/**
 * Wikilink Transformation Plugin
 *
 * Transforms Obsidian wikilink syntax to standard markdown links at build time.
 * Handles:
 * - [[Page Title]] → [Page Title](/articles/page-title)
 * - [[Page|Display Text]] → [Display Text](/articles/page)
 * - ![[image.jpg]] → ![image.jpg](/img/image.jpg)
 * - ![[image.jpg|alt text]] → ![alt text](/img/image.jpg)
 *
 * Runs during content:file:beforeParse hook for early transformation
 */

export default defineNitroPlugin((nitroApp) => {
  nitroApp.hooks.hook('content:file:beforeParse' as any, (file: any) => {
    // Only process markdown files in articles collection
    if (file._id && file._id.endsWith('.md') && file._id.includes('/articles/')) {
      if (file.body) {
        file.body = transformWikilinks(file.body);
        file.body = transformImageEmbeds(file.body);
      }
    }
  });
});

/**
 * Transform Obsidian wikilinks to markdown links
 * Patterns:
 * - [[P0 - Page Title]]
 * - [[Page Title|Display Text]]
 * - [[P1 - Long Title|Short]]
 */
function transformWikilinks(content: string): string {
  // Pattern: [[P0/P1/P2 - Page Title]] or [[Page Title]] with optional |Display Text
  const wikilinkPattern = /\[\[([^\]|]+)(?:\|([^\]]+))?\]\]/g;

  return content.replace(wikilinkPattern, (match, pageName, displayText) => {
    // Clean the page name: strip P0/P1/P2 prefix
    const cleanName = pageName.replace(/^P[012]\s*-\s*/i, '').trim();

    // Generate slug from clean name
    const slug = titleToSlug(cleanName);

    // Use display text if provided, otherwise use clean name
    const linkText = displayText ? displayText.trim() : cleanName;

    // Generate markdown link with /articles/ prefix
    return `[${linkText}](/articles/${slug})`;
  });
}

/**
 * Transform Obsidian image embeds to markdown image syntax
 * Patterns:
 * - ![[image.jpg]]
 * - ![[image.jpg|alt text]]
 */
function transformImageEmbeds(content: string): string {
  // Pattern: ![[filename]] or ![[filename|alt text]]
  const imagePattern = /!\[\[([^\]|]+)(?:\|([^\]]+))?\]\]/g;

  return content.replace(imagePattern, (match, filename, altText) => {
    // Use alt text if provided, otherwise use filename (without extension)
    const alt = altText?.trim() || filename.replace(/\.(jpg|jpeg|png|gif|svg|webp)$/i, '');

    // Generate markdown image syntax with /img/ prefix
    return `![${alt}](/img/${filename})`;
  });
}

/**
 * Convert a page title to a URL slug
 * Rules:
 * 1. Convert to lowercase
 * 2. Remove quotation marks
 * 3. Replace & with "and"
 * 4. Remove other special characters (keep alphanumeric and hyphens)
 * 5. Replace spaces with hyphens
 * 6. Collapse multiple hyphens to single hyphen
 * 7. Trim hyphens from start/end
 */
function titleToSlug(title: string): string {
  return title
    .toLowerCase()
    .replace(/['"]/g, '') // Remove quotes
    .replace(/&/g, 'and') // & → and
    .replace(/[^a-z0-9\s-]/g, '') // Remove special characters
    .replace(/\s+/g, '-') // Spaces → hyphens
    .replace(/-+/g, '-') // Collapse multiple hyphens
    .replace(/^-|-$/g, ''); // Trim hyphens from edges
}