gnome-shell/js/extensions/sharedInternals.js

import Gio from 'gi://Gio';
import GLib from 'gi://GLib';

import {bindtextdomain} from 'gettext';

const Config = imports.misc.config;

let _extensionManager = null;

/**
 * @param {object} extensionManager to use in utilities like `initTranslations()`
 */
export function setExtensionManager(extensionManager) {
    if (_extensionManager)
        throw new Error('Trying to override existing extension manager');

    _extensionManager = extensionManager;
}

export class ExtensionBase {
    #gettextDomain;

    /**
     * @param {object} metadata - metadata passed in when loading the extension
     */
    constructor(metadata) {
        if (this.constructor === ExtensionBase)
            throw new Error('ExtensionBase cannot be used directly.');

        if (!metadata)
            throw new Error(`${this.constructor.name} did not pass metadata to parent`);

        this.metadata = metadata;
    }

    /**
     * @type {string}
     */
    get uuid() {
        return this.metadata['uuid'];
    }

    /**
     * @type {Gio.File}
     */
    get dir() {
        return this.metadata['dir'];
    }

    /**
     * @type {string}
     */
    get path() {
        return this.metadata['path'];
    }

    /**
     * Get a GSettings object for schema, using schema files in
     * extensionsdir/schemas. If schema is omitted, it is taken
     * from metadata['settings-schema'].
     *
     * @param {string=} schema - the GSettings schema id
     *
     * @returns {Gio.Settings}
     */
    getSettings(schema) {
        schema ||= this.metadata['settings-schema'];

        // Expect USER extensions to have a schemas/ subfolder, otherwise assume a
        // SYSTEM extension that has been installed in the same prefix as the shell
        const schemaDir = this.dir.get_child('schemas');
        const defaultSource = Gio.SettingsSchemaSource.get_default();
        let schemaSource;
        if (schemaDir.query_exists(null)) {
            schemaSource = Gio.SettingsSchemaSource.new_from_directory(
                schemaDir.get_path(), defaultSource, false);
        } else {
            schemaSource = defaultSource;
        }

        const schemaObj = schemaSource.lookup(schema, true);
        if (!schemaObj)
            throw new Error(`Schema ${schema} could not be found for extension ${this.uuid}. Please check your installation`);

        return new Gio.Settings({settings_schema: schemaObj});
    }

    /**
     * Initialize Gettext to load translations from extensionsdir/locale. If
     * domain is not provided, it will be taken from metadata['gettext-domain']
     *
     * @param {string=} domain - the gettext domain to use
     */
    initTranslations(domain) {
        domain ||= this.metadata['gettext-domain'];

        if (!domain)
            throw new Error('initTranslations() was called without providing a valid domain');

        // Expect USER extensions to have a locale/ subfolder, otherwise assume a
        // SYSTEM extension that has been installed in the same prefix as the shell
        const localeDir = this.dir.get_child('locale');
        if (localeDir.query_exists(null))
            bindtextdomain(domain, localeDir.get_path());
        else
            bindtextdomain(domain, Config.LOCALEDIR);

        this.#gettextDomain = domain;
    }

    /**
     * Translate `str` using the extension's gettext domain
     *
     * @param {string} str - the string to translate
     *
     * @returns {string} the translated string
     */
    gettext(str) {
        this.#checkGettextDomain('gettext');
        return GLib.dgettext(this.#gettextDomain, str);
    }

    /**
     * Translate `str` and choose plural form using the extension's
     * gettext domain
     *
     * @param {string} str - the string to translate
     * @param {string} strPlural - the plural form of the string
     * @param {number} n - the quantity for which translation is needed
     *
     * @returns {string} the translated string
     */
    ngettext(str, strPlural, n) {
        this.#checkGettextDomain('ngettext');
        return GLib.dngettext(this.#gettextDomain, str, strPlural, n);
    }

    /**
     * Translate `str` in the context of `context` using the extension's
     * gettext domain
     *
     * @param {string} context - context to disambiguate `str`
     * @param {string} str - the string to translate
     *
     * @returns {string} the translated string
     */
    pgettext(context, str) {
        this.#checkGettextDomain('pgettext');
        return GLib.dpgettext2(this.#gettextDomain, context, str);
    }

    /**
     * @param {string} func
     */
    #checkGettextDomain(func) {
        if (!this.#gettextDomain)
            throw new Error(`${func}() is used without calling initTranslations() first`);
    }
}

/**
 * @private
 *
 * @returns {?object} - The current extension, or null if not called from
 * an extension.
 */
function getCurrentExtension() {
    const basePath = '/gnome-shell/extensions/';

    // Search for an occurrence of an extension stack frame
    // Start at 1 because 0 is the stack frame of this function
    const [, ...stack] = new Error().stack.split('\n');
    const extensionLine = stack.find(
        line => line.includes(basePath));

    if (!extensionLine)
        return null;

    // The exact stack line differs depending on where the function
    // was called (function or module scope), and whether it's called
    // from a module or legacy import (file:// URI vs. plain path).
    //
    // We don't have to care about the exact composition, all we need
    // is a string that can be traversed as path and contains the UUID
    let path = extensionLine.slice(extensionLine.indexOf(basePath));

    // Walk up the directory tree, looking for an extension with
    // the same UUID as a directory name.
    do {
        path = GLib.path_get_dirname(path);

        const dirName = GLib.path_get_basename(path);
        const extension = _extensionManager.lookup(dirName);
        if (extension !== undefined)
            return extension.stateObj;
    } while (path !== '/');

    return null;
}

/**
 * Translate @str using the extension's gettext domain
 *
 * @param {string} str - the string to translate
 *
 * @returns {string} - the translated string
 */
export function gettext(str) {
    return callExtensionGettextFunc('gettext', str);
}

/**
 * Translate @str and choose plural form using the extension's
 * gettext domain
 *
 * @param {string} str - the string to translate
 * @param {string} strPlural - the plural form of the string
 * @param {number} n - the quantity for which translation is needed
 *
 * @returns {string} - the translated string
 */
export function ngettext(str, strPlural, n) {
    return callExtensionGettextFunc('ngettext', str, strPlural, n);
}

/**
 * Translate @str in the context of @context using the extension's
 * gettext domain
 *
 * @param {string} context - context to disambiguate @str
 * @param {string} str - the string to translate
 *
 * @returns {string} - the translated string
 */
export function pgettext(context, str) {
    return callExtensionGettextFunc('pgettext', context, str);
}

/**
 * @private
 * @param {string} func - function name
 * @param {*[]} args - function arguments
 */
function callExtensionGettextFunc(func, ...args) {
    const extension = getCurrentExtension();

    if (!extension)
        throw new Error(`${func}() can only be called from extensions`);

    return extension[func](...args);
}