#include "termdriver.h"

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

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

#define CSI_MORE_SUBPARAM 0x80000000
#define CSI_NEXT_SUB(x)   ((x) & CSI_MORE_SUBPARAM)
#define CSI_PARAM(x)      ((x) & ~CSI_MORE_SUBPARAM)

struct XTermDriver {
  TickitTermDriver driver;

  int dcs_offset;
  char dcs_buffer[16];

  struct {
    unsigned int altscreen:1;
    unsigned int cursorvis:1;
    unsigned int cursorblink:1;
    unsigned int cursorshape:2;
    unsigned int mouse:2;
    unsigned int keypad:1;
  } mode;

  struct {
    unsigned int cursorshape:1;
    unsigned int slrm:1;
    unsigned int csi_sub_colon:1;
    unsigned int rgb8:1;
  } cap;

  struct {
    unsigned int cursorvis:1;
    unsigned int cursorblink:1;
    unsigned int cursorshape:2;
    unsigned int slrm:1;
  } initialised;
};

static bool print(TickitTermDriver *ttd, const char *str, size_t len)
{
  tickit_termdrv_write_str(ttd, str, len);
  return true;
}

static bool goto_abs(TickitTermDriver *ttd, int line, int col)
{
  if(line != -1 && col > 0)
    tickit_termdrv_write_strf(ttd, "\e[%d;%dH", line+1, col+1);
  else if(line != -1 && col == 0)
    tickit_termdrv_write_strf(ttd, "\e[%dH", line+1);
  else if(line != -1)
    tickit_termdrv_write_strf(ttd, "\e[%dd", line+1);
  else if(col > 0)
    tickit_termdrv_write_strf(ttd, "\e[%dG", col+1);
  else if(col != -1)
    tickit_termdrv_write_str(ttd, "\e[G", 3);

  return true;
}

static bool move_rel(TickitTermDriver *ttd, int downward, int rightward)
{
  if(downward > 1)
    tickit_termdrv_write_strf(ttd, "\e[%dB", downward);
  else if(downward == 1)
    tickit_termdrv_write_str(ttd, "\e[B", 3);
  else if(downward == -1)
    tickit_termdrv_write_str(ttd, "\e[A", 3);
  else if(downward < -1)
    tickit_termdrv_write_strf(ttd, "\e[%dA", -downward);

  if(rightward > 1)
    tickit_termdrv_write_strf(ttd, "\e[%dC", rightward);
  else if(rightward == 1)
    tickit_termdrv_write_str(ttd, "\e[C", 3);
  else if(rightward == -1)
    tickit_termdrv_write_str(ttd, "\e[D", 3);
  else if(rightward < -1)
    tickit_termdrv_write_strf(ttd, "\e[%dD", -rightward);

  return true;
}

static bool scrollrect(TickitTermDriver *ttd, const TickitRect *rect, int downward, int rightward)
{
  struct XTermDriver *xd = (struct XTermDriver *)ttd;

  if(!downward && !rightward)
    return true;

  int term_cols;
  tickit_term_get_size(ttd->tt, NULL, &term_cols);

  int right = tickit_rect_right(rect);

  /* Use DECSLRM only for 1 line of insert/delete, because any more and it's
   * likely better to use the generic system below
   */
  if(((xd->cap.slrm && rect->lines == 1) || (right == term_cols))
      && downward == 0) {
    if(right < term_cols)
      tickit_termdrv_write_strf(ttd, "\e[;%ds", right);

    for(int line = rect->top; line < tickit_rect_bottom(rect); line++) {
      goto_abs(ttd, line, rect->left);
      if(rightward > 1)
        tickit_termdrv_write_strf(ttd, "\e[%dP", rightward);  /* DCH */
      else if(rightward == 1)
        tickit_termdrv_write_str(ttd, "\e[P", 3);             /* DCH1 */
      else if(rightward == -1)
        tickit_termdrv_write_str(ttd, "\e[@", 3);             /* ICH1 */
      else if(rightward < -1)
        tickit_termdrv_write_strf(ttd, "\e[%d@", -rightward); /* ICH */
    }

    if(right < term_cols)
      tickit_termdrv_write_strf(ttd, "\e[s");

    return true;
  }

  if(xd->cap.slrm ||
     (rect->left == 0 && rect->cols == term_cols && rightward == 0)) {
    tickit_termdrv_write_strf(ttd, "\e[%d;%dr", rect->top + 1, tickit_rect_bottom(rect));

    if(rect->left > 0 || right < term_cols)
      tickit_termdrv_write_strf(ttd, "\e[%d;%ds", rect->left + 1, right);

    goto_abs(ttd, rect->top, rect->left);

    if(downward > 1)
      tickit_termdrv_write_strf(ttd, "\e[%dM", downward);  /* DL */
    else if(downward == 1)
      tickit_termdrv_write_str(ttd, "\e[M", 3);            /* DL1 */
    else if(downward == -1)
      tickit_termdrv_write_str(ttd, "\e[L", 3);            /* IL1 */
    else if(downward < -1)
      tickit_termdrv_write_strf(ttd, "\e[%dL", -downward); /* IL */

    if(rightward > 1)
      tickit_termdrv_write_strf(ttd, "\e[%d'~", rightward);  /* DECDC */
    else if(rightward == 1)
      tickit_termdrv_write_str(ttd, "\e['~", 4);             /* DECDC1 */
    else if(rightward == -1)
      tickit_termdrv_write_str(ttd, "\e['}", 4);             /* DECIC1 */
    if(rightward < -1)
      tickit_termdrv_write_strf(ttd, "\e[%d'}", -rightward); /* DECIC */

    tickit_termdrv_write_str(ttd, "\e[r", 3);

    if(rect->left > 0 || right < term_cols)
      tickit_termdrv_write_str(ttd, "\e[s", 3);

    return true;
  }

  return false;
}

static bool erasech(TickitTermDriver *ttd, int count, TickitMaybeBool moveend)
{
  if(count < 1)
    return true;

  /* Only use ECH if we're not in reverse-video mode. xterm doesn't do rv+ECH
   * properly
   */
  if(!tickit_pen_get_bool_attr(tickit_termdrv_current_pen(ttd), TICKIT_PEN_REVERSE)) {
    if(count == 1)
      tickit_termdrv_write_str(ttd, "\e[X", 3);
    else
      tickit_termdrv_write_strf(ttd, "\e[%dX", count);

    if(moveend == TICKIT_YES)
      move_rel(ttd, 0, count);
  }
  else {
     /* TODO: consider tickit_termdrv_write_chrfill(ttd, c, n)
     */
    char *spaces = tickit_termdrv_get_tmpbuffer(ttd, 64);
    memset(spaces, ' ', 64);
    while(count > 64) {
      tickit_termdrv_write_str(ttd, spaces, 64);
      count -= 64;
    }
    tickit_termdrv_write_str(ttd, spaces, count);

    if(moveend == TICKIT_NO)
      move_rel(ttd, 0, -count);
  }

  return true;
}

static bool clear(TickitTermDriver *ttd)
{
  tickit_termdrv_write_strf(ttd, "\e[2J", 4);
  return true;
}

static struct SgrOnOff { int on, off; } sgr_onoff[] = {
  {},         /* none */
  { 30, 39 }, /* fg */
  { 40, 49 }, /* bg */
  {  1, 22 }, /* bold */
  {  4, 24 }, /* under */
  {  3, 23 }, /* italic */
  {  7, 27 }, /* reverse */
  {  9, 29 }, /* strike */
  { 10, 10 }, /* altfont */
  {  5, 25 }, /* blink */
};

static bool chpen(TickitTermDriver *ttd, const TickitPen *delta, const TickitPen *final)
{
  struct XTermDriver *xd = (struct XTermDriver *)ttd;

  /* There can be at most 16 SGR parameters; 5 from each of 2 colours, and
   * 6 single attributes
   */
  int params[16];
  int pindex = 0;

  for(TickitPenAttr attr = 1; attr < TICKIT_N_PEN_ATTRS; attr++) {
    if(!tickit_pen_has_attr(delta, attr))
      continue;

    struct SgrOnOff *onoff = &sgr_onoff[attr];

    int val;

    switch(attr) {
    case TICKIT_PEN_FG:
    case TICKIT_PEN_BG:
      val = tickit_pen_get_colour_attr(delta, attr);
      if(val < 0)
        params[pindex++] = onoff->off;
      else if(xd->cap.rgb8 && tickit_pen_has_colour_attr_rgb8(delta, attr)) {
        TickitPenRGB8 rgb = tickit_pen_get_colour_attr_rgb8(delta, attr);
        params[pindex++] = (onoff->on+8) | CSI_MORE_SUBPARAM;
        params[pindex++] = 2             | CSI_MORE_SUBPARAM;
        params[pindex++] = rgb.r         | CSI_MORE_SUBPARAM;
        params[pindex++] = rgb.g         | CSI_MORE_SUBPARAM;
        params[pindex++] = rgb.b;
      }
      else if(val < 8)
        params[pindex++] = onoff->on + val;
      else if(val < 16)
        params[pindex++] = onoff->on+60 + val-8;
      else {
        params[pindex++] = (onoff->on+8) | CSI_MORE_SUBPARAM;
        params[pindex++] = 5 | CSI_MORE_SUBPARAM;
        params[pindex++] = val;
      }
      break;

    case TICKIT_PEN_UNDER:
      val = tickit_pen_get_int_attr(delta, attr);
      if(!val)
        params[pindex++] = onoff->off;
      else if(val == 1)
        params[pindex++] = onoff->on;
      else {
        params[pindex++] = onoff->on | CSI_MORE_SUBPARAM;
        params[pindex++] = val;
      }
      break;

    case TICKIT_PEN_ALTFONT:
      val = tickit_pen_get_int_attr(delta, attr);
      if(val < 0 || val >= 10)
        params[pindex++] = onoff->off;
      else
        params[pindex++] = onoff->on + val;
      break;

    case TICKIT_PEN_BOLD:
    case TICKIT_PEN_ITALIC:
    case TICKIT_PEN_REVERSE:
    case TICKIT_PEN_STRIKE:
    case TICKIT_PEN_BLINK:
      val = tickit_pen_get_bool_attr(delta, attr);
      params[pindex++] = val ? onoff->on : onoff->off;
      break;

    case TICKIT_N_PEN_ATTRS:
      break;
    }
  }

  if(pindex == 0)
    return true;

  /* If we're going to clear all the attributes then empty SGR is neater */
  if(!tickit_pen_is_nondefault(final))
    pindex = 0;

  /* Render params[] into a CSI string */

  size_t len = 3; /* ESC [ ... m */
  for(int i = 0; i < pindex; i++)
    len += snprintf(NULL, 0, "%d", CSI_PARAM(params[i])) + 1;
  if(pindex > 0)
    len--; /* Last one has no final separator */

  char *buffer = tickit_termdrv_get_tmpbuffer(ttd, len + 1);
  char *s = buffer;

  s += sprintf(s, "\e[");
  for(int i = 0; i < pindex-1; i++)
    s += sprintf(s, "%d%c", CSI_PARAM(params[i]),
        CSI_NEXT_SUB(params[i]) && xd->cap.csi_sub_colon ? ':' : ';');
  if(pindex > 0)
    s += sprintf(s, "%d", CSI_PARAM(params[pindex-1]));
  sprintf(s, "m");

  tickit_termdrv_write_str(ttd, buffer, len);

  return true;
}

static bool getctl_int(TickitTermDriver *ttd, TickitTermCtl ctl, int *value)
{
  struct XTermDriver *xd = (struct XTermDriver *)ttd;

  switch(ctl) {
    case TICKIT_TERMCTL_ALTSCREEN:
      *value = xd->mode.altscreen;
      return true;

    case TICKIT_TERMCTL_CURSORVIS:
      *value = xd->mode.cursorvis;
      return true;

    case TICKIT_TERMCTL_CURSORBLINK:
      *value = xd->mode.cursorblink;
      return true;

    case TICKIT_TERMCTL_MOUSE:
      *value = xd->mode.mouse;
      return true;

    case TICKIT_TERMCTL_CURSORSHAPE:
      *value = xd->mode.cursorshape;
      return true;

    case TICKIT_TERMCTL_KEYPAD_APP:
      *value = xd->mode.keypad;
      return true;

    case TICKIT_TERMCTL_COLORS:
      *value = xd->cap.rgb8 ? (1<<24) : 256;
      return true;

    default:
      return false;
  }
}

static int mode_for_mouse(TickitTermMouseMode mode)
{
  switch(mode) {
    case TICKIT_TERM_MOUSEMODE_CLICK: return 1000;
    case TICKIT_TERM_MOUSEMODE_DRAG:  return 1002;
    case TICKIT_TERM_MOUSEMODE_MOVE:  return 1003;

    case TICKIT_TERM_MOUSEMODE_OFF:
      break;
  }
  return 0;
}

static bool setctl_int(TickitTermDriver *ttd, TickitTermCtl ctl, int value)
{
  struct XTermDriver *xd = (struct XTermDriver *)ttd;

  switch(ctl) {
    case TICKIT_TERMCTL_ALTSCREEN:
      if(!xd->mode.altscreen == !value)
        return true;

      tickit_termdrv_write_str(ttd, value ? "\e[?1049h" : "\e[?1049l", 0);
      xd->mode.altscreen = !!value;
      return true;

    case TICKIT_TERMCTL_CURSORVIS:
      if(!xd->mode.cursorvis == !value)
        return true;

      tickit_termdrv_write_str(ttd, value ? "\e[?25h" : "\e[?25l", 0);
      xd->mode.cursorvis = !!value;
      return true;

    case TICKIT_TERMCTL_CURSORBLINK:
      if(xd->initialised.cursorblink && !xd->mode.cursorblink == !value)
        return true;

      tickit_termdrv_write_str(ttd, value ? "\e[?12h" : "\e[?12l", 0);
      xd->mode.cursorblink = !!value;
      return true;

    case TICKIT_TERMCTL_MOUSE:
      if(xd->mode.mouse == value)
        return true;

      /* Modes 1000, 1002 and 1003 are mutually exclusive; enabling any one
       * disables the other two
       */
      if(!value)
        tickit_termdrv_write_strf(ttd, "\e[?%dl\e[?1006l", mode_for_mouse(xd->mode.mouse));
      else
        tickit_termdrv_write_strf(ttd, "\e[?%dh\e[?1006h", mode_for_mouse(value));

      xd->mode.mouse = value;
      return true;

    case TICKIT_TERMCTL_CURSORSHAPE:
      if(xd->initialised.cursorshape && xd->mode.cursorshape == value)
        return true;

      if(xd->cap.cursorshape)
        tickit_termdrv_write_strf(ttd, "\e[%d q", value * 2 + (xd->mode.cursorblink ? -1 : 0));
      xd->mode.cursorshape = value;
      return true;

    case TICKIT_TERMCTL_KEYPAD_APP:
      if(!xd->mode.keypad == !value)
        return true;

      tickit_termdrv_write_strf(ttd, value ? "\e=" : "\e>");
      return true;

    default:
      return false;
  }
}

static bool setctl_str(TickitTermDriver *ttd, TickitTermCtl ctl, const char *value)
{
  switch(ctl) {
    case TICKIT_TERMCTL_ICON_TEXT:
      tickit_termdrv_write_strf(ttd, "\e]1;%s\e\\", value);
      return true;

    case TICKIT_TERMCTL_TITLE_TEXT:
      tickit_termdrv_write_strf(ttd, "\e]2;%s\e\\", value);
      return true;

    case TICKIT_TERMCTL_ICONTITLE_TEXT:
      tickit_termdrv_write_strf(ttd, "\e]0;%s\e\\", value);
      return true;

    default:
      return false;
  }
}

static void start(TickitTermDriver *ttd)
{
  // Enable DECSLRM
  tickit_termdrv_write_strf(ttd, "\e[?69h");

  // Find out if DECSLRM is actually supported
  tickit_termdrv_write_strf(ttd, "\e[?69$p");

  // Also query the current cursor visibility, blink status, and shape
  tickit_termdrv_write_strf(ttd, "\e[?25$p\e[?12$p\eP$q q\e\\");

  // Try to work out whether the terminal supports 24bit colours (RGB8) and
  // whether it understands : to separate sub-params
  tickit_termdrv_write_strf(ttd, "\e[38;5;255m\e[38:2:0:1:2m\eP$qm\e\\\e[m");

  /* Some terminals (e.g. xfce4-terminal) don't understand DECRQM and print
   * the raw bytes directly as output, while still claiming to be TERM=xterm
   * It doens't hurt at this point to clear the current line just in case.
   */
  tickit_termdrv_write_strf(ttd, "\e[G\e[K");

  tickit_term_flush(ttd->tt);
}

static bool started(TickitTermDriver *ttd)
{
  struct XTermDriver *xd = (struct XTermDriver *)ttd;

  return xd->initialised.cursorvis &&
         xd->initialised.cursorblink &&
         xd->initialised.cursorshape &&
         xd->initialised.slrm;
}

static int on_modereport(TickitTermDriver *ttd, int initial, int mode, int value)
{
  struct XTermDriver *xd = (struct XTermDriver *)ttd;

  if(initial == '?') // DEC mode
    switch(mode) {
      case 12: // Cursor blink
        if(value == 1)
          xd->mode.cursorblink = 1;
        xd->initialised.cursorblink = 1;
        break;
      case 25: // DECTCEM == Cursor visibility
        if(value == 1)
          xd->mode.cursorvis = 1;
        xd->initialised.cursorvis = 1;
        break;
      case 69: // DECVSSM
        if(value == 1 || value == 2)
          xd->cap.slrm = 1;
        xd->initialised.slrm = 1;
        break;
    }

  return 1;
}

static int on_decrqss(TickitTermDriver *ttd, const char *args, size_t arglen)
{
  struct XTermDriver *xd = (struct XTermDriver *)ttd;

  if(strneq(args + arglen - 2, " q", 2)) { // DECSCUSR
    int value;
    if(sscanf(args, "%d", &value)) {
      // value==1 or 2 => shape == 1, 3 or 4 => 2, etc..
      int shape = (value+1) / 2;
      xd->mode.cursorshape = shape;
      xd->cap.cursorshape = 1;
    }
    xd->initialised.cursorshape = 1;
  }
  else if(strneq(args + arglen - 1, "m", 1)) { // SGR
    // skip the initial number, find the first separator
    while(arglen && args[0] >= '0' && args[0] <= '9')
      args++, arglen--;
    if(!arglen)
      return 1;

    if(args[0] == ':')
      xd->cap.csi_sub_colon = 1;
    args++, arglen--;

    // If the palette index is 2 then the terminal understands rgb8
    int value;
    if(sscanf(args, "%d", &value) && value == 2)
      xd->cap.rgb8 = 1;
  }

  return 1;
}

static void teardown(TickitTermDriver *ttd)
{
  struct XTermDriver *xd = (struct XTermDriver *)ttd;

  if(xd->mode.mouse)
    tickit_termdrv_write_strf(ttd, "\e[?%dl\e[?1006l", mode_for_mouse(xd->mode.mouse));
  if(!xd->mode.cursorvis)
    tickit_termdrv_write_str(ttd, "\e[?25h", 0);
  if(xd->mode.altscreen)
    tickit_termdrv_write_str(ttd, "\e[?1049l", 0);
  if(xd->mode.keypad)
    tickit_termdrv_write_strf(ttd, "\e>");

  // Reset pen
  tickit_termdrv_write_str(ttd, "\e[m", 3);
}

static void resume(TickitTermDriver *ttd)
{
  struct XTermDriver *xd = (struct XTermDriver *)ttd;

  if(xd->mode.keypad)
    tickit_termdrv_write_strf(ttd, "\e=");
  if(xd->mode.altscreen)
    tickit_termdrv_write_str(ttd, "\e[?1049h", 0);
  if(!xd->mode.cursorvis)
    tickit_termdrv_write_str(ttd, "\e[?25l", 0);
  if(xd->mode.mouse)
    tickit_termdrv_write_strf(ttd, "\e[?%dh\e[?1006h", mode_for_mouse(xd->mode.mouse));
}

static void destroy(TickitTermDriver *ttd)
{
  struct XTermDriver *xd = (struct XTermDriver *)ttd;

  free(xd);
}

static TickitTermDriverVTable xterm_vtable = {
  .destroy    = destroy,
  .start      = start,
  .started    = started,
  .stop       = teardown,
  .pause      = teardown,
  .resume     = resume,
  .print      = print,
  .goto_abs   = goto_abs,
  .move_rel   = move_rel,
  .scrollrect = scrollrect,
  .erasech    = erasech,
  .clear      = clear,
  .chpen      = chpen,
  .getctl_int = getctl_int,
  .setctl_int = setctl_int,
  .setctl_str = setctl_str,
  .on_modereport = on_modereport,
  .on_decrqss    = on_decrqss,
};

static TickitTermDriver *new(const TickitTermProbeArgs *args)
{
  const char *termtype = args->termtype;

  if(strncmp(termtype, "xterm", 5) != 0)
    return NULL;

  switch(termtype[5]) {
    case 0: case '-':
      break;
    default:
      return NULL;
  }

  struct XTermDriver *xd = malloc(sizeof(struct XTermDriver));
  xd->driver.vtable = &xterm_vtable;

  xd->dcs_offset = -1;

  memset(&xd->mode, 0, sizeof xd->mode);
  xd->mode.cursorvis = 1;

  memset(&xd->cap, 0, sizeof xd->cap);

  memset(&xd->initialised, 0, sizeof xd->initialised);

  return (TickitTermDriver*)xd;
}

TickitTermDriverProbe tickit_termdrv_probe_xterm = {
  .new = new,
};