Slack Watcher

Gemfile

source "https://rubygems.org"
gem "slack-api"
gem "slack-rtmapi"
gem "dotenv"
gem "activesupport"

slack_watcher.rb

require 'slack'
require 'slack-rtmapi'
require 'dotenv'
require 'active_support'
require 'active_support/core_ext'

POST_CHANNEL_NAME = 'bot_devastation'

Dotenv.load

class StandardError
  def report
    "#{self.class}: #{message}\n#{backtrace.join("\n")}"
  end
end

class SlackChannelWatcher
  def initialize(channel_name_for_post)
    @channel_id_for_post = channel_name_to_id(channel_name_for_post)
  end

  def slack
    @slack ||= Slack.client(token: ENV['SLACK_TOKEN'])
  end

  def rtm_client(opts = {})
    url = SlackRTM.get_url(token: ENV['SLACK_TOKEN'])
    client = SlackRTM::Client.new(websocket_url: url)
    handle_message!(client)
    client
  end

  def channels(opts = {})
    opts{:clear_cache} ? (@channels = slack.channels_list['channels']) : (@channels ||= slack.channels_list['channels'])
  end

  def channel_name_to_id(name)
    channels.find { |channel| channel['name'] == name }['id']
  end

  def resolve_channel_name(id, opts = {})
    channel_info = channels.find { |channel| channel['id'] == id }
    if opts[:light]
      channel_info['name']
    else
      "<##{channel_info['id']}|#{channel_info['name']}>"
    end
  end

  def post_message(channel = @channel_id_for_post, text)
    slack.chat_postMessage(channel: channel, text: text, as_user: true)
  end

  def handle_message!(handled_rtm_client)
    handled_rtm_client.on(:message) do |message|
      begin
        case message['type']

        when 'channel_created'
          channels('update_cache')
          post_message("#{resolve_channel_name(message['channel']['id'])} っていうチャンネルができたみたいだけど……")

        when 'channel_rename'
          old_name = resolve_channel_name(message['channel']['id'], light: true)
          channels(clear_cache: true)
          new_name = resolve_channel_name(message['channel']['id'])
          post_message("##{old_name}が#{new_name}に変異したみたいだけどっ！")

        when 'channel_archive'
          channels(cleac_cache: true)
          post_message("またひとつ、#{resolve_channel_name(message['channel'])} っていうチャンネルがアーカイブの世界に閉じ込められた")

        when 'channel_deleted'
          post_message("っ、#{resolve_channel_name(message['channel'])} っていうチャンネルの気配が消えた……")

        when "bot_added"
          post_message("なんだか、<@#{message['bot']['id']}> っていう新しい#{message['bot']['name']}の気配を感じる")

        when "channel_unarchive"
          channels(clear_chache: true)
          post_message("墓地から#{resolve_channel_name(message['channel'])} っていうチャンネルを場に出す")

        when "emoji_changed"
          case message['subtype']
          when "add"
            post_message("うー、またわけのわからない :#{message['name']}: `#{message['name']}`  っていう絵文字が増えたー")

          when "remove"
            names = message['names'].map { |n| ":#{n}:" }.join(' ')
            post_message("#{names} っていう絵文字が消えたけど、別にいいよね")
          end
        end
      rescue => e
        post_message("なんかダメだった₍₍ (ง´･_･`)ว ⁾⁾\n#{message}\n#{e.report}")
      end
    end
  end
end

while
  channel_watcher = SlackChannelWatcher.new(POST_CHANNEL_NAME)
  begin
    channel_watcher.channels(clear_cache: true)
    channel_watcher.post_message("おはよう")
    channel_watcher.rtm_client.main_loop
  rescue => e
    puts e.report
    channel_watcher.post_message("(๑°⌓°๑)")
  end
  channel_watcher.post_message("(๑˃̵ᴗ˂̵)و")
end