/* $OpenBSD$ */

/*

 * Copyright (c) 2020 Anindya Mukherjee <anindya49@hotmail.com>

 *

 * Permission to use, copy, modify, and distribute this software for any

 * purpose with or without fee is hereby granted, provided that the above

 * copyright notice and this permission notice appear in all copies.

 *

 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES

 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF

 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR

 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES

 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER

 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING

 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

 */

#include "tmux.h"

#include <string.h>

/* Initialise virtual cursor. */

void

grid_reader_start(struct grid_reader *gr, struct grid *gd, u_int cx, u_int cy)

{

  gr->gd = gd;

  gr->cx = cx;

  gr->cy = cy;

}

/* Get cursor position from reader. */

void

grid_reader_get_cursor(struct grid_reader *gr, u_int *cx, u_int *cy)

{

  *cx = gr->cx;

  *cy = gr->cy;

}

/* Get length of line containing the cursor. */

u_int

grid_reader_line_length(struct grid_reader *gr)

{

  return (grid_line_length(gr->gd, gr->cy));

}

/* Move cursor forward one position. */

void

grid_reader_cursor_right(struct grid_reader *gr, int wrap, int all, int onemore)

{

  u_int     px;

  struct grid_cell  gc;

  if (all)

    px = gr->gd->sx;

  else if (onemore)

    px = grid_reader_line_length(gr);

  else {

    px = grid_reader_line_length(gr);

    if (px != 0)

      px--;

  }

  if (wrap && gr->cx >= px && gr->cy < gr->gd->hsize + gr->gd->sy - 1) {

    grid_reader_cursor_start_of_line(gr, 0);

    grid_reader_cursor_down(gr);

  } else if (gr->cx < px) {

    gr->cx++;

    while (gr->cx < px) {

      grid_get_cell(gr->gd, gr->cx, gr->cy, &gc);

      if (~gc.flags & GRID_FLAG_PADDING)

        break;

      gr->cx++;

    }

  }

}

/* Move cursor back one position. */

void

grid_reader_cursor_left(struct grid_reader *gr, int wrap)

{

  struct grid_cell  gc;

  while (gr->cx > 0) {

    grid_get_cell(gr->gd, gr->cx, gr->cy, &gc);

    if (~gc.flags & GRID_FLAG_PADDING)

      break;

    gr->cx--;

  }

  if (gr->cx == 0 && gr->cy > 0 &&

      (wrap ||

       grid_get_line(gr->gd, gr->cy - 1)->flags & GRID_LINE_WRAPPED)) {

    grid_reader_cursor_up(gr);

    grid_reader_cursor_end_of_line(gr, 0, 0);

  } else if (gr->cx > 0)

    gr->cx--;

}

/* Move cursor down one line. */

void

grid_reader_cursor_down(struct grid_reader *gr)

{

  struct grid_cell  gc;

  if (gr->cy < gr->gd->hsize + gr->gd->sy - 1)

    gr->cy++;

  while (gr->cx > 0) {

    grid_get_cell(gr->gd, gr->cx, gr->cy, &gc);

    if (~gc.flags & GRID_FLAG_PADDING)

      break;

    gr->cx--;

  }

}

/* Move cursor up one line. */

void

grid_reader_cursor_up(struct grid_reader *gr)

{

  struct grid_cell  gc;

  if (gr->cy > 0)

    gr->cy--;

  while (gr->cx > 0) {

    grid_get_cell(gr->gd, gr->cx, gr->cy, &gc);

    if (~gc.flags & GRID_FLAG_PADDING)

      break;

    gr->cx--;

  }

}

/* Move cursor to the start of the line. */

void

grid_reader_cursor_start_of_line(struct grid_reader *gr, int wrap)

{

  if (wrap) {

    while (gr->cy > 0 &&

        grid_get_line(gr->gd, gr->cy - 1)->flags &

            GRID_LINE_WRAPPED)

      gr->cy--;

  }

  gr->cx = 0;

}

/* Move cursor to the end of the line. */

void

grid_reader_cursor_end_of_line(struct grid_reader *gr, int wrap, int all)

{

  u_int yy;

  if (wrap) {

    yy = gr->gd->hsize + gr->gd->sy - 1;

    while (gr->cy < yy && grid_get_line(gr->gd, gr->cy)->flags &

        GRID_LINE_WRAPPED)

      gr->cy++;

  }

  if (all)

    gr->cx = gr->gd->sx;

  else

    gr->cx = grid_reader_line_length(gr);

}

/* Handle line wrapping while moving the cursor. */

static int

grid_reader_handle_wrap(struct grid_reader *gr, u_int *xx, u_int *yy)

{

  /*

   * Make sure the cursor lies within the grid reader's bounding area,

   * wrapping to the next line as necessary. Return zero if the cursor

   * would wrap past the bottom of the grid.

   */

  while (gr->cx > *xx) {

    if (gr->cy == *yy)

      return (0);

    grid_reader_cursor_start_of_line(gr, 0);

    grid_reader_cursor_down(gr);

    if (grid_get_line(gr->gd, gr->cy)->flags & GRID_LINE_WRAPPED)

      *xx = gr->gd->sx - 1;

    else

      *xx = grid_reader_line_length(gr);

  }

  return (1);

}

/* Check if character under cursor is in set. */

int

grid_reader_in_set(struct grid_reader *gr, const char *set)

{

  return (grid_in_set(gr->gd, gr->cx, gr->cy, set));

}

/* Move cursor to the start of the next word. */

void

grid_reader_cursor_next_word(struct grid_reader *gr, const char *separators)

{

  u_int xx, yy, width;

  /* Do not break up wrapped words. */

  if (grid_get_line(gr->gd, gr->cy)->flags & GRID_LINE_WRAPPED)

    xx = gr->gd->sx - 1;

  else

    xx = grid_reader_line_length(gr);

  yy = gr->gd->hsize + gr->gd->sy - 1;

  /*

   * When navigating via spaces (for example with next-space) separators

   * should be empty.

   *

   * If we started on a separator that is not whitespace, skip over

   * subsequent separators that are not whitespace. Otherwise, if we

   * started on a non-whitespace character, skip over subsequent

   * characters that are neither whitespace nor separators. Then, skip

   * over whitespace (if any) until the next non-whitespace character.

   */

  if (!grid_reader_handle_wrap(gr, &xx, &yy))

    return;

  if (!grid_reader_in_set(gr, WHITESPACE)) {

    if (grid_reader_in_set(gr, separators)) {

      do

        gr->cx++;

      while (grid_reader_handle_wrap(gr, &xx, &yy) &&

          grid_reader_in_set(gr, separators) &&

          !grid_reader_in_set(gr, WHITESPACE));

    } else {

      do

        gr->cx++;

      while (grid_reader_handle_wrap(gr, &xx, &yy) &&

          !(grid_reader_in_set(gr, separators) ||

          grid_reader_in_set(gr, WHITESPACE)));

    }

  }

  while (grid_reader_handle_wrap(gr, &xx, &yy) &&

      (width = grid_reader_in_set(gr, WHITESPACE)))

    gr->cx += width;

}

/* Move cursor to the end of the next word. */

void

grid_reader_cursor_next_word_end(struct grid_reader *gr, const char *separators)

{

  u_int xx, yy;

  /* Do not break up wrapped words. */

  if (grid_get_line(gr->gd, gr->cy)->flags & GRID_LINE_WRAPPED)

    xx = gr->gd->sx - 1;

  else

    xx = grid_reader_line_length(gr);

  yy = gr->gd->hsize + gr->gd->sy - 1;

  /*

   * When navigating via spaces (for example with next-space), separators

   * should be empty in both modes.

   *

   * If we started on a whitespace, move until reaching the first

   * non-whitespace character. If that character is a separator, treat

   * subsequent separators as a word, and continue moving until the first

   * non-separator. Otherwise, continue moving until the first separator

   * or whitespace.

   */

  while (grid_reader_handle_wrap(gr, &xx, &yy)) {

    if (grid_reader_in_set(gr, WHITESPACE))

      gr->cx++;

    else if (grid_reader_in_set(gr, separators)) {

      do

        gr->cx++;

      while (grid_reader_handle_wrap(gr, &xx, &yy) &&

          grid_reader_in_set(gr, separators) &&

          !grid_reader_in_set(gr, WHITESPACE));

      return;

    } else {

      do

        gr->cx++;

      while (grid_reader_handle_wrap(gr, &xx, &yy) &&

          !(grid_reader_in_set(gr, WHITESPACE) ||

          grid_reader_in_set(gr, separators)));

      return;

    }

  }

}

/* Move to the previous place where a word begins. */

void

grid_reader_cursor_previous_word(struct grid_reader *gr, const char *separators,

    int already, int stop_at_eol)

{

  int oldx, oldy, at_eol, word_is_letters;

  /* Move back to the previous word character. */

  if (already || grid_reader_in_set(gr, WHITESPACE)) {

    for (;;) {

      if (gr->cx > 0) {

        gr->cx--;

        if (!grid_reader_in_set(gr, WHITESPACE)) {

          word_is_letters =

              !grid_reader_in_set(gr, separators);

          break;

        }

      } else {

        if (gr->cy == 0)

          return;

        grid_reader_cursor_up(gr);

        grid_reader_cursor_end_of_line(gr, 0, 0);

        /* Stop if separator at EOL. */

        if (stop_at_eol && gr->cx > 0) {

          oldx = gr->cx;

          gr->cx--;

          at_eol = grid_reader_in_set(gr,

              WHITESPACE);

          gr->cx = oldx;

          if (at_eol) {

            word_is_letters = 0;

            break;

          }

        }

      }

    }

  } else

    word_is_letters = !grid_reader_in_set(gr, separators);

  /* Move back to the beginning of this word. */

  do {

    oldx = gr->cx;

    oldy = gr->cy;

    if (gr->cx == 0) {

      if (gr->cy == 0 ||

          (~grid_get_line(gr->gd, gr->cy - 1)->flags &

          GRID_LINE_WRAPPED))

        break;

      grid_reader_cursor_up(gr);

      grid_reader_cursor_end_of_line(gr, 0, 1);

    }

    if (gr->cx > 0)

      gr->cx--;

  } while (!grid_reader_in_set(gr, WHITESPACE) &&

      word_is_letters != grid_reader_in_set(gr, separators));

  gr->cx = oldx;

  gr->cy = oldy;

}

/* Compare grid cell to UTF-8 data. Return 1 if equal, 0 if not. */

static int

grid_reader_cell_equals_data(const struct grid_cell *gc,

    const struct utf8_data *ud)

{

  if (gc->flags & GRID_FLAG_PADDING)

    return (0);

  if (gc->flags & GRID_FLAG_TAB && ud->size == 1 && *ud->data == '\t')

    return (1);

  if (gc->data.size != ud->size)

    return (0);

  return (memcmp(gc->data.data, ud->data, gc->data.size) == 0);

}

/* Jump forward to character. */

int

grid_reader_cursor_jump(struct grid_reader *gr, const struct utf8_data *jc)

{

  struct grid_cell  gc;

  u_int     px, py, xx, yy;

  px = gr->cx;

  yy = gr->gd->hsize + gr->gd->sy - 1;

  for (py = gr->cy; py <= yy; py++) {

    xx = grid_line_length(gr->gd, py);

    while (px < xx) {

      grid_get_cell(gr->gd, px, py, &gc);

      if (grid_reader_cell_equals_data(&gc, jc)) {

        gr->cx = px;

        gr->cy = py;

        return (1);

      }

      px++;

    }

    if (py == yy ||

        !(grid_get_line(gr->gd, py)->flags & GRID_LINE_WRAPPED))

      return (0);

    px = 0;

  }

  return (0);

}

/* Jump back to character. */

int

grid_reader_cursor_jump_back(struct grid_reader *gr, const struct utf8_data *jc)

{

  struct grid_cell  gc;

  u_int     px, py, xx;

  xx = gr->cx + 1;

  for (py = gr->cy + 1; py > 0; py--) {

    for (px = xx; px > 0; px--) {

      grid_get_cell(gr->gd, px - 1, py - 1, &gc);

      if (grid_reader_cell_equals_data(&gc, jc)) {

        gr->cx = px - 1;

        gr->cy = py - 1;

        return (1);

      }

    }

    if (py == 1 ||

        !(grid_get_line(gr->gd, py - 2)->flags & GRID_LINE_WRAPPED))

      return (0);

    xx = grid_line_length(gr->gd, py - 2);

  }

  return (0);

}

/* Jump back to the first non-blank character of the line. */

void

grid_reader_cursor_back_to_indentation(struct grid_reader *gr)

{

  struct grid_cell  gc;

  u_int     px, py, xx, yy, oldx, oldy;

  yy = gr->gd->hsize + gr->gd->sy - 1;

  oldx = gr->cx;

  oldy = gr->cy;

  grid_reader_cursor_start_of_line(gr, 1);

  for (py = gr->cy; py <= yy; py++) {

    xx = grid_line_length(gr->gd, py);

    for (px = 0; px < xx; px++) {

      grid_get_cell(gr->gd, px, py, &gc);

      if ((gc.data.size != 1 || *gc.data.data != ' ') &&

          ~gc.flags & GRID_FLAG_TAB &&

          ~gc.flags & GRID_FLAG_PADDING) {

        gr->cx = px;

        gr->cy = py;

        return;

      }

    }

    if (~grid_get_line(gr->gd, py)->flags & GRID_LINE_WRAPPED)

      break;

  }

  gr->cx = oldx;

  gr->cy = oldy;

}