Add filter for schema file path as well

includes/class-solrpower-api.php

@@ -106,16 +106,25 @@ function submit_schema() {
 		/*
 		 * Solarium does not currently support submitting schemas to the server.
 		 * So we'll do it ourselves.
-		 * Let's check for a custom Schema.xml. It MUST be located in
-		 * wp-content/uploads/solr-for-wordpress-on-pantheon/schema.xml.
+		 * Let's check for a custom Schema.xml. It defaults to
+		 * wp-content/uploads/solr-for-wordpress-on-pantheon/schema.xml
+		 * and can be overridden with the filter 'solr_power_customer_schema_file_path'.
 		*/
 
 		$schema = SOLR_POWER_PATH . '/schema.xml';
 		$upload_dir = wp_upload_dir();
-		$custom_schema_file = path_join( $upload_dir['basedir'], 'solr-for-wordpress-on-pantheon/schema.xml' );
-		if ( file_exists( $custom_schema_file ) ) {
+		$custom_schema_file_path = path_join( $upload_dir['basedir'], 'solr-for-wordpress-on-pantheon/schema.xml' );
+
+		/**
+		 * Filter the custom schema file path
+		 *
+		 * @param string $custom_schema_file_path The default message.
+		 */
+		$custom_schema_file_path = apply_filters( 'solr_power_customer_schema_file_path', $custom_schema_file_path );
+
+		if ( file_exists( $custom_schema_file_path ) ) {
 			error_log( 'Solr Power: Uploading Schema from custom location' );
-			$schema = $custom_schema_file;
+			$schema = $custom_schema_file_path;
 		}
 
 		$path        = $this->compute_path();
@@ -162,7 +171,7 @@ function submit_schema() {
 		if ( 200 === (int) $curl_opts['http_code'] ) {
 			// Schema Upload Success.
 			$return_value = 'Schema Upload Success: ' . $curl_opts['http_code'];
-			if ( $schema == $custom_schema_file ) {
+			if ( $schema == $custom_schema_file_path ) {
 				$return_value = 'Custom ' . $return_value;
 			}
 			return $return_value;