Added filtering logic for multiple providers, along with many RSpec tests.

General structure of the filter rules is taken from discourse-slack-official, but re-written to be more robust and easier to understand.

assets/javascripts/discourse/routes/admin-plugins-chat.js.es6

@@ -2,7 +2,7 @@ import { ajax } from 'discourse/lib/ajax';
 
 export default Discourse.Route.extend({
   model() {
-    return ajax("/chat/list-integrations.json").then(result => {
+    return ajax("/chat/list-providers.json").then(result => {
       return result.chat;
     });
   }

config/settings.yml

@@ -1,3 +1,5 @@
 plugins:
-  discourse_chat_enabled:
-    default: false
+  chat_enabled:
+    default: false
+  chat_discourse_username:
+    default: system

lib/integration.rb

@@ -1,12 +0,0 @@
-module DiscourseChat
-	module Integration
-		def self.integrations
-	      constants.select do |constant|
-	        constant.to_s =~ /Integration$/
-	      end.map(&method(:const_get))
-	    end
-	end
-end
-
-require_relative "integration/slack/slack_integration.rb"
-require_relative "integration/telegram/telegram_integration.rb"

lib/integration/slack/slack_integration.rb

@@ -1,7 +0,0 @@
-module DiscourseChat
-	module Integration
-		module SlackIntegration
-			INTEGRATION_NAME = "slack".freeze
-		end
-	end
-end

lib/integration/telegram/telegram_integration.rb

@@ -1,7 +0,0 @@
-module DiscourseChat
-	module Integration
-		module TelegramIntegration
-			INTEGRATION_NAME = "telegram".freeze
-		end
-	end
-end

lib/manager.rb

@@ -0,0 +1,97 @@
+module DiscourseChat
+  module Manager
+    KEY_PREFIX = 'category_'.freeze
+
+    def self.guardian
+      Guardian.new(User.find_by(username: SiteSetting.chat_discourse_username))
+    end
+
+    def self.get_store_key(cat_id = nil)
+      "#{KEY_PREFIX}#{cat_id.present? ? cat_id : '*'}"
+    end
+
+    def self.get_rules_for_category(cat_id = nil)      
+      PluginStore.get(DiscourseChat::PLUGIN_NAME, get_store_key(cat_id)) || []
+    end
+
+    def self.trigger_notifications(post_id)
+      Rails.logger.info("Triggering chat notifications for post #{post_id}")
+
+      post = Post.find_by(id: post_id)
+
+      # Abort if the chat_user doesn't have permission to see the post
+      return if !guardian.can_see?(post) 
+
+      # Abort if the post is blank, or is non-regular (e.g. a "topic closed" notification)
+      return if post.blank? || post.post_type != Post.types[:regular]
+
+      topic = post.topic
+
+      # Abort if a private message (possible TODO: Add support for notifying about group PMs)
+      return if topic.blank? || topic.archetype == Archetype.private_message
+
+      # Load all the rules that apply to this topic's category
+      matching_rules = get_rules_for_category(topic.category_id)
+
+      if topic.category # Also load the rules for the wildcard category
+        matching_rules += get_rules_for_category(nil)
+      end
+
+      # If tagging is enabled, thow away rules that don't apply to this topic
+      if SiteSetting.tagging_enabled
+        topic_tags = topic.tags.present? ? topic.tags.pluck(:name) : []
+        matching_rules = matching_rules.select do |rule|
+          next true if rule[:tags].nil? or rule[:tags].empty? # Filter has no tags specified
+          any_tags_match = !((rule[:tags] & topic_tags).empty?)
+          next any_tags_match # If any tags match, keep this filter, otherwise throw away
+        end
+      end
+
+      # Sort by order of precedence (mute always wins; watch beats follow)
+      precedence = { 'mute' => 0, 'watch' => 1, 'follow' => 2}
+      sort_func = proc { |a, b| precedence[a[:filter]] <=> precedence[b[:filter]] }
+      matching_rules = matching_rules.sort(&sort_func)
+
+      # Take the first rule for each channel
+      uniq_func = proc { |rule| rule.values_at(:provider, :channel) }
+      matching_rules = matching_rules.uniq(&uniq_func)
+
+      # If a matching rule is set to mute, we can discard it now
+      matching_rules = matching_rules.select { |rule| rule[:filter] != "mute" }
+
+      # If this is not the first post, discard all "follow" rules
+      if not post.is_first_post?
+        matching_rules = matching_rules.select { |rule| rule[:filter] != "follow" }
+      end
+
+      # All remaining rules now require a notification to be sent
+      # If there are none left, abort
+      return false if matching_rules.empty?
+
+      # Loop through each rule, and trigger appropriate notifications
+      matching_rules.each do |rule|
+        Rails.logger.info("Sending notification to provider #{rule[:provider]}, channel #{rule[:channel]}")
+        provider = ::DiscourseChat::Provider.get_by_name(rule[:provider])
+        if provider
+          provider.trigger_notification(post, rule[:channel])
+        else
+          puts "Can't find provider"
+          # TODO: Handle when the provider does not exist
+        end
+      end
+
+    end
+
+    def self.create_rule(provider, channel, filter, category_id, tags)
+      raise "Invalid filter" if !['mute','follow','watch'].include?(filter)
+
+      data = get_rules_for_category(category_id)
+      tags = Tag.where(name: tags).pluck(:name)
+      tags = nil if tags.blank?
+
+      data.push(provider: provider, channel: channel, filter: filter, tags: tags)
+      PluginStore.set(DiscourseChat::PLUGIN_NAME, get_store_key(category_id), data)
+    end
+
+  end
+end

lib/provider.rb

@@ -0,0 +1,17 @@
+module DiscourseChat
+  module Provider
+    def self.providers
+      constants.select do |constant|
+        constant.to_s =~ /Provider$/
+      end.map(&method(:const_get))
+    end
+
+    def self.get_by_name(name)
+      self.providers.find{|p| p::PROVIDER_NAME == name}
+    end
+
+  end
+end
+
+require_relative "provider/slack/slack_provider.rb"
+require_relative "provider/telegram/telegram_provider.rb"

lib/provider/slack/slack_provider.rb

@@ -0,0 +1,7 @@
+module DiscourseChat
+  module Provider
+    module SlackProvider
+      PROVIDER_NAME = "slack".freeze
+    end
+  end
+end

lib/provider/telegram/telegram_provider.rb

@@ -0,0 +1,7 @@
+module DiscourseChat
+  module Provider
+    module TelegramProvider
+      PROVIDER_NAME = "telegram".freeze
+    end
+  end
+end

plugin.rb

@@ -3,7 +3,7 @@
 # version: 0.1
 # url: https://github.com/discourse/discourse-chat
 
-enabled_site_setting :discourse_chat_enabled
+enabled_site_setting :chat_enabled
 
 after_initialize do
 
@@ -16,13 +16,20 @@ after_initialize do
     end
   end
 
-  require_relative "lib/integration"
+  require_relative "lib/provider"
+  require_relative "lib/manager"
+
+  DiscourseEvent.on(:post_created) do |post|
+    if SiteSetting.chat_enabled?
+      ::DiscourseChat::Manager.trigger_notifications(post.id)
+    end
+  end
 
   class ::DiscourseChat::ChatController < ::ApplicationController
     requires_plugin DiscourseChat::PLUGIN_NAME
 
-    def list_integrations
-      render json: ::DiscourseChat::Integration.integrations.map {|x| x::INTEGRATION_NAME}
+    def list_providers
+      render json: ::DiscourseChat::Provider.providers.map {|x| x::PROVIDER_NAME}
     end
 
   end
@@ -33,7 +40,7 @@ after_initialize do
   add_admin_route 'chat.menu_title', 'chat'
 
   DiscourseChat::Engine.routes.draw do
-    get "/list-integrations" => "chat#list_integrations", constraints: AdminConstraint.new
+    get "/list-providers" => "chat#list_providers", constraints: AdminConstraint.new
   end
 
   Discourse::Application.routes.prepend do

spec/lib/manager_spec.rb

@@ -0,0 +1,194 @@
+require 'rails_helper'
+require_dependency 'post_creator'
+
+RSpec.describe DiscourseChat::Manager do
+
+  let(:manager) {::DiscourseChat::Manager}  
+  let(:category) {Fabricate(:category)}
+  let(:topic){Fabricate(:topic, category_id: category.id )}
+  let(:first_post) {Fabricate(:post, topic: topic)}
+  let(:second_post) {Fabricate(:post, topic: topic, post_number:2)}
+
+  describe '.trigger_notifications' do
+    before(:each) do 
+      module ::DiscourseChat::Provider::DummyProvider
+        PROVIDER_NAME = "dummy".freeze
+        @@sent_messages = []
+
+        def self.trigger_notification(post, channel)
+          @@sent_messages.push(post: post.id, channel: channel)
+        end
+
+        def self.sent_messages
+          @@sent_messages
+        end
+      end
+    end
+
+    after(:each) do
+      ::DiscourseChat::Provider.send(:remove_const, :DummyProvider)
+    end
+
+    let(:provider) {::DiscourseChat::Provider::DummyProvider}
+
+    it "should send a notification to watched and following channels for new topic" do
+      manager.create_rule('dummy', 'chan1', 'watch', category.id, nil)
+      manager.create_rule('dummy', 'chan2', 'follow', category.id, nil)
+      manager.create_rule('dummy', 'chan3', 'mute', category.id, nil)
+
+      manager.trigger_notifications(first_post.id)
+
+      expect(provider.sent_messages.map{|x| x[:channel]}).to contain_exactly('chan1', 'chan2')
+    end
+
+    it "should send a notification only to watched for reply" do
+      manager.create_rule('dummy', 'chan1', 'watch', category.id, nil)
+      manager.create_rule('dummy', 'chan2', 'follow', category.id, nil)
+      manager.create_rule('dummy', 'chan3', 'mute', category.id, nil)
+
+      manager.trigger_notifications(second_post.id)
+
+      expect(provider.sent_messages.map{|x| x[:channel]}).to contain_exactly('chan1')
+    end
+
+    it "should respect wildcard category settings" do
+      manager.create_rule('dummy', 'chan1', 'watch', nil, nil)
+
+      manager.trigger_notifications(first_post.id)
+
+      expect(provider.sent_messages.map{|x| x[:channel]}).to contain_exactly('chan1')
+    end
+
+    it "should respect mute over watch" do
+      manager.create_rule('dummy', 'chan1', 'watch', nil, nil) # Wildcard watch
+      manager.create_rule('dummy', 'chan1', 'mute', category.id, nil) # Specific mute
+
+      manager.trigger_notifications(first_post.id)
+
+      expect(provider.sent_messages.map{|x| x[:channel]}).to contain_exactly()
+    end
+
+    it "should respect watch over follow" do
+      manager.create_rule('dummy', 'chan1', 'follow', nil, nil)
+      manager.create_rule('dummy', 'chan1', 'watch', category.id, nil)
+
+      manager.trigger_notifications(second_post.id)
+
+      expect(provider.sent_messages.map{|x| x[:channel]}).to contain_exactly('chan1')
+    end
+
+    it "should not notify about private messages" do
+      manager.create_rule('dummy', 'chan1', 'watch', nil, nil)
+      private_post = Fabricate(:private_message_post)
+
+      manager.trigger_notifications(private_post.id)
+
+      expect(provider.sent_messages.map{|x| x[:channel]}).to contain_exactly()
+    end
+
+    it "should not notify about private messages" do
+      manager.create_rule('dummy', 'chan1', 'watch', nil, nil)
+      private_post = Fabricate(:private_message_post)
+
+      manager.trigger_notifications(private_post.id)
+
+      expect(provider.sent_messages.map{|x| x[:channel]}).to contain_exactly()
+    end
+
+    it "should not notify about posts the chat_user cannot see" do
+      manager.create_rule('dummy', 'chan1', 'watch', nil, nil)
+
+      # Create a group & user
+      group = Fabricate(:group, name: "friends")
+      user = Fabricate(:user, username: 'david')
+      group.add(user)
+
+      # Set the chat_user to the newly created non-admin user
+      SiteSetting.chat_discourse_username = 'david'
+
+      # Create a category
+      category = Fabricate(:category, name: "Test category")
+      topic.category = category
+      topic.save!
+
+      # Restrict category to admins only
+      category.set_permissions(Group[:admins] => :full)
+      category.save!
+
+      # Check no notification sent
+      manager.trigger_notifications(first_post.id)
+      expect(provider.sent_messages.map{|x| x[:channel]}).to contain_exactly()
+
+      # Now expose category to new user
+      category.set_permissions(Group[:friends] => :full)
+      category.save!
+
+      # Check notification sent
+      manager.trigger_notifications(first_post.id)
+      expect(provider.sent_messages.map{|x| x[:channel]}).to contain_exactly('chan1')
+
+    end
+
+    describe 'with tags enabled' do
+      let(:tag){Fabricate(:tag, name:'gsoc')}
+      let(:tagged_topic){Fabricate(:topic, category_id: category.id, tags: [tag])}
+      let(:tagged_first_post) {Fabricate(:post, topic: tagged_topic)}
+
+      before(:each) do
+        SiteSetting.tagging_enabled = true
+      end
+
+      it 'should still work for rules without any tags specified' do
+        manager.create_rule('dummy', 'chan1', 'watch', category.id, nil)
+
+        manager.trigger_notifications(first_post.id)
+        manager.trigger_notifications(tagged_first_post.id)
+
+        expect(provider.sent_messages.map{|x| x[:channel]}).to contain_exactly('chan1','chan1')
+      end
+
+      it 'should only match tagged topics when rule has tags' do
+        manager.create_rule('dummy', 'chan1', 'watch', category.id, [tag.name])
+
+        manager.trigger_notifications(first_post.id)
+        manager.trigger_notifications(tagged_first_post.id)
+
+        expect(provider.sent_messages.map{|x| x[:channel]}).to contain_exactly('chan1')
+      end
+
+    end
+  end
+
+
+  describe '.create_rule' do
+    it 'should add new rule correctly' do
+      expect do
+        manager.create_rule('dummy', 'chan1', 'watch', category.id, nil)
+      end.to change { manager.get_rules_for_category(category.id).length }.by(1)
+
+      expect do
+        manager.create_rule('dummy', 'chan2', 'follow', category.id, nil)
+      end.to change { manager.get_rules_for_category(category.id).length }.by(1)
+    end
+
+    it 'should accept tags correctly' do
+      tag = Fabricate(:tag)
+      expect do
+        manager.create_rule('dummy', 'chan1', 'watch', category.id, [tag.name, 'faketag'])
+      end.to change { manager.get_rules_for_category(category.id).length }.by(1)
+
+      expect(manager.get_rules_for_category(category.id).first[:tags]).to contain_exactly(tag.name)
+
+    end
+
+    it 'should error on invalid filter strings' do
+      expect do
+        manager.create_rule('dummy', 'chan1', 'invalid_filter', category.id, nil)
+      end.to raise_error(RuntimeError, "Invalid filter")
+    end
+
+
+  end
+
+
+end