Implement resolver lambda

cmd/resolver/function.py

@@ -0,0 +1,117 @@
+import os
+import requests
+import youtube_dl
+
+METADATA_URL = os.getenv('METADATA_URL', 'http://podsync.net/api/metadata/{feed_id}')
+print('Using metadata URL template: ' + METADATA_URL)
+
+
+class InvalidUsage(Exception):
+    pass
+
+
+opts = {
+    'quiet': True,
+    'no_warnings': True,
+    'forceurl': True,
+    'simulate': True,
+    'skip_download': True,
+    'call_home': False,
+    'nocheckcertificate': True
+}
+
+url_formats = {
+    'youtube': 'https://youtube.com/watch?v={}',
+    'vimeo': 'https://vimeo.com/{}',
+}
+
+
+def handler(event, context):
+    feed_id = event['feed_id']
+    video_id = event['video_id']
+
+    redirect_url = download(feed_id, video_id)
+
+    return {
+        'redirect_url': redirect_url,
+    }
+
+
+def download(feed_id, video_id):
+    if not feed_id:
+        raise InvalidUsage('Invalid feed id')
+
+    # Remove extension and check if video id is ok
+    video_id = os.path.splitext(video_id)[0]
+    if not video_id:
+        raise InvalidUsage('Invalid video id')
+
+    # Pull metadata from API server
+    metadata_url = METADATA_URL.format(feed_id=feed_id, video_id=video_id)
+    r = requests.get(url=metadata_url)
+    json = r.json()
+
+    # Build URL
+    provider = json['provider']
+    tpl = url_formats[provider]
+    if not tpl:
+        raise InvalidUsage('Invalid feed')
+    url = tpl.format(video_id)
+
+    redirect_url = _resolve(url, json)
+    return redirect_url
+
+
+def _resolve(url, metadata):
+    if not url:
+        raise InvalidUsage('Invalid URL')
+
+    print('Resolving %s' % url)
+
+    try:
+        provider = metadata['provider']
+
+        with youtube_dl.YoutubeDL(opts) as ytdl:
+            info = ytdl.extract_info(url, download=False)
+            if provider == 'youtube':
+                return _yt_choose_url(info, metadata)
+            elif provider == 'vimeo':
+                return _vimeo_choose_url(info, metadata)
+            else:
+                raise ValueError('undefined provider')
+    except Exception as e:
+        print(e)
+        raise
+
+
+def _yt_choose_url(info, metadata):
+    is_video = metadata['format'] == 'video'
+
+    # Filter formats by file extension
+    ext = 'mp4' if is_video else 'm4a'
+    fmt_list = [x for x in info['formats'] if x['ext'] == ext and 'acodec' in x and x['acodec'] != 'none']
+    if not len(fmt_list):
+        return info['url']
+
+    # Sort list by field (width for videos, file size for audio)
+    sort_field = 'width' if is_video else 'filesize'
+    # Sometime 'filesize' field can be None
+    if not all(x[sort_field] is not None for x in fmt_list):
+        sort_field = 'format_id'
+    ordered = sorted(fmt_list, key=lambda x: x[sort_field], reverse=True)
+
+    # Choose an item depending on quality, better at the beginning
+    is_high_quality = metadata['quality'] == 'high'
+    item = ordered[0] if is_high_quality else ordered[-1]
+    return item['url']
+
+
+def _vimeo_choose_url(info, metadata):
+    # Query formats with 'extension' = mp4 and 'format_id' = http-1080p/http-720p/../http-360p
+    fmt_list = [x for x in info['formats'] if x['ext'] == 'mp4' and x['format_id'].startswith('http-')]
+
+    ordered = sorted(fmt_list, key=lambda x: x['width'], reverse=True)
+    is_high_quality = metadata['quality'] == 'high'
+    item = ordered[0] if is_high_quality else ordered[-1]
+
+    return item['url']