feat(date): validate format template strings

Author: maartenpaauw

src/Elements/RichTexts/Date.php

@@ -6,6 +6,7 @@
 
 use SlackPhp\BlockKit\Property;
 use SlackPhp\BlockKit\Validation\RequiresAllOf;
+use SlackPhp\BlockKit\Validation\ValidDateFormat;
 use SlackPhp\BlockKit\Validation\ValidString;
 use SlackPhp\BlockKit\Validation\ValidUrl;
 
@@ -18,7 +19,7 @@ class Date extends RichTextElement
     #[Property]
     public ?int $timestamp;
 
-    #[Property, ValidString]
+    #[Property, ValidDateFormat]
     public ?string $format;
 
     #[Property, ValidUrl]

src/Validation/ValidDateFormat.php

@@ -0,0 +1,56 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SlackPhp\BlockKit\Validation;
+
+use Attribute;
+use SlackPhp\BlockKit\Component;
+
+#[Attribute(Attribute::TARGET_PROPERTY)]
+class ValidDateFormat implements PropertyRule
+{
+    private const ALLOWED_TEMPLATES = [
+        'ago',
+        'date',
+        'date_long',
+        'date_long_full',
+        'date_long_pretty',
+        'date_num',
+        'date_pretty',
+        'date_short',
+        'date_short_pretty',
+        'date_slash',
+        'day_divider_pretty',
+        'time',
+        'time_secs',
+    ];
+
+    public function check(Component $component, string $field, mixed $value): void
+    {
+        if ($value === null) {
+            return;
+        }
+
+        $format = (string) $value;
+
+        $templates = implode(', ', self::ALLOWED_TEMPLATES);
+        $templateRegex = implode('|', self::ALLOWED_TEMPLATES);
+        $validTemplatesRegex = '/^(?:(?!{[^{}]*}).|{(?:' . $templateRegex . ')})*$/';
+        $containsTemplateRegex = '/{(?:' . $templateRegex . ')}/';
+
+        if (preg_match($validTemplatesRegex, $format) !== 1) {
+            throw new ValidationException(
+                'The "%s" field of a valid "%s" component can only contain valid template strings (%s)',
+                [$field, $component->type->value, $templates],
+            );
+        }
+
+        if (preg_match($containsTemplateRegex, $format) !== 1) {
+            throw new ValidationException(
+                'The "%s" field of a valid "%s" component must at least contain one valid template string (%s)',
+                [$field, $component->type->value, $templates],
+            );
+        }
+    }
+}