#include "vterm_internal.h"

#include <stdio.h>
#include <string.h>

#define strneq(a,b,n) (strncmp(a,b,n)==0)

#if defined(DEBUG) && DEBUG > 1
# define DEBUG_GLYPH_COMBINE
#endif

static int on_resize(int rows, int cols, void *user);

/* Some convenient wrappers to make callback functions easier */

static void putglyph(VTermState *state, const uint32_t chars[], int width, VTermPos pos)
{
  VTermGlyphInfo info;
  info.chars = chars;
  info.width = width;
  info.protected_cell = state->protected_cell;
  info.dwl = state->lineinfo[pos.row].doublewidth;
  info.dhl = state->lineinfo[pos.row].doubleheight;

  if(state->callbacks && state->callbacks->putglyph)
    if((*state->callbacks->putglyph)(&info, pos, state->cbdata))
      return;

  DEBUG_LOG3("libvterm: Unhandled putglyph U+%04x at (%d,%d)\n", chars[0], pos.col, pos.row);
}

static void updatecursor(VTermState *state, VTermPos *oldpos, int cancel_phantom)
{
  if(state->pos.col == oldpos->col && state->pos.row == oldpos->row)
    return;

  if(cancel_phantom)
    state->at_phantom = 0;

  if(state->callbacks && state->callbacks->movecursor)
    if((*state->callbacks->movecursor)(state->pos, *oldpos, state->mode.cursor_visible, state->cbdata))
      return;
}

static void erase(VTermState *state, VTermRect rect, int selective)
{
  if(state->callbacks && state->callbacks->erase)
    if((*state->callbacks->erase)(rect, selective, state->cbdata))
      return;
}

static VTermState *vterm_state_new(VTerm *vt)
{
  VTermState *state = vterm_allocator_malloc(vt, sizeof(VTermState));

  state->vt = vt;

  state->rows = vt->rows;
  state->cols = vt->cols;

  state->mouse_col     = 0;
  state->mouse_row     = 0;
  state->mouse_buttons = 0;

  state->mouse_protocol = MOUSE_X10;

  state->callbacks = NULL;
  state->cbdata    = NULL;

  vterm_state_newpen(state);

  state->bold_is_highbright = 0;

  return state;
}

INTERNAL void vterm_state_free(VTermState *state)
{
  vterm_allocator_free(state->vt, state->tabstops);
  vterm_allocator_free(state->vt, state->lineinfo);
  vterm_allocator_free(state->vt, state->combine_chars);
  vterm_allocator_free(state->vt, state);
}

static void scroll(VTermState *state, VTermRect rect, int downward, int rightward)
{
  int rows;
  int cols;
  if(!downward && !rightward)
    return;

  rows = rect.end_row - rect.start_row;
  if(downward > rows)
    downward = rows;
  else if(downward < -rows)
    downward = -rows;

  cols = rect.end_col - rect.start_col;
  if(rightward > cols)
    rightward = cols;
  else if(rightward < -cols)
    rightward = -cols;

  /* Update lineinfo if full line */
  if(rect.start_col == 0 && rect.end_col == state->cols && rightward == 0) {
    int height = rect.end_row - rect.start_row - abs(downward);

    if(downward > 0)
      memmove(state->lineinfo + rect.start_row,
              state->lineinfo + rect.start_row + downward,
              height * sizeof(state->lineinfo[0]));
    else
      memmove(state->lineinfo + rect.start_row - downward,
              state->lineinfo + rect.start_row,
              height * sizeof(state->lineinfo[0]));
  }

  if(state->callbacks && state->callbacks->scrollrect)
    if((*state->callbacks->scrollrect)(rect, downward, rightward, state->cbdata))
      return;

  if(state->callbacks)
    vterm_scroll_rect(rect, downward, rightward,
        state->callbacks->moverect, state->callbacks->erase, state->cbdata);
}

static void linefeed(VTermState *state)
{
  if(state->pos.row == SCROLLREGION_BOTTOM(state) - 1) {
    VTermRect rect;
    rect.start_row = state->scrollregion_top;
    rect.end_row   = SCROLLREGION_BOTTOM(state);
    rect.start_col = SCROLLREGION_LEFT(state);
    rect.end_col   = SCROLLREGION_RIGHT(state);

    scroll(state, rect, 1, 0);
  }
  else if(state->pos.row < state->rows-1)
    state->pos.row++;
}

static void grow_combine_buffer(VTermState *state)
{
  size_t    new_size = state->combine_chars_size * 2;
  uint32_t *new_chars = vterm_allocator_malloc(state->vt, new_size * sizeof(new_chars[0]));

  memcpy(new_chars, state->combine_chars, state->combine_chars_size * sizeof(new_chars[0]));

  vterm_allocator_free(state->vt, state->combine_chars);

  state->combine_chars = new_chars;
  state->combine_chars_size = new_size;
}

static void set_col_tabstop(VTermState *state, int col)
{
  unsigned char mask = 1 << (col & 7);
  state->tabstops[col >> 3] |= mask;
}

static void clear_col_tabstop(VTermState *state, int col)
{
  unsigned char mask = 1 << (col & 7);
  state->tabstops[col >> 3] &= ~mask;
}

static int is_col_tabstop(VTermState *state, int col)
{
  unsigned char mask = 1 << (col & 7);
  return state->tabstops[col >> 3] & mask;
}

static int is_cursor_in_scrollregion(const VTermState *state)
{
  if(state->pos.row < state->scrollregion_top ||
     state->pos.row >= SCROLLREGION_BOTTOM(state))
    return 0;
  if(state->pos.col < SCROLLREGION_LEFT(state) ||
     state->pos.col >= SCROLLREGION_RIGHT(state))
    return 0;

  return 1;
}

static void tab(VTermState *state, int count, int direction)
{
  while(count > 0) {
    if(direction > 0) {
      if(state->pos.col >= THISROWWIDTH(state)-1)
        return;

      state->pos.col++;
    }
    else if(direction < 0) {
      if(state->pos.col < 1)
        return;

      state->pos.col--;
    }

    if(is_col_tabstop(state, state->pos.col))
      count--;
  }
}

#define NO_FORCE 0
#define FORCE    1

#define DWL_OFF 0
#define DWL_ON  1

#define DHL_OFF    0
#define DHL_TOP    1
#define DHL_BOTTOM 2

static void set_lineinfo(VTermState *state, int row, int force, int dwl, int dhl)
{
  VTermLineInfo info = state->lineinfo[row];

  if(dwl == DWL_OFF)
    info.doublewidth = DWL_OFF;
  else if(dwl == DWL_ON)
    info.doublewidth = DWL_ON;
  /* else -1 to ignore */

  if(dhl == DHL_OFF)
    info.doubleheight = DHL_OFF;
  else if(dhl == DHL_TOP)
    info.doubleheight = DHL_TOP;
  else if(dhl == DHL_BOTTOM)
    info.doubleheight = DHL_BOTTOM;

  if((state->callbacks &&
      state->callbacks->setlineinfo &&
      (*state->callbacks->setlineinfo)(row, &info, state->lineinfo + row, state->cbdata))
      || force)
    state->lineinfo[row] = info;
}

static int on_text(const char bytes[], size_t len, void *user)
{
  VTermState *state = user;
  uint32_t *codepoints;
  int npoints = 0;
  size_t eaten = 0;
  VTermEncodingInstance *encoding;
  int i = 0;

  VTermPos oldpos = state->pos;

  /* We'll have at most len codepoints, plus one from a previous incomplete
   * sequence. */
  codepoints = vterm_allocator_malloc(state->vt, (len + 1) * sizeof(uint32_t));

  encoding =
    state->gsingle_set     ? &state->encoding[state->gsingle_set] :
    !(bytes[eaten] & 0x80) ? &state->encoding[state->gl_set] :
    state->vt->mode.utf8   ? &state->encoding_utf8 :
                             &state->encoding[state->gr_set];

  (*encoding->enc->decode)(encoding->enc, encoding->data,
      codepoints, &npoints, state->gsingle_set ? 1 : (int)len,
      bytes, &eaten, len);

  /* There's a chance an encoding (e.g. UTF-8) hasn't found enough bytes yet
   * for even a single codepoint
   */
  if(!npoints)
  {
    vterm_allocator_free(state->vt, codepoints);
    return 0;
  }

  if(state->gsingle_set && npoints)
    state->gsingle_set = 0;

  /* This is a combining char. that needs to be merged with the previous
   * glyph output */
  if(vterm_unicode_is_combining(codepoints[i])) {
    /* See if the cursor has moved since */
    if(state->pos.row == state->combine_pos.row && state->pos.col == state->combine_pos.col + state->combine_width) {
#ifdef DEBUG_GLYPH_COMBINE
      int printpos;
      printf("DEBUG: COMBINING SPLIT GLYPH of chars {");
      for(printpos = 0; state->combine_chars[printpos]; printpos++)
        printf("U+%04x ", state->combine_chars[printpos]);
      printf("} + {");
#endif

      /* Find where we need to append these combining chars */
      int saved_i = 0;
      while(state->combine_chars[saved_i])
        saved_i++;

      /* Add extra ones */
      while(i < npoints && vterm_unicode_is_combining(codepoints[i])) {
        if(saved_i >= (int)state->combine_chars_size)
          grow_combine_buffer(state);
        state->combine_chars[saved_i++] = codepoints[i++];
      }
      if(saved_i >= (int)state->combine_chars_size)
        grow_combine_buffer(state);
      state->combine_chars[saved_i] = 0;

#ifdef DEBUG_GLYPH_COMBINE
      for(; state->combine_chars[printpos]; printpos++)
        printf("U+%04x ", state->combine_chars[printpos]);
      printf("}\n");
#endif

      /* Now render it */
      putglyph(state, state->combine_chars, state->combine_width, state->combine_pos);
    }
    else {
      DEBUG_LOG("libvterm: TODO: Skip over split char+combining\n");
    }
  }

  for(; i < npoints; i++) {
    /* Try to find combining characters following this */
    int glyph_starts = i;
    int glyph_ends;
    int width = 0;
    uint32_t *chars;

    for(glyph_ends = i + 1; glyph_ends < npoints; glyph_ends++)
      if(!vterm_unicode_is_combining(codepoints[glyph_ends]))
        break;

    chars = vterm_allocator_malloc(state->vt, (glyph_ends - glyph_starts + 1) * sizeof(uint32_t));

    for( ; i < glyph_ends; i++) {
      int this_width;
      chars[i - glyph_starts] = codepoints[i];
      this_width = vterm_unicode_width(codepoints[i]);
#ifdef DEBUG
      if(this_width < 0) {
        fprintf(stderr, "Text with negative-width codepoint U+%04x\n", codepoints[i]);
        abort();
      }
#endif
      width += this_width;
    }

    chars[glyph_ends - glyph_starts] = 0;
    i--;

#ifdef DEBUG_GLYPH_COMBINE
    int printpos;
    printf("DEBUG: COMBINED GLYPH of %d chars {", glyph_ends - glyph_starts);
    for(printpos = 0; printpos < glyph_ends - glyph_starts; printpos++)
      printf("U+%04x ", chars[printpos]);
    printf("}, onscreen width %d\n", width);
#endif

    if(state->at_phantom || state->pos.col + width > THISROWWIDTH(state)) {
      linefeed(state);
      state->pos.col = 0;
      state->at_phantom = 0;
    }

    if(state->mode.insert) {
      /* TODO: This will be a little inefficient for large bodies of text, as
       * it'll have to 'ICH' effectively before every glyph. We should scan
       * ahead and ICH as many times as required
       */
      VTermRect rect;
      rect.start_row = state->pos.row;
      rect.end_row   = state->pos.row + 1;
      rect.start_col = state->pos.col;
      rect.end_col   = THISROWWIDTH(state);
      scroll(state, rect, 0, -1);
    }

    putglyph(state, chars, width, state->pos);

    if(i == npoints - 1) {
      /* End of the buffer. Save the chars in case we have to combine with
       * more on the next call */
      int save_i;
      for(save_i = 0; chars[save_i]; save_i++) {
        if(save_i >= (int)state->combine_chars_size)
          grow_combine_buffer(state);
        state->combine_chars[save_i] = chars[save_i];
      }
      if(save_i >= (int)state->combine_chars_size)
        grow_combine_buffer(state);
      state->combine_chars[save_i] = 0;
      state->combine_width = width;
      state->combine_pos = state->pos;
    }

    if(state->pos.col + width >= THISROWWIDTH(state)) {
      if(state->mode.autowrap)
        state->at_phantom = 1;
    }
    else {
      state->pos.col += width;
    }
    vterm_allocator_free(state->vt, chars);
  }

  updatecursor(state, &oldpos, 0);

#ifdef DEBUG
  if(state->pos.row < 0 || state->pos.row >= state->rows ||
     state->pos.col < 0 || state->pos.col >= state->cols) {
    fprintf(stderr, "Position out of bounds after text: (%d,%d)\n",
        state->pos.row, state->pos.col);
    abort();
  }
#endif

  vterm_allocator_free(state->vt, codepoints);
  return (int)eaten;
}

static int on_control(unsigned char control, void *user)
{
  VTermState *state = user;

  VTermPos oldpos = state->pos;

  switch(control) {
  case 0x07: /* BEL - ECMA-48 8.3.3 */
    if(state->callbacks && state->callbacks->bell)
      (*state->callbacks->bell)(state->cbdata);
    break;

  case 0x08: /* BS - ECMA-48 8.3.5 */
    if(state->pos.col > 0)
      state->pos.col--;
    break;

  case 0x09: /* HT - ECMA-48 8.3.60 */
    tab(state, 1, +1);
    break;

  case 0x0a: /* LF - ECMA-48 8.3.74 */
  case 0x0b: /* VT */
  case 0x0c: /* FF */
    linefeed(state);
    if(state->mode.newline)
      state->pos.col = 0;
    break;

  case 0x0d: /* CR - ECMA-48 8.3.15 */
    state->pos.col = 0;
    break;

  case 0x0e: /* LS1 - ECMA-48 8.3.76 */
    state->gl_set = 1;
    break;

  case 0x0f: /* LS0 - ECMA-48 8.3.75 */
    state->gl_set = 0;
    break;

  case 0x84: /* IND - DEPRECATED but implemented for completeness */
    linefeed(state);
    break;

  case 0x85: /* NEL - ECMA-48 8.3.86 */
    linefeed(state);
    state->pos.col = 0;
    break;

  case 0x88: /* HTS - ECMA-48 8.3.62 */
    set_col_tabstop(state, state->pos.col);
    break;

  case 0x8d: /* RI - ECMA-48 8.3.104 */
    if(state->pos.row == state->scrollregion_top) {
      VTermRect rect;
      rect.start_row = state->scrollregion_top;
      rect.end_row   = SCROLLREGION_BOTTOM(state);
      rect.start_col = SCROLLREGION_LEFT(state);
      rect.end_col   = SCROLLREGION_RIGHT(state);

      scroll(state, rect, -1, 0);
    }
    else if(state->pos.row > 0)
        state->pos.row--;
    break;

  case 0x8e: /* SS2 - ECMA-48 8.3.141 */
    state->gsingle_set = 2;
    break;

  case 0x8f: /* SS3 - ECMA-48 8.3.142 */
    state->gsingle_set = 3;
    break;

  default:
    if(state->fallbacks && state->fallbacks->control)
      if((*state->fallbacks->control)(control, state->fbdata))
        return 1;

    return 0;
  }

  updatecursor(state, &oldpos, 1);

#ifdef DEBUG
  if(state->pos.row < 0 || state->pos.row >= state->rows ||
     state->pos.col < 0 || state->pos.col >= state->cols) {
    fprintf(stderr, "Position out of bounds after Ctrl %02x: (%d,%d)\n",
        control, state->pos.row, state->pos.col);
    abort();
  }
#endif

  return 1;
}

static int settermprop_bool(VTermState *state, VTermProp prop, int v)
{
  VTermValue val;
  val.boolean = v;
  return vterm_state_set_termprop(state, prop, &val);
}

static int settermprop_int(VTermState *state, VTermProp prop, int v)
{
  VTermValue val;
  val.number = v;
  return vterm_state_set_termprop(state, prop, &val);
}

static int settermprop_string(VTermState *state, VTermProp prop, const char *str, size_t len)
{
  char *strvalue;
  int r;
  VTermValue val;
  strvalue = vterm_allocator_malloc(state->vt, (len+1) * sizeof(char));
  strncpy(strvalue, str, len);
  strvalue[len] = 0;

  val.string = strvalue;
  r = vterm_state_set_termprop(state, prop, &val);
  vterm_allocator_free(state->vt, strvalue);
  return r;
}

static void savecursor(VTermState *state, int save)
{
  if(save) {
    state->saved.pos = state->pos;
    state->saved.mode.cursor_visible = state->mode.cursor_visible;
    state->saved.mode.cursor_blink   = state->mode.cursor_blink;
    state->saved.mode.cursor_shape   = state->mode.cursor_shape;

    vterm_state_savepen(state, 1);
  }
  else {
    VTermPos oldpos = state->pos;

    state->pos = state->saved.pos;

    settermprop_bool(state, VTERM_PROP_CURSORVISIBLE, state->saved.mode.cursor_visible);
    settermprop_bool(state, VTERM_PROP_CURSORBLINK,   state->saved.mode.cursor_blink);
    settermprop_int (state, VTERM_PROP_CURSORSHAPE,   state->saved.mode.cursor_shape);

    vterm_state_savepen(state, 0);

    updatecursor(state, &oldpos, 1);
  }
}

static int on_escape(const char *bytes, size_t len, void *user)
{
  VTermState *state = user;

  /* Easier to decode this from the first byte, even though the final
   * byte terminates it
   */
  switch(bytes[0]) {
  case ' ':
    if(len != 2)
      return 0;

    switch(bytes[1]) {
      case 'F': /* S7C1T */
        state->vt->mode.ctrl8bit = 0;
        break;

      case 'G': /* S8C1T */
        state->vt->mode.ctrl8bit = 1;
        break;

      default:
        return 0;
    }
    return 2;

  case '#':
    if(len != 2)
      return 0;

    switch(bytes[1]) {
      case '3': /* DECDHL top */
        if(state->mode.leftrightmargin)
          break;
        set_lineinfo(state, state->pos.row, NO_FORCE, DWL_ON, DHL_TOP);
        break;

      case '4': /* DECDHL bottom */
        if(state->mode.leftrightmargin)
          break;
        set_lineinfo(state, state->pos.row, NO_FORCE, DWL_ON, DHL_BOTTOM);
        break;

      case '5': /* DECSWL */
        if(state->mode.leftrightmargin)
          break;
        set_lineinfo(state, state->pos.row, NO_FORCE, DWL_OFF, DHL_OFF);
        break;

      case '6': /* DECDWL */
        if(state->mode.leftrightmargin)
          break;
        set_lineinfo(state, state->pos.row, NO_FORCE, DWL_ON, DHL_OFF);
        break;

      case '8': /* DECALN */
      {
        VTermPos pos;
        uint32_t E[] = { 'E', 0 };
        for(pos.row = 0; pos.row < state->rows; pos.row++)
          for(pos.col = 0; pos.col < ROWWIDTH(state, pos.row); pos.col++)
            putglyph(state, E, 1, pos);
        break;
      }

      default:
        return 0;
    }
    return 2;

  case '(': case ')': case '*': case '+': /* SCS */
    if(len != 2)
      return 0;

    {
      int setnum = bytes[0] - 0x28;
      VTermEncoding *newenc = vterm_lookup_encoding(ENC_SINGLE_94, bytes[1]);

      if(newenc) {
        state->encoding[setnum].enc = newenc;

        if(newenc->init)
          (*newenc->init)(newenc, state->encoding[setnum].data);
      }
    }

    return 2;

  case '7': /* DECSC */
    savecursor(state, 1);
    return 1;

  case '8': /* DECRC */
    savecursor(state, 0);
    return 1;

  case '<': /* Ignored by VT100. Used in VT52 mode to switch up to VT100 */
    return 1;

  case '=': /* DECKPAM */
    state->mode.keypad = 1;
    return 1;

  case '>': /* DECKPNM */
    state->mode.keypad = 0;
    return 1;

  case 'c': /* RIS - ECMA-48 8.3.105 */
  {
    VTermPos oldpos = state->pos;
    vterm_state_reset(state, 1);
    if(state->callbacks && state->callbacks->movecursor)
      (*state->callbacks->movecursor)(state->pos, oldpos, state->mode.cursor_visible, state->cbdata);
    return 1;
  }

  case 'n': /* LS2 - ECMA-48 8.3.78 */
    state->gl_set = 2;
    return 1;

  case 'o': /* LS3 - ECMA-48 8.3.80 */
    state->gl_set = 3;
    return 1;

  case '~': /* LS1R - ECMA-48 8.3.77 */
    state->gr_set = 1;
    return 1;

  case '}': /* LS2R - ECMA-48 8.3.79 */
    state->gr_set = 2;
    return 1;

  case '|': /* LS3R - ECMA-48 8.3.81 */
    state->gr_set = 3;
    return 1;

  default:
    return 0;
  }
}

static void set_mode(VTermState *state, int num, int val)
{
  switch(num) {
  case 4: /* IRM - ECMA-48 7.2.10 */
    state->mode.insert = val;
    break;

  case 20: /* LNM - ANSI X3.4-1977 */
    state->mode.newline = val;
    break;

  default:
    DEBUG_LOG1("libvterm: Unknown mode %d\n", num);
    return;
  }
}

static void set_dec_mode(VTermState *state, int num, int val)
{
  switch(num) {
  case 1:
    state->mode.cursor = val;
    break;

  case 5: /* DECSCNM - screen mode */
    settermprop_bool(state, VTERM_PROP_REVERSE, val);
    break;

  case 6: /* DECOM - origin mode */
    {
      VTermPos oldpos = state->pos;
      state->mode.origin = val;
      state->pos.row = state->mode.origin ? state->scrollregion_top : 0;
      state->pos.col = state->mode.origin ? SCROLLREGION_LEFT(state) : 0;
      updatecursor(state, &oldpos, 1);
    }
    break;

  case 7:
    state->mode.autowrap = val;
    break;

  case 12:
    settermprop_bool(state, VTERM_PROP_CURSORBLINK, val);
    break;

  case 25:
    settermprop_bool(state, VTERM_PROP_CURSORVISIBLE, val);
    break;

  case 69: /* DECVSSM - vertical split screen mode */
           /* DECLRMM - left/right margin mode */
    state->mode.leftrightmargin = val;
    if(val) {
      int row;

      /* Setting DECVSSM must clear doublewidth/doubleheight state of every line */
      for(row = 0; row < state->rows; row++)
        set_lineinfo(state, row, FORCE, DWL_OFF, DHL_OFF);
    }

    break;

  case 1000:
  case 1002:
  case 1003:
    settermprop_int(state, VTERM_PROP_MOUSE,
        !val          ? VTERM_PROP_MOUSE_NONE  :
        (num == 1000) ? VTERM_PROP_MOUSE_CLICK :
        (num == 1002) ? VTERM_PROP_MOUSE_DRAG  :
                        VTERM_PROP_MOUSE_MOVE);
    break;

  case 1005:
    state->mouse_protocol = val ? MOUSE_UTF8 : MOUSE_X10;
    break;

  case 1006:
    state->mouse_protocol = val ? MOUSE_SGR : MOUSE_X10;
    break;

  case 1015:
    state->mouse_protocol = val ? MOUSE_RXVT : MOUSE_X10;
    break;

  case 1047:
    settermprop_bool(state, VTERM_PROP_ALTSCREEN, val);
    break;

  case 1048:
    savecursor(state, val);
    break;

  case 1049:
    settermprop_bool(state, VTERM_PROP_ALTSCREEN, val);
    savecursor(state, val);
    break;

  case 2004:
    state->mode.bracketpaste = val;
    break;

  default:
    DEBUG_LOG1("libvterm: Unknown DEC mode %d\n", num);
    return;
  }
}

static void request_dec_mode(VTermState *state, int num)
{
  int reply;

  switch(num) {
    case 1:
      reply = state->mode.cursor;
      break;

    case 5:
      reply = state->mode.screen;
      break;

    case 6:
      reply = state->mode.origin;
      break;

    case 7:
      reply = state->mode.autowrap;
      break;

    case 12:
      reply = state->mode.cursor_blink;
      break;

    case 25:
      reply = state->mode.cursor_visible;
      break;

    case 69:
      reply = state->mode.leftrightmargin;
      break;

    case 1000:
      reply = state->mouse_flags == MOUSE_WANT_CLICK;
      break;

    case 1002:
      reply = state->mouse_flags == (MOUSE_WANT_CLICK|MOUSE_WANT_DRAG);
      break;

    case 1003:
      reply = state->mouse_flags == (MOUSE_WANT_CLICK|MOUSE_WANT_MOVE);
      break;

    case 1005:
      reply = state->mouse_protocol == MOUSE_UTF8;
      break;

    case 1006:
      reply = state->mouse_protocol == MOUSE_SGR;
      break;

    case 1015:
      reply = state->mouse_protocol == MOUSE_RXVT;
      break;

    case 1047:
      reply = state->mode.alt_screen;
      break;

    case 2004:
      reply = state->mode.bracketpaste;
      break;

    default:
      vterm_push_output_sprintf_ctrl(state->vt, C1_CSI, "?%d;%d$y", num, 0);
      return;
  }

  vterm_push_output_sprintf_ctrl(state->vt, C1_CSI, "?%d;%d$y", num, reply ? 1 : 2);
}

static int on_csi(const char *leader, const long args[], int argcount, const char *intermed, char command, void *user)
{
  VTermState *state = user;
  int leader_byte = 0;
  int intermed_byte = 0;
  VTermPos oldpos = state->pos;

  /* Some temporaries for later code */
  int count, val;
  int row, col;
  VTermRect rect;
  int selective;

  if(leader && leader[0]) {
    if(leader[1]) /* longer than 1 char */
      return 0;

    switch(leader[0]) {
    case '?':
    case '>':
      leader_byte = leader[0];
      break;
    default:
      return 0;
    }
  }

  if(intermed && intermed[0]) {
    if(intermed[1]) /* longer than 1 char */
      return 0;

    switch(intermed[0]) {
    case ' ':
    case '"':
    case '$':
    case '\'':
      intermed_byte = intermed[0];
      break;
    default:
      return 0;
    }
  }

  oldpos = state->pos;

#define LBOUND(v,min) if((v) < (min)) (v) = (min)
#define UBOUND(v,max) if((v) > (max)) (v) = (max)

#define LEADER(l,b) ((l << 8) | b)
#define INTERMED(i,b) ((i << 16) | b)

  switch(intermed_byte << 16 | leader_byte << 8 | command) {
  case 0x40: /* ICH - ECMA-48 8.3.64 */
    count = CSI_ARG_COUNT(args[0]);

    if(!is_cursor_in_scrollregion(state))
      break;

    rect.start_row = state->pos.row;
    rect.end_row   = state->pos.row + 1;
    rect.start_col = state->pos.col;
    if(state->mode.leftrightmargin)
      rect.end_col = SCROLLREGION_RIGHT(state);
    else
      rect.end_col = THISROWWIDTH(state);

    scroll(state, rect, 0, -count);

    break;

  case 0x41: /* CUU - ECMA-48 8.3.22 */
    count = CSI_ARG_COUNT(args[0]);
    state->pos.row -= count;
    state->at_phantom = 0;
    break;

  case 0x42: /* CUD - ECMA-48 8.3.19 */
    count = CSI_ARG_COUNT(args[0]);
    state->pos.row += count;
    state->at_phantom = 0;
    break;

  case 0x43: /* CUF - ECMA-48 8.3.20 */
    count = CSI_ARG_COUNT(args[0]);
    state->pos.col += count;
    state->at_phantom = 0;
    break;

  case 0x44: /* CUB - ECMA-48 8.3.18 */
    count = CSI_ARG_COUNT(args[0]);
    state->pos.col -= count;
    state->at_phantom = 0;
    break;

  case 0x45: /* CNL - ECMA-48 8.3.12 */
    count = CSI_ARG_COUNT(args[0]);
    state->pos.col = 0;
    state->pos.row += count;
    state->at_phantom = 0;
    break;

  case 0x46: /* CPL - ECMA-48 8.3.13 */
    count = CSI_ARG_COUNT(args[0]);
    state->pos.col = 0;
    state->pos.row -= count;
    state->at_phantom = 0;
    break;

  case 0x47: /* CHA - ECMA-48 8.3.9 */
    val = CSI_ARG_OR(args[0], 1);
    state->pos.col = val-1;
    state->at_phantom = 0;
    break;

  case 0x48: /* CUP - ECMA-48 8.3.21 */
    row = CSI_ARG_OR(args[0], 1);
    col = argcount < 2 || CSI_ARG_IS_MISSING(args[1]) ? 1 : CSI_ARG(args[1]);
    /* zero-based */
    state->pos.row = row-1;
    state->pos.col = col-1;
    if(state->mode.origin) {
      state->pos.row += state->scrollregion_top;
      state->pos.col += SCROLLREGION_LEFT(state);
    }
    state->at_phantom = 0;
    break;

  case 0x49: /* CHT - ECMA-48 8.3.10 */
    count = CSI_ARG_COUNT(args[0]);
    tab(state, count, +1);
    break;

  case 0x4a: /* ED - ECMA-48 8.3.39 */
  case LEADER('?', 0x4a): /* DECSED - Selective Erase in Display */
    selective = (leader_byte == '?');
    switch(CSI_ARG(args[0])) {
    case CSI_ARG_MISSING:
    case 0:
      rect.start_row = state->pos.row; rect.end_row = state->pos.row + 1;
      rect.start_col = state->pos.col; rect.end_col = state->cols;
      if(rect.end_col > rect.start_col)
        erase(state, rect, selective);

      rect.start_row = state->pos.row + 1; rect.end_row = state->rows;
      rect.start_col = 0;
      for(row = rect.start_row; row < rect.end_row; row++)
	set_lineinfo(state, row, FORCE, DWL_OFF, DHL_OFF);
      if(rect.end_row > rect.start_row)
        erase(state, rect, selective);
      break;

    case 1:
      rect.start_row = 0; rect.end_row = state->pos.row;
      rect.start_col = 0; rect.end_col = state->cols;
      for(row = rect.start_row; row < rect.end_row; row++)
	set_lineinfo(state, row, FORCE, DWL_OFF, DHL_OFF);
      if(rect.end_col > rect.start_col)
        erase(state, rect, selective);

      rect.start_row = state->pos.row; rect.end_row = state->pos.row + 1;
                          rect.end_col = state->pos.col + 1;
      if(rect.end_row > rect.start_row)
        erase(state, rect, selective);
      break;

    case 2:
      rect.start_row = 0; rect.end_row = state->rows;
      rect.start_col = 0; rect.end_col = state->cols;
      for(row = rect.start_row; row < rect.end_row; row++)
	set_lineinfo(state, row, FORCE, DWL_OFF, DHL_OFF);
      erase(state, rect, selective);
      break;
    }
    break;

  case 0x4b: /* EL - ECMA-48 8.3.41 */
  case LEADER('?', 0x4b): /* DECSEL - Selective Erase in Line */
    selective = (leader_byte == '?');
    rect.start_row = state->pos.row;
    rect.end_row   = state->pos.row + 1;

    switch(CSI_ARG(args[0])) {
    case CSI_ARG_MISSING:
    case 0:
      rect.start_col = state->pos.col; rect.end_col = THISROWWIDTH(state); break;
    case 1:
      rect.start_col = 0; rect.end_col = state->pos.col + 1; break;
    case 2:
      rect.start_col = 0; rect.end_col = THISROWWIDTH(state); break;
    default:
      return 0;
    }

    if(rect.end_col > rect.start_col)
      erase(state, rect, selective);

    break;

  case 0x4c: /* IL - ECMA-48 8.3.67 */
    count = CSI_ARG_COUNT(args[0]);

    if(!is_cursor_in_scrollregion(state))
      break;

    rect.start_row = state->pos.row;
    rect.end_row   = SCROLLREGION_BOTTOM(state);
    rect.start_col = SCROLLREGION_LEFT(state);
    rect.end_col   = SCROLLREGION_RIGHT(state);

    scroll(state, rect, -count, 0);

    break;

  case 0x4d: /* DL - ECMA-48 8.3.32 */
    count = CSI_ARG_COUNT(args[0]);

    if(!is_cursor_in_scrollregion(state))
      break;

    rect.start_row = state->pos.row;
    rect.end_row   = SCROLLREGION_BOTTOM(state);
    rect.start_col = SCROLLREGION_LEFT(state);
    rect.end_col   = SCROLLREGION_RIGHT(state);

    scroll(state, rect, count, 0);

    break;

  case 0x50: /* DCH - ECMA-48 8.3.26 */
    count = CSI_ARG_COUNT(args[0]);

    if(!is_cursor_in_scrollregion(state))
      break;

    rect.start_row = state->pos.row;
    rect.end_row   = state->pos.row + 1;
    rect.start_col = state->pos.col;
    if(state->mode.leftrightmargin)
      rect.end_col = SCROLLREGION_RIGHT(state);
    else
      rect.end_col = THISROWWIDTH(state);

    scroll(state, rect, 0, count);

    break;

  case 0x53: /* SU - ECMA-48 8.3.147 */
    count = CSI_ARG_COUNT(args[0]);

    rect.start_row = state->scrollregion_top;
    rect.end_row   = SCROLLREGION_BOTTOM(state);
    rect.start_col = SCROLLREGION_LEFT(state);
    rect.end_col   = SCROLLREGION_RIGHT(state);

    scroll(state, rect, count, 0);

    break;

  case 0x54: /* SD - ECMA-48 8.3.113 */
    count = CSI_ARG_COUNT(args[0]);

    rect.start_row = state->scrollregion_top;
    rect.end_row   = SCROLLREGION_BOTTOM(state);
    rect.start_col = SCROLLREGION_LEFT(state);
    rect.end_col   = SCROLLREGION_RIGHT(state);

    scroll(state, rect, -count, 0);

    break;

  case 0x58: /* ECH - ECMA-48 8.3.38 */
    count = CSI_ARG_COUNT(args[0]);

    rect.start_row = state->pos.row;
    rect.end_row   = state->pos.row + 1;
    rect.start_col = state->pos.col;
    rect.end_col   = state->pos.col + count;
    UBOUND(rect.end_col, THISROWWIDTH(state));

    erase(state, rect, 0);
    break;

  case 0x5a: /* CBT - ECMA-48 8.3.7 */
    count = CSI_ARG_COUNT(args[0]);
    tab(state, count, -1);
    break;

  case 0x60: /* HPA - ECMA-48 8.3.57 */
    col = CSI_ARG_OR(args[0], 1);
    state->pos.col = col-1;
    state->at_phantom = 0;
    break;

  case 0x61: /* HPR - ECMA-48 8.3.59 */
    count = CSI_ARG_COUNT(args[0]);
    state->pos.col += count;
    state->at_phantom = 0;
    break;

  case 0x63: /* DA - ECMA-48 8.3.24 */
    val = CSI_ARG_OR(args[0], 0);
    if(val == 0)
      /* DEC VT100 response */
      vterm_push_output_sprintf_ctrl(state->vt, C1_CSI, "?1;2c");
    break;

  case LEADER('>', 0x63): /* DEC secondary Device Attributes */
    /* This returns xterm version number 100. */
    vterm_push_output_sprintf_ctrl(state->vt, C1_CSI, ">%d;%d;%dc", 0, 100, 0);
    break;

  case 0x64: /* VPA - ECMA-48 8.3.158 */
    row = CSI_ARG_OR(args[0], 1);
    state->pos.row = row-1;
    if(state->mode.origin)
      state->pos.row += state->scrollregion_top;
    state->at_phantom = 0;
    break;

  case 0x65: /* VPR - ECMA-48 8.3.160 */
    count = CSI_ARG_COUNT(args[0]);
    state->pos.row += count;
    state->at_phantom = 0;
    break;

  case 0x66: /* HVP - ECMA-48 8.3.63 */
    row = CSI_ARG_OR(args[0], 1);
    col = argcount < 2 || CSI_ARG_IS_MISSING(args[1]) ? 1 : CSI_ARG(args[1]);
    /* zero-based */
    state->pos.row = row-1;
    state->pos.col = col-1;
    if(state->mode.origin) {
      state->pos.row += state->scrollregion_top;
      state->pos.col += SCROLLREGION_LEFT(state);
    }
    state->at_phantom = 0;
    break;

  case 0x67: /* TBC - ECMA-48 8.3.154 */
    val = CSI_ARG_OR(args[0], 0);

    switch(val) {
    case 0:
      clear_col_tabstop(state, state->pos.col);
      break;
    case 3:
    case 5:
      for(col = 0; col < state->cols; col++)
        clear_col_tabstop(state, col);
      break;
    case 1:
    case 2:
    case 4:
      break;
    /* TODO: 1, 2 and 4 aren't meaningful yet without line tab stops */
    default:
      return 0;
    }
    break;

  case 0x68: /* SM - ECMA-48 8.3.125 */
    if(!CSI_ARG_IS_MISSING(args[0]))
      set_mode(state, CSI_ARG(args[0]), 1);
    break;

  case LEADER('?', 0x68): /* DEC private mode set */
    if(!CSI_ARG_IS_MISSING(args[0]))
      set_dec_mode(state, CSI_ARG(args[0]), 1);
    break;

  case 0x6a: /* HPB - ECMA-48 8.3.58 */
    count = CSI_ARG_COUNT(args[0]);
    state->pos.col -= count;
    state->at_phantom = 0;
    break;

  case 0x6b: /* VPB - ECMA-48 8.3.159 */
    count = CSI_ARG_COUNT(args[0]);
    state->pos.row -= count;
    state->at_phantom = 0;
    break;

  case 0x6c: /* RM - ECMA-48 8.3.106 */
    if(!CSI_ARG_IS_MISSING(args[0]))
      set_mode(state, CSI_ARG(args[0]), 0);
    break;

  case LEADER('?', 0x6c): /* DEC private mode reset */
    if(!CSI_ARG_IS_MISSING(args[0]))
      set_dec_mode(state, CSI_ARG(args[0]), 0);
    break;

  case 0x6d: /* SGR - ECMA-48 8.3.117 */
    vterm_state_setpen(state, args, argcount);
    break;

  case 0x6e: /* DSR - ECMA-48 8.3.35 */
  case LEADER('?', 0x6e): /* DECDSR */
    val = CSI_ARG_OR(args[0], 0);

    {
      char *qmark = (leader_byte == '?') ? "?" : "";

      switch(val) {
      case 0: case 1: case 2: case 3: case 4:
        /* ignore - these are replies */
        break;
      case 5:
        vterm_push_output_sprintf_ctrl(state->vt, C1_CSI, "%s0n", qmark);
        break;
      case 6: /* CPR - cursor position report */
        vterm_push_output_sprintf_ctrl(state->vt, C1_CSI, "%s%d;%dR", qmark, state->pos.row + 1, state->pos.col + 1);
        break;
      }
    }
    break;


  case LEADER('!', 0x70): /* DECSTR - DEC soft terminal reset */
    vterm_state_reset(state, 0);
    break;

  case LEADER('?', INTERMED('$', 0x70)):
    request_dec_mode(state, CSI_ARG(args[0]));
    break;

  case INTERMED(' ', 0x71): /* DECSCUSR - DEC set cursor shape */
    val = CSI_ARG_OR(args[0], 1);

    switch(val) {
    case 0: case 1:
      settermprop_bool(state, VTERM_PROP_CURSORBLINK, 1);
      settermprop_int (state, VTERM_PROP_CURSORSHAPE, VTERM_PROP_CURSORSHAPE_BLOCK);
      break;
    case 2:
      settermprop_bool(state, VTERM_PROP_CURSORBLINK, 0);
      settermprop_int (state, VTERM_PROP_CURSORSHAPE, VTERM_PROP_CURSORSHAPE_BLOCK);
      break;
    case 3:
      settermprop_bool(state, VTERM_PROP_CURSORBLINK, 1);
      settermprop_int (state, VTERM_PROP_CURSORSHAPE, VTERM_PROP_CURSORSHAPE_UNDERLINE);
      break;
    case 4:
      settermprop_bool(state, VTERM_PROP_CURSORBLINK, 0);
      settermprop_int (state, VTERM_PROP_CURSORSHAPE, VTERM_PROP_CURSORSHAPE_UNDERLINE);
      break;
    case 5:
      settermprop_bool(state, VTERM_PROP_CURSORBLINK, 1);
      settermprop_int (state, VTERM_PROP_CURSORSHAPE, VTERM_PROP_CURSORSHAPE_BAR_LEFT);
      break;
    case 6:
      settermprop_bool(state, VTERM_PROP_CURSORBLINK, 0);
      settermprop_int (state, VTERM_PROP_CURSORSHAPE, VTERM_PROP_CURSORSHAPE_BAR_LEFT);
      break;
    }

    break;

  case INTERMED('"', 0x71): /* DECSCA - DEC select character protection attribute */
    val = CSI_ARG_OR(args[0], 0);

    switch(val) {
    case 0: case 2:
      state->protected_cell = 0;
      break;
    case 1:
      state->protected_cell = 1;
      break;
    }

    break;

  case 0x72: /* DECSTBM - DEC custom */
    state->scrollregion_top = CSI_ARG_OR(args[0], 1) - 1;
    state->scrollregion_bottom = argcount < 2 || CSI_ARG_IS_MISSING(args[1]) ? -1 : CSI_ARG(args[1]);
    LBOUND(state->scrollregion_top, 0);
    UBOUND(state->scrollregion_top, state->rows);
    LBOUND(state->scrollregion_bottom, -1);
    if(state->scrollregion_top == 0 && state->scrollregion_bottom == state->rows)
      state->scrollregion_bottom = -1;
    else
      UBOUND(state->scrollregion_bottom, state->rows);

    if(SCROLLREGION_BOTTOM(state) <= state->scrollregion_top) {
      /* Invalid */
      state->scrollregion_top    = 0;
      state->scrollregion_bottom = -1;
    }

    break;

  case 0x73: /* DECSLRM - DEC custom */
    /* Always allow setting these margins, just they won't take effect without DECVSSM */
    state->scrollregion_left = CSI_ARG_OR(args[0], 1) - 1;
    state->scrollregion_right = argcount < 2 || CSI_ARG_IS_MISSING(args[1]) ? -1 : CSI_ARG(args[1]);
    LBOUND(state->scrollregion_left, 0);
    UBOUND(state->scrollregion_left, state->cols);
    LBOUND(state->scrollregion_right, -1);
    if(state->scrollregion_left == 0 && state->scrollregion_right == state->cols)
      state->scrollregion_right = -1;
    else
      UBOUND(state->scrollregion_right, state->cols);

    if(state->scrollregion_right > -1 &&
       state->scrollregion_right <= state->scrollregion_left) {
      /* Invalid */
      state->scrollregion_left  = 0;
      state->scrollregion_right = -1;
    }

    break;

  case 0x74:
    switch(CSI_ARG(args[0])) {
      case 8: /* CSI 8 ; rows ; cols t  set size */
	if (argcount == 3)
	  on_resize(CSI_ARG(args[1]), CSI_ARG(args[2]), state);
    }
    break;

  case INTERMED('\'', 0x7D): /* DECIC */
    count = CSI_ARG_COUNT(args[0]);

    if(!is_cursor_in_scrollregion(state))
      break;

    rect.start_row = state->scrollregion_top;
    rect.end_row   = SCROLLREGION_BOTTOM(state);
    rect.start_col = state->pos.col;
    rect.end_col   = SCROLLREGION_RIGHT(state);

    scroll(state, rect, 0, -count);

    break;

  case INTERMED('\'', 0x7E): /* DECDC */
    count = CSI_ARG_COUNT(args[0]);

    if(!is_cursor_in_scrollregion(state))
      break;

    rect.start_row = state->scrollregion_top;
    rect.end_row   = SCROLLREGION_BOTTOM(state);
    rect.start_col = state->pos.col;
    rect.end_col   = SCROLLREGION_RIGHT(state);

    scroll(state, rect, 0, count);

    break;

  default:
    if(state->fallbacks && state->fallbacks->csi)
      if((*state->fallbacks->csi)(leader, args, argcount, intermed, command, state->fbdata))
        return 1;

    return 0;
  }

  if(state->mode.origin) {
    LBOUND(state->pos.row, state->scrollregion_top);
    UBOUND(state->pos.row, SCROLLREGION_BOTTOM(state)-1);
    LBOUND(state->pos.col, SCROLLREGION_LEFT(state));
    UBOUND(state->pos.col, SCROLLREGION_RIGHT(state)-1);
  }
  else {
    LBOUND(state->pos.row, 0);
    UBOUND(state->pos.row, state->rows-1);
    LBOUND(state->pos.col, 0);
    UBOUND(state->pos.col, THISROWWIDTH(state)-1);
  }

  updatecursor(state, &oldpos, 1);

#ifdef DEBUG
  if(state->pos.row < 0 || state->pos.row >= state->rows ||
     state->pos.col < 0 || state->pos.col >= state->cols) {
    fprintf(stderr, "Position out of bounds after CSI %c: (%d,%d)\n",
        command, state->pos.row, state->pos.col);
    abort();
  }

  if(SCROLLREGION_BOTTOM(state) <= state->scrollregion_top) {
    fprintf(stderr, "Scroll region height out of bounds after CSI %c: %d <= %d\n",
        command, SCROLLREGION_BOTTOM(state), state->scrollregion_top);
    abort();
  }

  if(SCROLLREGION_RIGHT(state) <= SCROLLREGION_LEFT(state)) {
    fprintf(stderr, "Scroll region width out of bounds after CSI %c: %d <= %d\n",
        command, SCROLLREGION_RIGHT(state), SCROLLREGION_LEFT(state));
    abort();
  }
#endif

  return 1;
}

static int on_osc(const char *command, size_t cmdlen, void *user)
{
  VTermState *state = user;

  if(cmdlen < 2)
    return 0;

  if(strneq(command, "0;", 2)) {
    settermprop_string(state, VTERM_PROP_ICONNAME, command + 2, cmdlen - 2);
    settermprop_string(state, VTERM_PROP_TITLE, command + 2, cmdlen - 2);
    return 1;
  }
  else if(strneq(command, "1;", 2)) {
    settermprop_string(state, VTERM_PROP_ICONNAME, command + 2, cmdlen - 2);
    return 1;
  }
  else if(strneq(command, "2;", 2)) {
    settermprop_string(state, VTERM_PROP_TITLE, command + 2, cmdlen - 2);
    return 1;
  }
  else if(strneq(command, "12;", 3)) {
    settermprop_string(state, VTERM_PROP_CURSORCOLOR, command + 3, cmdlen - 3);
    return 1;
  }
  else if(state->fallbacks && state->fallbacks->osc)
    if((*state->fallbacks->osc)(command, cmdlen, state->fbdata))
      return 1;

  return 0;
}

static void request_status_string(VTermState *state, const char *command, size_t cmdlen)
{
  if(cmdlen == 1)
    switch(command[0]) {
      case 'm': /* Query SGR */
        {
          long args[20];
          int argc = vterm_state_getpen(state, args, sizeof(args)/sizeof(args[0]));
	  int argi;
          vterm_push_output_sprintf_ctrl(state->vt, C1_DCS, "1$r");
          for(argi = 0; argi < argc; argi++)
            vterm_push_output_sprintf(state->vt,
                argi == argc - 1             ? "%d" :
                CSI_ARG_HAS_MORE(args[argi]) ? "%d:" :
                                               "%d;",
                CSI_ARG(args[argi]));
          vterm_push_output_sprintf(state->vt, "m");
          vterm_push_output_sprintf_ctrl(state->vt, C1_ST, "");
        }
        return;
      case 'r': /* Query DECSTBM */
        vterm_push_output_sprintf_dcs(state->vt, "1$r%d;%dr", state->scrollregion_top+1, SCROLLREGION_BOTTOM(state));
        return;
      case 's': /* Query DECSLRM */
        vterm_push_output_sprintf_dcs(state->vt, "1$r%d;%ds", SCROLLREGION_LEFT(state)+1, SCROLLREGION_RIGHT(state));
        return;
    }

  if(cmdlen == 2) {
    if(strneq(command, " q", 2)) {
      int reply;
      switch(state->mode.cursor_shape) {
        case VTERM_PROP_CURSORSHAPE_BLOCK:     reply = 2; break;
        case VTERM_PROP_CURSORSHAPE_UNDERLINE: reply = 4; break;
	default: /* VTERM_PROP_CURSORSHAPE_BAR_LEFT */  reply = 6; break;
      }
      if(state->mode.cursor_blink)
        reply--;
      vterm_push_output_sprintf_dcs(state->vt, "1$r%d q", reply);
      return;
    }
    else if(strneq(command, "\"q", 2)) {
      vterm_push_output_sprintf_dcs(state->vt, "1$r%d\"q", state->protected_cell ? 1 : 2);
      return;
    }
  }

  vterm_push_output_sprintf_dcs(state->vt, "0$r%.s", (int)cmdlen, command);
}

static int on_dcs(const char *command, size_t cmdlen, void *user)
{
  VTermState *state = user;

  if(cmdlen >= 2 && strneq(command, "$q", 2)) {
    request_status_string(state, command+2, cmdlen-2);
    return 1;
  }
  else if(state->fallbacks && state->fallbacks->dcs)
    if((*state->fallbacks->dcs)(command, cmdlen, state->fbdata))
      return 1;

  return 0;
}

static int on_resize(int rows, int cols, void *user)
{
  VTermState *state = user;
  VTermPos oldpos = state->pos;
  VTermPos delta = { 0, 0 };

  if(cols != state->cols) {
    unsigned char *newtabstops = vterm_allocator_malloc(state->vt, (cols + 7) / 8);

    /* TODO: This can all be done much more efficiently bytewise */
    int col;
    for(col = 0; col < state->cols && col < cols; col++) {
      unsigned char mask = 1 << (col & 7);
      if(state->tabstops[col >> 3] & mask)
        newtabstops[col >> 3] |= mask;
      else
        newtabstops[col >> 3] &= ~mask;
      }

    for( ; col < cols; col++) {
      unsigned char mask = 1 << (col & 7);
      if(col % 8 == 0)
        newtabstops[col >> 3] |= mask;
      else
        newtabstops[col >> 3] &= ~mask;
    }

    vterm_allocator_free(state->vt, state->tabstops);
    state->tabstops = newtabstops;
  }

  if(rows != state->rows) {
    VTermLineInfo *newlineinfo = vterm_allocator_malloc(state->vt, rows * sizeof(VTermLineInfo));

    int row;
    for(row = 0; row < state->rows && row < rows; row++) {
      newlineinfo[row] = state->lineinfo[row];
    }

    for( ; row < rows; row++) {
      newlineinfo[row].doublewidth = 0;
      newlineinfo[row].doubleheight = 0;
    }

    vterm_allocator_free(state->vt, state->lineinfo);
    state->lineinfo = newlineinfo;
  }

  state->rows = rows;
  state->cols = cols;

  if(state->scrollregion_bottom > -1)
    UBOUND(state->scrollregion_bottom, state->rows);
  if(state->scrollregion_right > -1)
    UBOUND(state->scrollregion_right, state->cols);

  if(state->callbacks && state->callbacks->resize)
    (*state->callbacks->resize)(rows, cols, &delta, state->cbdata);

  if(state->at_phantom && state->pos.col < cols-1) {
    state->at_phantom = 0;
    state->pos.col++;
  }

  state->pos.row += delta.row;
  state->pos.col += delta.col;

  if(state->pos.row >= rows)
    state->pos.row = rows - 1;
  if(state->pos.col >= cols)
    state->pos.col = cols - 1;

  updatecursor(state, &oldpos, 1);

  return 1;
}

static const VTermParserCallbacks parser_callbacks = {
  on_text, /* text */
  on_control, /* control */
  on_escape, /* escape */
  on_csi, /* csi */
  on_osc, /* osc */
  on_dcs, /* dcs */
  on_resize /* resize */
};

VTermState *vterm_obtain_state(VTerm *vt)
{
  VTermState *state;
  if(vt->state)
    return vt->state;

  state = vterm_state_new(vt);
  vt->state = state;

  state->combine_chars_size = 16;
  state->combine_chars = vterm_allocator_malloc(state->vt, state->combine_chars_size * sizeof(state->combine_chars[0]));

  state->tabstops = vterm_allocator_malloc(state->vt, (state->cols + 7) / 8);

  state->lineinfo = vterm_allocator_malloc(state->vt, state->rows * sizeof(VTermLineInfo));

  state->encoding_utf8.enc = vterm_lookup_encoding(ENC_UTF8, 'u');
  if(*state->encoding_utf8.enc->init != NULL)
    (*state->encoding_utf8.enc->init)(state->encoding_utf8.enc, state->encoding_utf8.data);

  vterm_parser_set_callbacks(vt, &parser_callbacks, state);

  return state;
}

void vterm_state_reset(VTermState *state, int hard)
{
  VTermEncoding *default_enc;

  state->scrollregion_top = 0;
  state->scrollregion_bottom = -1;
  state->scrollregion_left = 0;
  state->scrollregion_right = -1;

  state->mode.keypad          = 0;
  state->mode.cursor          = 0;
  state->mode.autowrap        = 1;
  state->mode.insert          = 0;
  state->mode.newline         = 0;
  state->mode.alt_screen      = 0;
  state->mode.origin          = 0;
  state->mode.leftrightmargin = 0;
  state->mode.bracketpaste    = 0;

  state->vt->mode.ctrl8bit   = 0;

  {
    int col;
    for(col = 0; col < state->cols; col++)
      if(col % 8 == 0)
	set_col_tabstop(state, col);
      else
	clear_col_tabstop(state, col);
  }

  {
    int row;
    for(row = 0; row < state->rows; row++)
      set_lineinfo(state, row, FORCE, DWL_OFF, DHL_OFF);
  }

  if(state->callbacks && state->callbacks->initpen)
    (*state->callbacks->initpen)(state->cbdata);

  vterm_state_resetpen(state);

  default_enc = state->vt->mode.utf8 ?
      vterm_lookup_encoding(ENC_UTF8,      'u') :
      vterm_lookup_encoding(ENC_SINGLE_94, 'B');

  {
    int i;
    for(i = 0; i < 4; i++) {
      state->encoding[i].enc = default_enc;
      if(default_enc->init)
	(*default_enc->init)(default_enc, state->encoding[i].data);
    }
  }

  state->gl_set = 0;
  state->gr_set = 1;
  state->gsingle_set = 0;

  state->protected_cell = 0;

  /* Initialise the props */
  settermprop_bool(state, VTERM_PROP_CURSORVISIBLE, 1);
  settermprop_bool(state, VTERM_PROP_CURSORBLINK,   1);
  settermprop_int (state, VTERM_PROP_CURSORSHAPE,   VTERM_PROP_CURSORSHAPE_BLOCK);

  if(hard) {
    VTermRect rect = { 0, 0, 0, 0 };

    state->pos.row = 0;
    state->pos.col = 0;
    state->at_phantom = 0;

    rect.end_row = state->rows;
    rect.end_col =  state->cols;
    erase(state, rect, 0);
  }
}

void vterm_state_get_cursorpos(const VTermState *state, VTermPos *cursorpos)
{
  *cursorpos = state->pos;
}

void vterm_state_set_callbacks(VTermState *state, const VTermStateCallbacks *callbacks, void *user)
{
  if(callbacks) {
    state->callbacks = callbacks;
    state->cbdata = user;

    if(state->callbacks && state->callbacks->initpen)
      (*state->callbacks->initpen)(state->cbdata);
  }
  else {
    state->callbacks = NULL;
    state->cbdata = NULL;
  }
}

void *vterm_state_get_cbdata(VTermState *state)
{
  return state->cbdata;
}

void vterm_state_set_unrecognised_fallbacks(VTermState *state, const VTermParserCallbacks *fallbacks, void *user)
{
  if(fallbacks) {
    state->fallbacks = fallbacks;
    state->fbdata = user;
  }
  else {
    state->fallbacks = NULL;
    state->fbdata = NULL;
  }
}

void *vterm_state_get_unrecognised_fbdata(VTermState *state)
{
  return state->fbdata;
}

int vterm_state_set_termprop(VTermState *state, VTermProp prop, VTermValue *val)
{
  /* Only store the new value of the property if usercode said it was happy.
   * This is especially important for altscreen switching */
  if(state->callbacks && state->callbacks->settermprop)
    if(!(*state->callbacks->settermprop)(prop, val, state->cbdata))
      return 0;

  switch(prop) {
  case VTERM_PROP_TITLE:
  case VTERM_PROP_ICONNAME:
  case VTERM_PROP_CURSORCOLOR:
    /* we don't store these, just transparently pass through */
    return 1;
  case VTERM_PROP_CURSORVISIBLE:
    state->mode.cursor_visible = val->boolean;
    return 1;
  case VTERM_PROP_CURSORBLINK:
    state->mode.cursor_blink = val->boolean;
    return 1;
  case VTERM_PROP_CURSORSHAPE:
    state->mode.cursor_shape = val->number;
    return 1;
  case VTERM_PROP_REVERSE:
    state->mode.screen = val->boolean;
    return 1;
  case VTERM_PROP_ALTSCREEN:
    state->mode.alt_screen = val->boolean;
    if(state->mode.alt_screen) {
      VTermRect rect = {0, 0, 0, 0};
      rect.end_row = state->rows;
      rect.end_col = state->cols;
      erase(state, rect, 0);
    }
    return 1;
  case VTERM_PROP_MOUSE:
    state->mouse_flags = 0;
    if(val->number)
      state->mouse_flags |= MOUSE_WANT_CLICK;
    if(val->number == VTERM_PROP_MOUSE_DRAG)
      state->mouse_flags |= MOUSE_WANT_DRAG;
    if(val->number == VTERM_PROP_MOUSE_MOVE)
      state->mouse_flags |= MOUSE_WANT_MOVE;
    return 1;
  }

  return 0;
}

const VTermLineInfo *vterm_state_get_lineinfo(const VTermState *state, int row)
{
  return state->lineinfo + row;
}