Downloader: Implement a very basic proof of concept version

Missing a LOT of tankiness, ways to configure, conversion to bustime, etc.

downloader/downloader/__main__.py

@@ -1,6 +1,8 @@
 import logging
 
+import argh
+
 from downloader.main import main
 
 logging.basicConfig(level=logging.INFO)
-main()
+argh.dispatch_command(main)

downloader/downloader/main.py

@@ -1,4 +1,53 @@
 
+import hashlib
+import logging
+import os
+import time
+from base64 import b64encode
 
-def main():
-	pass
+import twitch
+
+
+def download_segments(base_dir, name, uri):
+	# NOTE: This function is not written to be resilient, do not rely on it.
+	# There's no retry, no atomic rename for file writing, file name format is bad,
+	# skips segments with missing info, doesn't confirm lengths, other issues.
+	# Doesn't use monotonic time.
+	INTERVAL = 2
+	prev_segments = []
+	while True:
+		last_check = time.time()
+		logging.info("Getting playlist")
+		playlist = twitch.get_media_playlist(uri)
+		for segment in playlist.segments:
+			if segment.uri in prev_segments:
+				continue
+			if not segment.date:
+				logging.warning("Segment has no date given, skipping")
+				continue
+			segment_data = twitch.get_segment(segment.uri)
+			segment_hash = hashlib.sha256(segment_data).digest()
+			filename = os.path.join(
+				base_dir, name,
+				"{}-{}".format(segment.date, segment.duration),
+				"{}.ts".format(b64encode(segment_hash, "-_")),
+			)
+			logging.info("Writing segment {}".format(filename))
+			if not os.path.exists(os.path.dirname(filename)):
+				os.makedirs(os.path.dirname(filename))
+			with open(filename, 'w') as f:
+				f.write(segment_data)
+		prev_segments = [segment.uri for segment in playlist.segments]
+		# Wait up to 2s until 2s after last_check
+		elapsed = time.time() - last_check
+		time.sleep(max(0, INTERVAL - elapsed))
+
+
+def main(channel, base_dir=".", qualities=""):
+	qualities = qualities.split(",") if qualities else []
+	master_playlist = twitch.get_master_playlist(channel)
+	uris = twitch.get_media_playlist_uris(master_playlist, qualities)
+	if len(uris) != 1:
+		raise NotImplementedError
+	(name, uri), = uris.items()
+	download_segments(base_dir, name, uri)

downloader/downloader/twitch.py

@@ -72,7 +72,7 @@ def get_media_playlist_uris(master_playlist, target_qualities):
 		raise ValueError("Master playlist has no variants")
 
 	for variant in master_playlist.playlists:
-		if any(media.uri for media in variant.medias):
+		if any(media.uri for media in variant.media):
 			logging.warning("Variant has a rendition with its own URI: {}".format(variant))
 
 	by_name = {variant_name(variant): variant for variant in master_playlist.playlists}