// Copyright (c) Meta Platforms, Inc. and affiliates.

/**
 * @file parseOutlineFromMarkdown.ts
 * @input Uses Markdown's canonical AST parser and heading slug helpers
 * @output Exports parseOutlineFromMarkdown for extracting heading outlines from Markdown
 * @position Pure compatibility utility; consumed by useOutlineFromMarkdown and public exports
 *
 * SYNC: When modified, update these files to stay in sync:
 * - /packages/core/src/Outline/Outline.doc.mjs
 * - /packages/core/src/Outline/index.ts
 */

import { parseMarkdownAstInternal, slugify, uniqueSlug } from "../Markdown/parser.js";
import { markdownAstText } from "../Markdown/ast.js";
import { markdownExtensionText, prepareMarkdownPlugins } from "../Markdown/plugins/protocol.js";
import type { MarkdownExtensionNode, MarkdownPluginEntry } from "../Markdown/plugins/protocol.js";
import type { OutlineItem } from "./types.js";

/**
 * Extract heading items from a Markdown string.
 *
 * Uses Markdown's parser so fenced code blocks, tables, lists, and inline
 * formatting are interpreted consistently with rendered Markdown output.
 * Ids come from the parser's shared slug helpers, so they always match the
 * `id` attributes Markdown renders on its headings.
 */
export interface ParseOutlineFromMarkdownOptions<Node extends MarkdownExtensionNode = never> {
  readonly plugins?: ReadonlyArray<MarkdownPluginEntry<Node>>;
  /** Match Markdown's transform finality while content is streaming. */
  readonly isFinal?: boolean;
}
export function parseOutlineFromMarkdown<Node extends MarkdownExtensionNode = never>(markdown: string, options?: ParseOutlineFromMarkdownOptions<Node>): OutlineItem[] {
  const prepared = options?.plugins == null ? undefined : prepareMarkdownPlugins(options.plugins);
  const counts = new Map<string, number>();
  return parseMarkdownAstInternal(markdown, {
    plugins: options?.plugins
  }, options?.isFinal ?? true).children.filter(block => block.type === 'heading').map(block => {
    const label = markdownAstText(block.children, node => markdownExtensionText(prepared, node)).trim();
    return {
      id: uniqueSlug(slugify(label), counts),
      label,
      level: block.depth
    };
  });
}