Add support for lists, playQueues, and playlists to Plex controller. (#…

…418)

* Add support for playQueues, playlists, lists of media w/ startItem arg

Thanks to recent changes by @jjlawren to PlexAPI's playQueues, this adds support for playing additional types of media to Chromecasts when using Python-PlexAPI (4.1.1+).

Adds list, playQueue, and playlist support (possibly just fixes playlists, they weren't working for me before). Also adds the ability to start at any point in the list/queue/playlist by providing a media item as startItem.

* Refactor _reset_playback offset

* Ex. Playing lists, playlists, playQueues, media, w/ or w/o startItem.

* Formatting, SP, and grammar of docstring, logs, and comments.

* Pass existing playQueues as is unless startItem is used

This makes it so you can pass a playQueue without stripping it's args. You can still use startItem by using the playQueue's args and not the play media method:

`Plex.server.createPlayQueue(media, shuffle=1, continuous=1, startItem=media[3])`

* Typo

examples/plex_multi_example.py

@@ -0,0 +1,156 @@
+"""
+Examples of the Plex controller playing on a Chromecast.
+
+DEMO TYPES:
+  * simple: Picks the first item it finds in your libray and plays it.
+  * list: Creates a list of items from your library and plays them.
+  * playqueue: Creates a playqueue and plays it.
+  * playlist: Creates a playlist, plays it, then deletes it.
+
+All demos with the exception of 'simple' can use startItem.
+startItem lets you start playback anywhere in the list of items.
+turning this option on will pick an item in the middle of the list to start from.
+
+This demo uses features that require the latest Python-PlexAPI
+pip install plexapi
+
+"""
+
+import pychromecast
+import argparse
+import logging
+import zeroconf
+import sys
+
+from pychromecast.controllers.plex import PlexController
+from plexapi.server import PlexServer
+
+
+# Change to the friendly name of your Chromecast.
+CAST_NAME = "Office TV"
+
+# Replace with your own Plex URL, including port.
+PLEX_URL = "http://192.168.1.3:32400"
+
+# Replace with your Plex token. See link below on how to find it:
+# https://support.plex.tv/articles/204059436-finding-an-authentication-token-x-plex-token/
+PLEX_TOKEN = "Y0urT0k3nH3rE"
+
+# Library of items to pick from for tests. Use "episode", "movie", or "track".
+PLEX_LIBRARY = "episode"
+
+# The demo type you'd like to run.
+# Options are "single", "list", "playqueue", or "playlist"
+DEMO_TYPE = "playqueue"
+
+# If demo type is anything other than "single",
+# make this True to see a demo of startItem.
+START_ITEM = True
+
+parser = argparse.ArgumentParser(
+    description="How to play media items, lists, playQueues, "
+    "and playlists to a Chromecast device."
+)
+parser.add_argument("--show-debug", help="Enable debug log", action="store_true")
+parser.add_argument(
+    "--show-zeroconf-debug", help="Enable zeroconf debug log", action="store_true"
+)
+parser.add_argument(
+    "--cast", help='Name of cast device (default: "%(default)s").', default=CAST_NAME
+)
+parser.add_argument(
+    "--url", help='URL of your Plex Server (default: "%(default)s").', default=PLEX_URL
+)
+parser.add_argument(
+    "--library",
+    help="The library you'd like to test: episode, movie, or track (default: '%(default)s').",
+    default=PLEX_LIBRARY,
+)
+parser.add_argument("--token", help="Your Plex token.", default=PLEX_TOKEN)
+parser.add_argument(
+    "--demo",
+    help="The demo you'd like to run: single, list, playqueue, or playlist (default: '%(default)s').",
+    default=DEMO_TYPE,
+)
+parser.add_argument(
+    "--startitem",
+    help="If demo type is anything other than 'single', set to True to see a demo of startItem (default: '%(default)s').",
+    default=START_ITEM,
+)
+
+args = parser.parse_args()
+if args.show_debug:
+    logging.basicConfig(level=logging.DEBUG)
+if args.show_zeroconf_debug:
+    print("Zeroconf version: " + zeroconf.__version__)
+    logging.getLogger("zeroconf").setLevel(logging.DEBUG)
+startItem = None
+
+
+def media_info(media, items):
+    print(f"Cast Device: {cast.name}")
+    print(f"Media Type: {type(media)}")
+    print(f"Media Items: {items}")
+
+
+def start_item_info(media):
+    if args.startitem:
+        print(f"Starting From: {media}")
+
+
+chromecasts, browser = pychromecast.get_listed_chromecasts(friendly_names=[args.cast])
+cast = next((cc for cc in chromecasts if cc.name == args.cast), None)
+
+if not cast:
+    print(f"No chromecast with name '{args.cast}' found.")
+    foundCasts = ", ".join([cc.name for cc in pychromecast.get_chromecasts()[0]])
+    print(f"Chromecasts found: {foundCasts}")
+    sys.exit(1)
+
+plex_server = PlexServer(args.url, args.token)
+
+# Create a list of 5 items from the selected library.
+libraryItems = plex_server.library.search(
+    libtype=args.library, sort="addedAt:desc", limit=5
+)
+
+if args.demo == "single":
+    # Use a single item as media.
+    media = libraryItems[0]
+    media_info(media, libraryItems[0])
+elif args.demo == "list":
+    # Use the unaltered list as media.
+    media = libraryItems
+    # Set starting position to the 2nd item if startItem demo.
+    startItem = libraryItems[1] if args.startitem else None
+    # Print info
+    media_info(libraryItems, libraryItems)
+    start_item_info(libraryItems[1])
+elif args.demo == "playqueue":
+    # Convert list into a playqueue for media.
+    media = plex_server.createPlayQueue(libraryItems)
+    # Set starting position to the 3rd item if startItem demo.
+    startItem = libraryItems[2] if args.startitem else None
+    # Print info
+    media_info(media, media.items)
+    start_item_info(libraryItems[2])
+elif args.demo == "playlist":
+    # Convert list into a playlist for media.
+    media = plex_server.createPlaylist("pychromecast test playlist", libraryItems)
+    # Set starting position to the 4th item if startItem demo.
+    startItem = libraryItems[3] if args.startitem else None
+    # Print info
+    media_info(media, media.items())
+    start_item_info(libraryItems[2])
+
+plex_c = PlexController()
+cast.register_handler(plex_c)
+cast.wait()
+
+# Plays the media item, list, playlist, or playqueue.
+# If startItem = None it is ignored and playback starts at first item,
+# otherwise playback starts at the position of the media item given.
+plex_c.block_until_playing(media, startItem=startItem)
+
+if getattr(media, "TYPE", None) == "playlist":
+    media.delete()