import { type FastifyInstance } from 'fastify';
import { eq, and, desc, or, inArray, sql } from 'drizzle-orm';
import { contentItems } from '../../db/schema/index';
import { createReadStream, statSync } from 'node:fs';
import { extname, basename } from 'node:path';
import { appConfig } from '../../config/index';

/** Audio file extensions and their MIME types. */
const AUDIO_MIME_TYPES: Record<string, string> = {
  '.mp3': 'audio/mpeg',
  '.m4a': 'audio/mp4',
  '.opus': 'audio/opus',
  '.ogg': 'audio/ogg',
  '.aac': 'audio/aac',
  '.flac': 'audio/flac',
  '.wav': 'audio/wav',
  '.wma': 'audio/x-ms-wma',
  '.webm': 'audio/webm',
};

/** Known audio container format strings from yt-dlp. */
const AUDIO_FORMATS = ['mp3', 'm4a', 'opus', 'ogg', 'aac', 'flac', 'wav', 'webm'];

/**
 * Escape special XML characters in a string.
 */
function escapeXml(str: string): string {
  return str
    .replace(/&/g, '&amp;')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
    .replace(/'/g, '&apos;');
}

/**
 * Format seconds into HH:MM:SS for itunes:duration.
 */
function formatDuration(seconds: number): string {
  const h = Math.floor(seconds / 3600);
  const m = Math.floor((seconds % 3600) / 60);
  const s = seconds % 60;
  if (h > 0) {
    return `${h}:${String(m).padStart(2, '0')}:${String(s).padStart(2, '0')}`;
  }
  return `${m}:${String(s).padStart(2, '0')}`;
}

/**
 * Guess MIME type from a file path or format string.
 */
function guessMimeType(filePath: string | null, format: string | null): string {
  if (filePath) {
    const ext = extname(filePath).toLowerCase();
    if (AUDIO_MIME_TYPES[ext]) return AUDIO_MIME_TYPES[ext];
  }
  if (format) {
    const ext = `.${format.toLowerCase()}`;
    if (AUDIO_MIME_TYPES[ext]) return AUDIO_MIME_TYPES[ext];
  }
  return 'audio/mpeg'; // safe default
}

/**
 * Build the base URL for constructing absolute feed URLs.
 * Uses the request's Host header to generate URLs that work
 * regardless of reverse proxy configuration.
 */
function buildBaseUrl(request: { headers: Record<string, string | string[] | undefined>; protocol: string }): string {
  const host = request.headers.host || `localhost:${appConfig.port}`;
  const proto = request.headers['x-forwarded-proto'] || request.protocol || 'http';
  return `${proto}://${host}`;
}

/**
 * Feed & media route plugin.
 *
 * Registers:
 *   GET /api/v1/feed/rss — RSS 2.0 podcast feed of downloaded audio (no auth)
 *   GET /api/v1/media/:id/:filename — serves downloaded media files (no auth)
 */
export async function feedRoutes(fastify: FastifyInstance): Promise<void> {
  /**
   * GET /api/v1/feed/rss — RSS 2.0 podcast feed with iTunes namespace.
   *
   * Returns all downloaded audio content as podcast episodes.
   * No authentication required — RSS readers can't send API keys.
   */
  fastify.get('/api/v1/feed/rss', async (request, reply) => {
    const db = fastify.db;
    const baseUrl = buildBaseUrl(request);

    // Query downloaded items that are audio (by contentType or format)
    const rows = await db
      .select()
      .from(contentItems)
      .where(
        and(
          eq(contentItems.status, 'downloaded'),
          or(
            eq(contentItems.contentType, 'audio'),
            inArray(contentItems.format, AUDIO_FORMATS)
          )
        )
      )
      .orderBy(desc(contentItems.downloadedAt), desc(contentItems.id))
      .limit(500);

    const now = new Date().toUTCString();

    // Build RSS XML
    const items = rows.map((row) => {
      const fileName = row.filePath ? basename(row.filePath) : `${row.id}.mp3`;
      const enclosureUrl = `${baseUrl}/api/v1/media/${row.id}/${encodeURIComponent(fileName)}`;
      const mimeType = guessMimeType(row.filePath, row.format);
      const fileSize = row.fileSize ?? 0;
      const pubDate = row.publishedAt
        ? new Date(row.publishedAt).toUTCString()
        : row.downloadedAt
          ? new Date(row.downloadedAt).toUTCString()
          : now;
      const guid = `tubearr-${row.id}-${row.platformContentId}`;
      const duration = row.duration ? formatDuration(row.duration) : '';

      return `    <item>
      <title>${escapeXml(row.title)}</title>
      <description>${escapeXml(row.title)}</description>
      <enclosure url="${escapeXml(enclosureUrl)}" length="${fileSize}" type="${mimeType}" />
      <pubDate>${pubDate}</pubDate>
      <guid isPermaLink="false">${escapeXml(guid)}</guid>${duration ? `\n      <itunes:duration>${duration}</itunes:duration>` : ''}
    </item>`;
    }).join('\n');

    const feedUrl = `${baseUrl}/api/v1/feed/rss`;

    const xml = `<?xml version="1.0" encoding="UTF-8"?>
<rss version="2.0"
  xmlns:itunes="http://www.itunes.com/dtds/podcast-1.0.dtd"
  xmlns:atom="http://www.w3.org/2005/Atom">
  <channel>
    <title>Tubearr Audio Feed</title>
    <link>${escapeXml(baseUrl)}</link>
    <description>Downloaded audio from Tubearr</description>
    <language>en</language>
    <lastBuildDate>${now}</lastBuildDate>
    <atom:link href="${escapeXml(feedUrl)}" rel="self" type="application/rss+xml" />
    <itunes:author>Tubearr</itunes:author>
    <itunes:summary>Downloaded audio from Tubearr</itunes:summary>
    <itunes:explicit>false</itunes:explicit>
${items}
  </channel>
</rss>`;

    return reply
      .type('application/rss+xml; charset=utf-8')
      .header('Cache-Control', 'public, max-age=300')
      .send(xml);
  });

  /**
   * GET /api/v1/media/:id/:filename — Serve a downloaded media file.
   *
   * Looks up the content item by ID, verifies it has a file on disk,
   * and streams it back. The :filename param is for podcast app display
   * purposes; the actual file is located via the DB filePath column.
   *
   * No authentication required — podcast apps need direct file access.
   */
  fastify.get<{ Params: { id: string; filename: string } }>(
    '/api/v1/media/:id/:filename',
    async (request, reply) => {
      const id = parseInt(request.params.id, 10);
      if (isNaN(id) || id < 1) {
        return reply.status(400).send({
          statusCode: 400,
          error: 'Bad Request',
          message: 'Invalid content item ID',
        });
      }

      const db = fastify.db;
      const rows = await db
        .select({
          filePath: contentItems.filePath,
          fileSize: contentItems.fileSize,
          format: contentItems.format,
          status: contentItems.status,
        })
        .from(contentItems)
        .where(eq(contentItems.id, id))
        .limit(1);

      if (rows.length === 0) {
        return reply.status(404).send({
          statusCode: 404,
          error: 'Not Found',
          message: `Content item ${id} not found`,
        });
      }

      const item = rows[0];

      if (item.status !== 'downloaded' || !item.filePath) {
        return reply.status(404).send({
          statusCode: 404,
          error: 'Not Found',
          message: `No downloaded file for content item ${id}`,
        });
      }

      // Resolve file path (may be relative to media path)
      const filePath = item.filePath.startsWith('/')
        ? item.filePath
        : `${appConfig.mediaPath}/${item.filePath}`;

      let stat;
      try {
        stat = statSync(filePath);
      } catch {
        request.log.warn({ contentId: id, filePath }, '[feed] Media file not found on disk');
        return reply.status(404).send({
          statusCode: 404,
          error: 'Not Found',
          message: 'Media file not found on disk',
        });
      }

      const mimeType = guessMimeType(item.filePath, item.format);

      // Support range requests for podcast app seeking
      const range = request.headers.range;
      if (range) {
        const parts = range.replace(/bytes=/, '').split('-');
        const start = parseInt(parts[0], 10);
        const end = parts[1] ? parseInt(parts[1], 10) : stat.size - 1;
        const chunkSize = end - start + 1;

        const stream = createReadStream(filePath, { start, end });
        return reply
          .status(206)
          .header('Content-Range', `bytes ${start}-${end}/${stat.size}`)
          .header('Accept-Ranges', 'bytes')
          .header('Content-Length', chunkSize)
          .header('Content-Type', mimeType)
          .send(stream);
      }

      const stream = createReadStream(filePath);
      return reply
        .header('Content-Length', stat.size)
        .header('Content-Type', mimeType)
        .header('Accept-Ranges', 'bytes')
        .header('Content-Disposition', `inline; filename="${encodeURIComponent(basename(item.filePath))}"`)
        .send(stream);
    }
  );
}