API: Overhaul ApiResult, make format=xml not throw, and add json formatversion

ApiResult was a mess: some methods could only be used with an array
reference instead of manipulating the stored data, methods that had both
array-ref and internal-data versions had names that didn't at all
correspond, some methods that worked on an array reference were
annoyingly non-static, and then the whole mess with setIndexedTagName.

ApiFormatXml is also entirely annoying to deal with, as it liked to
throw exceptions if certain metadata wasn't provided that no other
formatter required. Its legacy also means we have this silly convention
of using empty-string rather than boolean true, annoying restrictions on
keys (leading to things that should be hashes being arrays of key-value
object instead), '*' used as a key all over the place, and so on.

So, changes here:
* ApiResult is no longer an ApiBase or a ContextSource.
* Wherever sensible, ApiResult provides a static method working on an
  arrayref and a non-static method working on internal data.
* Metadata is now always added to ApiResult's internal data structure.
  Formatters are responsible for stripping it if necessary. "raw mode"
  is deprecated.
* New metadata to replace the '*' key, solve the array() => '[]' vs '{}'
  question, and so on.
* New class for formatting warnings and errors using i18n messages, and
  support for multiple errors and a more machine-readable format for
  warnings. For the moment, though, the actual output will not be changing
  yet (see T47843 for future plans).
* New formatversion parameter for format=json and format=php, to select
  between BC mode and the modern output.
* In BC mode, booleans will be converted to empty-string presence style;
  modules currently returning booleans will need to use
  ApiResult::META_BC_BOOLS to preserve their current output.

Actual changes to the API modules' output (e.g. actually returning
booleans for the new formatversion) beyond the use of
ApiResult::setContentValue() are left for a future change.

Bug: T76728
Bug: T57371
Bug: T33629
Change-Id: I7b37295e8862b188d1f3b0cd07f66ac34629678f

1 files changed, 191 insertions, 0 deletions

diff --git a/includes/api/ApiMessage.php b/includes/api/ApiMessage.php
new file mode 100644
index 000000000000..6717c390bbfc
--- /dev/null
+++ b/includes/api/ApiMessage.php
@@ -0,0 +1,191 @@
+<?php
+/**
+ * Defines an interface for messages with additional machine-readable data for
+ * use by the API, and provides concrete implementations of that interface.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * Interface for messages with machine-readable data for use by the API
+ * @since 1.25
+ * @ingroup API
+ */
+interface IApiMessage extends MessageSpecifier {
+	/**
+	 * Returns a machine-readable code for use by the API
+	 *
+	 * The message key is often sufficient, but sometimes there are multiple
+	 * messages used for what is really the same underlying condition (e.g.
+	 * badaccess-groups and badaccess-group0)
+	 * @return string
+	 */
+	public function getApiCode();
+
+	/**
+	 * Returns additional machine-readable data about the error condition
+	 * @return array
+	 */
+	public function getApiData();
+
+	/**
+	 * Sets the machine-readable code for use by the API
+	 * @param string|null $code If null, the message key should be returned by self::getApiCode()
+	 * @param array|null $data If non-null, passed to self::setApiData()
+	 */
+	public function setApiCode( $code, array $data = null );
+
+	/**
+	 * Sets additional machine-readable data about the error condition
+	 * @param array $data
+	 */
+	public function setApiData( array $data );
+}
+
+/**
+ * Extension of Message implementing IApiMessage
+ * @since 1.25
+ * @ingroup API
+ * @todo: Would be nice to use a Trait here to avoid code duplication
+ */
+class ApiMessage extends Message implements IApiMessage {
+	protected $apiCode = null;
+	protected $apiData = array();
+
+	/**
+	 * Create an IApiMessage for the message
+	 *
+	 * This returns $msg if it's an IApiMessage, calls 'new ApiRawMessage' if
+	 * $msg is a RawMessage, or calls 'new ApiMessage' in all other cases.
+	 *
+	 * @param Message|RawMessage|array|string $msg
+	 * @param string|null $code
+	 * @param array|null $data
+	 * @return ApiMessage
+	 */
+	public static function create( $msg, $code = null, array $data = null ) {
+		if ( $msg instanceof IApiMessage ) {
+			return $msg;
+		} elseif ( $msg instanceof RawMessage ) {
+			return new ApiRawMessage( $msg, $code, $data );
+		} else {
+			return new ApiMessage( $msg, $code, $data );
+		}
+	}
+
+	/**
+	 * @param Message|string|array $msg
+	 *  - Message: is cloned
+	 *  - array: first element is $key, rest are $params to Message::__construct
+	 *  - string: passed to Message::__construct
+	 * @param string|null $code
+	 * @param array|null $data
+	 * @return ApiMessage
+	 */
+	public function __construct( $msg, $code = null, array $data = null ) {
+		if ( $msg instanceof Message ) {
+			foreach ( get_class_vars( get_class( $this ) ) as $key => $value ) {
+				if ( isset( $msg->$key ) ) {
+					$this->$key = $msg->$key;
+				}
+			}
+		} elseif ( is_array( $msg ) ) {
+			$key = array_shift( $msg );
+			parent::__construct( $key, $msg );
+		} else {
+			parent::__construct( $msg );
+		}
+		$this->apiCode = $code;
+		$this->apiData = (array)$data;
+	}
+
+	public function getApiCode() {
+		return $this->apiCode === null ? $this->getKey() : $this->apiCode;
+	}
+
+	public function setApiCode( $code, array $data = null ) {
+		$this->apiCode = $code;
+		if ( $data !== null ) {
+			$this->setApiData( $data );
+		}
+	}
+
+	public function getApiData() {
+		return $this->apiData;
+	}
+
+	public function setApiData( array $data ) {
+		$this->apiData = $data;
+	}
+}
+
+/**
+ * Extension of RawMessage implementing IApiMessage
+ * @since 1.25
+ * @ingroup API
+ * @todo: Would be nice to use a Trait here to avoid code duplication
+ */
+class ApiRawMessage extends RawMessage implements IApiMessage {
+	protected $apiCode = null;
+	protected $apiData = array();
+
+	/**
+	 * @param RawMessage|string|array $msg
+	 *  - RawMessage: is cloned
+	 *  - array: first element is $key, rest are $params to RawMessage::__construct
+	 *  - string: passed to RawMessage::__construct
+	 * @param string|null $code
+	 * @param array|null $data
+	 * @return ApiMessage
+	 */
+	public function __construct( $msg, $code = null, array $data = null ) {
+		if ( $msg instanceof RawMessage ) {
+			foreach ( get_class_vars( get_class( $this ) ) as $key => $value ) {
+				if ( isset( $msg->$key ) ) {
+					$this->$key = $msg->$key;
+				}
+			}
+		} elseif ( is_array( $msg ) ) {
+			$key = array_shift( $msg );
+			parent::__construct( $key, $msg );
+		} else {
+			parent::__construct( $msg );
+		}
+		$this->apiCode = $code;
+		$this->apiData = (array)$data;
+	}
+
+	public function getApiCode() {
+		return $this->apiCode === null ? $this->getKey() : $this->apiCode;
+	}
+
+	public function setApiCode( $code, array $data = null ) {
+		$this->apiCode = $code;
+		if ( $data !== null ) {
+			$this->setApiData( $data );
+		}
+	}
+
+	public function getApiData() {
+		return $this->apiData;
+	}
+
+	public function setApiData( array $data ) {
+		$this->apiData = $data;
+	}
+}