Cleaned up code

spotify-backup.py

@@ -1,113 +1,146 @@
 import argparse 
+import BaseHTTPServer
+import codecs
+import json
+import re
+import sys
+import time
 import urllib
 import urllib2
-import json
-import time
 import webbrowser
-import sys
-import BaseHTTPServer
-import re
-import codecs
 
 class SpotifyAPI:
+	
+	# Requires an OAuth token.
 	def __init__(self, auth):
 		self._auth = auth
 	
+	# Gets a resource from the Spotify API and returns the object.
 	def get(self, url, params={}, tries=3):
+		# Construct the correct URL.
 		if not url.startswith('https://api.spotify.com/v1/'):
 			url = 'https://api.spotify.com/v1/' + url
 		if params:
 			url += ('&' if '?' in url else '?') + urllib.urlencode(params)
-		
+	
-		try:
+		# Try the sending off the request a specified number of times before giving up.
-			return json.load(urllib2.urlopen(urllib2.Request(url, None, {'Authorization': 'Bearer ' + self._auth})))
+		for _ in xrange(tries):
-		except urllib2.HTTPError as err:
+			try:
-			log('Couldn\'t load URL: {} ({} {})'.format(url, err.code, err.reason))
+				req = urllib2.Request(url)
-			if tries <= 0:
+				req.add_header('Authorization', 'Bearer ' + self._auth)
-				sys.exit(1)
+				return json.load(urllib2.urlopen(req))
-			time.sleep(2)
+			except urllib2.HTTPError as err:
-			log('Trying again...')
+				log('Couldn\'t load URL: {} ({} {})'.format(url, err.code, err.reason))
-			return self.get(url, tries=tries-1)
+				time.sleep(2)
-
+				log('Trying again...')
-	def list(self, path, params={}):
+		sys.exit(1)
-		response = self.get(path, params)
+	
+	# The Spotify API breaks long lists into multiple pages. This method automatically
+	# fetches all pages and joins them, returning in a single list of objects.
+	def list(self, url, params={}):
+		response = self.get(url, params)
 		items = response['items']
 		while response['next']:
 			response = self.get(response['next'])
 			items += response['items']
 		return items
 	
-	_LISTEN_PORT_NUMBER = 43019
+	# Pops open a browser window for a user to log in and authorize API access.
-	
 	@staticmethod
 	def authorize(client_id, scope):
 		webbrowser.open('https://accounts.spotify.com/authorize?' + urllib.urlencode({
 			'response_type': 'token',
 			'client_id': client_id,
 			'scope': scope,
-			'redirect_uri': 'http://127.0.0.1:{}/redirect'.format(SpotifyAPI._LISTEN_PORT_NUMBER)
+			'redirect_uri': 'http://127.0.0.1:{}/redirect'.format(SpotifyAPI._SERVER_PORT)
 		}))
-		httpd = SpotifyAPI._AuthorizationListener('', SpotifyAPI._LISTEN_PORT_NUMBER)
+	
+		# Start a simple, local HTTP server to listen for the authorization token... (i.e. a hack).
+		server = SpotifyAPI._AuthorizationServer('127.0.0.1', SpotifyAPI._SERVER_PORT)
 		try:
 			while True:
-				httpd.handle_request()
+				server.handle_request()
 		except SpotifyAPI._Authorization as auth:
 			return SpotifyAPI(auth.access_token)
-			
+	
-	class _AuthorizationListener(BaseHTTPServer.HTTPServer):
+	# The port that the local server listens on. Don't change this,
+	# as Spotify only will redirect to certain predefined URLs.
+	_SERVER_PORT = 43019
+	
+	class _AuthorizationServer(BaseHTTPServer.HTTPServer):
 		def __init__(self, host, port):
 			BaseHTTPServer.HTTPServer.__init__(self, (host, port), SpotifyAPI._AuthorizationHandler)
+		
+		# Disable the default error handling.
 		def handle_error(self, request, client_address):
 			raise
-
+	
 	class _AuthorizationHandler(BaseHTTPServer.BaseHTTPRequestHandler):
 		def do_GET(self):
+			# The Spotify API has redirected here, but access_token is hidden in the URL fragment.
+			# Read it using JavaScript and send it to /token as an actual query string...
 			if self.path.startswith('/redirect'):
 				self.send_response(200)
 				self.send_header('Content-Type', 'text/html')
 				self.end_headers()
 				self.wfile.write('<script>location.replace("token?" + location.hash.slice(1));</script>')
+			
+			# Read access_token and use an exception to kill the server listening...
 			elif self.path.startswith('/token?'):
 				self.send_response(200)
 				self.send_header('Content-Type', 'text/html')
 				self.end_headers()
 				self.wfile.write('<script>close()</script>Thanks! You may now close this window.')
 				raise SpotifyAPI._Authorization(re.search('access_token=([^&]*)', self.path).group(1))
+			
 			else:
 				self.send_error(404)
-				
+		
+		# Disable the default logging.
 		def log_message(self, format, *args):
 			pass
-				
+	
 	class _Authorization(Exception):
 		def __init__(self, access_token):
 			self.access_token = access_token
-		
+
 def log(str):
 	print u'[{}] {}'.format(time.strftime('%I:%M:%S'), str).encode(sys.stdout.encoding, errors='replace')
 
 def main():
-	parser = argparse.ArgumentParser(description='Exports your Spotify playlists. By default, opens a browser window to authorize the Spotify Web API, but you can manually specify an OAuth token with the --token option.')
+	# Parse arguments.
-	parser.add_argument('--token', metavar='OAUTH_TOKEN', help='use a Spotify OAuth token (requires the `playlist-read-private` permission)')
+	parser = argparse.ArgumentParser(description='Exports your Spotify playlists. By default, opens a browser window'
+	                                           + 'to authorize the Spotify Web API, but you can also manually specify'
+	                                           + ' an OAuth token with the --token option.')
+	parser.add_argument('--token', metavar='OAUTH_TOKEN', help='use a Spotify OAuth token (requires the '
+	                                           + '`playlist-read-private` permission)')
 	parser.add_argument('--format', default='txt', choices=['json', 'txt'], help='output format (default: txt)')
 	parser.add_argument('file', help='output filename')
 	args = parser.parse_args()
-
+	
+	# Log into the Spotify API.
 	if args.token:
 		spotify = SpotifyAPI(args.token)
 	else:
 		spotify = SpotifyAPI.authorize(client_id='5c098bcc800e45d49e476265bc9b6934', scope='playlist-read-private')
-
+	
+	# Get the ID of the logged in user.
 	me = spotify.get('me')
 	log(u'Logged in as {display_name} ({id})'.format(**me))
+
+	# List all playlists and all track in each playlist.
 	playlists = spotify.list('users/{user_id}/playlists'.format(user_id=me['id']), {'limit': 50})
 	for playlist in playlists:
 		log(u'Loading playlist: {name} ({tracks[total]} songs)'.format(**playlist))
 		playlist['tracks'] = spotify.list(playlist['tracks']['href'], {'limit': 100})
-		
+	
+	# Write the file.
 	with codecs.open(args.file, 'w', 'utf-8') as f:
+		# JSON file.
 		if args.format == 'json':
 			json.dump(playlists, f)
+		
+		# Tab-separated file.
 		elif args.format == 'txt':
 			for playlist in playlists:
 				f.write(playlist['name'] + '\r\n')