feat: email abstract

src/Abstracts/EmailAbstract.php

@@ -58,6 +58,9 @@ abstract class EmailAbstract implements EmailInterface {
      */
     abstract public function get_id(): string;
 
+    /**
+     * @return string
+     */
     public function get_template_name(): string {
         return 'default';
     }
@@ -298,6 +301,10 @@ abstract class EmailAbstract implements EmailInterface {
      * @return array|string|string[]
      */
     protected function replace_placeholders( string $string ): string {
+        if ( empty( $this->placeholders ) ) {
+            return $string;
+        }
+
         return (string) str_replace( array_keys( $this->placeholders ), array_values( $this->placeholders ), $string );
     }
 

src/Abstracts/EmailInterface.php

@@ -11,6 +11,13 @@ interface EmailInterface {
      */
     public function get_id(): string;
 
+    /**
+     * Get template name.
+     *
+     * @return string
+     */
+    public function get_template_name(): string;
+
     /**
      * @return string
      */