/**
 * TPhimX - Cloudflare Worker HLS Media Proxy & R2 Auto-Cache CDN
 * 
 * Features:
 * 1. CORS Bypass: Attaches Access-Control-Allow-Origin: * to all requests.
 * 2. Range Requests: Supports seeking/scrubbing in HLS players (206 Partial Content).
 * 3. Dynamic R2 Caching: Checks R2 first. On cache miss, fetches original video segment,
 *    caches it into R2, and pipes it back to the client.
 * 4. Playlist Rewriter: Rewrites .m3u8 relative and absolute URLs to route all subsequent
 *    .ts media segment requests through this Worker and cache them in R2 automatically.
 */

export default {
  async fetch(request, env, ctx) {
    const urlObj = new URL(request.url);
    const targetUrlStr = urlObj.searchParams.get('url');
    const hasR2 = env.tphimx_movie !== undefined;

    if (!targetUrlStr) {
      // Direct R2 Path-based Request: e.g. /fbi-part-one/360p/index.m3u8
      const pathname = urlObj.pathname;
      if (pathname && pathname !== '/') {
        if (!hasR2) {
          return new Response('R2 Cache storage is not enabled on this Worker account yet.', {
            status: 400,
            headers: { 'Access-Control-Allow-Origin': '*' }
          });
        }
        const r2Key = pathname.replace(/^\/+/, ''); // Convert leading slash to relative key
        try {
          const object = await env.tphimx_movie.get(r2Key);
          if (object !== null) {
            // Cache HIT - Serve directly from R2
            const headers = new Headers();
            object.writeHttpMetadata(headers);
            headers.set('Access-Control-Allow-Origin', '*');
            headers.set('X-TPhimX-Cache', 'HIT (Direct R2 Path)');
            
            // Handle Range Requests for seekability
            const rangeHeader = request.headers.get('Range');
            if (rangeHeader && object.size > 0) {
              const parts = rangeHeader.replace(/bytes=/, "").split("-");
              const start = parseInt(parts[0], 10);
              const end = parts[1] ? parseInt(parts[1], 10) : object.size - 1;
              
              if (start >= 0 && end < object.size && start <= end) {
                const slicedObject = await env.tphimx_movie.get(r2Key, {
                  range: { offset: start, length: end - start + 1 }
                });
                
                headers.set('Content-Range', `bytes ${start}-${end}/${object.size}`);
                headers.set('Content-Length', String(end - start + 1));
                
                return new Response(slicedObject.body, {
                  status: 206,
                  headers
                });
              }
            }
            
            return new Response(object.body, {
              status: 200,
              headers
            });
          } else {
            return new Response('File not found in R2 bucket', { 
              status: 404, 
              headers: { 'Access-Control-Allow-Origin': '*' } 
            });
          }
        } catch (err) {
          return new Response(`R2 Path Error: ${err.message}`, { 
            status: 500, 
            headers: { 'Access-Control-Allow-Origin': '*' } 
          });
        }
      }

      return new Response(JSON.stringify({ 
        error: 'Missing "url" search parameter.',
        usage: `${urlObj.origin}/?url=https://example.com/stream.m3u8`
      }), {
        status: 400,
        headers: {
          'Content-Type': 'application/json',
          'Access-Control-Allow-Origin': '*'
        }
      });
    }

    // Handle OPTIONS Preflight request
    if (request.method === 'OPTIONS') {
      return new Response(null, {
        status: 204,
        headers: {
          'Access-Control-Allow-Origin': '*',
          'Access-Control-Allow-Methods': 'GET, HEAD, OPTIONS',
          'Access-Control-Allow-Headers': '*',
          'Access-Control-Max-Age': '86400'
        }
      });
    }

    let targetUrl;
    try {
      targetUrl = new URL(targetUrlStr);
    } catch (e) {
      return new Response('Invalid target URL format', { status: 400, headers: { 'Access-Control-Allow-Origin': '*' } });
    }

    // Generate unique storage key for Cloudflare R2
    // Scheme: cache/<hostname>/<clean_pathname>
    const cleanPath = targetUrl.pathname.replace(/^\/+/, '');
    const r2Key = `cache/${targetUrl.hostname}/${cleanPath}`;

    // 1. Check if file already exists in Cloudflare R2 bucket (Only check if R2 is enabled)
    if (hasR2) {
      try {
        const object = await env.tphimx_movie.get(r2Key);
        if (object !== null) {
          // Cache HIT - Serve directly from R2
          const headers = new Headers();
          object.writeHttpMetadata(headers);
          headers.set('Access-Control-Allow-Origin', '*');
          headers.set('X-TPhimX-Cache', 'HIT (Cloudflare R2)');
          
          // Handle Range Requests for seekability
          const rangeHeader = request.headers.get('Range');
          if (rangeHeader && object.size > 0) {
            const parts = rangeHeader.replace(/bytes=/, "").split("-");
            const start = parseInt(parts[0], 10);
            const end = parts[1] ? parseInt(parts[1], 10) : object.size - 1;
            
            if (start >= 0 && end < object.size && start <= end) {
              // Slice the R2 object
              const slicedObject = await env.tphimx_movie.get(r2Key, {
                range: { offset: start, length: end - start + 1 }
              });
              
              headers.set('Content-Range', `bytes ${start}-${end}/${object.size}`);
              headers.set('Content-Length', String(end - start + 1));
              
              return new Response(slicedObject.body, {
                status: 206,
                headers
              });
            }
          }
          
          return new Response(object.body, {
            status: 200,
            headers
          });
        }
      } catch (err) {
        // Log error but fallback to fetching from source to prevent playback interruption
        console.error('R2 read error:', err.message);
      }
    }

    // Cache MISS - Fetch from original media source server
    try {
      // Forward request headers like Range
      const fetchHeaders = new Headers();
      
      // Bypass anti-hotlinking/Referer checks of media providers (e.g. s2.phim1280.tv)
      const targetOrigin = targetUrl.origin;
      fetchHeaders.set('Referer', targetOrigin + '/');
      fetchHeaders.set('Origin', targetOrigin);
      fetchHeaders.set('User-Agent', 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36');
      
      const range = request.headers.get('Range');
      if (range) fetchHeaders.set('Range', range);
      
      const response = await fetch(targetUrlStr, {
        headers: fetchHeaders
      });

      if (!response.ok && response.status !== 206) {
        const responseText = await response.text().catch(() => '');
        return new Response(JSON.stringify({
          error: `Failed to fetch original media source (HTTP ${response.status})`,
          targetUrl: targetUrlStr,
          sentHeaders: Object.fromEntries(fetchHeaders.entries()),
          responseHeaders: Object.fromEntries(response.headers.entries()),
          responseBody: responseText.substring(0, 500)
        }), {
          status: response.status,
          headers: {
            'Content-Type': 'application/json',
            'Access-Control-Allow-Origin': '*'
          }
        });
      }

      const contentType = response.headers.get('Content-Type') || '';
      const isM3U8 = targetUrl.pathname.endsWith('.m3u8') || 
                     contentType.includes('mpegurl') || 
                     contentType.includes('application/x-mpegURL');

      if (isM3U8) {
        // Rewrite HLS playlist URLs to route through this Worker Proxy
        let playlistText = await response.text();
        const baseTargetUrl = targetUrl.origin + targetUrl.pathname.substring(0, targetUrl.pathname.lastIndexOf('/') + 1);

        const lines = playlistText.split('\n');
        const rewrittenLines = lines.map(line => {
          const trimmed = line.trim();
          if (trimmed.length === 0 || trimmed.startsWith('#')) {
            return line;
          }

          // Resolve absolute URL
          let absoluteUrl = trimmed;
          if (!trimmed.startsWith('http://') && !trimmed.startsWith('https://')) {
            if (trimmed.startsWith('/')) {
              absoluteUrl = targetUrl.origin + trimmed;
            } else {
              absoluteUrl = baseTargetUrl + trimmed;
            }
          }

          // Rewritten relative segment URL to pipe through the worker
          return `${urlObj.origin}/?url=${encodeURIComponent(absoluteUrl)}`;
        });

        const rewrittenPlaylist = rewrittenLines.join('\n');
        const playlistBuffer = new TextEncoder().encode(rewrittenPlaylist);

        // Save the rewritten playlist into Cloudflare R2 bucket (only if R2 is enabled)
        if (hasR2) {
          ctx.waitUntil(
            env.tphimx_movie.put(r2Key, playlistBuffer, {
              httpMetadata: { contentType: 'application/x-mpegURL' }
            }).catch(e => console.error('R2 Put Error:', e.message))
          );
        }

        return new Response(rewrittenPlaylist, {
          status: 200,
          headers: {
            'Content-Type': 'application/x-mpegURL',
            'Access-Control-Allow-Origin': '*',
            'X-TPhimX-Cache': hasR2 ? 'MISS (Rewritten & Cached)' : 'MISS (Rewritten)'
          }
        });
      } else {
        // Fetch raw binary segment file (.ts)
        const segmentData = await response.arrayBuffer();

        // Save the segment file into Cloudflare R2 bucket asynchronously (only if R2 is enabled)
        if (hasR2) {
          ctx.waitUntil(
            env.tphimx_movie.put(r2Key, segmentData, {
              httpMetadata: { contentType: contentType }
            }).catch(e => console.error('R2 Put Error:', e.message))
          );
        }

        // Build Response
        const headers = new Headers();
        headers.set('Content-Type', contentType);
        headers.set('Access-Control-Allow-Origin', '*');
        headers.set('X-TPhimX-Cache', 'MISS (Cached Segment)');
        
        if (response.status === 206) {
          const contentRange = response.headers.get('Content-Range');
          if (contentRange) headers.set('Content-Range', contentRange);
          return new Response(segmentData, {
            status: 206,
            headers
          });
        }

        return new Response(segmentData, {
          status: 200,
          headers
        });
      }
    } catch (fetchErr) {
      return new Response(`Proxy error: ${fetchErr.message}`, {
        status: 502,
        headers: { 'Access-Control-Allow-Origin': '*' }
      });
    }
  }
};