flesh out webhook framework

fulcrm_webhook.module

@@ -38,8 +38,35 @@ function fulcrm_webhook_menu() {
 
 function fulcrm_webhook_webhook( $uuid ) {
     if ( $uuid === variable_get( 'fulcrm_webhook_url' ) ) {
-        drupal_json_output( array( 'status' => 'ok' ) );
+        $headers = getallheaders();
+        $payload = null;
+        $payload_error = null;
+        $method = $_SERVER[ 'REQUEST_METHOD' ];
+
+        if ( array_key_exists( 'Content-Type', $headers ) && ( $headers[ 'Content-Type' ] === 'application/json' ) ) {
+            $payload = json_decode( file_get_contents( "php://input" ) );
+            $payload_error = json_last_error();
+            $payload_error_msg = json_last_error_msg();
+        }
+
+        switch ( $method ) {
+        case 'GET':
+            drupal_json_output( array( "status" => "error", "info" => "GET requests do nothing; webhooks must be POST, PATCH, PUT, or DELETE" ) );
+            break;
+        case 'DELETE':
+        case 'POST':
+        case 'PATCH':
+        case 'PUT':
+            if ( $payload === null ) {
+                // actually do something :)
+                drupal_json_output( array( 'status' => 'error', 'info' => $payload_error_msg ) );
+            } else {
+                drupal_json_output( array( 'status' => 'ok', 'headers' => $headers, 'method' => $method ) );
+            }
+            break;
+        default:
+        }
     } else {
-        drupal_json_output( array( 'error' => 'incorrect webhook UUID' ) );
+        drupal_access_denied();
     }
 }