1 files changed, 89 insertions, 0 deletions
diff --git a/MLEB/Translate/src/Utilities/Json/JsonCodec.php b/MLEB/Translate/src/Utilities/Json/JsonCodec.php
new file mode 100644
index 00000000..2d1bb693
--- /dev/null
+++ b/MLEB/Translate/src/Utilities/Json/JsonCodec.php
@@ -0,0 +1,89 @@
+<?php
+declare( strict_types = 1 );
+
+namespace MediaWiki\Extension\Translate\Utilities\Json;
+
+use FormatJson;
+use InvalidArgumentException;
+use JsonSerializable;
+use Wikimedia\Assert\Assert;
+
+/**
+ * Helper class to serialize/unserialize things to/from JSON.
+ * This class, and related classes can be removed once Translate needs to support only
+ * MW >= 1.36. We can then use the JsonCodec class present in core.
+ *
+ * Differences between JsonCodec in the core:
+ * - unserialize only supports strings
+ * - does not detect non serializable data
+ *
+ * See Change-Id: I5433090ae8e2b3f2a4590cc404baf838025546ce
+ * @license GPL-2.0-or-later
+ * @since 2020.12
+ */
+class JsonCodec {
+	public const TYPE_ANNOTATION = '_type_';
+
+	public function unserialize( ?string $json, string $expectedClass = null ) {
+		Assert::precondition(
+			!$expectedClass || is_subclass_of( $expectedClass, JsonUnserializable::class ),
+			'$expectedClass parameter must be subclass of JsonUnserializable, got ' . $expectedClass
+		);
+
+		$jsonStatus = FormatJson::parse( $json, FormatJson::FORCE_ASSOC );
+		if ( !$jsonStatus->isGood() ) {
+			// TODO: in PHP 7.3, we can use JsonException
+			throw new InvalidArgumentException( "Bad JSON: {$jsonStatus}" );
+		}
+		$json = $jsonStatus->getValue();
+
+		if ( !$this->canMakeNewFromValue( $json ) ) {
+			if ( $expectedClass ) {
+				throw new InvalidArgumentException( 'JSON did not have ' . self::TYPE_ANNOTATION );
+			}
+			return $json;
+		}
+
+		$class = $json[self::TYPE_ANNOTATION];
+		if ( !class_exists( $class ) || !is_subclass_of( $class, JsonUnserializable::class ) ) {
+			throw new InvalidArgumentException( "Invalid target class {$class}" );
+		}
+
+		$obj = $class::newFromJsonArray( $json );
+		if ( $expectedClass && !$obj instanceof $expectedClass ) {
+			$actualClass = get_class( $obj );
+			throw new InvalidArgumentException( "Expected {$expectedClass}, got {$actualClass}" );
+		}
+		return $obj;
+	}
+
+	public function serialize( $value ): string {
+		if ( $value instanceof JsonSerializable ) {
+			$json = $value->jsonSerialize();
+		} else {
+			$json = FormatJson::encode( $value, false, FormatJson::ALL_OK );
+		}
+
+		if ( !$json ) {
+			throw new InvalidArgumentException(
+				'Failed to encode JSON. Error ' . json_last_error_msg()
+			);
+		}
+
+		return $json;
+	}
+
+	/** Is it likely possible to make a new instance from $json serialization? */
+	private function canMakeNewFromValue( $json ): bool {
+		$classAnnotation = self::TYPE_ANNOTATION;
+		if ( is_array( $json ) ) {
+			return array_key_exists( $classAnnotation, $json );
+		}
+		if ( is_object( $json ) ) {
+			return $json->$classAnnotation;
+		}
+		return false;
+	}
+}
+
+class_alias( JsonCodec::class, '\MediaWiki\Extensions\Translate\JsonCodec' );