Evaluate $upgrading numeric value when checking if maintenance mode is active (#22)

---------

Co-authored-by: Pascal Birchler <pascalb@google.com>
Co-authored-by: Daniel Bachhuber <daniel@bachhuber.co>

Author: 3 people

features/maintenance-mode.feature

@@ -55,3 +55,34 @@ Feature: Manage maintenance mode of WordPress install.
       """
       Error: Maintenance mode already deactivated.
       """
+
+    When I run `wp maintenance-mode activate`
+    Then STDOUT should be:
+      """
+      Enabling Maintenance mode...
+      Success: Activated Maintenance mode.
+      """
+
+  Scenario: Check maintenance mode status when expression is used.
+
+    When I run `wp eval "file_put_contents('.maintenance', '<?php \$upgrading=(time()-601);'); "`
+    And I try `wp maintenance-mode is-active`
+    Then the return code should be 1
+    And STDERR should contain:
+      """
+      Warning: Unable to read the maintenance file timestamp, non-numeric value detected.
+      """
+
+  Scenario: Check maintenance mode status when numeric timestamp is used.
+
+    When I run `wp eval "file_put_contents('.maintenance', '<?php \$upgrading=' . ( time() + 100 ) . ';'); "`
+    And I run `wp maintenance-mode is-active`
+    Then the return code should be 0
+
+    When I run `wp eval "file_put_contents('.maintenance', '<?php \$upgrading =' . ( time() + 100 )  . ';')  ; "`
+    And I run `wp maintenance-mode is-active`
+    Then the return code should be 0
+
+    When I run `wp eval "file_put_contents('.maintenance', '<?php \$upgrading= ' . ( time() + 100 )  . ';'); "`
+    And I run `wp maintenance-mode is-active`
+    Then the return code should be 0

src/MaintenanceModeCommand.php

@@ -132,7 +132,26 @@ private function get_maintenance_mode_status() {
 
 		$maintenance_file = trailingslashit( $wp_filesystem->abspath() ) . '.maintenance';
 
-		return $wp_filesystem->exists( $maintenance_file );
+		if ( ! $wp_filesystem->exists( $maintenance_file ) ) {
+			return false;
+		}
+
+		// We use the timestamp defined in the .maintenance file
+		// to check if the maintenance is available.
+		$upgrading = 0;
+
+		$contents = $wp_filesystem->get_contents( $maintenance_file );
+		$matches  = [];
+		if ( preg_match( '/upgrading\s*=\s*(\d+)\s*;/i', $contents, $matches ) ) {
+			$upgrading = (int) $matches[1];
+		} else {
+			WP_CLI::warning( 'Unable to read the maintenance file timestamp, non-numeric value detected.' );
+		}
+		// The logic here is based on the core WordPress `wp_is_maintenance_mode()` function.
+		if ( ( time() - $upgrading ) >= 10 * MINUTE_IN_SECONDS ) {
+			return false;
+		}
+		return true;
 	}
 
 	/**