This project attempts to create a simple/flexible bot framework using the best of Elixir/Erlang/OTP. For now it only supports the Matrix messaging protocol, however it would be reasonably straightforward to introduce some kind of adapter pattern or something to support other chat services and would happily take PRs for something like that. The recommended use for this framework is to create your own mix project and bring this in as a dependency. You can define your own commands or just use the packaged ones and you configure that in your project.

Commands are a way of perfoming an action when someone uses the magic keyword. The command prefix must be configured, but lets assume it is "bender". An example command (that comes packaged with this project) is the echo command.

The implementation is very simple:

defmodule Bender.Commands.Echo do
  use Bender.Command

  @usage "echo <message>"
  @short_description "responds with <message>"

  def handle_event({{:command, "echo", message}, meta}, state) do
    respond(message, meta)
    {:ok, state}
  end
end

This framework uses GenEvent for dispatching the commands. You can use all the deliciousness of pattern matching to match the commands you are interested in.

The important part of the pattern match is {:command, "echo", message}. In the case that someone says bender echo hello world these will come through like {:command, "echo", "hello world"}. The other parts of the pattern match are just metadata/session data. You can use meta[:author].user_id if you want to know who sent the message.

The module attributes @usage and @short_description will be included in the output of bender help if they are defined.

The commands that your bot actually runs must be configured and you can mix and match between packaged commands and any commands you define.

The config setup for this project is as follows:

config :bender,
  command_prefix: "bender",
  matrix_home_server: "matrix.org",
  matrix_user: "bender",
  matrix_password: "bender",
  commands: [Bender.Commands.Echo, Bender.Commands.Ping],
  room_names: ["#bender:matrix.org"]

You must set all of these when you include this dependency in your project, however you can easily run this project as is and the above credentials will log you into matrix.org and you can play around with your bot.

The package can be installed as:

1. Add bender to your list of dependencies in mix.exs:

    def deps do
    	[{:bender, git: "https://github.com/DylanGriffith/bender.git"}]
    end
   

2. Ensure bender is started before your application:

    def application do
    	[applications: [:bender]]
    end