This document describes how event hooks work in the Translate extension;
how to add hooks for an event; and how to run hooks for an event.

For a more comprehensive guide to hooks, navigate to your root MediaWiki
directory, and then find /docs/hooks.txt.

== Rationale ==

Hooks allow us to decouple optionally-run code from code that is run for
everyone. It allows MediaWiki hackers, third-party developers and local
administrators to define code that will be run at certain points in the mainline
code, and to modify the data run by that mainline code. Hooks can keep mainline
code simple, and make it easier to write extensions. Hooks are a principled
alternative to local patches.

== Writing hooks ==

=== PHP hooks ===
For a guide to PHP hooks, navigate to your root MediaWiki
directory, and then find docs/hooks.txt.

=== JavaScript hooks ===
JavaScript hooks for the Translate extension are a little different. To use
them, declare a dependency on ext.translate.hooks:

 $wgResourceModules['...'] = array(
 	'scripts' => '...js',
 	'dependencies' => array( 'ext.translate.hooks' ),
 );

And then in that module use:
 mw.translateHooks.add( name, hookFunction );

where name is a string, but hookFunction is not (unlike in the case of PHP hooks)
but rather a function reference. Return values from JavaScript hooks are ignored.

== Events and parameters ==

This is a list of known events and parameters; please add to it if you're going
to add events to the Translate extension.

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=== PHP events ===

;SpecialTranslate::executeTask: You can output the default task output
 RequestContext  $context: For adding output, accessing current interface language etc.
 TranslateTask   $task = null: Current task if any
 MessageGroup    $group
 array           $options: Active options

;Translate:MessageGroupStats:isIncluded: Controls whether message group is shown for a given language in language or message group statistics. Mostly used internally by Translate to hide discouraged groups and groups restricted to certain languages.
 string          $groupId: Message group id
 string          $code: Language code

;TranslateBeforeAddModules: Provides an opportunity to load extra modules
 array          &$modules: List of resource loader module names

;TranslateEventMessageMembershipChange: When group gets new messages or loses messages
 MessageHandle   $handle
 array           $old Previous groups
 array           $new Current groups

;TranslateEventMessageGroupStateChange: Event triggered when a message group workflow state is changed in a language
 MessageGroup    $group: Message group instance
 string          $code: Language code
 string          $oldState
 string          $newState

;TranslateEventTranslationEdit: Event triggered when a translation is created or changed
 MessageHandle   $handle

;TranslateEventTranslationReview: Event triggered when a translation is proofread
 MessageHandle   $handle

;TranslateFormatMessageBeforeTable: Provides an opportunity to manipulate the display of translation strings (messages) in the main table
 string         &$message: The message that will be displayed
 TMessage        $m: Object representing the source object, useful for $m->original() and $m->translation()
 MessageGroup    $group: The source message group
 string          $targetLanguage: The language for which translations are being shown
 array          &$extraAttribs: An array of attributes that will be added to the table row

;TranslateGetBoxes: Provides an opportunity to add or remove "boxes" (translation helpers) from the translation interface
 MessageGroup    $group: The message group being worked on
 MessageHandle   $handle: An object representing the translation page (e.g. 'MediaWiki:Example/qqq')
 array          &$boxes: An associative array to be appended to (format: 'name' => 'some HTML string')

;TranslateGetAPIMessageGroupsParameterDescs: Provides an opportunity to document any parameters added with 'TranslateGetAPIMessageGroupsParameterList'.
 array          &$paramDescs: An associative array of parameters, name => description.
 string          $p: The prefix for action=query&meta=messagegroups (currently mg, but could change), useful for documentation

;TranslateGetAPIMessageGroupsParameterList: Allows extra parameters to be added to the action=query&meta=messagegroups module
 array          &$params: An associative array of possible parameters (name => details; see ApiQueryMessageGroups.php for correct spacing)

;TranslateGetAPIMessageGroupsPropertyDescs: Allows extra properties to be added to captured by action=query&meta=messagegroups&mgprop=foo|bar|bat module
 array          &$properties: An associative array of properties, name => description.

;TranslateGetExtraInputs: Provides an opportunity to add extra form inputs to to the default translation editor
 string         &$translation: The translation as it stands
 string         &$extraInputs: The extra input space, ready for HTML to be appended

;TranslateGetSpecialTranslateOptions: Provides an opportunity for overriding task values
 array          &$defaults: Associative array of default values
 array          &$nondefaults: Associative array of nondefault (override) values

;Translate:GettextFFS:headerFields: Allows to customize headers of exported Gettext files per group. Certain X-headers nor Plural-Forms cannot be customized.
 array          &$headers: List of prefilled headers. You can remove, change or add new headers.
 MessageGroup    $group: Message group instance
 string          $code: Language code

;TranslateMessageGroupPathVariables: Allows to manipulate the list of variables for message group path patterns.
 MessageGroup    $group
 array          &$variables: Variable name => replacement

;TranslateMessageTableInit: When creating new MessageTable
 MessageTable   &$table: Default implementation that can be accessed or even replaced
 IContextSource  $context:
 MessageCollection $collection
 MessageGroup    $group

;Translate:newTranslation: Event triggered when non-fuzzy translation has been made
 MessageHandle   $handle
 int             $revisionId
 string          $text: Content of the new translation
 User            $user: User who created or changed the translation

;TranslatePostInitGroups: Hook to register new message groups to Translate. Manual cache clear may be needed to have this hook executed.
 array          &$groups: Map of message group id to message group instance
 array          &$deps: List of dependencies as supported by DependecyWrapper class from MediaWiki
 array          &$autoload: List of autoloaded classes. Key is the name of the class and value is filename.

;TranslatePrefillTranslation: Provides an opportunity for a new translation to start not from as a carte blanche (the default) but from some prefilled string
 string         &$translation: The translation string as it stands
 MessageHandle   $handle: The current MessageHandle object

;TranslateProcessAPIMessageGroupsProperties: Allows exrra property requests to be acted upon, and the new new properties returned
 array          &$a: Associative array of the properties of $group that will be returned
 array           $props: Associative array ($name => true) of properties the user has specifically requested
 array           $params: Parameter input by the user (unprefixed name => value)
 MessageGroup    $g: The group in question

;TranslateSupportedLanguages: Allows removing languages from language selectors. For adding $wgExtraLanguage names is recommended.
 array          &$list: List of languages indexed by language code
 string          $language: Language code of the language of which language names are in

;TranslateTranslationAids: Make new translation aids available to any message group (which must choose an implementation in its getTranslationAids() method).
 array          &$types: List of translation aid identifiers, numerically indexed

;AddNewAccount: Replica of the core hook, see https://www.mediawiki.org/wiki/Manual:Hooks/AddNewAccount

=== JavaScript events ===

;afterSubmit: Provides an opportunity to modify a Translate translation form immediately after it is submitted
 jQuery          form: The form that has just been submitted

;beforeSubmit: Provides an opportunity to modify a Translate translation form immediately before it is submitted
 jQuery          form: The form being submitted

;formatMessageBeforeTable: Provides an opportunity to manipulate the display of translation strings (messages) in the main table
 object          message: The message object, with a range of useful (and manipulable) properties

;showTranslationHelpers: Provides an opportunity to handle custom translation helpers
 object          result.helpers: JSON subset focusing on the helpers returned e.g. result.helpers.definition
 jQuery          translateEditor.$editor: The current translation-editing form
