Add ls command to list channels

mmcli.py

@@ -238,6 +238,60 @@ def cat(mm_api: mattermost.MMApi, cmdline_args):
 		print_initial_messages()
 
 
+def ls(mm_api: mattermost.MMApi, cmdline_args):
+	# TODO Doesn't work for channel creation and deletion yet
+
+	# In a list to allow overwriting from within print_initial_channels without using global
+	backlog = [ [] ]
+	backlog_lock = threading.Lock()
+
+	team = resolve_team(mm_api, cmdline_args.team)
+
+	events = {"channel_converted", "channel_created", "channel_deleted", "channel_updated"}
+
+	def print_initial_channels():
+		for channel in mm_api.get_team_channels(team["id"]):
+			print(str_for_chan(lambda x: x, channel, cmdline_args))
+
+		with backlog_lock:
+			for channel in backlog[0]:
+				print(str_for_chan(lambda x: x, channel, cmdline_args))
+			backlog[0] = None
+
+	if cmdline_args.follow:
+		def simple_websocket_callback(_mmws, event_data):
+			if event_data.get("event") in events:
+				channel = json.loads(event_data["data"]["channel"])
+				if channel["team_id"] != team["id"]:
+					return
+				print(str_for_chan(lambda x: x, channel, cmdline_args))
+
+		def initial_websocket_callback(mmws: MMws, event_data):
+			if event_data.get("event") in events:
+				channel = json.loads(event_data["data"]["channel"])
+				if channel["team_id"] != team["id"]:
+					return
+				with backlog_lock:
+					if backlog[0] is not None:
+						backlog[0].append(channel)
+						return
+					else:
+						mmws.ws_handler = simple_websocket_callback
+						simple_websocket_callback(mmws, event_data)
+
+		ws_url = http_to_ws(mm_api._url) + "/v4/websocket"
+		mmws = MMws(initial_websocket_callback, mm_api.access_token, ws_url)
+
+		thread = threading.Thread(target=print_initial_channels)
+		thread.setDaemon(True)
+		thread.start()
+
+		mmws.run_websocket()
+
+	else:
+		print_initial_channels()
+
+
 def send(mm_api: mattermost.MMApi, cmdline_args):
 	read_stdin = cmdline_args.message is None or cmdline_args.channel is None
 
@@ -288,9 +342,26 @@ def str_for_post(attribute, post, cmdline_args):
 	assert False
 
 
+def str_for_chan(attribute, channel, cmdline_args):
+	obj = {
+		k: v
+		for k, v in map(attribute, channel.items())
+	}
+
+	if cmdline_args.format == "json":
+		return json.dumps(obj)
+	if cmdline_args.format == "tsv":
+		# TODO
+		header = tsv_escape(obj.get("header", ""))
+		purpose = tsv_escape(obj.get("purpose", ""))
+		return f"{obj['id']}\t{obj['name']}\t{obj.get('display_name')}\t{obj.get('create_at')}\t{obj.get('delete_at')}\t{purpose}\t{header}"
+	assert False
+
+
 ACTIONS = {
 	"login": {"function": login, "accesstoken_required": False},
 	"cat": {"function": cat},
+	"ls": {"function": ls},
 	"send": {"function": send},
 }
 
@@ -346,6 +417,10 @@ Hint: JSON output can be filtered on the command line with jq(1).
 	parser_cat.add_argument("--since", help="all after timestamp")
 	parser_cat.add_argument("-f", "--follow", action="store_true", help="keep running, printing new posts as they come in")
 
+	parser_ls = subparsers.add_parser("ls", help="list channels")
+	parser_ls.add_argument("team", help="URL name of team")
+	parser_ls.add_argument("-f", "--follow", action="store_true", help="keep running, printing changes to channels as they come in")
+
 	parser_send = subparsers.add_parser("send", help="send message(s)")
 	parser_send.add_argument(
 		"--channel", help="URL names of team and channel: '<team>/<channel>'; if not provided, "