Handle empty messages in bot framework by default

zulip_bots/README.md

@@ -107,9 +107,11 @@ Each bot library simply needs to do the following:
 
 - Define a class that supports the methods `usage`
 and `handle_message`.
+- Optionally add a class member `ACCEPT_EMPTY_MESSAGES`, to
+specify that empty messages will be passed to the bot.
 - Set `handler_class` to be the name of that class.
 
-(We make this a two-step process to reduce code repetition
+(We make this a three-step process to reduce code repetition
 and to add abstraction.)
 
 ## Portability

zulip_bots/zulip_bots/bots/wikipedia/wikipedia.py

@@ -18,6 +18,11 @@ class WikipediaHandler(object):
     kind of external issue tracker as well.
     '''
 
+    META = {'name': 'Wikipedia',
+            'description': 'Searches Wikipedia for a term and returns the top article.',
+            'no_defaults': True,  # Let bot handle all messages
+    }
+
     def usage(self):
         return '''
             This plugin will allow users to directly search

zulip_bots/zulip_bots/bots/xkcd/xkcd.py

@@ -6,6 +6,8 @@
 XKCD_TEMPLATE_URL = 'https://xkcd.com/%s/info.0.json'
 LATEST_XKCD_URL = 'https://xkcd.com/info.0.json'
 
+from collections import OrderedDict
+
 class XkcdHandler(object):
     '''
     This plugin provides several commands that can be used for fetch a comic
@@ -14,6 +16,16 @@ class XkcdHandler(object):
     commands.
     '''
 
+    META = {'name': 'XKCD',
+            'description': 'Fetches comic strips from https://xkcd.com.',
+            'no_defaults': False,
+            'commands': OrderedDict([
+                ('latest', "Show the latest comic strip"),
+                ('random', "Show a random comic strip"),
+                ('<comic id>', "Show a comic strip with a specific 'comic id'"),
+            ])
+    }
+
     def usage(self):
         return '''
             This plugin allows users to fetch a comic strip provided by

zulip_bots/zulip_bots/lib.py

@@ -18,6 +18,8 @@
 
 from zulip import Client
 
+from collections import OrderedDict
+
 def exit_gracefully(signum, frame):
     # type: (int, Optional[Any]) -> None
     sys.exit(0)
@@ -156,7 +158,59 @@ def run_message_handler_for_bot(lib_module, quiet, config_file, bot_name):
 
     state_handler = StateHandler()
 
+    # Bot details and default commands from defaults, then override if provided
+    bot_details = { 'name': bot_name.capitalize(),
+                    'description': "",
+                    'commands': {},
+                    'no_defaults': False,
+    }
+    def def_about():
+        desc = bot_details['description']
+        return "**{}**{}".format(bot_details['name'],
+                                 "" if desc == "" else ": {}".format(desc))
+    def def_help():
+        return ("\n".join("**{}** - {}".format(k, v[1])
+                          for k, v in default_commands.items() if k != '') +
+                "\n" +
+                "\n".join("**{}** - {}".format(k, v)
+                          for k, v in bot_details['commands'].items() if k != ''))
+    def def_commands():
+        return "**Commands**: {} {}".format(
+            " ".join(k for k in default_commands if k != ''),
+            " ".join(k for k in bot_details['commands'] if k != ''))
+    default_commands = OrderedDict([
+        ('', lambda: ("Oops. Your message was empty.", )),
+        ('about', (def_about, "The type and use of this bot")),
+        ('usage', ((lambda: message_handler.usage(), "Bot-provided usage text"))),
+        ('help', (lambda: "{}\n{}\n{}".format(def_about(), message_handler.usage(), def_help()),
+                 "This help text")),
+        ('commands', (def_commands, "A short list of supported commands"))
+    ])
+    # Update bot_details from those in class, if present
+    try:
+        bot_details.update(lib_module.handler_class.META)
+    except AttributeError:
+        pass
+    # Update default_commands from any changes in bot_details
+    if bot_details['no_defaults']:  # Bot class will handle all commands
+        default_commands = {}
+    else:
+        if len(bot_details['commands']) == 0:  # No commands specified, so don't use this feature
+            del default_commands['commands']
+            del default_commands['help']
+        else:
+            for command in bot_details['commands']:  # Bot commands override defaults
+                if command in default_commands:
+                    del default_commands[command]
+    # Sync default_commands changes with bot_details
+    if len(default_commands) == 0:
+        bot_details['no_defaults'] = True
+>>>>>>> 49217e1... Bots: Alternative extended default commands approach.
+
     if not quiet:
+        print("Running {} Bot:".format(bot_details['name']))
+        if bot_details['description'] != "":
+            print("\n{}".format(bot_details['description']))
         print(message_handler.usage())
 
     def extract_query_without_mention(message, client):
@@ -198,6 +252,18 @@ def handle_message(message):
                 return
 
         if is_private_message or is_mentioned:
+            # Handle any default_commands first
+            if len(default_commands) > 0:
+                if '' in default_commands and len(message['content']) == 0:
+                    restricted_client.send_reply(message, default_commands[''][0]())
+                    return
+                for command in default_commands:
+                    if command == '':
+                        continue
+                    if message['content'].startswith(command):
+                        restricted_client.send_reply(message, default_commands[command][0]())
+                        return
+            # ...then pass anything else to bot to deal with
             message_handler.handle_message(
                 message=message,
                 bot_handler=restricted_client,