import { LintResult } from '../linter.js';
import { Root } from 'mdast';
import { visit } from 'unist-util-visit';
import yaml from 'js-yaml';

export function checkFrontmatter(tree: Root): LintResult[] {
  const results: LintResult[] = [];
  let foundFrontmatter = false;

  visit(tree, 'yaml', (node: any) => {
    foundFrontmatter = true;
    try {
      const frontmatter = yaml.load(node.value) as any;

      if (!frontmatter || typeof frontmatter !== 'object') {
        results.push({ ruleId: '1', message: 'Frontmatter is invalid YAML' });
        return;
      }

      if (!frontmatter.hasOwnProperty('title')) {
        results.push({ ruleId: '1', message: 'Frontmatter missing "title" field' });
      }

      if (!frontmatter.hasOwnProperty('draft')) {
        results.push({ ruleId: '1', message: 'Frontmatter missing "draft" field' });
      }

    } catch (e) {
      results.push({ ruleId: '1', message: 'Frontmatter contains invalid YAML syntax' });
    }
  });

  if (!foundFrontmatter) {
    results.push({ ruleId: '1', message: 'Frontmatter is missing' });
  }

  return results;
}