Helper method for max text field length and validate alias length

Summary: Ref T8992, Validate alias text field length.

Test Plan: Create Phurl with alias of more than 64 characters. Get error. Reduce length of alias to successfully save Phurl.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: Korvin

Maniphest Tasks: T8992

Differential Revision: https://secure.phabricator.com/D14403

src/applications/phurl/editor/PhabricatorPhurlURLEditor.php

@@ -119,6 +119,19 @@ final class PhabricatorPhurlURLEditor
         }
         break;
       case PhabricatorPhurlURLTransaction::TYPE_ALIAS:
+        $overdrawn = $this->validateIsTextFieldTooLong(
+          $object->getName(),
+          $xactions,
+          64);
+
+        if ($overdrawn) {
+          $errors[] = new PhabricatorApplicationTransactionValidationError(
+            $type,
+            pht('Alias Too Long'),
+            pht('The alias can be no longer than 64 characters.'),
+            nonempty(last($xactions), null));
+        }
+
         foreach ($xactions as $xaction) {
           if ($xaction->getOldValue() != $xaction->getNewValue()) {
             $new_alias = $xaction->getNewValue();

src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php

@@ -2177,6 +2177,51 @@ abstract class PhabricatorApplicationTransactionEditor
     return true;
   }
 
+  /**
+   * Check that text field input isn't longer than a specified length.
+   *
+   * A text field input is invalid if the length of the input is longer than a
+   * specified length. This length can be determined by the space allotted in
+   * the database, or given arbitrarily.
+   * This method is intended to make implementing @{method:validateTransaction}
+   * more convenient:
+   *
+   *   $overdrawn = $this->validateIsTextFieldTooLong(
+   *     $object->getName(),
+   *     $xactions,
+   *     $field_length);
+   *
+   * This will return `true` if the net effect of the object and transactions
+   * is a field that is too long.
+   *
+   * @param wild Current field value.
+   * @param list<PhabricatorApplicationTransaction> Transactions editing the
+   *          field.
+   * @param integer for maximum field length.
+   * @return bool True if the field will be too long after edits.
+   */
+  protected function validateIsTextFieldTooLong(
+    $field_value,
+    array $xactions,
+    $length) {
+
+    if ($xactions) {
+      $new_value_length = phutil_utf8_strlen(last($xactions)->getNewValue());
+      if ($new_value_length <= $length) {
+        return false;
+      } else {
+        return true;
+      }
+    }
+
+    $old_value_length = phutil_utf8_strlen($field_value);
+    if ($old_value_length <= $length) {
+      return false;
+    }
+
+    return true;
+  }
+
 
 /* -(  Implicit CCs  )------------------------------------------------------- */