/**
* @license Copyright (c) 2003-2026, CKSource Holding sp. z o.o. All rights reserved.
* For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-licensing-options
*/
/**
* @module utils/translation-service
*/
import type { Translations } from "./locale.js";
import { type ArrayOrItem } from "./toarray.js";
declare global {
	var CKEDITOR_TRANSLATIONS: Translations;
}
/**
* Adds translations to existing ones or overrides the existing translations. These translations will later
* be available for the {@link module:utils/locale~Locale#t `t()`} function.
*
* The `translations` is an object which consists of `messageId: translation` pairs. Note that the message ID can be
* either constructed from the message string or from the message ID if it was passed
* (this happens rarely and mostly for short messages or messages with placeholders).
* Since the editor displays only the message string, the message ID can be found either in the source code or in the
* built translations for another language.
*
* ```ts
* add( 'pl', {
* 	'Cancel': 'Anuluj',
* 	'IMAGE': 'obraz', // Note that the `IMAGE` comes from the message ID, while the string can be `image`.
* } );
* ```
*
* If the message is supposed to support various plural forms, make sure to provide an array with the singular form and all plural forms:
*
* ```ts
* add( 'pl', {
* 	'Add space': [ 'Dodaj spację', 'Dodaj %0 spacje', 'Dodaj %0 spacji' ]
* } );
* ```
*
* You should also specify the third argument (the `getPluralForm()` function) that will be used to determine the plural form if no
* language file was loaded for that language. All language files coming from CKEditor 5 sources will have this option set, so
* these plural form rules will be reused by other translations added to the registered languages. The `getPluralForm()` function
* can return either a Boolean or a number.
*
* ```ts
* add( 'en', {
* 	// ... Translations.
* }, n => n !== 1 );
* add( 'pl', {
* 	// ... Translations.
* }, n => n == 1 ? 0 : n % 10 >= 2 && n % 10 <= 4 && ( n % 100 < 10 || n % 100 >= 20 ) ? 1 : 2 );
* ```
*
* All translations extend the global `window.CKEDITOR_TRANSLATIONS` object. An example of this object can be found below:
*
* ```ts
* {
* 	pl: {
* 		dictionary: {
* 			'Cancel': 'Anuluj',
* 			'Add space': [ 'Dodaj spację', 'Dodaj %0 spacje', 'Dodaj %0 spacji' ]
* 		},
* 		// A function that returns the plural form index.
* 		getPluralForm: n => n == 1 ? 0 : n % 10 >= 2 && n % 10 <= 4 && ( n % 100 < 10 || n % 100 >= 20 ) ? 1 : 2 );
* 	}
* 	// Other languages.
* 	}
* ```
*
* If you cannot import { this function } from this module (e.g. because you use a CKEditor 5 build), you can
* still add translations by extending the global `window.CKEDITOR_TRANSLATIONS` object by using a function like
* the one below:
*
* ```ts
* function addTranslations( language, translations, getPluralForm ) {
* 	if ( !global.window.CKEDITOR_TRANSLATIONS ) {
* 		global.window.CKEDITOR_TRANSLATIONS = {};
* 	}

* 	if ( !global.window.CKEDITOR_TRANSLATIONS[ language ] ) {
* 		global.window.CKEDITOR_TRANSLATIONS[ language ] = {};
* 	}
*
* 	const languageTranslations = global.window.CKEDITOR_TRANSLATIONS[ language ];
*
* 	languageTranslations.dictionary = languageTranslations.dictionary || {};
* 	languageTranslations.getPluralForm = getPluralForm || languageTranslations.getPluralForm;
*
* 	// Extend the dictionary for the given language.
* 	Object.assign( languageTranslations.dictionary, translations );
* }
* ```
*
* @param language Target language.
* @param translations An object with translations which will be added to the dictionary.
* For each message ID the value should be either a translation or an array of translations if the message
* should support plural forms.
* @param getPluralForm A function that returns the plural form index (a number).
*/
export declare function add(language: string, translations: {
	readonly [messageId: string]: string | ReadonlyArray<string>;
}, getPluralForm?: (n: number) => number): void;
/**
* **Note:** This method is internal, use {@link module:utils/locale~Locale#t the `t()` function} instead to translate
* the editor UI parts.
*
* This function is responsible for translating messages to the specified language. It uses translations added perviously
* by {@link module:utils/translation-service~add} (a translations dictionary and the `getPluralForm()` function
* to provide accurate translations of plural forms).
*
* When no translation is defined in the dictionary or the dictionary does not exist, this function returns
* the original message string or the message plural depending on the number of elements.
*
* ```ts
* translate( 'pl', { string: 'Cancel' } ); // 'Cancel'
* ```
*
* The third optional argument is the number of elements, based on which the single form or one of the plural forms
* should be picked when the message is supposed to support various plural forms.
*
* ```ts
* translate( 'en', { string: 'Add a space', plural: 'Add %0 spaces' }, 1 ); // 'Add a space'
* translate( 'en', { string: 'Add a space', plural: 'Add %0 spaces' }, 3 ); // 'Add %0 spaces'
* ```
*
* The message should provide an ID using the `id` property when the message strings are not unique and their
* translations should be different.
*
* ```ts
* translate( 'en', { string: 'image', id: 'ADD_IMAGE' } );
* translate( 'en', { string: 'image', id: 'AN_IMAGE' } );
* ```
*
* @internal
* @param language Target language.
* @param message A message that will be translated.
* @param quantity The number of elements for which a plural form should be picked from the target language dictionary.
* @param translations Translations passed in editor config, if not provided use the global `window.CKEDITOR_TRANSLATIONS`.
* @returns Translated sentence.
*/
export declare function _translate(language: string, message: Message, quantity?: number, translations?: Translations): string;
/**
* Clears dictionaries for test purposes.
*
* @internal
*/
export declare function _clear(): void;
/**
* If array then merge objects which are inside otherwise return given object.
*
* @internal
* @param translations Translations passed in editor config.
*/
export declare function _unifyTranslations(translations?: ArrayOrItem<Translations>): Translations | undefined;
/**
* The internationalization message interface. A message that implements this interface can be passed to the `t()` function
* to be translated to the target UI language.
*/
export interface Message {
	/**
	* The message string to translate. Acts as a default translation if the translation for a given language
	* is not defined. When the message is supposed to support plural forms, the string should be the English singular form of the message.
	*/
	readonly string: string;
	/**
	* The message ID. If passed, the message ID is taken from this property instead of the `message.string`.
	* This property is useful when various messages share the same message string, for example, the `editor` string in `in the editor`
	* and `my editor` sentences.
	*/
	readonly id?: string;
	/**
	* The plural form of the message. This property should be skipped when a message is not supposed
	* to support plural forms. Otherwise it should always be set to a string with the English plural form of the message.
	*/
	readonly plural?: string;
}