#if 0 /*
#/  ================================================================
#/
#/    ui.c
#/
#/  ================================================================
#/
#/    Self-compilation shell script
#/
SRC=${0##*./}
BIN=${SRC%.*}
gcc                                         \
  -Wall -Wextra -Werror -pedantic           \
  -Wno-old-style-declaration                \
  -Wno-missing-braces                       \
  -Wno-unused-variable                      \
  -Wno-unused-but-set-variable              \
  -Wno-unused-parameter                     \
  -Wno-overlength-strings                   \
  -O3                                       \
  -fsanitize=undefined,address,leak -mshstk \
  -lX11 -lm                                 \
  -o $BIN $SRC &&                           \
  ./$BIN $@ && rm $BIN
exit $? # */
#endif

#include "../reduced_system_layer.c"

#define CHAR_NUM_BITS_X 6
#define CHAR_NUM_BITS_Y 7
#define CHAR_NUM_BITS   (CHAR_NUM_BITS_X * CHAR_NUM_BITS_Y)

enum {
  OP_SET,
  OP_XOR,
};

u64 bitfont[] = {
  0xbc0000000000, 0xc00300000, 0x5fd5040093f24fc9, 0xa00a2c2a1a280105, 0xc000415e6f, 0x400000020be0000, 0x1c38a8400000007d, 0x40002043e1020215, 0x408102000000010, 0x9800000000020002, 0xf913e00000033, 0x53200000207c8800, 0x3654880000099, 0x54b800000f840e00, 0xe953c000001a, 0x953e000000674080, 0x1e54b800000f, 0x490000000000240, 0x88a08000000, 0x20a220050a142850, 0x6520800000, 0x912f801eab260be, 0x800034952bf0001f, 0xc850bf0000921427, 0xf00010a54afc0003, 0xd29427800002142b, 0x840007e1023f0000, 0x7d09100000217e, 0x3f000188a08fc000, 0xc30c0cfc00000810, 0x27803f101013f00f, 0xc244bf0000f214, 0x4bf0002f21427800, 0xc254a480006c24, 0x407c00102fc08100, 0xf208080f0000fa0, 0x531007d81c607c0, 0xc208288c031141, 0x83fc00046954b10, 0x180e03000000, 0x41040000000ff04, 0x8102040810000404, 0x2a54600000000101, 0x309123e0000e, 0xc912180000a22447, 0x8000062a54700007, 0xe52a4300000029f0, 0xa0000602043e0001, 0x1d48000002074, 0x1f000003610f8000, 0x13e04f800000010, 0x470000780813e00f, 0x184893e0000e224, 0x23e0001f12243000, 0x82a54100000008, 0x40780000009f0200, 0xe208080e0001f20, 0xa22007981860780, 0x82082888022282, 0x16c200004ca95320, 0x7f000004, 0x408200000086d04, 0x8204,
};

#define BITFONT_LEN ((i64) (sizeof bitfont / sizeof *bitfont))

i64 char_column_offset(c32 c, i64 column_index) {
  if (column_index < 0 || column_index >= CHAR_NUM_BITS_X)
    return -1;
  return (c - 32) * CHAR_NUM_BITS + column_index * CHAR_NUM_BITS_Y;
}

b8 char_bit(i64 column_offset, i64 row_index) {
  if (column_offset < 0 || column_offset / 64 >= BITFONT_LEN || row_index < 0 || row_index >= CHAR_NUM_BITS_Y)
    return 0;

  i64 bit_index   = column_offset + row_index;
  i64 qword_index = bit_index / 64;
  if (qword_index < 0 || qword_index >= BITFONT_LEN)
    return 0;
  u64 mask        = 1ull << (bit_index % 64);
  return !!(bitfont[qword_index] & mask);
}

u64 char_column_convolved(c32 c, i64 column_index) {
  if (column_index < 0 || column_index >= CHAR_NUM_BITS_X)
    return 0;

  u64 column = 0;
  i64 offset = char_column_offset(c, column_index);

  for (i64 y = 0; y < CHAR_NUM_BITS_Y; ++y)
    if (char_bit(offset, y))
      column |= 3ull << y;

  return column;
}

b8 char_column_empty(c32 c, i64 column_index) {
  if (column_index < 0 || column_index >= CHAR_NUM_BITS_X)
    return 1;

  i64 offset = char_column_offset(c, column_index);

  for (i64 y = 0; y < CHAR_NUM_BITS_Y; ++y)
    if (char_bit(offset, y))
      return 0;

  return 1;
}

i64 char_width(c32 c) {
  if (c < 32)
    return 0;
  if (c == ' ' || c > 127)
    return 4;

  i64 width = 0;

  for (; width < CHAR_NUM_BITS_X; ++width)
    if (char_column_empty(c, width) && char_column_empty(c, width + 1))
      break;

  return width;
}

i64 char_spacing(i64 num_chars, c32 *text, i64 index) {
  assert(text != NULL);

  if (index < 0 || index + 1 >= num_chars)
    return 0;

  u64 a = char_column_convolved(text[index], char_width(text[index]) - 1);
  u64 b = char_column_convolved(text[index + 1], 0);

  if (!!(a & b))
    return 1;

  return 0;
}

i64 text_cursor(i64 num_chars, c32 *text) {
  assert(text != NULL);

  i64 cursor = 0;

  for (i64 i = 0; i < num_chars; ++i) {
    if (text[i] <= ' ') {
      if (text[i] == '\n')
        cursor = 0;
      else if (text[i] == '\b' && i > 0)
        cursor -= char_width(text[i - 1]) + char_spacing(num_chars, text, i - 1);
      else if (text[i] == '\r')
        cursor = 0;
      else
        cursor += char_width(' ') + char_spacing(num_chars, text, i);
      continue;
    }
    cursor += char_width(text[i]) + char_spacing(num_chars, text, i);
  }

  return cursor;
}

i64 enum_text_columns(i64 num_chars, c32 *text) {
  assert(text != NULL);

  i64 cols = 0;
  i64 n    = 0;

  for (i64 i = 0; i < num_chars; ++i) {
    if (text[i] <= ' ') {
      if (text[i] == '\n') {
        if (cols < n)
          cols = n;
        n = 0;
      } else if (text[i] == '\b' && i > 0) {
        if (cols < n)
          cols = n;
        n -= char_width(text[i - 1]) + char_spacing(num_chars, text, i - 1);
      } else if (text[i] == '\r') {
        if (cols < n)
          cols = n;
        n = 0;
      } else
        n += char_width(' ') + char_spacing(num_chars, text, i);
      continue;
    }
    n += char_width(text[i]) + char_spacing(num_chars, text, i);
  }

  if (cols < n)
    cols = n;

  return cols;
}

i64 enum_text_rows(i64 num_chars, c32 *text) {
  assert(text != NULL);

  i64 rows = 0;

  for (i64 i = 0; i <= num_chars; ++i)
    if (i == num_chars || text[i] == '\n') {
      if (rows > 0)
        ++rows;
      rows += CHAR_NUM_BITS_Y;
    }

  return rows;
}

void print_text(u32 color, f64 x0, f64 y0, f64 scale_x, f64 scale_y, i64 num_chars, c32 *text) {
  assert(text != NULL);

  f64 x = x0;
  f64 y = y0;

  f64 kx = scale_x;
  f64 h  = scale_y * CHAR_NUM_BITS_Y;

  for (i64 n = 0; n < num_chars; ++n) {
    if (text[n] <= ' ') {
      if (text[n] == '\n') {
        x  = x0;
        y += scale_y * (CHAR_NUM_BITS_Y + 1);
      }
      else if (text[n] == '\b' && n > 0)
        x -= kx * (char_width(text[n - 1]) + char_spacing(num_chars, text, n - 1));
      else if (text[n] == '\r')
        x  = x0;
      else
        x += kx * (char_width(' ') + char_spacing(num_chars, text, n));
      continue;
    }

    i64 num_cols = char_width(text[n]);
    f64 w        = num_cols * kx;

    i64 i0 = (i64) floor(x + .5);
    i64 i1 = (i64) floor(x + w + .5);
    i64 j0 = (i64) floor(y + .5);
    i64 j1 = (i64) floor(y + h + .5);

    for (i64 i = i0; i < i1; ++i) {
      if (i < 0) continue;
      if (i >= platform.frame_width) break;

      i64 column = ((i - i0) * num_cols) / (i1 - i0);
      i64 offset = char_column_offset(text[n], column);

      for (i64 j = j0; j < j1; ++j) {
        if (j < 0) continue;
        if (j >= platform.frame_height) break;

        i64 row = ((j - j0) * CHAR_NUM_BITS_Y) / (j1 - j0);

        if (char_bit(offset, row))
          platform.pixels[j * platform.frame_width + i] = color;
      }
    }

    x += kx * (num_cols + char_spacing(num_chars, text, n));
  }
}

void draw_panel(u32 op, u32 color, f64 x0, f64 y0, f64 width, f64 height) {
  i64 i0 = (i64) floor(x0 + .5);
  i64 j0 = (i64) floor(y0 + .5);
  i64 i1 = (i64) floor(x0 + width + .5);
  i64 j1 = (i64) floor(y0 + height + .5);

  if (i0 < 0) i0 = 0;
  if (j0 < 0) j0 = 0;
  if (i1 >= platform.frame_width)  i1 = platform.frame_width  - 1;
  if (j1 >= platform.frame_height) j1 = platform.frame_height - 1;

  for (i64 j = j0; j < j1; ++j)
    for (i64 i = i0; i < i1; ++i)
      if (op == OP_XOR)
        platform.pixels[j * platform.frame_width + i] ^= color;
      else
        platform.pixels[j * platform.frame_width + i] = color;
}

void draw_text_area(u32 color, f64 x0, f64 y0, f64 width, f64 height, f64 max_scale_x, f64 max_scale_y, i64 num_chars, c32 *text) {
  assert(max_scale_x > 1e-6);
  assert(max_scale_y > 1e-6);

  i64 num_columns = enum_text_columns(num_chars, text);
  i64 num_rows    = enum_text_rows(num_chars, text);

  f64 scale_x = width  / num_columns;
  f64 scale_y = height / num_rows;

  f64 kx = scale_x / max_scale_x;
  f64 ky = scale_y / max_scale_y;

  f64 k = kx < ky ? kx : ky;

  kx = k * max_scale_x;
  ky = k * max_scale_y;

  print_text(color, x0, y0, kx, ky, num_chars, text);
}

void draw_text_cursor(u32 color, f64 x0, f64 y0, f64 width, f64 height, f64 max_scale_x, f64 max_scale_y, i64 cursor, i64 selection, i64 num_chars, c32 *text) {
  assert(max_scale_x > 1e-6);
  assert(max_scale_y > 1e-6);

  i64 num_columns = enum_text_columns(num_chars, text);
  i64 num_rows    = enum_text_rows(num_chars, text);
  i64 cursor_x    = text_cursor(cursor, text);
  i64 cursor_y    = enum_text_rows(cursor, text);
  f64 scale_x = width  / num_columns;
  f64 scale_y = height / num_rows;

  f64 kx = scale_x / max_scale_x;
  f64 ky = scale_y / max_scale_y;

  f64 k = kx < ky ? kx : ky;

  kx = k * max_scale_x;
  ky = k * max_scale_y;

  if (selection != 0) {
    i64 selection_x, selection_y;

    if (selection > 0) {
      selection_x = text_cursor(cursor + selection, text);
      selection_y = enum_text_rows(cursor + selection, text);
    } else {
      selection_x = cursor_x;
      selection_y = cursor_y;
      cursor_x    = text_cursor(cursor + selection, text);
      cursor_y    = enum_text_rows(cursor + selection, text);
    }

    if (cursor_y == selection_y)
      draw_panel(OP_XOR, color,
        x0 + kx * cursor_x,
        y0 + ky * cursor_y - ky * (CHAR_NUM_BITS_Y + 1),
        kx * (selection_x - cursor_x),
        ky * (CHAR_NUM_BITS_Y + 1)
      );
    else {
      draw_panel(OP_XOR, color,
        x0 + kx * cursor_x,
        y0 + ky * cursor_y - ky * (CHAR_NUM_BITS_Y + 1),
        kx * (num_columns - cursor_x),
        ky * (CHAR_NUM_BITS_Y + 1)
      );
      for (i64 j = cursor_y + CHAR_NUM_BITS_Y + 1; j < selection_y; j += CHAR_NUM_BITS_Y + 1)
        draw_panel(OP_XOR, color,
          x0,
          y0 + ky * j - ky * (CHAR_NUM_BITS_Y + 1),
          kx * num_columns,
          ky * (CHAR_NUM_BITS_Y + 1)
        );
      draw_panel(OP_XOR, color,
        x0,
        y0 + ky * selection_y - ky * (CHAR_NUM_BITS_Y + 1),
        kx * selection_x,
        ky * (CHAR_NUM_BITS_Y + 1)
      );
    }
  } else
    draw_panel(OP_XOR, color, x0 + kx * cursor_x, y0 + ky * cursor_y - ky * CHAR_NUM_BITS_Y, kx * .5, ky * (CHAR_NUM_BITS_Y - 1));
}

i32 main(i32 argc, c8 **argv) {
  (void) argc;
  (void) argv;

  platform = (Platform) {
    .title        = "UI",
    .frame_width  = 960,
    .frame_height = 720,
  };

  p_init();

  b8 button_0_down    = 0;
  b8 button_1_down    = 0;
  b8 button_1_checked = 0;

  i64        text_len  = 0;
  static c32 text[512] = {0};

  i64 cursor    = 0;
  i64 selection = 0;

  while (!platform.done) {
    p_wait_events();

    for (i32 j = 0; j < platform.frame_height; ++j)
      for (i32 i = 0; i < platform.frame_width; ++i)
        platform.pixels[j * platform.frame_width + i] = 0x302000;

    if (platform.cursor_x >= 40 && platform.cursor_x < 100 && platform.cursor_y >= 40 && platform.cursor_y < 100) {
      button_0_down = platform.key_down[BUTTON_LEFT];
      if (button_0_down)
        draw_panel(OP_SET, 0xffffff, 40, 40, 60, 60);
      else
        draw_panel(OP_SET, 0x00ff00, 40, 40, 60, 60);
    } else {
      button_0_down = 0;
      draw_panel(OP_SET, 0x208020, 40, 40, 60, 60);
    }

    if (platform.cursor_x >= 40 && platform.cursor_x < 100 && platform.cursor_y >= 120 && platform.cursor_y < 180) {
      button_1_down = platform.key_down[BUTTON_LEFT];
      if (platform.key_pressed[BUTTON_LEFT])
        button_1_checked = !button_1_checked;
      if (button_1_down)
        draw_panel(OP_SET, 0xffffff, 40, 120, 60, 60);
      else if (button_1_checked)
        draw_panel(OP_SET, 0xff8080, 40, 120, 60, 60);
      else
        draw_panel(OP_SET, 0x80ff80, 40, 120, 60, 60);
    } else {
      button_1_down = 0;
      if (button_1_checked)
        draw_panel(OP_SET, 0xff0000, 40, 120, 60, 60);
      else
        draw_panel(OP_SET, 0x00ff00, 40, 120, 60, 60);
    }

    i64 w  = platform.frame_width  / 2;
    i64 h  = platform.frame_height / 2;
    i64 x0 = w / 2;
    i64 y0 = h / 2;

    i64 color = 0xff7f7f;

    if (platform.cursor_x >= x0 && platform.cursor_x < x0 + w &&
        platform.cursor_y >= y0 && platform.cursor_y < y0 + h)
      color = 0xffffff;

    for (i64 i = 0; i < platform.input_size; ++i)
      if (platform.input[i].ctrl)
        switch (platform.input[i].key) {
          case 'v': {
            if (selection != 0) {
              i64 i0 = selection < 0 ? cursor + selection : cursor;
              i64 i1 = selection < 0 ? cursor : cursor + selection;
              for (i64 i = 0; i1 + i < text_len; ++i)
                text[i0 + i] = text[i1 + i];
              selection = 0;
              cursor    = i0;
              text_len -= i1 - i0;
            }

            for (i64 n = 0; n < platform.clipboard_size;) {
              c32 c = utf8_read(platform.clipboard_size - n, platform.clipboard + n);

              if (text_len < (i64) (sizeof text / sizeof *text)) {
                for (i64 j = text_len; j > cursor; --j)
                  text[j] = text[j - 1];
                text[cursor++] = c;
                ++text_len;
              }

              n += utf8_size(c);
            }
          } break;

          case 'x': {
            i64       len = 0;
            static c8 buf[1024];

            i64 i0 = selection < 0 ? cursor + selection : cursor;
            i64 i1 = selection < 0 ? cursor : cursor + selection;
            for (i64 i = 0; len + 4 <= (i64) sizeof buf && i < i1 - i0; ++i)
              len += utf8_write(text[i0 + i], buf + len);

            if (len > 0)
              p_clipboard_write(len, buf);

            for (i64 i = 0; i1 + i < text_len; ++i)
              text[i0 + i] = text[i1 + i];
            selection = 0;
            cursor    = i0;
            text_len -= i1 - i0;
          } break;

          case 'c': {
            i64       len = 0;
            static c8 buf[1024];

            i64 i0 = selection < 0 ? cursor + selection : cursor;
            i64 i1 = selection < 0 ? cursor : cursor + selection;
            for (i64 i = 0; len + 4 <= (i64) sizeof buf && i < i1 - i0; ++i)
              len += utf8_write(text[i0 + i], buf + len);

            if (len > 0)
              p_clipboard_write(len, buf);
          } break;

          default:;
        }
      else
        switch (platform.input[i].key) {
          case KEY_LEFT:
            if (platform.key_down[MOD_SHIFT]) {
              if (cursor > 0)
                ++selection;
            } else if (selection != 0) {
              cursor = selection < 0 ? cursor + selection + 1 : cursor + 1;
              selection = 0;
            }
            if (cursor > 0)
              --cursor;
            break;

          case KEY_RIGHT:
            if (platform.key_down[MOD_SHIFT]) {
              if (cursor < text_len)
                --selection;
            } else if (selection != 0) {
              cursor = selection < 0 ? cursor - 1 : cursor + selection - 1;
              selection = 0;
            }
            if (cursor < text_len)
              ++cursor;
            break;

          case '\b':
            if (selection != 0) {
              i64 i0 = selection < 0 ? cursor + selection : cursor;
              i64 i1 = selection < 0 ? cursor : cursor + selection;
              for (i64 i = 0; i1 + i < text_len; ++i)
                text[i0 + i] = text[i1 + i];
              selection = 0;
              cursor    = i0;
              text_len -= i1 - i0;
            } else if (cursor > 0 && text_len > 0) {
              for (i64 i = cursor; i < text_len; ++i)
                text[i - 1] = text[i];
              --cursor;
              --text_len;
            }
            break;

          case KEY_DELETE:
            if (selection != 0) {
              i64 i0 = selection < 0 ? cursor + selection : cursor;
              i64 i1 = selection < 0 ? cursor : cursor + selection;
              for (i64 i = 0; i1 + i < text_len; ++i)
                text[i0 + i] = text[i1 + i];
              selection = 0;
              cursor    = i0;
              text_len -= i1 - i0;
            } else if (cursor < text_len) {
              for (i64 i = cursor + 1; i < text_len; ++i)
                text[i - 1] = text[i];
              --text_len;
            }
            break;

          case '\n':
          case '\r':
          case '\t':
            platform.input[i].c = platform.input[i].key;
            //  fallthrough

          default:
            if (platform.input[i].c) {
              if (selection != 0) {
                i64 i0 = selection < 0 ? cursor + selection : cursor;
                i64 i1 = selection < 0 ? cursor : cursor + selection;
                for (i64 i = 0; i1 + i < text_len; ++i)
                  text[i0 + i] = text[i1 + i];
                selection = 0;
                cursor    = i0;
                text_len -= i1 - i0;
              }

              if (text_len < (i64) (sizeof text / sizeof *text)) {
                for (i64 i = text_len; i > cursor; --i)
                  text[i] = text[i - 1];
                text[cursor++] = platform.input[i].c;
                ++text_len;
              }
            }
        }

    draw_text_area(0, x0 + 8, y0 - 8, w, h, 10., 10., text_len, text);
    draw_text_area(color, x0, y0, w, h, 10., 10., text_len, text);
    draw_text_cursor(0xffffff, x0, y0, w, h, 10., 10., cursor, selection, text_len, text);

    p_render_frame();
  }

  p_cleanup();
  return 0;
}