feat: Add content validation support

Author: DannyvdSluijs

src/JsonSchema/ConstraintError.php

@@ -58,6 +58,8 @@ class ConstraintError extends Enum
     public const PROPERTY_NAMES = 'propertyNames';
     public const TYPE = 'type';
     public const UNIQUE_ITEMS = 'uniqueItems';
+    public const CONTENT_MEDIA_TYPE = 'contentMediaType';
+    public const CONTENT_ENCODING = 'contentEncoding';
 
     /**
      * @return string
@@ -115,7 +117,9 @@ public function getMessage()
             self::PROPERTIES_MAX => 'Must contain no more than %d properties',
             self::PROPERTY_NAMES => 'Property name %s is invalid',
             self::TYPE => '%s value found, but %s is required',
-            self::UNIQUE_ITEMS => 'There are no duplicates allowed in the array'
+            self::UNIQUE_ITEMS => 'There are no duplicates allowed in the array',
+            self::CONTENT_MEDIA_TYPE => 'Value is not valid with content media type',
+            self::CONTENT_ENCODING => 'Value is not valid with content encoding',
         ];
 
         if (!isset($messages[$name])) {

src/JsonSchema/Constraints/Drafts/Draft07/ContentConstraint.php

@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+namespace JsonSchema\Constraints\Drafts\Draft07;
+
+use JsonSchema\ConstraintError;
+use JsonSchema\Constraints\ConstraintInterface;
+use JsonSchema\Constraints\Factory;
+use JsonSchema\Entity\ErrorBagProxy;
+use JsonSchema\Entity\JsonPointer;
+use JsonSchema\Tool\DeepComparer;
+
+class ContentConstraint implements ConstraintInterface
+{
+    use ErrorBagProxy;
+
+    public function __construct(?Factory $factory = null)
+    {
+        $this->initialiseErrorBag($factory ?: new Factory());
+    }
+
+    public function check(&$value, $schema = null, ?JsonPointer $path = null, $i = null): void
+    {
+        if (!property_exists($schema, 'contentMediaType') && !property_exists($schema, 'contentEncoding')) {
+            return;
+        }
+        if (! is_string($value)) {
+            return;
+        }
+
+        $decodedValue = $value;
+
+        if (property_exists($schema, 'contentEncoding')) {
+            if ($schema->contentEncoding === 'base64') {
+                if (!preg_match('/^[A-Za-z0-9+\/=]+$/', $decodedValue)) {
+                    $this->addError(ConstraintError::CONTENT_ENCODING(), $path, ['contentEncoding' => $schema->contentEncoding]);
+                    return;
+                }
+                $decodedValue = base64_decode($decodedValue);
+            }
+        }
+
+        if (property_exists($schema, 'contentMediaType')) {
+            if ($schema->contentMediaType === 'application/json') {
+                json_decode($decodedValue, false);
+                if (json_last_error() === JSON_ERROR_NONE) {
+                    return;
+                }
+            }
+
+            $this->addError(ConstraintError::CONTENT_MEDIA_TYPE(), $path, ['contentMediaType' => $schema->contentMediaType]);
+
+        }
+
+    }
+}

src/JsonSchema/Constraints/Drafts/Draft07/Draft07Constraint.php

@@ -65,6 +65,7 @@ public function check(&$value, $schema = null, ?JsonPointer $path = null, $i = n
         $this->checkForKeyword('multipleOf', $value, $schema, $path, $i);
         $this->checkForKeyword('format', $value, $schema, $path, $i);
         $this->checkForKeyword('pattern', $value, $schema, $path, $i);
+        $this->checkForKeyword('content', $value, $schema, $path, $i);
     }
 
     /**

src/JsonSchema/Constraints/Drafts/Draft07/Factory.php

@@ -43,5 +43,6 @@ class Factory extends \JsonSchema\Constraints\Factory
         'properties' => PropertiesConstraint::class,
         'items' => ItemsConstraint::class,
         'ref' => RefConstraint::class,
+        'content' => ContentConstraint::class,
     ];
 }