
          }
          // zero padding to specified precision?
          if (num_of_digits < precision)
            number_of_zeros_to_pad = precision - num_of_digits;
        }
        // zero padding to specified minimal field width?
        if (!justify_left && zero_padding) {
          int n = (int)(min_field_width - (str_arg_l
                                           + number_of_zeros_to_pad));
          if (n > 0)
            number_of_zeros_to_pad += n;
        }
        break;
      }

      case 'f':
      case 'e':
      case 'E':
      case 'g':
      case 'G':
      {
        // floating point
        char format[40];
        int l;
        int remove_trailing_zeroes = FALSE;

        double f = tvs ? tv_float(tvs, &arg_idx) : va_arg(ap, double);
        double abs_f = f < 0 ? -f : f;

        if (fmt_spec == 'g' || fmt_spec == 'G') {
          // can't use %g directly, cause it prints "1.0" as "1"
          if ((abs_f >= 0.001 && abs_f < 10000000.0) || abs_f == 0.0)
            fmt_spec = 'f';
          else
            fmt_spec = fmt_spec == 'g' ? 'e' : 'E';
          remove_trailing_zeroes = TRUE;
        }

        if (fmt_spec == 'f' && abs_f > 1.0e307) {
          // avoid a buffer overflow
          strcpy(tmp, "inf");
          str_arg_l = 3;
        } else {
          format[0] = '%';
          l = 1;
          if (precision_specified) {
            size_t max_prec = TMP_LEN - 10;

            // make sure we don't get more digits than we have room for
            if (fmt_spec == 'f' && abs_f > 1.0)
              max_prec -= (size_t)log10(abs_f);
            if (precision > max_prec)
              precision = max_prec;
            l += sprintf(format + 1, ".%d", (int)precision);
          }
          format[l] = fmt_spec;
          format[l + 1] = NUL;
          str_arg_l = sprintf(tmp, format, f);

          if (remove_trailing_zeroes) {
            int i;
            char *tp;

            // using %g or %G: remove superfluous zeroes
            if (fmt_spec == 'f')
              tp = tmp + str_arg_l - 1;
            else {
              tp = (char *)vim_strchr((char_u *)tmp,
                                      fmt_spec == 'e' ? 'e' : 'E');
              if (tp) {
                // remove superfluous '+' and leading zeroes from exponent
                if (tp[1] == '+') {
                  // change "1.0e+07" to "1.0e07"
                  STRMOVE(tp + 1, tp + 2);
                  --str_arg_l;
                }
                i = (tp[1] == '-') ? 2 : 1;
                while (tp[i] == '0') {
                  // change "1.0e07" to "1.0e7"
                  STRMOVE(tp + i, tp + i + 1);
                  --str_arg_l;
                }
                --tp;
              }
            }

            if (tp != NULL && !precision_specified)
              // remove trailing zeroes, but keep the one just after a dot
              while (tp > tmp + 2 && *tp == '0' && tp[-1] != '.') {
                STRMOVE(tp, tp + 1);
                --tp;
                --str_arg_l;
              }
          } else {
            // be consistent: some printf("%e") use 1.0e+12 and some 1.0e+012;
            // remove one zero in the last case
            char *tp = (char *)vim_strchr((char_u *)tmp,
                                          fmt_spec == 'e' ? 'e' : 'E');
            if (tp && (tp[1] == '+' || tp[1] == '-') && tp[2] == '0'
                && ascii_isdigit(tp[3]) && ascii_isdigit(tp[4])) {
              STRMOVE(tp + 2, tp + 3);
              --str_arg_l;
            }
          }
        }
        str_arg = tmp;
        break;
      }

      default:
        // unrecognized conversion specifier, keep format string as-is
        zero_padding = 0;  // turn zero padding off for non-numeric conversion
        justify_left = 1;
        min_field_width = 0;  // reset flags

        // discard the unrecognized conversion, just keep
        // the unrecognized conversion character
        str_arg = p;
        str_arg_l = 0;
        if (*p)
          str_arg_l++;  // include invalid conversion specifier
                        // unchanged if not at end-of-string
        break;
      }

      if (*p)
        p++;  // step over the just processed conversion specifier

      // insert padding to the left as requested by min_field_width;
      // this does not include the zero padding in case of numerical conversions
      if (!justify_left) {
        assert(str_arg_l <= SIZE_MAX - number_of_zeros_to_pad);
        if (min_field_width > str_arg_l + number_of_zeros_to_pad) {
          // left padding with blank or zero
          size_t pn = min_field_width - (str_arg_l + number_of_zeros_to_pad);
          if (str_avail) {
            size_t avail = str_m - str_l;
            memset(str + str_l, zero_padding ? '0' : ' ', MIN(pn, avail));
            str_avail = pn < avail;
          }
          assert(pn <= SIZE_MAX - str_l);
          str_l += pn;
        }
      }

      // zero padding as requested by the precision or by the minimal
      // field width for numeric conversions required?
      if (number_of_zeros_to_pad == 0) {
        // will not copy first part of numeric right now,
        // force it to be copied later in its entirety
        zero_padding_insertion_ind = 0;
      } else {
        // insert first part of numerics (sign or '0x') before zero padding
        if (zero_padding_insertion_ind > 0) {
          size_t zn = zero_padding_insertion_ind;
          if (str_avail) {
            size_t avail = str_m - str_l;
            memmove(str + str_l, str_arg, MIN(zn, avail));
            str_avail = zn < avail;
          }
          assert(zn <= SIZE_MAX - str_l);
          str_l += zn;
        }

        // insert zero padding as requested by precision or min field width
        if (number_of_zeros_to_pad > 0) {
          size_t zn = number_of_zeros_to_pad;
          if (str_avail) {
            size_t avail = str_m - str_l;
            memset(str + str_l, '0', MIN(zn, avail));
            str_avail = zn < avail;
          }
          assert(zn <= SIZE_MAX - str_l);
          str_l += zn;
        }
      }

      // insert formatted string
      // (or as-is conversion specifier for unknown conversions)
      if (str_arg_l > zero_padding_insertion_ind) {
        size_t sn = str_arg_l - zero_padding_insertion_ind;
        if (str_avail) {
          size_t avail = str_m - str_l;
          memmove(str + str_l,
                  str_arg + zero_padding_insertion_ind,
                  MIN(sn, avail));
          str_avail = sn < avail;
        }
        assert(sn <= SIZE_MAX - str_l);
        str_l += sn;
      }

      // insert right padding
      if (justify_left) {
        assert(str_arg_l <= SIZE_MAX - number_of_zeros_to_pad);
        if (min_field_width > str_arg_l + number_of_zeros_to_pad) {
          // right blank padding to the field width
          size_t pn = min_field_width - (str_arg_l + number_of_zeros_to_pad);
          if (str_avail) {
            size_t avail = str_m - str_l;
            memset(str + str_l, ' ', MIN(pn, avail));
            str_avail = pn < avail;
          }
          assert(pn <= SIZE_MAX - str_l);
          str_l += pn;
        }
      }
    }
  }

  if (str_m > 0) {
    // make sure the string is nul-terminated even at the expense of
    // overwriting the last character (shouldn't happen, but just in case)
    str[str_l <= str_m - 1 ? str_l : str_m - 1] = '\0';
  }

  if (tvs && tvs[arg_idx - 1].v_type != VAR_UNKNOWN)
    EMSG(_("E767: Too many arguments to printf()"));

  // return the number of characters formatted (excluding trailing nul
  // character); that is, the number of characters that would have been
  // written to the buffer if it were large enough.
  return (int)str_l;
}
