post_as_a_bot.rb is a Ruby script that posts a message in a Mattermost channel as a bot user

post_as_a_bot.rb

#!/bin/ruby

require 'uri'
require 'httparty'

# ## post_as_a_bot.rb
# 
# ### About
# 
# post_as_a_bot.rb is a Ruby script that posts a message in a Mattermost channel as a bot user
# 
# ### Usage:
#
# **Dependencies:** This script requires that you install Ruby -
# https://www.ruby-lang.org/en/documentation/installation/ - and install the
# required gems:
#
# - uri
# - httparty
#
# Once you have Ruby installed, install them with this command: 
#
#     gem install uri httparty
# 
# 1. Create a a bot account and record the authentication token
# 2. Add the bot account to the team and channel you want it to post to
# 3. Create a file in this directory with the following format:
# 
# ```yaml
# test_server:
# 	url: https://<Mattermost Server URL>/ <- INCLUDE TRAILING SLASH
# 	login_id: <Bot username>
# 	auth_token: <Auth Token>
# ```
# 
# 4. Get the team name and channel name from the channel URL, which is available
# in the channel menu. For example, this URL -
# https://mattermost.example.com/ad-1/channels/saepe-5 - will have the team
# `ad-1` and the channel `saepe-5`
#   
# 5. Run the script through Ruby: `ruby post_as_a_bot.rb team-name channel-name "This is a bot"`

$config = YAML.load(
	File.open('conf.yaml').read
)

class MattermostApi
	include HTTParty

	format :json
	# UNCOMMENT NEXT LINE TO DEBUG REQUESTS
	debug_output $stdout
	
	def initialize(config)
		# Default Options
		@options = {
			headers: {
				'Content-Type' => 'application/json',
				'User-Agent' => 'Mattermost-HTTParty'
			},
			# TODO Make this more secure
			verify: false
		}

		# check the config for mattermost_url
		if ! (config.key?("url") && url_valid?(config['url']))
			raise 'url is required in configuration'
		end

		@base_uri = config['url'] + 'api/v4/'

		token = nil

		if config.key?('auth_token')
			token = config['auth_token']
		else
			# Use password login
			if (config.key?('login_id') && config.key?('password'))
				token = get_login_token(config['login_id'], config['password'])
			end
		end

		if token.nil?
			raise 'token not set, check for token or login_id and password'
		end
		
		@options[:headers]['Authorization'] = "Bearer #{token}"
		@options[:body] = nil
	end

	def url_valid?(url)
		url = URI.parse(url) rescue false
	end

	def post_to_channel(team_name, channel_name, message)
		team_id = get_team_id(team_name)
		channel_id = get_channel_id_by_name(channel_name, team_id)['id']
		
		create_post(channel_id, message)
	end

	def get_channel_id_by_name(channel_name, team_id)
		get_url("teams/#{team_id}/channels/name/#{channel_name}")
	end

	def create_post(channel_id, message)
		data = {channel_id: channel_id, message: message}

		post_data(data, 'posts')
	end

	
	## Sends a direct message to a user
	def send_direct_message(to_user, message)
		# Find the recipient's user ID
		to_id = get_user_by_name(to_user)['id']
		# Get the current user's ID
		from_id = self.get_current_user['id']

		data = [to_id, from_id]

		# Create the direct message channel if it isn't already
		channel = post_data(data, 'channels/direct')
		
		# create the post int he channel
		create_post(channel['id'], message)
	end

	def get_user_by_name(login_id)
		JSON.parse(self.class.get("#{@base_uri}users/username/#{login_id}", @options).to_s)
	end

	def get_current_user
		get_url('users/me')
	end

	def get_team_id(team_name)
		team = self.get_url("teams/name/#{team_name}")

		return team['id']
	end

	def post_data(payload, request_url)
		options = @options
		options[:body] = payload.to_json
		
		return self.class.post("#{@base_uri}#{request_url}", options)
	end

	def get_url(url)
		JSON.parse(self.class.get("#{@base_uri}#{url}", @options).to_s)
	end
end

$mm = MattermostApi.new($config['test_server'])

team_name = ARGV[0]
channel_name = ARGV[1]
message = ARGV[2]

if channel_name.start_with?("@")
	$mm.send_direct_message(channel_name[1...], message)
else
	$mm.post_to_channel(team_name, channel_name, message)	
end