From 1df0159f6518345647b54cd4bfcdc8942cb8d6c5 Mon Sep 17 00:00:00 2001
From: Muhsin Keloth <muhsinkeramam@gmail.com>
Date: Mon, 21 Apr 2025 19:50:08 +0530
Subject: [PATCH] chore: add oauth flow

---
 .../github/callbacks_controller.rb            | 71 +++++++++++++++++++
 app/helpers/github/integration_helper.rb      | 47 ++++++++++++
 app/models/integrations/app.rb                | 25 ++++++-
 config/integration/apps.yml                   |  2 +-
 config/routes.rb                              |  4 ++
 5 files changed, 147 insertions(+), 2 deletions(-)
 create mode 100644 app/controllers/github/callbacks_controller.rb
 create mode 100644 app/helpers/github/integration_helper.rb

diff --git a/app/controllers/github/callbacks_controller.rb b/app/controllers/github/callbacks_controller.rb
new file mode 100644
index 000000000..0bbd9b46c
--- /dev/null
+++ b/app/controllers/github/callbacks_controller.rb
@@ -0,0 +1,71 @@
+class Github::CallbacksController < ApplicationController
+  include Github::IntegrationHelper
+
+  def show
+    @response = oauth_client.auth_code.get_token(
+      params[:code],
+      redirect_uri: "#{base_url}/github/callback"
+    )
+
+    handle_response
+  rescue StandardError => e
+    Rails.logger.error("Github callback error: #{e.message}")
+    redirect_to github_redirect_uri
+  end
+
+  private
+
+  def oauth_client
+    app_id = GlobalConfigService.load('GITHUB_CLIENT_ID', nil)
+    app_secret = GlobalConfigService.load('GITHUB_CLIENT_SECRET', nil)
+
+    OAuth2::Client.new(
+      app_id,
+      app_secret,
+      {
+        site: 'https://github.com',
+        token_url: '/login/oauth/access_token',
+        authorize_url: '/login/oauth/authorize'
+      }
+    )
+  end
+
+  def handle_response
+    hook = account.hooks.new(
+      access_token: parsed_body['access_token'],
+      status: 'enabled',
+      app_id: 'github',
+      settings: {
+        token_type: parsed_body['token_type'],
+        scope: parsed_body['scope']
+      }
+    )
+    hook.save!
+    redirect_to github_redirect_uri
+  rescue StandardError => e
+    Rails.logger.error("Github callback error: #{e.message}")
+    redirect_to github_redirect_uri
+  end
+
+  def account
+    @account ||= Account.find(account_id)
+  end
+
+  def account_id
+    return unless params[:state]
+
+    verify_github_token(params[:state])
+  end
+
+  def github_redirect_uri
+    "#{ENV.fetch('FRONTEND_URL', nil)}/app/accounts/#{account.id}/settings/integrations/github"
+  end
+
+  def parsed_body
+    @parsed_body ||= @response.response.parsed
+  end
+
+  def base_url
+    ENV.fetch('FRONTEND_URL', 'http://localhost:3000')
+  end
+end
diff --git a/app/helpers/github/integration_helper.rb b/app/helpers/github/integration_helper.rb
new file mode 100644
index 000000000..ad1cb880c
--- /dev/null
+++ b/app/helpers/github/integration_helper.rb
@@ -0,0 +1,47 @@
+module Github::IntegrationHelper
+  # Generates a signed JWT token for Github integration
+  #
+  # @param account_id [Integer] The account ID to encode in the token
+  # @return [String, nil] The encoded JWT token or nil if client secret is missing
+  def generate_github_token(account_id)
+    return if client_secret.blank?
+
+    JWT.encode(token_payload(account_id), client_secret, 'HS256')
+  rescue StandardError => e
+    Rails.logger.error("Failed to generate Github token: #{e.message}")
+    nil
+  end
+
+  def token_payload(account_id)
+    {
+      sub: account_id,
+      iat: Time.current.to_i
+    }
+  end
+
+  # Verifies and decodes a Github JWT token
+  #
+  # @param token [String] The JWT token to verify
+  # @return [Integer, nil] The account ID from the token or nil if invalid
+  def verify_github_token(token)
+    return if token.blank? || client_secret.blank?
+
+    decode_token(token, client_secret)
+  end
+
+  private
+
+  def client_secret
+    @client_secret ||= GlobalConfigService.load('GITHUB_CLIENT_SECRET', nil)
+  end
+
+  def decode_token(token, secret)
+    JWT.decode(token, secret, true, {
+                 algorithm: 'HS256',
+                 verify_expiration: true
+               }).first['sub']
+  rescue StandardError => e
+    Rails.logger.error("Unexpected error verifying Github token: #{e.message}")
+    nil
+  end
+end
diff --git a/app/models/integrations/app.rb b/app/models/integrations/app.rb
index 080438ffd..d99d9a2ac 100644
--- a/app/models/integrations/app.rb
+++ b/app/models/integrations/app.rb
@@ -1,5 +1,6 @@
 class Integrations::App
   include Linear::IntegrationHelper
+  include Github::IntegrationHelper
   attr_accessor :params
 
   def initialize(params)
@@ -29,7 +30,12 @@ class Integrations::App
   # There is no way to get the account_id from the linear callback
   # so we are using the generate_linear_token method to generate a token and encode it in the state parameter
   def encode_state
-    generate_linear_token(Current.account.id)
+    case params[:id]
+    when 'linear'
+      generate_linear_token(Current.account.id)
+    when 'github'
+      generate_github_token(Current.account.id)
+    end
   end
 
   def action
@@ -38,6 +44,8 @@ class Integrations::App
       "#{params[:action]}&client_id=#{ENV.fetch('SLACK_CLIENT_ID', nil)}&redirect_uri=#{self.class.slack_integration_url}"
     when 'linear'
       build_linear_action
+    when 'github'
+      build_github_action
     else
       params[:action]
     end
@@ -70,6 +78,17 @@ class Integrations::App
     ].join('&')
   end
 
+  def build_github_action
+    app_id = GlobalConfigService.load('GITHUB_CLIENT_ID', nil)
+    [
+      "#{params[:action]}?response_type=code",
+      "client_id=#{app_id}",
+      "redirect_uri=#{self.class.github_integration_url}",
+      "state=#{encode_state}",
+      'scope=repo'
+    ].join('&')
+  end
+
   def enabled?(account)
     case params[:id]
     when 'webhook'
@@ -93,6 +112,10 @@ class Integrations::App
     "#{ENV.fetch('FRONTEND_URL', nil)}/linear/callback"
   end
 
+  def self.github_integration_url
+    "#{ENV.fetch('FRONTEND_URL', nil)}/github/callback"
+  end
+
   class << self
     def apps
       Hashie::Mash.new(APPS_CONFIG)
diff --git a/config/integration/apps.yml b/config/integration/apps.yml
index e44c17c77..637c80dff 100644
--- a/config/integration/apps.yml
+++ b/config/integration/apps.yml
@@ -190,6 +190,6 @@ github:
   id: github
   logo: github.png
   i18n_key: github
-  action: /github
+  action: https://github.com/login/oauth/authorize
   hook_type: account
   allow_multiple_hooks: false
diff --git a/config/routes.rb b/config/routes.rb
index 46199db12..5ffcc4c66 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -479,6 +479,10 @@ Rails.application.routes.draw do
     resources :delivery_status, only: [:create]
   end
 
+  namespace :github do
+    get :callback, to: 'callbacks#show'
+  end
+
   get 'microsoft/callback', to: 'microsoft/callbacks#show'
   get 'google/callback', to: 'google/callbacks#show'
   get 'instagram/callback', to: 'instagram/callbacks#show'