Proyectos de Subversion Moodle

// This file is part of Moodle - http://moodle.org/

//

// Moodle 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 3 of the License, or

// (at your option) any later version.

//

// Moodle 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 Moodle.  If not, see <http://www.gnu.org/licenses/>.

import * as Log from 'core/log';

import * as Truncate from 'core/truncate';

import * as UserDate from 'core/user_date';

import Pending from 'core/pending';

import {getStrings} from 'core/str';

import IconSystem from 'core/icon_system';

import config from 'core/config';

import mustache from 'core/mustache';

import Loader from './loader';

import {getNormalisedComponent} from 'core/utils';

/** @var {string} The placeholder character used for standard strings (unclean) */

const placeholderString = 's';

/** @var {string} The placeholder character used for cleaned strings */

const placeholderCleanedString = 'c';

/**

 * Template Renderer Class.

 *

 * Note: This class is not intended to be instantiated directly. Instead, use the core/templates module.

 *

 * @module     core/local/templates/renderer

 * @copyright  2023 Andrew Lyons <andrew@nicols.co.uk>

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 * @since      4.3

 */

export default class Renderer {

    /** @var {string[]} requiredStrings - Collection of strings found during the rendering of one template */

    requiredStrings = null;

    /** @var {object[]} requiredDates - Collection of dates found during the rendering of one template */

    requiredDates = [];

    /** @var {string[]} requiredJS - Collection of js blocks found during the rendering of one template */

    requiredJS = null;

    /** @var {String} themeName for the current render */

    currentThemeName = '';

    /** @var {Number} uniqInstances Count of times this constructor has been called. */

    static uniqInstances = 0;

    /** @var {Object[]} loadTemplateBuffer - List of templates to be loaded */

    static loadTemplateBuffer = [];

    /** @var {Bool} isLoadingTemplates - Whether templates are currently being loaded */

    static isLoadingTemplates = false;

    /** @var {Object} iconSystem - Object extending core/iconsystem */

    iconSystem = null;

    /** @var {Array} disallowedNestedHelpers - List of helpers that can't be called within other helpers */

    static disallowedNestedHelpers = [

        'js',

    ];

    /** @var {String[]} templateCache - Cache of already loaded template strings */

    static templateCache = {};

    /**

     * Cache of already loaded template promises.

     *

     * @type {Promise[]}

     * @static

     * @private

     */

    static templatePromises = {};

    /**

     * The loader used to fetch templates.

     * @type {Loader}

     * @static

     * @private

     */

    static loader = Loader;

    /**

     * Constructor

     *

     * Each call to templates.render gets it's own instance of this class.

     */

    constructor() {

        this.requiredStrings = [];

        this.requiredJS = [];

        this.requiredDates = [];

        this.currentThemeName = '';

    }

    /**

     * Set the template loader to use for all Template renderers.

     *

     * @param {Loader} loader

     */

    static setLoader(loader) {

        this.loader = loader;

    }

    /**

     * Get the Loader used to fetch templates.

     *

     * @returns {Loader}

     */

    static getLoader() {

        return this.loader;

    }

    /**

     * Render a single image icon.

     *

     * @method renderIcon

     * @private

     * @param {string} key The icon key.

     * @param {string} component The component name.

     * @param {string} title The icon title

     * @returns {Promise}

     */

    async renderIcon(key, component, title) {

        // Preload the module to do the icon rendering based on the theme iconsystem.

        component = getNormalisedComponent(component);

        await this.setupIconSystem();

        const template = await Renderer.getLoader().getTemplate(

            this.iconSystem.getTemplateName(),

            this.currentThemeName,

        );

        return this.iconSystem.renderIcon(

            key,

            component,

            title,

            template

        );

    }

    /**

     * Helper to set up the icon system.

     */

    async setupIconSystem() {

        if (!this.iconSystem) {

            this.iconSystem = await IconSystem.instance();

        }

        return this.iconSystem;

    }

    /**

     * Render image icons.

     *

     * @method pixHelper

     * @private

     * @param {object} context The mustache context

     * @param {string} sectionText The text to parse arguments from.

     * @param {function} helper Used to render the alt attribute of the text.

     * @returns {string}

     */

    pixHelper(context, sectionText, helper) {

        const parts = sectionText.split(',');

        let key = '';

        let component = '';

        let text = '';

        if (parts.length > 0) {

            key = helper(parts.shift().trim(), context);

        }

        if (parts.length > 0) {

            component = helper(parts.shift().trim(), context);

        }

        if (parts.length > 0) {

            text = helper(parts.join(',').trim(), context);

        }

        // Note: We cannot use Promises in Mustache helpers.

        // We must fetch straight from the Loader cache.

        // The Loader cache is statically defined on the Loader class and should be used by all children.

        const Loader = Renderer.getLoader();

        const templateName = this.iconSystem.getTemplateName();

        const searchKey = Loader.getSearchKey(this.currentThemeName, templateName);

        const template = Loader.getTemplateFromCache(searchKey);

        component = getNormalisedComponent(component);

        // The key might have been escaped by the JS Mustache engine which

        // converts forward slashes to HTML entities. Let us undo that here.

        key = key.replace(///gi, '/');

        return this.iconSystem.renderIcon(

            key,

            component,

            text,

            template

        );

    }

    /**

     * Render blocks of javascript and save them in an array.

     *

     * @method jsHelper

     * @private

     * @param {object} context The current mustache context.

     * @param {string} sectionText The text to save as a js block.

     * @param {function} helper Used to render the block.

     * @returns {string}

     */

    jsHelper(context, sectionText, helper) {

        this.requiredJS.push(helper(sectionText, context));

        return '';

    }

    /**

     * String helper used to render {{#str}}abd component { a : 'fish'}{{/str}}

     * into a get_string call.

     *

     * @method stringHelper

     * @private

     * @param {object} context The current mustache context.

     * @param {string} sectionText The text to parse the arguments from.

     * @param {function} helper Used to render subsections of the text.

     * @returns {string}

     */

    stringHelper(context, sectionText, helper) {

        // A string instruction is in the format:

        // key, component, params.

        let parts = sectionText.split(',');

        const key = parts.length > 0 ? parts.shift().trim() : '';

        const component = parts.length > 0 ? getNormalisedComponent(parts.shift().trim()) : '';

        let param = parts.length > 0 ? parts.join(',').trim() : '';

        if (param !== '') {

            // Allow variable expansion in the param part only.

            param = helper(param, context);

        }

        if (param.match(/^{\s*"/gm)) {

            // If it can't be parsed then the string is not a JSON format.

            try {

                const parsedParam = JSON.parse(param);

                // Handle non-exception-throwing cases, e.g. null, integer, boolean.

                if (parsedParam && typeof parsedParam === "object") {

                    param = parsedParam;

                }

            } catch (err) {

                // This was probably not JSON.

                // Keep the error message visible but do not promote it because it may not be an error.

                window.console.warn(err.message);

            }

        }

        const index = this.requiredStrings.length;

        this.requiredStrings.push({

            key,

            component,

            param,

        });

        // The placeholder must not use {{}} as those can be misinterpreted by the engine.

        return `[[_s${index}]]`;

    }

    /**

     * String helper to render {{#cleanstr}}abd component { a : 'fish'}{{/cleanstr}}

     * into a get_string following by an HTML escape.

     *

     * @method cleanStringHelper

     * @private

     * @param {object} context The current mustache context.

     * @param {string} sectionText The text to parse the arguments from.

     * @param {function} helper Used to render subsections of the text.

     * @returns {string}

     */

    cleanStringHelper(context, sectionText, helper) {

        // We're going to use [[_cx]] format for clean strings, where x is a number.

        // Hence, replacing 's' with 'c' in the placeholder that stringHelper returns.

        return this

            .stringHelper(context, sectionText, helper)

            .replace(placeholderString, placeholderCleanedString);

    }

    /**

     * Quote helper used to wrap content in quotes, and escape all special JSON characters present in the content.

     *

     * @method quoteHelper

     * @private

     * @param {object} context The current mustache context.

     * @param {string} sectionText The text to parse the arguments from.

     * @param {function} helper Used to render subsections of the text.

     * @returns {string}

     */

    quoteHelper(context, sectionText, helper) {

        let content = helper(sectionText.trim(), context);

        // Escape the {{ and JSON encode.

        // This involves wrapping {{, and }} in change delimeter tags.

        content = JSON.stringify(content);

        content = content.replace(/([{}]{2,3})/g, '{{=<% %>=}}$1<%={{ }}=%>');

        return content;

    }

    /**

     * Shorten text helper to truncate text and append a trailing ellipsis.

     *

     * @method shortenTextHelper

     * @private

     * @param {object} context The current mustache context.

     * @param {string} sectionText The text to parse the arguments from.

     * @param {function} helper Used to render subsections of the text.

     * @returns {string}

     */

    shortenTextHelper(context, sectionText, helper) {

        // Non-greedy split on comma to grab section text into the length and

        // text parts.

        const parts = sectionText.match(/(.*?),(.*)/);

        // The length is the part matched in the first set of parethesis.

        const length = parts[1].trim();

        // The length is the part matched in the second set of parethesis.

        const text = parts[2].trim();

        const content = helper(text, context);

        return Truncate.truncate(content, {

            length,

            words: true,

            ellipsis: '...'

        });

    }

    /**

     * User date helper to render user dates from timestamps.

     *

     * @method userDateHelper

     * @private

     * @param {object} context The current mustache context.

     * @param {string} sectionText The text to parse the arguments from.

     * @param {function} helper Used to render subsections of the text.

     * @returns {string}

     */

    userDateHelper(context, sectionText, helper) {

        // Non-greedy split on comma to grab the timestamp and format.

        const parts = sectionText.match(/(.*?),(.*)/);

        const timestamp = helper(parts[1].trim(), context);

        const format = helper(parts[2].trim(), context);

        const index = this.requiredDates.length;

        this.requiredDates.push({

            timestamp: timestamp,

            format: format

        });

        return `[[_t_${index}]]`;

    }

    /**

     * Return a helper function to be added to the context for rendering the a

     * template.

     *

     * This will parse the provided text before giving it to the helper function

     * in order to remove any disallowed nested helpers to prevent one helper

     * from calling another.

     *

     * In particular to prevent the JS helper from being called from within another

     * helper because it can lead to security issues when the JS portion is user

     * provided.

     *

     * @param  {function} helperFunction The helper function to add

     * @param  {object} context The template context for the helper function

     * @returns {Function} To be set in the context

     */

    addHelperFunction(helperFunction, context) {

        return function() {

            return function(sectionText, helper) {

                // Override the disallowed helpers in the template context with

                // a function that returns an empty string for use when executing

                // other helpers. This is to prevent these helpers from being

                // executed as part of the rendering of another helper in order to

                // prevent any potential security issues.

                const originalHelpers = Renderer.disallowedNestedHelpers.reduce((carry, name) => {

                    if (context.hasOwnProperty(name)) {

                        carry[name] = context[name];

                    }

                    return carry;

                }, {});

                Renderer.disallowedNestedHelpers.forEach((helperName) => {

                    context[helperName] = () => '';

                });

                // Execute the helper with the modified context that doesn't include

                // the disallowed nested helpers. This prevents the disallowed

                // helpers from being called from within other helpers.

                const result = helperFunction.apply(this, [context, sectionText, helper]);

                // Restore the original helper implementation in the context so that

                // any further rendering has access to them again.

                for (const name in originalHelpers) {

                    context[name] = originalHelpers[name];

                }

                return result;

            }.bind(this);

        }.bind(this);

    }

    /**

     * Add some common helper functions to all context objects passed to templates.

     * These helpers match exactly the helpers available in php.

     *

     * @method addHelpers

     * @private

     * @param {Object} context Simple types used as the context for the template.

     * @param {String} themeName We set this multiple times, because there are async calls.

     */

    addHelpers(context, themeName) {

        this.currentThemeName = themeName;

        this.requiredStrings = [];

        this.requiredJS = [];

        context.uniqid = (Renderer.uniqInstances++);

        // Please note that these helpers _must_ not return a Promise.

        context.str = this.addHelperFunction(this.stringHelper, context);

        context.cleanstr = this.addHelperFunction(this.cleanStringHelper, context);

        context.pix = this.addHelperFunction(this.pixHelper, context);

        context.js = this.addHelperFunction(this.jsHelper, context);

        context.quote = this.addHelperFunction(this.quoteHelper, context);

        context.shortentext = this.addHelperFunction(this.shortenTextHelper, context);

        context.userdate = this.addHelperFunction(this.userDateHelper, context);

        context.globals = {config: config};

        context.currentTheme = themeName;

    }

    /**

     * Get all the JS blocks from the last rendered template.

     *

     * @method getJS

     * @private

     * @returns {string}

     */

    getJS() {

        return this.requiredJS.join(";\n");

    }

    /**

     * Treat strings in content.

     *

     * The purpose of this method is to replace the placeholders found in a string

     * with the their respective translated strings.

     *

     * Previously we were relying on String.replace() but the complexity increased with

     * the numbers of strings to replace. Now we manually walk the string and stop at each

     * placeholder we find, only then we replace it. Most of the time we will

     * replace all the placeholders in a single run, at times we will need a few

     * more runs when placeholders are replaced with strings that contain placeholders

     * themselves.

     *

     * @param {String} content The content in which string placeholders are to be found.

     * @param {Map} stringMap The strings to replace with.

     * @returns {String} The treated content.

     */

    treatStringsInContent(content, stringMap) {

        // Placeholders are in the for [[_sX]] or [[_cX]] where X is the string index.

        const stringPattern = /(?<placeholder>\[\[_(?<stringType>[cs])(?<stringIndex>\d+)\]\])/g;

        // A helpre to fetch the string for a given placeholder.

        const getUpdatedString = ({placeholder, stringType, stringIndex}) => {

            if (stringMap.has(placeholder)) {

                return stringMap.get(placeholder);

            }

            if (stringType === placeholderCleanedString) {

                // Attempt to find the unclean string and clean it. Store it for later use.

                const uncleanString = stringMap.get(`[[_s${stringIndex}]]`);

                if (uncleanString) {

                    stringMap.set(placeholder, mustache.escape(uncleanString));

                    return stringMap.get(placeholder);

                }

            }

            Log.debug(`Could not find string for pattern ${placeholder}`);

            return '';

        };

        // Find all placeholders in the content and replace them with their respective strings.

        let match;

        while ((match = stringPattern.exec(content)) !== null) {

            let updatedContent = content.slice(0, match.index);

            updatedContent += getUpdatedString(match.groups);

            updatedContent += content.slice(match.index + match.groups.placeholder.length);

            content = updatedContent;

        }

        return content;

    }

    /**

     * Treat strings in content.

     *

     * The purpose of this method is to replace the date placeholders found in the

     * content with the their respective translated dates.

     *

     * @param {String} content The content in which string placeholders are to be found.

     * @param {Array} dates The dates to replace with.

     * @returns {String} The treated content.

     */

    treatDatesInContent(content, dates) {

        dates.forEach((date, index) => {

            content = content.replace(

                new RegExp(`\\[\\[_t_${index}\\]\\]`, 'g'),

                date,

            );

        });

        return content;

    }

    /**

     * Render a template and then call the callback with the result.

     *

     * @method doRender

     * @private

     * @param {string|Promise} templateSourcePromise The mustache template to render.

     * @param {Object} context Simple types used as the context for the template.

     * @param {String} themeName Name of the current theme.

     * @returns {Promise<object<string, string>>} The rendered HTML and JS.

     */

    async doRender(templateSourcePromise, context, themeName) {

        this.currentThemeName = themeName;

        const iconTemplate = this.iconSystem.getTemplateName();

        const pendingPromise = new Pending('core/templates:doRender');

        const [templateSource] = await Promise.all([

            templateSourcePromise,

            Renderer.getLoader().getTemplate(iconTemplate, themeName),

        ]);

        this.addHelpers(context, themeName);

        // Render the template.

        const renderedContent = await mustache.render(

            templateSource,

            context,

            // Note: The third parameter is a function that will be called to process partials.

            (partialName) => Renderer.getLoader().partialHelper(partialName, themeName),

        );

        const {html, js} = await this.processRenderedContent(renderedContent);

        pendingPromise.resolve();

        return {html, js};

    }

    /**

     * Process the rendered content, treating any strings and applying and helper strings, dates, etc.

     * @param {string} renderedContent

     * @returns {Promise<object<string, string>>} The rendered HTML and JS.

     */

    async processRenderedContent(renderedContent) {

        let html = renderedContent.trim();

        let js = this.getJS();

        if (this.requiredStrings.length > 0) {

            // Fetch the strings into a new Map using the placeholder as an index.

            // Note: We only fetch the unclean version. Cleaning of strings happens lazily in treatStringsInContent.

            const stringMap = new Map(

                (await getStrings(this.requiredStrings)).map((string, index) => (

                    [`[[_s${index}]]`, string]

                ))

            );

            // Make sure string substitutions are done for the userdate

            // values as well.

            this.requiredDates = this.requiredDates.map(function(date) {

                return {

                    timestamp: this.treatStringsInContent(date.timestamp, stringMap),

                    format: this.treatStringsInContent(date.format, stringMap)

                };

            }.bind(this));

            // Why do we not do another call the render here?

            //

            // Because that would expose DOS holes. E.g.

            // I create an assignment called "{{fish" which

            // would get inserted in the template in the first pass

            // and cause the template to die on the second pass (unbalanced).

            html = this.treatStringsInContent(html, stringMap);

            js = this.treatStringsInContent(js, stringMap);

        }

        // This has to happen after the strings replacement because you can

        // use the string helper in content for the user date helper.

        if (this.requiredDates.length > 0) {

            const dates = await UserDate.get(this.requiredDates);

            html = this.treatDatesInContent(html, dates);

            js = this.treatDatesInContent(js, dates);

        }

        return {html, js};

    }

    /**

     * Load a template and call doRender on it.

     *

     * @method render

     * @private

     * @param {string} templateName - should consist of the component and the name of the template like this:

     *                              core/menu (lib/templates/menu.mustache) or

     *                              tool_bananas/yellow (admin/tool/bananas/templates/yellow.mustache)

     * @param {Object} [context={}] - Could be array, string or simple value for the context of the template.

     * @param {string} [themeName] - Name of the current theme.

     * @returns {Promise<object>} Native promise object resolved when the template has been rendered.}

     */

    async render(

        templateName,

        context = {},

        themeName = config.theme,

    ) {

        this.currentThemeName = themeName;

        // Preload the module to do the icon rendering based on the theme iconsystem.

        await this.setupIconSystem();

        const templateSource = Renderer.getLoader().cachePartials(templateName, themeName);

        return this.doRender(templateSource, context, themeName);

    }

}