Extend the usage function and add descriptions for commands

User-facing help text is now kept in a dictionary where command tuples
map to help entries. This greatly simplifies maintenance should more
commands be added in the future.

Additionally, every command now has a short description that serves to
give players a quick overview of its functionality.

botcmd.py

@@ -1,5 +1,6 @@
 import threading
 import time
+from collections import namedtuple
 
 import channel
 
@@ -13,6 +14,8 @@ irc_chan = None
 
 game_channel = None
 
+HelpEntry = namedtuple('HelpEntry', ['synopsis', 'desc', 'is_sub'])
+
 def chunk(l, n):
 	assert 0 < n
 	chunked = []
@@ -122,6 +125,33 @@ def send_event(event):
 	game_channel.send(event)
 
 def usage(command):
+	entries = {
+		('status',)  : HelpEntry('!status', 'Show the game status.', False),
+		('ready',)   : HelpEntry('!ready', 'Mark yourself as ready.', False),
+		('unready',) : HelpEntry('!unready', 'Mark yourself as not ready.', False),
+		('kill',)    : HelpEntry('!kill', 'Stop the game.', False),
+		('leave',)   : HelpEntry('!leave', 'Leave the game.', False),
+		('players',) : HelpEntry('!players', 'Show a list of players.', False),
+		('cards',)   : HelpEntry('!cards', 'Show the cards in your hand.', False),
+		('origins',) : HelpEntry('!origins', 'Show the cardcast codes of the decks containing the cards that can be picked currently.', False),
+		('redeal',)  : HelpEntry('!redeal', 'Remove all cards from your hand and redeal.', False),
+		('start',)   : HelpEntry('!start [<preset>]', 'Start a game with the specified preset. If no preset is given, use "default". Available presets are: default, empty, offtopia, offtopia-random', False),
+		('join',)    : HelpEntry('!join [<message>]', 'Join the game with the specified message.', False),
+		('kick',)    : HelpEntry('!kick <nick>', 'Kick the specified player from the game.', False),
+		('card',)    : HelpEntry('[!card] <number[,number,...]> ...', 'Pick the specified cards. If multiple numbers are specified for a single pick, play one of them at random.', False),
+		('jape',)    : HelpEntry('[!jape] <number[,number,...]> ...', 'See !card.', False),
+		('deck',)    : HelpEntry('!deck add | remove | list', 'Manage decks.', True),
+		('bot',)     : HelpEntry('!bot add | remove', 'Manage bots.', True),
+		('limit',)   : HelpEntry('!limit [<number> [<type>]]', 'Show or adjust the win limit. Type can be "r" for rounds and "p" for points.', False),
+		('help',)    : HelpEntry('!help [command [subcommand]]', 'Show a synopsis and description for the specified command.', False),
+
+		('deck', 'add')    : HelpEntry('!deck add <code> | random', 'Add the deck with the specified cardcast code (or pick one randomly).', False),
+		('deck', 'remove') : HelpEntry('!deck remove <code>', 'Remove the deck with the specified cardcast code.', False),
+		('deck', 'list')   : HelpEntry('!deck list', 'List selected decks.', False),
+		('bot',  'add')    : HelpEntry('!bot add <type> [<name>]', 'Add a bot of the specified type and name. If the name is omitted, name the bot after its type.', False),
+		('bot',  'remove') : HelpEntry('!bot remove <name>', 'Remove the specified bot.', False),
+	}
+
 	if type(command) == str:
 		command = [command]
 
@@ -130,55 +160,17 @@ def usage(command):
 			command[0] = command[0][1:]
 
 	if len(command) == 0:
-		return '!status !start !ready !unready !kill !join !leave !players !kick !deck !limit !card !cards !origins !redeal !help'
-
-	elif len(command) == 1:
-		if command[0] in ('status', 'ready', 'unready', 'kill', 'join', 'leave', 'players', 'cards', 'origins', 'redeal'):
-			return 'Usage: !%s' % (command[0])
-		elif command[0] == 'start':
-			return 'Usage: !start [<preset>]'
-		elif command[0] == 'join':
-			return 'Usage: !join [<message>]'
-		elif command[0] == 'kick':
-			return 'Usage: !kick <nick>'
-		elif command[0] == 'card':
-			return 'Usage: [!card] <number[,number,...]> ...'
-		elif command[0] == 'jape':
-			return 'Usage: [!jape] <number[,number,...]> ...'
-		elif command[0] == 'deck':
-			return 'Subcommands: !deck add | remove | list'
-		elif command[0] == 'bot':
-			return 'Subcommands: !bot add | remove'
-		elif command[0] == 'limit':
-			return 'Usage: !limit [<number> [<type>]]'
-		elif command[0] == 'help':
-			return 'Usage: !help [command [subcommmand]]'
-		else:
-			return 'No such command !%s' % (command[0])
-
-	elif len(command) == 2:
-		if command[0] == 'deck':
-			if command[1] == 'add':
-				return 'Usage: !deck add <code> | random'
-			elif command[1] == 'remove':
-				return 'Usage: !deck remove <code>'
-			elif command[1] == 'list':
-				return 'Usage: !deck list'
-			else:
-				return 'No such subcommand !%s %s' % (command[0], command[1])
-		elif command[0] == 'bot':
-			if command[1] == 'add':
-				return 'Usage: !bot add <type> [<name>]'
-			elif command[1] == 'remove':
-				return 'Usage: !bot remove <name>'
-			else:
-				return 'No such subcommand !%s %s' % (command[0], command[1])
-		else:
-			return 'No such subcommand !%s %s' % (command[0], command[1])
-
-	else:
+		return ' '.join(sorted(set('!' + cmd[0] for cmd in entries.keys())))
+	elif len(command) > 2:
 		return 'Uh, how did we get %i args?' % len(command)
 
+	key = tuple(command)
+	if key in entries:
+		e = entries[key]
+		return '%s: %s      %s' % ('Subcommands' if e.is_sub else 'Usage', e.synopsis, e.desc)
+	else:
+		return 'No such command !%s' % ' '.join(command)
+
 def parse_command(message, nick, irc):
 	def send(m):
 		global irc_chan