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/>.

/**

 * Submit button JavaScript. All submit buttons will be automatically disabled once the form is

 * submitted, unless that submission results in an error/cancelling the submit.

 *

 * @module core_form/submit

 * @copyright 2019 The Open University

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

 * @since 3.8

 */

import {eventTypes} from 'core_form/events';

/** @property {number} ID for setInterval used when polling for download cookie */

let cookieListener = 0;

/** @property {Array} Array of buttons that need re-enabling if we get a download cookie */

const cookieListeningButtons = [];

/** @property {number} Number of files uploading. */

let currentUploadCount = 0;

/** @property {Array} Array of buttons that need re-enabling if we get a upload process. */

const uploadListeningButtons = [];

/** @property {Boolean} Is upload listeners registered? */

let uploadListenersRegistered = false;

/**

 * Listens in case a download cookie is provided.

 *

 * This function is used to detect file downloads. If there is a file download then we get a

 * beforeunload event, but the page is never unloaded and when the file download completes we

 * should re-enable the buttons. We detect this by watching for a specific cookie.

 *

 * PHP function \core_form\util::form_download_complete() can be used to send this cookie.

 *

 * @param {HTMLElement} button Button to re-enable

 */

const listenForDownloadCookie = (button) => {

    cookieListeningButtons.push(button);

    if (!cookieListener) {

        cookieListener = setInterval(() => {

            // Look for cookie.

            const parts = document.cookie.split(getCookieName() + '=');

            if (parts.length == 2) {

                // We found the cookie, so the file is ready. Expire the cookie and cancel polling.

                clearDownloadCookie();

                clearInterval(cookieListener);

                cookieListener = 0;

                // Re-enable all the buttons.

                cookieListeningButtons.forEach((button) => {

                    button.disabled = false;

                });

            }

        }, 500);

    }

};

/**

 * Gets a unique name for the download cookie.

 *

 * @returns {string} Cookie name

 */

const getCookieName = () => {

    return 'moodledownload_' + M.cfg.sesskey;

};

/**

 * Clears the download cookie if there is one.

 */

const clearDownloadCookie = () => {

    document.cookie = encodeURIComponent(getCookieName()) + '=deleted; expires=' + new Date(0).toUTCString();

};

/**

 * Enable submit buttons when all files are uploaded.

 */

const checkUploadCount = () => {

    if (currentUploadCount) {

        uploadListeningButtons.forEach(button => {

            button.disabled = true;

        });

    } else {

        uploadListeningButtons.forEach(button => {

            button.disabled = false;

        });

    }

};

/**

 * Initialises submit buttons.

 *

 * @param {String} elementId Form button element

 * @listens event:uploadStarted

 * @listens event:uploadCompleted

 */

export const init = (elementId) => {

    const button = document.getElementById(elementId);

    if (button === null) {

        // Exit early if invalid element id passed.

        return;

    }

    // If buttons are disabled by default, we do not enable them when file upload completed event is fired.

    if (!button.disabled) {

        uploadListeningButtons.push(button);

    }

    if (!uploadListenersRegistered) {

        // Add event listener for file upload start.

        document.addEventListener(eventTypes.uploadStarted, () => {

            currentUploadCount++;

            checkUploadCount();

        });

        // Add event listener for file upload complete.

        document.addEventListener(eventTypes.uploadCompleted, () => {

            currentUploadCount--;

            checkUploadCount();

        });

        uploadListenersRegistered = true;

    }

    // If the form has double submit protection disabled, do nothing.

    if (button.form.dataset.doubleSubmitProtection === 'off') {

        return;

    }

    button.form.addEventListener('submit', function(event) {

        // Only disable it if the browser is really going to another page as a result of the

        // submit.

        const disableAction = function() {

            // If the submit was cancelled, or the button is already disabled, don't do anything.

            if (event.defaultPrevented || button.disabled) {

                return;

            }

            button.disabled = true;

            clearDownloadCookie();

            listenForDownloadCookie(button);

        };

        window.addEventListener('beforeunload', disableAction);

        // If there is no beforeunload event as a result of this form submit, then the form

        // submit must have been cancelled, so don't disable the button if the page is

        // unloaded later.

        setTimeout(function() {

            window.removeEventListener('beforeunload', disableAction);

        }, 1);

    }, false);

};