Implement placeholders

doc/swagger.json

@@ -44,6 +44,17 @@ paths:
                 description: "Error message, only included if an error has occurred"
                 required: false
 definitions:
+  Placeholder:
+    type: "object"
+    properties:
+      name:
+        type: "string"
+        required: true
+        description: "Name of the placeholder - will be converted to ALL CAPS by the server if it isn't already"
+      value:
+        type: "string"
+        required: false
+        description: "Value to insert into placeholder"
   Attachment:
     type: "object"
     properties:
@@ -107,6 +118,11 @@ definitions:
         description: "Array of `Attachment` objects to be attached to the email"
         items:
           $ref: "#/definitions/Attachment"
+      placeholders:
+        type: "array"
+        description: "Array of `Placeholder` objects. Any occurrences of `{PLACEHOLDER_NAME}` (`name` in all caps enclosed with curly brackets) in the email's HTML or plain text will be replaced by `value`."
+        items:
+          $ref: "#/definitions/Placeholder"
       key:
         type: "string"
         description: "API key to authenticate request with"

sender.php

@@ -22,6 +22,11 @@ try {
     $html = ($json["html"] ? $json["html"] : ($json["htmlurl"] ? file_get_contents($json["htmlurl"]) : null));
     $text = ($json["text"] ? $json["text"] : ($json["texturl"] ? file_get_contents($json["texturl"]) : null));
 
+    foreach ($json["placeholders"] as $placeholder) {
+        $html = str_replace("{".strtoupper($placeholder["name"])."}", $placeholder["value"], $html);
+        $text = str_replace("{".strtoupper($placeholder["name"])."}", $placeholder["value"], $text);
+    }
+
     $mailer->isSMTP();
     $mailer->Host = $MAIL_HOST;
     $mailer->SMTPAuth = (bool) $MAIL_USER;