An python-based IRC bot using Twisted. Original inspiration came from thepeopleseason/olga. Why re-implement another bot? Because olga is written in perl, and I wanted something a bit more sane to look at.

All requirements for helga are listed in requirements.txt. However, there is a single external requirement, and that is MongoDB. You don't need it, per se, but many of the included plugins use MongoDB for storing consistent state between restarts.

Start by creating a virtualenv where helga will reside:

$ virtualenv helga
$ cd helga
$ source bin/activate

Then grab the latest copy and install requirements:

$ git clone https://github.com/shaunduncan/helga src/helga
$ cd src/helga
$ python setup.py develop
$ pip install -r requirements.txt

Once you have performed the above steps, there will be a helga executable placed in the bin dir of your virtualenv. Run helga by calling this:

$ /path/to/venv/bin/helga

Note that this uses the default settings file, helga.settings to start. You can, and should, use your own custom setttings. This file must a be an importable python file on $PYTHONPATH. To run helga with your custom settings file, set an environment variable HELGA_SETTINGS to be a python import path:

$ export HELGA_SETTINGS=path.to.mysettings

This will preserve any defaults in helga.settings, but you can override at will.

The included Vagrantfile will let you spin up a VM to run both MongoDB and an IRC server for local development. Once you've followed the previous instructions for installing helga, simply vagrant up. This will forward host ports 6667 (irc) and 27017 (mongo) to the guest. At this point, simply runing helga from the command line will connect to this VM.

Helga supports plugins outside of the core source code. Plugins have a minimal API, but there are some basic rules that should be followed. All core plugin implementations can be found in helga.plugins.core. The basic requirement for plugins is that they have a process attribute that is a callable and determines if the plugin should handle a message, and a run method that actually performs the legwork of what the plugin should do. By convention, the process method should accept four arguments:

• client: an instance of helga.comm.Client
• channel: the channel on which the message was received
• nick: the current nick of the message sender
• message: the message string itself

The run is a bit different as it is up to the plugin implementation itself to decide what arguments are necessary to generate a response. This method should be called by process and should return one of:

• None or empty string, if no response is to be sent over IRC
• Non-empty string for a single line response
• List of strings for multiline responses

Really, as long as you follow the above conventions, you can write plugins however you wish. However, you should try to keep plugins simple and use the included decorators command, match, and preprocessor (explained later). However, if you prefer writing a plugin as a class, you can subclass the included Plugin base class, provided you have followed the above rules. Here is a simple example:

import time
from helga.plugins.core import Plugin

class MyPlugin(Plugin):
    def run(self, channel, nick, message):
        return 'Current timestamp: {0}'.format(time.time())

    def process(self, channel, nick, message):
        if message.startswith('!time'):
            return self.run(channel, nick, message)

NOTE the previous example is not the preferred way. You should use the included decorators instead (shown below).

For the most part, there are two main types of plugins: commands and matches. Commands are plugins that require a user to specifically ask for helga to perform some action. For example, helga haiku or helga google something to search. Matches are on the other hand are intended to be autoresponders that give some extra meaning or context to what a user has said. For example, if helga matches for a string "foo":

<sduncan> i'm talking about foo in this message
<helga> sduncan is talking about foo

For the sake of simplicity, there are two convenient decorators for authoring these types of plugins (which is usually the case). For example:

from helga.plugins import command, match

@command('foo', aliases=['foobar'], help="The foo command")
def foo(client, channel, nick, message, cmd, args):
    # This is run on "helga foo" or "helga foobar"
    return "Running the foo command"

@match(r'bar')
def bar(client, channel, nick, message, matches):
    # This will run whenever a user mentions the word 'bar'
    return "{0} said bar!".format(nick)

You may notice in the above example that each decorated function accepts different arguments. For commands, there are two additional arguments cmd and args. The former is the parsed command that was used to run the method (which could be "foo" in the above case, or the alias "foobar"). The latter is a list of whitespace delimited strings that follow the parsed commend. For example helga foo a b c would mean the args param would be ['a', 'b', 'c'].

For the match plugin, the single additional argument is matches which is for the most part, the result of re.findall. However, the @match decorator accepts a callable in place of a regex string. This callable should accept one argument: the message being processed. It should return a value that can be evaluated for truthiness and will be passed to the decorated function as the matches parameter.

Plugins can also be message preprocessors. These are callables that may perform some modification on an incoming message prior to that message being delivered to any plugins. Preprocessors should accept arguments (in order) for client, channel, nick, and message and should return a three-tuple consisting of (in order) channel, nick, and message. To declare a function as a preprocessor, a convenient decorator can be used:

from helga.plugins import preprocessor

@preprocessor
def blank_message(client, channel, nick, message):
    return channel, nick, ''

Some plugins do both matching and act as a command. For this reason, plugin decorators are chainable. However, remember that different plugin types expect decorated functions to accept different arguments. It is best to accept *args for these:

from helga.plugins import command, match, preprocessor

@preprocessor
@match(r'bar')
@command('foo')
def complex(client, channel, nick, message, *args):
    # len(args) == 0 for preprocessors
    # len(args) == 1 for matches
    # len(args) == 2 for commands

You can control the priority in which a plugin is run. Note though, that preprocessors will always run first. A priority value should be an integer value. There are no limits or bounds for this value, but know that a higher value will mean a higher priority. If you are writing Plugin subclass style plugins, you will need to set a priority attribute of your object. This is done automatically if you call super(MyClass, self).__init__(priority=some_value) in your class's __init__.

However, if you are using the preferred decorator style for writing plugins, you can supply a priority keyword argument to the decorator:

from helga import command, match, preprocessor

@preprocessor(priority=10)
def foo_preprocess(*args):
    pass

@command('foo', priority=20)
def foo_command(*args):
    pass

@match(r'foo', priority=30)
def foo_match(*args):
    pass

For convenience, there are constants that can be used for setting priorities:

• PRIORITY_LOW = 25
• PRIORITY_NORMAL = 50
• PRIORITY_HIGH = 75

Also, each decorator/plugin type has its own default value for priority:

• Preprocessors have default priority of PRIORITY_NORMAL
• Commands have default priority of PRIORITY_NORMAL
• Matches have default priority of PRIORITY_LOW

Helga uses setuptools entry points for plugin loading. Once you've written a plugin you wish to use, you will need to make sure your python package's setup.py contains an entry_point under the group name helga_plugins. For example:

entry_points = {
    'helga_plugins': [
        'plugin_name = mylib.mymodule:MyPluginClass',
    ],
},

Note that if you are using decorated function for a plugin, you will want to specify the method name for your entry point, i.e. mylib.mymodule:myfn.

Here are some plugins that have been written that you can use:

Written a plugin? Send a pull request to be listed in the above table!

All tests are written to be run via tox. To run the test suite, inside your virtualenv:

$ cd src/helga
$ tox

Contributions are welcomed, as well as any bug reports! Please note that any pull request will be denied if tests run via tox do not pass

Copyright (c) 2013 Shaun Duncan

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.