// This file is part of Moodle - https://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/>.

/**
 * Provides the required functionality for an autocomplete element to select a user.
 *
 * @module      core_user/form_user_selector
 * @copyright   2020 David Mudrák <david@moodle.com>
 * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

import Ajax from 'core/ajax';
import {render as renderTemplate} from 'core/templates';
import {getString} from 'core/str';

/**
 * Load the list of users matching the query and render the selector labels for them.
 *
 * @param {String} selector The selector of the auto complete element.
 * @param {String} query The query string.
 * @param {Function} callback A callback function receiving an array of results.
 * @param {Function} failure A function to call in case of failure, receiving the error message.
 */
export async function transport(selector, query, callback, failure) {

    const request = {
        methodname: 'core_user_search_identity',
        args: {
            query: query
        }
    };

    try {
        const response = await Ajax.call([request])[0];

        if (response.overflow) {
            const msg = await getString('toomanyuserstoshow', 'core', '>' + response.maxusersperpage);
            callback(msg);

        } else {
            let labels = [];
            response.list.forEach(user => {
                labels.push(renderTemplate('core_user/form_user_selector_suggestion', user));
            });
            labels = await Promise.all(labels);

            response.list.forEach((user, index) => {
                user.label = labels[index];
            });

            callback(response.list);
        }

    } catch (e) {
        failure(e);
    }
}

/**
 * Process the results for auto complete elements.
 *
 * @param {String} selector The selector of the auto complete element.
 * @param {Array} results An array or results returned by {@see transport()}.
 * @return {Array} New array of the selector options.
 */
export function processResults(selector, results) {

    if (!Array.isArray(results)) {
        return results;

    } else {
        return results.map(result => ({value: result.id, label: result.label}));
    }
}