Restructure omni services and add Chatwoot research snapshot

research/chatwoot/app/services/whatsapp/facebook_api_client.rb

@@ -0,0 +1,125 @@
+class Whatsapp::FacebookApiClient
+  BASE_URI = 'https://graph.facebook.com'.freeze
+
+  def initialize(access_token = nil)
+    @access_token = access_token
+    @api_version = GlobalConfigService.load('WHATSAPP_API_VERSION', 'v22.0')
+  end
+
+  def exchange_code_for_token(code)
+    response = HTTParty.get(
+      "#{BASE_URI}/#{@api_version}/oauth/access_token",
+      query: {
+        client_id: GlobalConfigService.load('WHATSAPP_APP_ID', ''),
+        client_secret: GlobalConfigService.load('WHATSAPP_APP_SECRET', ''),
+        code: code
+      }
+    )
+
+    handle_response(response, 'Token exchange failed')
+  end
+
+  def fetch_phone_numbers(waba_id)
+    response = HTTParty.get(
+      "#{BASE_URI}/#{@api_version}/#{waba_id}/phone_numbers",
+      query: { access_token: @access_token }
+    )
+
+    handle_response(response, 'WABA phone numbers fetch failed')
+  end
+
+  def debug_token(input_token)
+    response = HTTParty.get(
+      "#{BASE_URI}/#{@api_version}/debug_token",
+      query: {
+        input_token: input_token,
+        access_token: build_app_access_token
+      }
+    )
+
+    handle_response(response, 'Token validation failed')
+  end
+
+  def register_phone_number(phone_number_id, pin)
+    response = HTTParty.post(
+      "#{BASE_URI}/#{@api_version}/#{phone_number_id}/register",
+      headers: request_headers,
+      body: { messaging_product: 'whatsapp', pin: pin.to_s }.to_json
+    )
+
+    handle_response(response, 'Phone registration failed')
+  end
+
+  def phone_number_verified?(phone_number_id)
+    response = HTTParty.get(
+      "#{BASE_URI}/#{@api_version}/#{phone_number_id}",
+      headers: request_headers
+    )
+
+    data = handle_response(response, 'Phone status check failed')
+    data['code_verification_status'] == 'VERIFIED'
+  end
+
+  def subscribe_waba_webhook(waba_id, callback_url, verify_token)
+    # Step 1: Subscribe app to WABA first (required before override)
+    # Meta requires the app to be subscribed before using override_callback_uri
+    # See: https://github.com/chatwoot/chatwoot/issues/13097
+    subscribe_app_to_waba(waba_id)
+
+    # Step 2: Override callback URL for this specific WABA
+    override_waba_callback(waba_id, callback_url, verify_token)
+  end
+
+  def subscribe_app_to_waba(waba_id)
+    response = HTTParty.post(
+      "#{BASE_URI}/#{@api_version}/#{waba_id}/subscribed_apps",
+      headers: request_headers
+    )
+
+    handle_response(response, 'App subscription to WABA failed')
+  end
+
+  def override_waba_callback(waba_id, callback_url, verify_token)
+    response = HTTParty.post(
+      "#{BASE_URI}/#{@api_version}/#{waba_id}/subscribed_apps",
+      headers: request_headers,
+      body: {
+        override_callback_uri: callback_url,
+        verify_token: verify_token,
+        subscribed_fields: %w[messages smb_message_echoes]
+      }.to_json
+    )
+
+    handle_response(response, 'Webhook callback override failed')
+  end
+
+  def unsubscribe_waba_webhook(waba_id)
+    response = HTTParty.delete(
+      "#{BASE_URI}/#{@api_version}/#{waba_id}/subscribed_apps",
+      headers: request_headers
+    )
+
+    handle_response(response, 'Webhook unsubscription failed')
+  end
+
+  private
+
+  def request_headers
+    {
+      'Authorization' => "Bearer #{@access_token}",
+      'Content-Type' => 'application/json'
+    }
+  end
+
+  def build_app_access_token
+    app_id = GlobalConfigService.load('WHATSAPP_APP_ID', '')
+    app_secret = GlobalConfigService.load('WHATSAPP_APP_SECRET', '')
+    "#{app_id}|#{app_secret}"
+  end
+
+  def handle_response(response, error_message)
+    raise "#{error_message}: #{response.body}" unless response.success?
+
+    response.parsed_response
+  end
+end