extern "C" {
#include "../libs/libgrapheme/grapheme.h"
}
#include "../include/editor.h"
#include "../include/ts.h"
#include "../include/utils.h"

Editor *new_editor(const char *filename, Coord position, Coord size) {
  Editor *editor = new Editor();
  if (!editor)
    return nullptr;
  uint32_t len = 0;
  char *str = load_file(filename, &len);
  if (!str) {
    free_editor(editor);
    return nullptr;
  }
  editor->filename = filename;
  editor->position = position;
  editor->size = size;
  editor->tree = nullptr;
  editor->cursor = {0, 0};
  editor->cursor_preffered = UINT32_MAX;
  editor->selection_active = false;
  editor->selection = {0, 0};
  editor->scroll = {0, 0};
  editor->root = load(str, len, optimal_chunk_size(len));
  free(str);
  editor->folded.resize(editor->root->line_count + 2);
  if (len <= (1024 * 128)) {
    editor->parser = ts_parser_new();
    Language language = language_for_file(filename);
    editor->language = language.fn();
    ts_parser_set_language(editor->parser, editor->language);
    std::string query = get_exe_dir() + "/../grammar/" + language.name + ".scm";
    editor->query = load_query(query.c_str(), editor);
  }
  return editor;
}

void free_editor(Editor *editor) {
  ts_parser_delete(editor->parser);
  if (editor->tree)
    ts_tree_delete(editor->tree);
  if (editor->query)
    ts_query_delete(editor->query);
  free_rope(editor->root);
  delete editor;
}

void ensure_scroll(Editor *editor) {
  std::shared_lock knot_lock(editor->knot_mtx);
  if (editor->cursor.row < editor->scroll.row ||
      (editor->cursor.row == editor->scroll.row &&
       editor->cursor.col <= editor->scroll.col)) {
    LineIterator *it = begin_l_iter(editor->root, editor->cursor.row);
    if (!it)
      return;
    uint32_t len;
    char *line = next_line(it, &len);
    if (!line) {
      free(it);
      return;
    }
    if (len > 0 && line[len - 1] == '\n')
      --len;
    uint32_t rows = 1;
    uint32_t cols = 0;
    uint32_t offset = 0;
    uint32_t old_offset = 0;
    while (offset < len) {
      uint32_t inc =
          grapheme_next_character_break_utf8(line + offset, len - offset);
      int width = display_width(line + offset, inc);
      if (cols + width > editor->size.col) {
        rows++;
        cols = 0;
        if (editor->cursor.col > old_offset && editor->cursor.col <= offset) {
          editor->scroll.row = editor->cursor.row;
          editor->scroll.col = old_offset;
          free(line);
          free(it);
          return;
        }
        old_offset = offset;
      }
      cols += width;
      offset += inc;
    }
    free(line);
    free(it);
    editor->scroll.row = editor->cursor.row;
    editor->scroll.col = (editor->cursor.col == 0) ? 0 : old_offset;
  } else {
    uint32_t line_index = editor->scroll.row;
    LineIterator *it = begin_l_iter(editor->root, line_index);
    if (!it)
      return;
    uint32_t max_visual_lines = editor->size.row;
    Coord *scroll_queue = (Coord *)malloc(sizeof(Coord) * max_visual_lines);
    uint32_t q_head = 0;
    uint32_t q_size = 0;
    bool first_visual_line = true;
    while (true) {
      if (editor->folded[line_index]) {
        if (editor->folded[line_index] == 2) {
          Coord fold_coord = {line_index, 0};
          if (q_size < max_visual_lines) {
            scroll_queue[(q_head + q_size) % max_visual_lines] = fold_coord;
            q_size++;
          } else {
            scroll_queue[q_head] = fold_coord;
            q_head = (q_head + 1) % max_visual_lines;
          }
          if (line_index == editor->cursor.row) {
            editor->scroll = scroll_queue[q_head];
            break;
          }
        }
        do {
          char *line = next_line(it, nullptr);
          if (!line)
            break;
          free(line);
          line_index++;
        } while (line_index < editor->size.row &&
                 editor->folded[line_index] == 1);
        continue;
      }
      uint32_t line_len;
      char *line = next_line(it, &line_len);
      if (!line)
        break;
      if (line_len > 0 && line[line_len - 1] == '\n')
        line_len--;
      uint32_t current_byte_offset = 0;
      if (first_visual_line) {
        current_byte_offset += editor->scroll.col;
        first_visual_line = false;
      }
      while (current_byte_offset < line_len ||
             (line_len == 0 && current_byte_offset == 0)) {
        Coord current_coord = {line_index, current_byte_offset};
        if (q_size < max_visual_lines) {
          scroll_queue[(q_head + q_size) % max_visual_lines] = current_coord;
          q_size++;
        } else {
          scroll_queue[q_head] = current_coord;
          q_head = (q_head + 1) % max_visual_lines;
        }
        uint32_t col = 0;
        uint32_t local_render_offset = 0;
        uint32_t line_left = line_len - current_byte_offset;
        while (line_left > 0 && col < editor->size.col) {
          uint32_t cluster_len = grapheme_next_character_break_utf8(
              line + current_byte_offset + local_render_offset, line_left);
          int width = display_width(
              line + current_byte_offset + local_render_offset, cluster_len);
          if (col + width > editor->size.col)
            break;
          local_render_offset += cluster_len;
          line_left -= cluster_len;
          col += width;
        }
        if (line_index == editor->cursor.row) {
          bool cursor_found = false;
          if (editor->cursor.col >= current_byte_offset &&
              editor->cursor.col < current_byte_offset + local_render_offset)
            cursor_found = true;
          else if (editor->cursor.col == line_len &&
                   current_byte_offset + local_render_offset == line_len)
            cursor_found = true;
          if (cursor_found) {
            editor->scroll = scroll_queue[q_head];
            free(line);
            free(scroll_queue);
            free(it);
            return;
          }
        }
        current_byte_offset += local_render_offset;
        if (line_len == 0)
          break;
      }
      line_index++;
      free(line);
    }
    free(scroll_queue);
    free(it);
  }
}

void fold(Editor *editor, uint32_t start_line, uint32_t end_line) {
  if (!editor)
    return;
  for (uint32_t i = start_line; i <= end_line && i < editor->size.row; i++)
    editor->folded[i] = 1;
  editor->folded[start_line] = 2;
}

void update_render_fold_marker(uint32_t row, uint32_t cols) {
  const char *marker = "... folded ...";
  uint32_t len = strlen(marker);
  uint32_t i = 0;
  for (; i < len && i < cols; i++)
    update(row, i, (char[2]){marker[i], 0}, 0xc6c6c6, 0, 0);
  for (; i < cols; i++)
    update(row, i, " ", 0xc6c6c6, 0, 0);
}

void apply_edit(std::vector<Span> &spans, uint32_t x, int64_t y) {
  Span key{.start = x, .end = 0, .hl = nullptr};
  auto it = std::lower_bound(
      spans.begin(), spans.end(), key,
      [](const Span &a, const Span &b) { return a.start < b.start; });
  size_t idx = std::distance(spans.begin(), it);
  while (idx > 0 && spans.at(idx - 1).end > x)
    --idx;
  for (size_t i = idx; i < spans.size();) {
    Span &s = spans.at(i);
    if (s.start < x && s.end > x) {
      s.end += y;
    } else if (s.start > x) {
      s.start += y;
      s.end += y;
    }
    if (s.end <= s.start)
      spans.erase(spans.begin() + i);
    else
      ++i;
  }
}

void render_editor(Editor *editor) {
  uint32_t sel_start = 0, sel_end = 0;
  if (editor->selection_active) {
    uint32_t sel1 = line_to_byte(editor->root, editor->cursor.row, nullptr) +
                    editor->cursor.col;
    uint32_t sel2 = line_to_byte(editor->root, editor->selection.row, nullptr) +
                    editor->selection.col;
    if (sel1 <= sel2) {
      sel_start = sel1;
      sel_end = sel2;
    } else {
      sel_start = sel2;
      sel_end = sel1;
    }
  }
  Coord cursor = {UINT32_MAX, UINT32_MAX};
  uint32_t line_index = editor->scroll.row;
  SpanCursor span_cursor(editor->spans);
  std::shared_lock knot_lock(editor->knot_mtx);
  LineIterator *it = begin_l_iter(editor->root, line_index);
  if (!it)
    return;
  uint32_t rendered_rows = 0;
  uint32_t global_byte_offset = line_to_byte(editor->root, line_index, nullptr);
  span_cursor.sync(global_byte_offset);
  while (rendered_rows < editor->size.row) {
    if (editor->folded[line_index]) {
      if (editor->folded[line_index] == 2) {
        update_render_fold_marker(rendered_rows, editor->size.col);
        rendered_rows++;
      }
      do {
        uint32_t line_len;
        char *line = next_line(it, &line_len);
        if (!line)
          break;
        global_byte_offset += line_len;
        if (line_len > 0 && line[line_len - 1] == '\n')
          global_byte_offset--;
        global_byte_offset++;
        free(line);
        line_index++;
      } while (line_index < editor->size.row &&
               editor->folded[line_index] == 1);
      continue;
    }
    uint32_t line_len;
    char *line = next_line(it, &line_len);
    if (!line)
      break;
    if (line_len > 0 && line[line_len - 1] == '\n')
      line_len--;
    uint32_t current_byte_offset = 0;
    if (rendered_rows == 0)
      current_byte_offset += editor->scroll.col;
    while (current_byte_offset < line_len && rendered_rows < editor->size.row) {
      uint32_t col = 0;
      uint32_t local_render_offset = 0;
      uint32_t line_left = line_len - current_byte_offset;
      while (line_left > 0 && col < editor->size.col) {
        if (line_index == editor->cursor.row &&
            editor->cursor.col == (current_byte_offset + local_render_offset)) {
          cursor.row = editor->position.row + rendered_rows;
          cursor.col = editor->position.col + col;
        }
        uint32_t absolute_byte_pos =
            global_byte_offset + current_byte_offset + local_render_offset;
        Highlight *hl = span_cursor.get_highlight(absolute_byte_pos);
        uint32_t fg = hl ? hl->fg : 0xFFFFFF;
        uint32_t bg = hl ? hl->bg : 0;
        uint8_t fl = hl ? hl->flags : 0;
        if (editor->selection_active && absolute_byte_pos >= sel_start &&
            absolute_byte_pos < sel_end)
          bg = 0x555555;
        uint32_t cluster_len = grapheme_next_character_break_utf8(
            line + current_byte_offset + local_render_offset, line_left);
        std::string cluster(line + current_byte_offset + local_render_offset,
                            cluster_len);
        int width = display_width(cluster.c_str(), cluster_len);
        if (col + width > editor->size.col)
          break;
        update(editor->position.row + rendered_rows, editor->position.col + col,
               cluster.c_str(), fg, bg, fl);
        local_render_offset += cluster_len;
        line_left -= cluster_len;
        col += width;
        while (width-- > 1)
          update(editor->position.row + rendered_rows,
                 editor->position.col + col - width, "\x1b", fg, bg, fl);
      }
      if (line_index == editor->cursor.row &&
          editor->cursor.col == (current_byte_offset + local_render_offset)) {
        cursor.row = editor->position.row + rendered_rows;
        cursor.col = editor->position.col + col;
      }
      if (editor->selection_active &&
          global_byte_offset + line_len + 1 > sel_start &&
          global_byte_offset + line_len + 1 <= sel_end &&
          col < editor->size.col) {
        update(editor->position.row + rendered_rows, editor->position.col + col,
               " ", 0, 0x555555, 0);
        col++;
      }
      while (col < editor->size.col) {
        update(editor->position.row + rendered_rows, editor->position.col + col,
               " ", 0xFFFFFF, 0, 0);
        col++;
      }
      rendered_rows++;
      current_byte_offset += local_render_offset;
    }
    if (line_len == 0 ||
        (current_byte_offset >= line_len && rendered_rows == 0)) {
      if (editor->cursor.row == line_index) {
        cursor.row = editor->position.row + rendered_rows;
        cursor.col = editor->position.col;
      }
      uint32_t col = 0;
      if (editor->selection_active &&
          global_byte_offset + line_len + 1 > sel_start &&
          global_byte_offset + line_len + 1 <= sel_end) {
        update(editor->position.row + rendered_rows, editor->position.col + col,
               " ", 0, 0x555555, 0);
        col++;
      }
      while (col < editor->size.col) {
        update(editor->position.row + rendered_rows, editor->position.col + col,
               " ", 0xFFFFFF, 0, 0);
        col++;
      }
      rendered_rows++;
    }
    global_byte_offset += line_len + 1;
    line_index++;
    free(line);
  }
  if (cursor.row != UINT32_MAX && cursor.col != UINT32_MAX)
    set_cursor(cursor.row, cursor.col, 1);
  while (rendered_rows < editor->size.row) {
    for (uint32_t col = 0; col < editor->size.col; col++)
      update(editor->position.row + rendered_rows, editor->position.col + col,
             " ", 0xFFFFFF, 0, 0);
    rendered_rows++;
  }
  free(it);
}