#include "indent.h"
#include "charset.h"
#include "memline.h"
#include "misc1.h"
#include "misc2.h"
#include "option.h"
#include "regexp.h"
#include "undo.h"

/*
 * Count the size (in window cells) of the indent in the current line.
 */
int get_indent(void)         {
  return get_indent_str(ml_get_curline(), (int)curbuf->b_p_ts);
}

/*
 * Count the size (in window cells) of the indent in line "lnum".
 */
int get_indent_lnum(linenr_T lnum)
{
  return get_indent_str(ml_get(lnum), (int)curbuf->b_p_ts);
}

/*
 * Count the size (in window cells) of the indent in line "lnum" of buffer
 * "buf".
 */
int get_indent_buf(buf_T *buf, linenr_T lnum)
{
  return get_indent_str(ml_get_buf(buf, lnum, FALSE), (int)buf->b_p_ts);
}

/*
 * count the size (in window cells) of the indent in line "ptr", with
 * 'tabstop' at "ts"
 */
int get_indent_str(char_u *ptr, int ts)
{
  int count = 0;

  for (; *ptr; ++ptr) {
    if (*ptr == TAB)        /* count a tab for what it is worth */
      count += ts - (count % ts);
    else if (*ptr == ' ')
      ++count;                  /* count a space for one */
    else
      break;
  }
  return count;
}

/*
 * Set the indent of the current line.
 * Leaves the cursor on the first non-blank in the line.
 * Caller must take care of undo.
 * "flags":
 *	SIN_CHANGED:	call changed_bytes() if the line was changed.
 *	SIN_INSERT:	insert the indent in front of the line.
 *	SIN_UNDO:	save line for undo before changing it.
 * Returns TRUE if the line was changed.
 */
int
set_indent (
    int size,                           /* measured in spaces */
    int flags
)
{
  char_u      *p;
  char_u      *newline;
  char_u      *oldline;
  char_u      *s;
  int todo;
  int ind_len;                      /* measured in characters */
  int line_len;
  int doit = FALSE;
  int ind_done = 0;                 /* measured in spaces */
  int tab_pad;
  int retval = FALSE;
  int orig_char_len = -1;           /* number of initial whitespace chars when
                                       'et' and 'pi' are both set */

  /*
   * First check if there is anything to do and compute the number of
   * characters needed for the indent.
   */
  todo = size;
  ind_len = 0;
  p = oldline = ml_get_curline();

  /* Calculate the buffer size for the new indent, and check to see if it
   * isn't already set */

  /* if 'expandtab' isn't set: use TABs; if both 'expandtab' and
   * 'preserveindent' are set count the number of characters at the
   * beginning of the line to be copied */
  if (!curbuf->b_p_et || (!(flags & SIN_INSERT) && curbuf->b_p_pi)) {
    /* If 'preserveindent' is set then reuse as much as possible of
     * the existing indent structure for the new indent */
    if (!(flags & SIN_INSERT) && curbuf->b_p_pi) {
      ind_done = 0;

      /* count as many characters as we can use */
      while (todo > 0 && vim_iswhite(*p)) {
        if (*p == TAB) {
          tab_pad = (int)curbuf->b_p_ts
                    - (ind_done % (int)curbuf->b_p_ts);
          /* stop if this tab will overshoot the target */
          if (todo < tab_pad)
            break;
          todo -= tab_pad;
          ++ind_len;
          ind_done += tab_pad;
        } else   {
          --todo;
          ++ind_len;
          ++ind_done;
        }
        ++p;
      }

      /* Set initial number of whitespace chars to copy if we are
       * preserving indent but expandtab is set */
      if (curbuf->b_p_et)
        orig_char_len = ind_len;

      /* Fill to next tabstop with a tab, if possible */
      tab_pad = (int)curbuf->b_p_ts - (ind_done % (int)curbuf->b_p_ts);
      if (todo >= tab_pad && orig_char_len == -1) {
        doit = TRUE;
        todo -= tab_pad;
        ++ind_len;
        /* ind_done += tab_pad; */
      }
    }

    /* count tabs required for indent */
    while (todo >= (int)curbuf->b_p_ts) {
      if (*p != TAB)
        doit = TRUE;
      else
        ++p;
      todo -= (int)curbuf->b_p_ts;
      ++ind_len;
      /* ind_done += (int)curbuf->b_p_ts; */
    }
  }
  /* count spaces required for indent */
  while (todo > 0) {
    if (*p != ' ')
      doit = TRUE;
    else
      ++p;
    --todo;
    ++ind_len;
    /* ++ind_done; */
  }

  /* Return if the indent is OK already. */
  if (!doit && !vim_iswhite(*p) && !(flags & SIN_INSERT))
    return FALSE;

  /* Allocate memory for the new line. */
  if (flags & SIN_INSERT)
    p = oldline;
  else
    p = skipwhite(p);
  line_len = (int)STRLEN(p) + 1;

  /* If 'preserveindent' and 'expandtab' are both set keep the original
   * characters and allocate accordingly.  We will fill the rest with spaces
   * after the if (!curbuf->b_p_et) below. */
  if (orig_char_len != -1) {
    newline = alloc(orig_char_len + size - ind_done + line_len);
    if (newline == NULL)
      return FALSE;
    todo = size - ind_done;
    ind_len = orig_char_len + todo;        /* Set total length of indent in
                                            * characters, which may have been
                                            * undercounted until now  */
    p = oldline;
    s = newline;
    while (orig_char_len > 0) {
      *s++ = *p++;
      orig_char_len--;
    }

    /* Skip over any additional white space (useful when newindent is less
     * than old) */
    while (vim_iswhite(*p))
      ++p;

  } else   {
    todo = size;
    newline = alloc(ind_len + line_len);
    if (newline == NULL)
      return FALSE;
    s = newline;
  }

  /* Put the characters in the new line. */
  /* if 'expandtab' isn't set: use TABs */
  if (!curbuf->b_p_et) {
    /* If 'preserveindent' is set then reuse as much as possible of
     * the existing indent structure for the new indent */
    if (!(flags & SIN_INSERT) && curbuf->b_p_pi) {
      p = oldline;
      ind_done = 0;

      while (todo > 0 && vim_iswhite(*p)) {
        if (*p == TAB) {
          tab_pad = (int)curbuf->b_p_ts
                    - (ind_done % (int)curbuf->b_p_ts);
          /* stop if this tab will overshoot the target */
          if (todo < tab_pad)
            break;
          todo -= tab_pad;
          ind_done += tab_pad;
        } else   {
          --todo;
          ++ind_done;
        }
        *s++ = *p++;
      }

      /* Fill to next tabstop with a tab, if possible */
      tab_pad = (int)curbuf->b_p_ts - (ind_done % (int)curbuf->b_p_ts);
      if (todo >= tab_pad) {
        *s++ = TAB;
        todo -= tab_pad;
      }

      p = skipwhite(p);
    }

    while (todo >= (int)curbuf->b_p_ts) {
      *s++ = TAB;
      todo -= (int)curbuf->b_p_ts;
    }
  }
  while (todo > 0) {
    *s++ = ' ';
    --todo;
  }
  mch_memmove(s, p, (size_t)line_len);

  /* Replace the line (unless undo fails). */
  if (!(flags & SIN_UNDO) || u_savesub(curwin->w_cursor.lnum) == OK) {
    ml_replace(curwin->w_cursor.lnum, newline, FALSE);
    if (flags & SIN_CHANGED)
      changed_bytes(curwin->w_cursor.lnum, 0);
    /* Correct saved cursor position if it is in this line. */
    if (saved_cursor.lnum == curwin->w_cursor.lnum) {
      if (saved_cursor.col >= (colnr_T)(p - oldline))
        /* cursor was after the indent, adjust for the number of
         * bytes added/removed */
        saved_cursor.col += ind_len - (colnr_T)(p - oldline);
      else if (saved_cursor.col >= (colnr_T)(s - newline))
        /* cursor was in the indent, and is now after it, put it back
         * at the start of the indent (replacing spaces with TAB) */
        saved_cursor.col = (colnr_T)(s - newline);
    }
    retval = TRUE;
  } else
    vim_free(newline);

  curwin->w_cursor.col = ind_len;
  return retval;
}

/*
 * Copy the indent from ptr to the current line (and fill to size)
 * Leaves the cursor on the first non-blank in the line.
 * Returns TRUE if the line was changed.
 */
int copy_indent(int size, char_u *src)
{
  char_u      *p = NULL;
  char_u      *line = NULL;
  char_u      *s;
  int todo;
  int ind_len;
  int line_len = 0;
  int tab_pad;
  int ind_done;
  int round;

  /* Round 1: compute the number of characters needed for the indent
   * Round 2: copy the characters. */
  for (round = 1; round <= 2; ++round) {
    todo = size;
    ind_len = 0;
    ind_done = 0;
    s = src;

    /* Count/copy the usable portion of the source line */
    while (todo > 0 && vim_iswhite(*s)) {
      if (*s == TAB) {
        tab_pad = (int)curbuf->b_p_ts
                  - (ind_done % (int)curbuf->b_p_ts);
        /* Stop if this tab will overshoot the target */
        if (todo < tab_pad)
          break;
        todo -= tab_pad;
        ind_done += tab_pad;
      } else   {
        --todo;
        ++ind_done;
      }
      ++ind_len;
      if (p != NULL)
        *p++ = *s;
      ++s;
    }

    /* Fill to next tabstop with a tab, if possible */
    tab_pad = (int)curbuf->b_p_ts - (ind_done % (int)curbuf->b_p_ts);
    if (todo >= tab_pad && !curbuf->b_p_et) {
      todo -= tab_pad;
      ++ind_len;
      if (p != NULL)
        *p++ = TAB;
    }

    /* Add tabs required for indent */
    while (todo >= (int)curbuf->b_p_ts && !curbuf->b_p_et) {
      todo -= (int)curbuf->b_p_ts;
      ++ind_len;
      if (p != NULL)
        *p++ = TAB;
    }

    /* Count/add spaces required for indent */
    while (todo > 0) {
      --todo;
      ++ind_len;
      if (p != NULL)
        *p++ = ' ';
    }

    if (p == NULL) {
      /* Allocate memory for the result: the copied indent, new indent
       * and the rest of the line. */
      line_len = (int)STRLEN(ml_get_curline()) + 1;
      line = alloc(ind_len + line_len);
      if (line == NULL)
        return FALSE;
      p = line;
    }
  }

  /* Append the original line */
  mch_memmove(p, ml_get_curline(), (size_t)line_len);

  /* Replace the line */
  ml_replace(curwin->w_cursor.lnum, line, FALSE);

  /* Put the cursor after the indent. */
  curwin->w_cursor.col = ind_len;
  return TRUE;
}

/*
 * Return the indent of the current line after a number.  Return -1 if no
 * number was found.  Used for 'n' in 'formatoptions': numbered list.
 * Since a pattern is used it can actually handle more than numbers.
 */
int get_number_indent(linenr_T lnum)
{
  colnr_T col;
  pos_T pos;

  regmatch_T regmatch;
  int lead_len = 0;             /* length of comment leader */

  if (lnum > curbuf->b_ml.ml_line_count)
    return -1;
  pos.lnum = 0;

  /* In format_lines() (i.e. not insert mode), fo+=q is needed too...  */
  if ((State & INSERT) || has_format_option(FO_Q_COMS))
    lead_len = get_leader_len(ml_get(lnum), NULL, FALSE, TRUE);
  regmatch.regprog = vim_regcomp(curbuf->b_p_flp, RE_MAGIC);
  if (regmatch.regprog != NULL) {
    regmatch.rm_ic = FALSE;

    /* vim_regexec() expects a pointer to a line.  This lets us
     * start matching for the flp beyond any comment leader...  */
    if (vim_regexec(&regmatch, ml_get(lnum) + lead_len, (colnr_T)0)) {
      pos.lnum = lnum;
      pos.col = (colnr_T)(*regmatch.endp - ml_get(lnum));
      pos.coladd = 0;
    }
    vim_regfree(regmatch.regprog);
  }

  if (pos.lnum == 0 || *ml_get_pos(&pos) == NUL)
    return -1;
  getvcol(curwin, &pos, &col, NULL, NULL);
  return (int)col;
}