/**
 * Markdown autoformat extension for TipTap.
 *
 * Adds custom input rules that are NOT provided by built-in TipTap extensions.
 *   - [text](url)   → clickable link
 *   - `- [ ] `      → checkbox task-list item (GFM task list). See #722.
 *   - `- [x] `      → checked task-list item. See #722.
 *
 * Other rules (headings, bullet/ordered lists, code blocks, bold, italic,
 * strikethrough, inline code, blockquote, horizontal rule) are already
 * provided by StarterKit.
 */

import { Extension, InputRule } from '@tiptap/core';
import { linkInputRegex as _unusedLinkRegex } from '../autoformat-rules.js';
void _unusedLinkRegex;

export const MarkdownAutoformat = Extension.create({
  name: 'markdownAutoformat',

  addInputRules() {
    const rules: InputRule[] = [];

    // [text](url) → Link
    // When user types [link text](https://example.com), replace with a
    // linked text node. Requires the Link extension to be registered.
    const linkType = this.editor.schema.marks.link;
    if (linkType) {
      rules.push(
        new InputRule({
          find: /(?:^|\s)\[([^\]]+)\]\(([^)]+)\)$/,
          handler: ({ state, range, match }) => {
            const linkText = match[1];
            const href = match[2];

            // Determine if we matched a leading space
            const fullMatch = match[0];
            const hasLeadingSpace = fullMatch !== `[${linkText}](${href})`;
            const start = hasLeadingSpace ? range.from + 1 : range.from;

            const mark = linkType.create({ href });
            const textNode = state.schema.text(linkText, [mark]);

            const tr = state.tr;
            tr.replaceWith(start, range.to, textNode);
          },
        })
      );
    }

    // GFM task-list autoformat: `- [ ] ` or `- [x] ` at the very start of
    // an empty paragraph transforms the paragraph into a single-item
    // TaskList. #722 — TaskList's built-in input rule doesn't accept the
    // GFM markdown form (it only reacts to literal `- [ ] ` but only as a
    // child of an existing bullet-list context in some versions).
    const taskListType = this.editor.schema.nodes.taskList;
    const taskItemType = this.editor.schema.nodes.taskItem;
    const paragraphType = this.editor.schema.nodes.paragraph;
    if (taskListType && taskItemType && paragraphType) {
      rules.push(
        new InputRule({
          // Match at the very start of a paragraph: - [ ]  or * [x]  etc.
          find: /^\s*(?:[-*+])\s+\[([xX ])\]\s$/,
          handler: ({ state, range, match, chain: _c, commands }) => {
            void _c; void commands;
            const checked = /[xX]/.test(match[1] ?? ' ');
            const { tr } = state;
            const $from = state.doc.resolve(range.from);
            // Replace the whole paragraph start (from block start) with a
            // taskList > taskItem > paragraph (empty). Delete the "- [ ] "
            // literal prefix so the cursor sits inside the task item ready
            // for the user to type.
            const blockStart = $from.before($from.depth);
            const blockEnd = $from.after($from.depth);
            const emptyPara = paragraphType.create();
            const taskItem = taskItemType.create({ checked }, emptyPara);
            const taskList = taskListType.create(null, taskItem);
            tr.replaceRangeWith(blockStart, blockEnd, taskList);
          },
        })
      );
    }

    return rules;
  },
});