import type { RuleBlock } from 'markdown-it/lib/parser_block';

import type { TocPluginOptions } from './tocPlugin';

/**
 * Forked and modified from `markdown-it-toc-done-right`.
 *
 * - Remove the `inlineOptions` support.
 * - Use `markdown-it` default renderer to render token whenever possible.
 *
 * @see https://github.com/nagaozen/markdown-it-toc-done-right
 */
export const createTocBlockRule = ({
  pattern,
  containerTag,
  containerClass,
}: Pick<
  Required<TocPluginOptions>,
  'pattern' | 'containerTag' | 'containerClass'
>): RuleBlock => {
  return (state, startLine, endLine, silent): boolean => {
    // If it's indented more than 3 spaces, it should be a code block.
    if (state.sCount[startLine] - state.blkIndent >= 4) {
      return false;
    }

    const pos = state.bMarks[startLine] + state.tShift[startLine];
    const max = state.eMarks[startLine];

    /**
     * Use whitespace as a line tokenizer and extract the first token to test against the
     * placeholder anchored pattern, rejecting if `false`.
     */
    const lineFirstToken = state.src.slice(pos, max).split(' ')[0];
    if (!pattern.test(lineFirstToken)) return false;

    if (silent) return true;

    state.line = startLine + 1;

    // Generate `toc_open` token. It will be rendered by the `markdown-it` default renderer.
    const tokenOpen = state.push('toc_open', containerTag, 1);
    tokenOpen.markup = '';
    tokenOpen.map = [startLine, state.line];
    if (containerClass) {
      tokenOpen.attrSet('class', containerClass);
    }

    // Generate `toc_body` token. It will be rendered by our custom renderer.
    const tokenBody = state.push('toc_body', '', 0);
    tokenBody.markup = lineFirstToken;
    tokenBody.map = [startLine, state.line];
    tokenBody.hidden = true;

    // Generate `toc_close` token. It will be rendered by the `markdown-it` default renderer.
    const tokenClose = state.push('toc_close', containerTag, -1);
    tokenClose.markup = '';
    tokenBody.map = [startLine, state.line];

    return true;
  };
};