add product meta change_time handler (#3576)

Summary:

Changes Made - 
1. Added is_updating_last_change_time flag to be protect from infinite loop of update_post_meta hook
2. Added hook for updated_post_meta
3. Added update_last_change_time - It validates & performs the update on _last_change_time
4.  Added perform_last_change_time_update to actually perform the update

Reviewed By: devbodaghe

Differential Revision: D81231383

Author: rithikb24

facebook-commerce.php

@@ -225,6 +225,13 @@ class WC_Facebookcommerce_Integration extends WC_Integration {
 	public const FB_SYNC_TIMEOUT     = 30;
 	public const FB_PRIORITY_MID     = 9;
 
+	/**
+	 * Static flag to prevent infinite loops when updating last change time.
+	 *
+	 * @var bool
+	 */
+	private static $is_updating_last_change_time = false;
+
 	/**
 	 * Facebook exception test mode switch.
 	 *
@@ -400,6 +407,9 @@ public function __construct( WC_Facebookcommerce $facebook_for_woocommerce ) {
 
 		// Init Whatsapp Utility Event Processor
 		$this->wa_utility_event_processor = $this->load_whatsapp_utility_event_processor();
+
+		// Track programmatic changes that don't update post_modified
+		add_action( 'updated_post_meta', array( $this, 'update_product_last_change_time' ), 10, 4 );
 	}
 
 	/**
@@ -2111,6 +2121,77 @@ private function should_update_product_change_time( $product_id, $meta_key ) {
 		return true;
 	}
 
+	/**
+	 * Performs the actual product last change time update with proper flag management.
+	 *
+	 * @param int $product_id Product ID.
+	 * @since 3.5.8
+	 */
+	private function perform_product_last_change_time_update( $product_id ) {
+		// Set flag to prevent infinite loops
+		self::$is_updating_last_change_time = true;
+
+		try {
+			$current_time = time();
+
+			// Update the database
+			update_post_meta( $product_id, '_last_change_time', $current_time );
+
+			// Update cache for rate limiting
+			$this->set_last_change_time_cache( $product_id, $current_time );
+
+		} finally {
+			// Always reset flag, even if update fails
+			self::$is_updating_last_change_time = false;
+		}
+	}
+
+	/**
+	 * Updates the _last_change_time meta field when wp_postmeta table is updated.
+	 *
+	 * @param int    $meta_id    ID of the metadata entry to update.
+	 * @param int    $product_id  Post ID.
+	 * @param string $meta_key   Meta key.
+	 * @param mixed  $meta_value Meta value.
+	 * @since 3.5.8
+	 */
+	public function update_product_last_change_time( $meta_id, $product_id, $meta_key, $meta_value ) {
+		// Guard against infinite loops
+		if ( self::$is_updating_last_change_time ) {
+			return;
+		}
+
+		try {
+			// Run all validation checks first
+			if ( ! $this->should_update_product_change_time( $product_id, $meta_key ) ) {
+				return;
+			}
+
+			// All checks passed - proceed with update
+			$this->perform_product_last_change_time_update( $product_id );
+
+		} catch ( \Exception $e ) {
+			// Ensure flag is reset even on exception
+			self::$is_updating_last_change_time = false;
+
+			Logger::log(
+				'Error updating last change time for product',
+				[
+					'event'      => 'update_last_change_time_error',
+					'product_id' => $product_id,
+					'meta_key'   => $meta_key,
+					'meta_id'    => $meta_id,
+				],
+				[
+					'should_send_log_to_meta'        => false,
+					'should_save_log_in_woocommerce' => true,
+					'woocommerce_log_level'          => \WC_Log_Levels::ERROR,
+				],
+				$e
+			);
+		}
+	}
+
 	/**
 	 * Checks if the last change time update is rate limited for a product.
 	 *