Vmeda.Online/src/app/services/utils/utils.ts

// (C) Copyright 2015 Moodle Pty Ltd.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import { Injectable, NgZone } from '@angular/core';
import { InAppBrowserObject } from '@ionic-native/in-app-browser';
import { Subscription } from 'rxjs';

import { CoreApp } from '@services/app';
import { CoreEvents, CoreEventsProvider } from '@services/events';
import { CoreFile } from '@services/file';
import { CoreLang } from '@services/lang';
import { CoreWS, CoreWSError } from '@services/ws';
import { CoreDomUtils } from '@services/utils/dom';
import { CoreMimetypeUtils } from '@services/utils/mimetype';
import { CoreTextUtils } from '@services/utils/text';
import {
    makeSingleton, Clipboard, InAppBrowser, Platform, FileOpener, WebIntent, QRScanner, Translate
} from '@singletons/core.singletons';
import { CoreLogger } from '@singletons/logger';

/*
 * "Utils" service with helper functions.
 */
@Injectable()
export class CoreUtilsProvider {
    protected DONT_CLONE = ['[object FileEntry]', '[object DirectoryEntry]', '[object DOMFileSystem]'];
    protected logger: CoreLogger;
    protected iabInstance: InAppBrowserObject;
    protected uniqueIds: {[name: string]: number} = {};
    protected qrScanData: {deferred: PromiseDefer<any>, observable: Subscription};

    constructor(protected zone: NgZone) {
        this.logger = CoreLogger.getInstance('CoreUtilsProvider');

        Platform.instance.ready().then(() => {
            const win = <any> window;

            if (win.cordova && win.cordova.InAppBrowser) {
                // Override the default window.open with the InAppBrowser one.
                win.open = win.cordova.InAppBrowser.open;
            }
        });
    }

    /**
     * Given an error, add an extra warning to the error message and return the new error message.
     *
     * @param error Error object or message.
     * @param defaultError Message to show if the error is not a string.
     * @return New error message.
     */
    addDataNotDownloadedError(error: any, defaultError?: string): string {
        let errorMessage = error;

        if (error && typeof error != 'string') {
            errorMessage = CoreTextUtils.instance.getErrorMessageFromError(error);
        }

        if (typeof errorMessage != 'string') {
            errorMessage = defaultError || '';
        }

        if (!this.isWebServiceError(error)) {
            // Local error. Add an extra warning.
             errorMessage += '<br><br>' + Translate.instance.instant('core.errorsomedatanotdownloaded');
        }

        return errorMessage;
    }

    /**
     * Similar to Promise.all, but if a promise fails this function's promise won't be rejected until ALL promises have finished.
     *
     * @param promises Promises.
     * @return Promise resolved if all promises are resolved and rejected if at least 1 promise fails.
     */
    allPromises(promises: Promise<any>[]): Promise<any> {
        if (!promises || !promises.length) {
            return Promise.resolve();
        }

        return new Promise((resolve, reject): void => {
            const total = promises.length;
            let count = 0;
            let hasFailed = false;
            let error;

            promises.forEach((promise) => {
                promise.catch((err) => {
                    hasFailed = true;
                    error = err;
                }).finally(() => {
                    count++;

                    if (count === total) {
                        // All promises have finished, reject/resolve.
                        if (hasFailed) {
                            reject(error);
                        } else {
                            resolve();
                        }
                    }
                });
            });
        });
    }

    /**
     * Converts an array of objects to an object, using a property of each entry as the key.
     * It can also be used to convert an array of strings to an object where the keys are the elements of the array.
     * E.g. [{id: 10, name: 'A'}, {id: 11, name: 'B'}] => {10: {id: 10, name: 'A'}, 11: {id: 11, name: 'B'}}
     *
     * @param array The array to convert.
     * @param propertyName The name of the property to use as the key. If not provided, the whole item will be used.
     * @param result Object where to put the properties. If not defined, a new object will be created.
     * @return The object.
     */
    arrayToObject(array: any[], propertyName?: string, result?: any): any {
        result = result || {};
        array.forEach((entry) => {
            const key = propertyName ? entry[propertyName] : entry;
            result[key] = entry;
        });

        return result;
    }

    /**
     * Compare two objects. This function won't compare functions and proto properties, it's a basic compare.
     * Also, this will only check if itemA's properties are in itemB with same value. This function will still
     * return true if itemB has more properties than itemA.
     *
     * @param itemA First object.
     * @param itemB Second object.
     * @param maxLevels Number of levels to reach if 2 objects are compared.
     * @param level Current deep level (when comparing objects).
     * @param undefinedIsNull True if undefined is equal to null. Defaults to true.
     * @return Whether both items are equal.
     */
    basicLeftCompare(itemA: any, itemB: any, maxLevels: number = 0, level: number = 0, undefinedIsNull: boolean = true): boolean {
        if (typeof itemA == 'function' || typeof itemB == 'function') {
            return true; // Don't compare functions.
        } else if (typeof itemA == 'object' && typeof itemB == 'object') {
            if (level >= maxLevels) {
                return true; // Max deep reached.
            }

            let equal = true;
            for (const name in itemA) {
                const value = itemA[name];
                if (name == '$$hashKey') {
                    // Ignore $$hashKey property since it's a "calculated" property.
                    return;
                }

                if (!this.basicLeftCompare(value, itemB[name], maxLevels, level + 1)) {
                    equal = false;
                }
            }

            return equal;
        } else {
            if (undefinedIsNull && (
                (typeof itemA == 'undefined' && itemB === null) || (itemA === null && typeof itemB == 'undefined'))) {
                return true;
            }

            // We'll treat "2" and 2 as the same value.
            const floatA = parseFloat(itemA);
            const floatB = parseFloat(itemB);

            if (!isNaN(floatA) && !isNaN(floatB)) {
                return floatA == floatB;
            }

            return itemA === itemB;
        }
    }

    /**
     * Blocks leaving a view.
     * @deprecated, use ionViewCanLeave instead.
     */
    blockLeaveView(): void {
        return;
    }

    /**
     * Check if a URL has a redirect.
     *
     * @param url The URL to check.
     * @return Promise resolved with boolean_ whether there is a redirect.
     */
    checkRedirect(url: string): Promise<boolean> {
        if (window.fetch) {
            const win = <any> window; // Convert to <any> to be able to use AbortController (not supported by our TS version).
            const initOptions: any = {
                redirect: 'follow',
            };
            let controller;

            // Some browsers implement fetch but no AbortController.
            if (win.AbortController) {
                controller = new win.AbortController();
                initOptions.signal = controller.signal;
            }

            return this.timeoutPromise(window.fetch(url, initOptions), CoreWS.instance.getRequestTimeout())
                    .then((response: Response) => {
                return response.redirected;
            }).catch((error) => {
                if (error.timeout && controller) {
                    // Timeout, abort the request.
                    controller.abort();
                }

                // There was a timeout, cannot determine if there's a redirect. Assume it's false.
                return false;
            });
        } else {
            // Cannot check if there is a redirect, assume it's false.
            return Promise.resolve(false);
        }
    }

    /**
     * Close the InAppBrowser window.
     *
     * @param closeAll Desktop only. True to close all secondary windows, false to close only the "current" one.
     */
    closeInAppBrowser(closeAll?: boolean): void {
        if (this.iabInstance) {
            this.iabInstance.close();
            if (closeAll && CoreApp.instance.isDesktop()) {
                // @todo require('electron').ipcRenderer.send('closeSecondaryWindows');
            }
        }
    }

    /**
     * Clone a variable. It should be an object, array or primitive type.
     *
     * @param source The variable to clone.
     * @param level Depth we are right now inside a cloned object. It's used to prevent reaching max call stack size.
     * @return Cloned variable.
     */
    clone(source: any, level: number = 0): any {
        if (level >= 20) {
            // Max 20 levels.
            this.logger.error('Max depth reached when cloning object.', source);

            return source;
        }

        if (Array.isArray(source)) {
            // Clone the array and all the entries.
            const newArray = [];
            for (let i = 0; i < source.length; i++) {
                newArray[i] = this.clone(source[i], level + 1);
            }

            return newArray;
        } else if (typeof source == 'object' && source !== null) {
            // Check if the object shouldn't be copied.
            if (source && source.toString && this.DONT_CLONE.indexOf(source.toString()) != -1) {
                // Object shouldn't be copied, return it as it is.
                return source;
            }

            // Clone the object and all the subproperties.
            const newObject = {};
            for (const name in source) {
                newObject[name] = this.clone(source[name], level + 1);
            }

            return newObject;
        } else {
            // Primitive type or unknown, return it as it is.
            return source;
        }
    }

    /**
     * Copy properties from one object to another.
     *
     * @param from Object to copy the properties from.
     * @param to Object where to store the properties.
     * @param clone Whether the properties should be cloned (so they are different instances).
     */
    copyProperties(from: any, to: any, clone: boolean = true): void {
        for (const name in from) {
            if (clone) {
                to[name] = this.clone(from[name]);
            } else {
                to[name] = from[name];
            }
        }
    }

    /**
     * Copies a text to clipboard and shows a toast message.
     *
     * @param text Text to be copied
     * @return Promise resolved when text is copied.
     */
    copyToClipboard(text: string): Promise<any> {
        return Clipboard.instance.copy(text).then(() => {
            // Show toast using ionicLoading.
            return CoreDomUtils.instance.showToast('core.copiedtoclipboard', true);
        }).catch(() => {
            // Ignore errors.
        });
    }

    /**
     * Create a "fake" WS error for local errors.
     *
     * @param message The message to include in the error.
     * @param needsTranslate If the message needs to be translated.
     * @return Fake WS error.
     */
    createFakeWSError(message: string, needsTranslate?: boolean): CoreWSError {
        return CoreWS.instance.createFakeWSError(message, needsTranslate);
    }

    /**
     * Empties an array without losing its reference.
     *
     * @param array Array to empty.
     */
    emptyArray(array: any[]): void {
        array.length = 0; // Empty array without losing its reference.
    }

    /**
     * Removes all properties from an object without losing its reference.
     *
     * @param object Object to remove the properties.
     */
    emptyObject(object: object): void {
        for (const key in object) {
            if (object.hasOwnProperty(key)) {
                delete object[key];
            }
        }
    }

    /**
     * Execute promises one depending on the previous.
     *
     * @param orderedPromisesData Data to be executed including the following values:
     *                            - func: Function to be executed.
     *                            - context: Context to pass to the function. This allows using "this" inside the function.
     *                            - params: Array of data to be sent to the function.
     *                            - blocking: Boolean. If promise should block the following.
     * @return Promise resolved when all promises are resolved.
     */
    executeOrderedPromises(orderedPromisesData: any[]): Promise<any> {
        const promises = [];
        let dependency = Promise.resolve();

        // Execute all the processes in order.
        for (const i in orderedPromisesData) {
            const data = orderedPromisesData[i];
            let promise;

            // Add the process to the dependency stack.
            promise = dependency.finally(() => {
                let prom;

                try {
                    prom = data.func.apply(data.context, data.params || []);
                } catch (e) {
                    this.logger.error(e.message);

                    return;
                }

                return prom;
            });
            promises.push(promise);

            // If the new process is blocking, we set it as the dependency.
            if (data.blocking) {
                dependency = promise;
            }
        }

        // Return when all promises are done.
        return this.allPromises(promises);
    }

    /**
     * Flatten an object, moving subobjects' properties to the first level.
     * It supports 2 notations: dot notation and square brackets.
     * E.g.: {a: {b: 1, c: 2}, d: 3} -> {'a.b': 1, 'a.c': 2, d: 3}
     *
     * @param obj Object to flatten.
     * @param useDotNotation Whether to use dot notation '.' or square brackets '['.
     * @return Flattened object.
     */
    flattenObject(obj: object, useDotNotation?: boolean): object {
        const toReturn = {};

        for (const name in obj) {
            if (!obj.hasOwnProperty(name)) {
                continue;
            }

            const value = obj[name];
            if (typeof value == 'object' && !Array.isArray(value)) {
                const flatObject = this.flattenObject(value);
                for (const subName in flatObject) {
                    if (!flatObject.hasOwnProperty(subName)) {
                        continue;
                    }

                    const newName = useDotNotation ? name + '.' + subName : name + '[' + subName + ']';
                    toReturn[newName] = flatObject[subName];
                }
            } else {
                toReturn[name] = value;
            }
        }

        return toReturn;
    }

    /**
     * Given an array of strings, return only the ones that match a regular expression.
     *
     * @param array Array to filter.
     * @param regex RegExp to apply to each string.
     * @return Filtered array.
     */
    filterByRegexp(array: string[], regex: RegExp): string[] {
        if (!array || !array.length) {
            return [];
        }

        return array.filter((entry) => {
            const matches = entry.match(regex);

            return matches && matches.length;
        });
    }

    /**
     * Filter the list of site IDs based on a isEnabled function.
     *
     * @param siteIds Site IDs to filter.
     * @param isEnabledFn Function to call for each site. It receives a siteId param and all the params sent to this function
     *                    after 'checkAll'.
     * @param checkAll True if it should check all the sites, false if it should check only 1 and treat them all
     *                 depending on this result.
     * @param ...args All the params sent after checkAll will be passed to isEnabledFn.
     * @return Promise resolved with the list of enabled sites.
     */
    filterEnabledSites(siteIds: string[], isEnabledFn: (siteId, ...args: any[]) => boolean | Promise<boolean>, checkAll?: boolean,
            ...args: any[]): Promise<string[]> {
        const promises = [];
        const enabledSites = [];

        for (const i in siteIds) {
            const siteId = siteIds[i];
            if (checkAll || !promises.length) {
                promises.push(Promise.resolve(isEnabledFn.apply(isEnabledFn, [siteId].concat(args))).then((enabled) => {
                    if (enabled) {
                        enabledSites.push(siteId);
                    }
                }));
            }
        }

        return this.allPromises(promises).catch(() => {
            // Ignore errors.
        }).then(() => {
            if (!checkAll) {
                // Checking 1 was enough, so it will either return all the sites or none.
                return enabledSites.length ? siteIds : [];
            } else {
                return enabledSites;
            }
        });
    }

    /**
     * Given a float, prints it nicely. Localized floats must not be used in calculations!
     * Based on Moodle's format_float.
     *
     * @param float The float to print.
     * @return Locale float.
     */
    formatFloat(float: any): string {
        if (typeof float == 'undefined' || float === null || typeof float == 'boolean') {
            return '';
        }

        const localeSeparator = Translate.instance.instant('core.decsep');

        // Convert float to string.
        float += '';

        return float.replace('.', localeSeparator);
    }

    /**
     * Returns a tree formatted from a plain list.
     * List has to be sorted by depth to allow this function to work correctly. Errors can be thrown if a child node is
     * processed before a parent node.
     *
     * @param list List to format.
     * @param parentFieldName Name of the parent field to match with children.
     * @param idFieldName Name of the children field to match with parent.
     * @param rootParentId The id of the root.
     * @param maxDepth Max Depth to convert to tree. Children found will be in the last level of depth.
     * @return Array with the formatted tree, children will be on each node under children field.
     */
    formatTree(list: any[], parentFieldName: string = 'parent', idFieldName: string = 'id', rootParentId: number = 0,
            maxDepth: number = 5): any[] {
        const map = {};
        const mapDepth = {};
        const tree = [];
        let parent;
        let id;

        list.forEach((node, index): void => {
            id = node[idFieldName];
            parent = node[parentFieldName];
            node.children = [];

            if (!id || !parent) {
                this.logger.error(`Node with incorrect ${idFieldName}:${id} or ${parentFieldName}:${parent} found on formatTree`);
            }

            // Use map to look-up the parents.
            map[id] = index;
            if (parent != rootParentId) {
                const parentNode = list[map[parent]];
                if (parentNode) {
                    if (mapDepth[parent] == maxDepth) {
                        // Reached max level of depth. Proceed with flat order. Find parent object of the current node.
                        const parentOfParent = parentNode[parentFieldName];
                        if (parentOfParent) {
                            // This element will be the child of the node that is two levels up the hierarchy
                            // (i.e. the child of node.parent.parent).
                            list[map[parentOfParent]].children.push(node);
                            // Assign depth level to the same depth as the parent (i.e. max depth level).
                            mapDepth[id] = mapDepth[parent];
                            // Change the parent to be the one that is two levels up the hierarchy.
                            node.parent = parentOfParent;
                        } else {
                            this.logger.error(`Node parent of parent:${parentOfParent} not found on formatTree`);
                        }
                    } else {
                        parentNode.children.push(node);
                        // Increase the depth level.
                        mapDepth[id] = mapDepth[parent] + 1;
                    }
                } else {
                    this.logger.error(`Node parent:${parent} not found on formatTree`);
                }
            } else {
                tree.push(node);

                // Root elements are the first elements in the tree structure, therefore have the depth level 1.
                mapDepth[id] = 1;
            }
        });

        return tree;
    }

    /**
     * Get country name based on country code.
     *
     * @param code Country code (AF, ES, US, ...).
     * @return Country name. If the country is not found, return the country code.
     */
    getCountryName(code: string): string {
        const countryKey = 'assets.countries.' + code;
        const countryName = Translate.instance.instant(countryKey);

        return countryName !== countryKey ? countryName : code;
    }

    /**
     * Get list of countries with their code and translated name.
     *
     * @return Promise resolved with the list of countries.
     */
    getCountryList(): Promise<any> {
        // Get the keys of the countries.
        return this.getCountryKeysList().then((keys) => {
            // Now get the code and the translated name.
            const countries = {};

            keys.forEach((key) => {
                if (key.indexOf('assets.countries.') === 0) {
                    const code = key.replace('assets.countries.', '');
                    countries[code] = Translate.instance.instant(key);
                }
            });

            return countries;
        });
    }

    /**
     * Get list of countries with their code and translated name. Sorted by the name of the country.
     *
     * @return Promise resolved with the list of countries.
     */
    getCountryListSorted(): Promise<any[]> {
        // Get the keys of the countries.
        return this.getCountryList().then((countries) => {
            // Sort translations.
            const sortedCountries = [];

            Object.keys(countries).sort((a, b) => countries[a].localeCompare(countries[b])).forEach((key) => {
                sortedCountries.push({code: key, name: countries[key]});
            });

            return sortedCountries;
        });
    }

    /**
     * Get the list of language keys of the countries.
     *
     * @return Promise resolved with the countries list. Rejected if not translated.
     */
    protected getCountryKeysList(): Promise<string[]> {
        // It's possible that the current language isn't translated, so try with default language first.
        const defaultLang = CoreLang.instance.getDefaultLanguage();

        return this.getCountryKeysListForLanguage(defaultLang).catch(() => {
            // Not translated, try to use the fallback language.
            const fallbackLang = CoreLang.instance.getFallbackLanguage();

            if (fallbackLang === defaultLang) {
                // Same language, just reject.
                return Promise.reject('Countries not found.');
            }

            return this.getCountryKeysListForLanguage(fallbackLang);
        });
    }

    /**
     * Get the list of language keys of the countries, based on the translation table for a certain language.
     *
     * @param lang Language to check.
     * @return Promise resolved with the countries list. Rejected if not translated.
     */
    protected getCountryKeysListForLanguage(lang: string): Promise<string[]> {
        // Get the translation table for the language.
        return CoreLang.instance.getTranslationTable(lang).then((table): any => {
            // Gather all the keys for countries,
            const keys = [];

            for (const name in table) {
                if (name.indexOf('assets.countries.') === 0) {
                    keys.push(name);
                }
            }

            if (keys.length === 0) {
                // Not translated, reject.
                return Promise.reject('Countries not found.');
            }

            return keys;
        });
    }

    /**
     * Get the mimetype of a file given its URL. It'll try to guess it using the URL, if that fails then it'll
     * perform a HEAD request to get it. It's done in this order because pluginfile.php can return wrong mimetypes.
     * This function is in here instead of MimetypeUtils to prevent circular dependencies.
     *
     * @param url The URL of the file.
     * @return Promise resolved with the mimetype.
     */
    getMimeTypeFromUrl(url: string): Promise<string> {
        // First check if it can be guessed from the URL.
        const extension = CoreMimetypeUtils.instance.guessExtensionFromUrl(url);
        const mimetype = CoreMimetypeUtils.instance.getMimeType(extension);

        if (mimetype) {
            return Promise.resolve(mimetype);
        }

        // Can't be guessed, get the remote mimetype.
        return CoreWS.instance.getRemoteFileMimeType(url).then((mimetype) => {
            return mimetype || '';
        });
    }

    /**
     * Get a unique ID for a certain name.
     *
     * @param name The name to get the ID for.
     * @return Unique ID.
     */
    getUniqueId(name: string): number {
        if (!this.uniqueIds[name]) {
            this.uniqueIds[name] = 0;
        }

        return ++this.uniqueIds[name];
    }

    /**
     * Given a list of files, check if there are repeated names.
     *
     * @param files List of files.
     * @return String with error message if repeated, false if no repeated.
     */
    hasRepeatedFilenames(files: any[]): string | boolean {
        if (!files || !files.length) {
            return false;
        }

        const names = [];

        // Check if there are 2 files with the same name.
        for (let i = 0; i < files.length; i++) {
            const name = files[i].filename || files[i].name;
            if (names.indexOf(name) > -1) {
                return Translate.instance.instant('core.filenameexist', { $a: name });
            } else {
                names.push(name);
            }
        }

        return false;
    }

    /**
     * Gets the index of the first string that matches a regular expression.
     *
     * @param array Array to search.
     * @param regex RegExp to apply to each string.
     * @return Index of the first string that matches the RegExp. -1 if not found.
     */
    indexOfRegexp(array: string[], regex: RegExp): number {
        if (!array || !array.length) {
            return -1;
        }

        for (let i = 0; i < array.length; i++) {
            const entry = array[i];
            const matches = entry.match(regex);

            if (matches && matches.length) {
                return i;
            }
        }

        return -1;
    }

    /**
     * Return true if the param is false (bool), 0 (number) or "0" (string).
     *
     * @param value Value to check.
     * @return Whether the value is false, 0 or "0".
     */
    isFalseOrZero(value: any): boolean {
        return typeof value != 'undefined' && (value === false || value === 'false' || parseInt(value, 10) === 0);
    }

    /**
     * Return true if the param is true (bool), 1 (number) or "1" (string).
     *
     * @param value Value to check.
     * @return Whether the value is true, 1 or "1".
     */
    isTrueOrOne(value: any): boolean {
        return typeof value != 'undefined' && (value === true || value === 'true' || parseInt(value, 10) === 1);
    }

    /**
     * Given an error returned by a WS call, check if the error is generated by the app or it has been returned by the WebSwervice.
     *
     * @param error Error to check.
     * @return Whether the error was returned by the WebService.
     */
    isWebServiceError(error: any): boolean {
        return error && (typeof error.warningcode != 'undefined' || (typeof error.errorcode != 'undefined' &&
                error.errorcode != 'invalidtoken' && error.errorcode != 'userdeleted' && error.errorcode != 'upgraderunning' &&
                error.errorcode != 'forcepasswordchangenotice' && error.errorcode != 'usernotfullysetup' &&
                error.errorcode != 'sitepolicynotagreed' && error.errorcode != 'sitemaintenance' &&
                (error.errorcode != 'accessexception' || error.message.indexOf('Invalid token - token expired') == -1)));
    }

    /**
     * Given a list (e.g. a,b,c,d,e) this function returns an array of 1->a, 2->b, 3->c etc.
     * Taken from make_menu_from_list on moodlelib.php (not the same but similar).
     *
     * @param list The string to explode into array bits
     * @param defaultLabel Element that will become default option, if not defined, it won't be added.
     * @param separator The separator used within the list string. Default ','.
     * @param defaultValue Element that will become default option value. Default 0.
     * @return The now assembled array
     */
    makeMenuFromList(list: string, defaultLabel?: string, separator: string = ',', defaultValue?: any): any[] {
        // Split and format the list.
        const split = list.split(separator).map((label, index) => {
            return {
                label: label.trim(),
                value: index + 1
            };
        });

        if (defaultLabel) {
            split.unshift({
                label: defaultLabel,
                value: defaultValue || 0
            });
        }

        return split;
    }

    /**
     * Merge two arrays, removing duplicate values.
     *
     * @param array1 The first array.
     * @param array2 The second array.
     * @param [key] Key of the property that must be unique. If not specified, the whole entry.
     * @return Merged array.
     */
    mergeArraysWithoutDuplicates(array1: any[], array2: any[], key?: string): any[] {
        return this.uniqueArray(array1.concat(array2), key);
    }

    /**
     * Check if a value isn't null or undefined.
     *
     * @param value Value to check.
     * @return True if not null and not undefined.
     */
    notNullOrUndefined(value: any): boolean {
        return typeof value != 'undefined' && value !== null;
    }

    /**
     * Open a file using platform specific method.
     *
     * @param path The local path of the file to be open.
     * @return Promise resolved when done.
     */
    async openFile(path: string): Promise<void> {
        // Convert the path to a native path if needed.
        path = CoreFile.instance.unconvertFileSrc(path);

        const extension = CoreMimetypeUtils.instance.getFileExtension(path);
        const mimetype = CoreMimetypeUtils.instance.getMimeType(extension);

        if (mimetype == 'text/html' && CoreApp.instance.isAndroid()) {
            // Open HTML local files in InAppBrowser, in system browser some embedded files aren't loaded.
            this.openInApp(path);

            return;
        }

        // Path needs to be decoded, the file won't be opened if the path has %20 instead of spaces and so.
        try {
            path = decodeURIComponent(path);
        } catch (ex) {
            // Error, use the original path.
        }

        try {
            await FileOpener.instance.open(path, mimetype);
        } catch (error) {
            this.logger.error('Error opening file ' + path + ' with mimetype ' + mimetype);
            this.logger.error('Error: ', JSON.stringify(error));

            if (!extension || extension.indexOf('/') > -1 || extension.indexOf('\\') > -1) {
                // Extension not found.
                error = Translate.instance.instant('core.erroropenfilenoextension');
            } else {
                error = Translate.instance.instant('core.erroropenfilenoapp');
            }

            throw error;
        }
    }

    /**
     * Open a URL using InAppBrowser.
     * Do not use for files, refer to {@link openFile}.
     *
     * @param url The URL to open.
     * @param options Override default options passed to InAppBrowser.
     * @return The opened window.
     */
    openInApp(url: string, options?: any): InAppBrowserObject {
        if (!url) {
            return;
        }

        options = options || {};
        options.usewkwebview = 'yes'; // Force WKWebView in iOS.

        if (!options.enableViewPortScale) {
            options.enableViewPortScale = 'yes'; // Enable zoom on iOS.
        }

        if (!options.allowInlineMediaPlayback) {
            options.allowInlineMediaPlayback = 'yes'; // Allow playing inline videos in iOS.
        }

        if (!options.location && CoreApp.instance.isIOS() && url.indexOf('file://') === 0) {
            // The URL uses file protocol, don't show it on iOS.
            // In Android we keep it because otherwise we lose the whole toolbar.
            options.location = 'no';
        }

        this.iabInstance = InAppBrowser.instance.create(url, '_blank', options);

        if (CoreApp.instance.isDesktop() || CoreApp.instance.isMobile()) {
            let loadStopSubscription;
            const loadStartUrls = [];

            // Trigger global events when a url is loaded or the window is closed. This is to make it work like in Ionic 1.
            const loadStartSubscription = this.iabInstance.on('loadstart').subscribe((event) => {
                // Execute the callback in the Angular zone, so change detection doesn't stop working.
                this.zone.run(() => {
                    // Store the last loaded URLs (max 10).
                    loadStartUrls.push(event.url);
                    if (loadStartUrls.length > 10) {
                        loadStartUrls.shift();
                    }

                    CoreEvents.instance.trigger(CoreEventsProvider.IAB_LOAD_START, event);
                });
            });

            if (CoreApp.instance.isAndroid()) {
                // Load stop is needed with InAppBrowser v3. Custom URL schemes no longer trigger load start, simulate it.
                loadStopSubscription = this.iabInstance.on('loadstop').subscribe((event) => {
                    // Execute the callback in the Angular zone, so change detection doesn't stop working.
                    this.zone.run(() => {
                        if (loadStartUrls.indexOf(event.url) == -1) {
                            // The URL was stopped but not started, probably a custom URL scheme.
                            CoreEvents.instance.trigger(CoreEventsProvider.IAB_LOAD_START, event);
                        }
                    });
                });
            }

            const exitSubscription = this.iabInstance.on('exit').subscribe((event) => {
                // Execute the callback in the Angular zone, so change detection doesn't stop working.
                this.zone.run(() => {
                    loadStartSubscription.unsubscribe();
                    loadStopSubscription && loadStopSubscription.unsubscribe();
                    exitSubscription.unsubscribe();
                    CoreEvents.instance.trigger(CoreEventsProvider.IAB_EXIT, event);
                });
            });
        }

        return this.iabInstance;
    }

    /**
     * Open a URL using a browser.
     * Do not use for files, refer to {@link openFile}.
     *
     * @param url The URL to open.
     */
    openInBrowser(url: string): void {
        if (CoreApp.instance.isDesktop()) {
            // @todo
        } else {
            window.open(url, '_system');
        }
    }

    /**
     * Open an online file using platform specific method.
     * Specially useful for audio and video since they can be streamed.
     *
     * @param url The URL of the file.
     * @return Promise resolved when opened.
     */
    openOnlineFile(url: string): Promise<void> {
        if (CoreApp.instance.isAndroid()) {
            // In Android we need the mimetype to open it.
            return this.getMimeTypeFromUrl(url).catch(() => {
                // Error getting mimetype, return undefined.
            }).then((mimetype) => {
                if (!mimetype) {
                    // Couldn't retrieve mimetype. Return error.
                    return Promise.reject(Translate.instance.instant('core.erroropenfilenoextension'));
                }

                const options = {
                    action: WebIntent.instance.ACTION_VIEW,
                    url,
                    type: mimetype
                };

                return WebIntent.instance.startActivity(options).catch((error) => {
                    this.logger.error('Error opening online file ' + url + ' with mimetype ' + mimetype);
                    this.logger.error('Error: ', JSON.stringify(error));

                    return Promise.reject(Translate.instance.instant('core.erroropenfilenoapp'));
                });
            });
        }

        // In the rest of platforms we need to open them in InAppBrowser.
        this.openInApp(url);

        return Promise.resolve();
    }

    /**
     * Converts an object into an array, losing the keys.
     *
     * @param obj Object to convert.
     * @return Array with the values of the object but losing the keys.
     */
    objectToArray(obj: object): any[] {
        return Object.keys(obj).map((key) => {
            return obj[key];
        });
    }

    /**
     * Converts an object into an array of objects, where each entry is an object containing
     * the key and value of the original object.
     * For example, it can convert {size: 2} into [{name: 'size', value: 2}].
     *
     * @param obj Object to convert.
     * @param keyName Name of the properties where to store the keys.
     * @param valueName Name of the properties where to store the values.
     * @param sortByKey True to sort keys alphabetically, false otherwise. Has priority over sortByValue.
     * @param sortByValue True to sort values alphabetically, false otherwise.
     * @return Array of objects with the name & value of each property.
     */
    objectToArrayOfObjects(obj: object, keyName: string, valueName: string, sortByKey?: boolean, sortByValue?: boolean): any[] {
        // Get the entries from an object or primitive value.
        const getEntries = (elKey, value): any[] | any => {
            if (typeof value == 'undefined' || value == null) {
                // Filter undefined and null values.
                return;
            } else if (typeof value == 'object') {
                // It's an object, return at least an entry for each property.
                const keys = Object.keys(value);
                let entries = [];

                keys.forEach((key) => {
                    const newElKey = elKey ? elKey + '[' + key + ']' : key;
                    const subEntries = getEntries(newElKey, value[key]);

                    if (subEntries) {
                        entries = entries.concat(subEntries);
                    }
                });

                return entries;
            } else {
                // Not an object, return a single entry.
                const entry = {};
                entry[keyName] = elKey;
                entry[valueName] = value;

                return entry;
            }
        };

        if (!obj) {
            return [];
        }

        // "obj" will always be an object, so "entries" will always be an array.
        const entries = <any[]> getEntries('', obj);
        if (sortByKey || sortByValue) {
            return entries.sort((a, b) => {
                if (sortByKey) {
                    return a[keyName] >= b[keyName] ? 1 : -1;
                } else {
                    return a[valueName] >= b[valueName] ? 1 : -1;
                }
            });
        }

        return entries;
    }

    /**
     * Converts an array of objects into an object with key and value. The opposite of objectToArrayOfObjects.
     * For example, it can convert [{name: 'size', value: 2}] into {size: 2}.
     *
     * @param objects List of objects to convert.
     * @param keyName Name of the properties where the keys are stored.
     * @param valueName Name of the properties where the values are stored.
     * @param keyPrefix Key prefix if neededs to delete it.
     * @return Object.
     */
    objectToKeyValueMap(objects: object[], keyName: string, valueName: string, keyPrefix?: string): {[name: string]: any} {
        if (!objects) {
            return;
        }

        const prefixSubstr = keyPrefix ? keyPrefix.length : 0;
        const mapped = {};
        objects.forEach((item) => {
            const key = prefixSubstr > 0 ? item[keyName].substr(prefixSubstr) : item[keyName];
            mapped[key] = item[valueName];
        });

        return mapped;
    }

    /**
     * Convert an object to a format of GET param. E.g.: {a: 1, b: 2} -> a=1&b=2
     *
     * @param object Object to convert.
     * @param removeEmpty Whether to remove params whose value is null/undefined.
     * @return GET params.
     */
    objectToGetParams(object: any, removeEmpty: boolean = true): string {
        // First of all, flatten the object so all properties are in the first level.
        const flattened = this.flattenObject(object);
        let result = '';
        let joinChar = '';

        for (const name in flattened) {
            let value = flattened[name];

            if (removeEmpty && (value === null || typeof value == 'undefined')) {
                continue;
            }

            if (typeof value == 'boolean') {
                value = value ? 1 : 0;
            }

            result += joinChar + name + '=' + value;
            joinChar = '&';
        }

        return result;
    }

    /**
     * Add a prefix to all the keys in an object.
     *
     * @param data Object.
     * @param prefix Prefix to add.
     * @return Prefixed object.
     */
    prefixKeys(data: any, prefix: string): any {
        const newObj = {};
        const keys = Object.keys(data);

        keys.forEach((key) => {
            newObj[prefix + key] = data[key];
        });

        return newObj;
    }

    /**
     * Similar to AngularJS $q.defer().
     *
     * @return The deferred promise.
     */
    promiseDefer<T>(): PromiseDefer<T> {
        const deferred: PromiseDefer<T> = {};
        deferred.promise = new Promise((resolve, reject): void => {
            deferred.resolve = resolve;
            deferred.reject = reject;
        });

        return deferred;
    }

    /**
     * Given a promise, returns true if it's rejected or false if it's resolved.
     *
     * @param promise Promise to check
     * @return Promise resolved with boolean: true if the promise is rejected or false if it's resolved.
     */
    promiseFails(promise: Promise<any>): Promise<boolean> {
        return promise.then(() => {
            return false;
        }).catch(() => {
            return true;
        });
    }

    /**
     * Given a promise, returns true if it's resolved or false if it's rejected.
     *
     * @param promise Promise to check
     * @return Promise resolved with boolean: true if the promise it's resolved or false if it's rejected.
     */
    promiseWorks(promise: Promise<any>): Promise<boolean> {
        return promise.then(() => {
            return true;
        }).catch(() => {
            return false;
        });
    }

    /**
     * Tests to see whether two arrays or objects have the same value at a particular key.
     * Missing values are replaced by '', and the values are compared with ===.
     * Booleans and numbers are cast to string before comparing.
     *
     * @param obj1 The first object or array.
     * @param obj2 The second object or array.
     * @param key Key to check.
     * @return Whether the two objects/arrays have the same value (or lack of one) for a given key.
     */
    sameAtKeyMissingIsBlank(obj1: any, obj2: any, key: string): boolean {
        let value1 = typeof obj1[key] != 'undefined' ? obj1[key] : '';
        let value2 = typeof obj2[key] != 'undefined' ? obj2[key] : '';

        if (typeof value1 == 'number' || typeof value1 == 'boolean') {
            value1 = '' + value1;
        }
        if (typeof value2 == 'number' || typeof value2 == 'boolean') {
            value2 = '' + value2;
        }

        return value1 === value2;
    }

    /**
     * Stringify an object, sorting the properties. It doesn't sort arrays, only object properties. E.g.:
     * {b: 2, a: 1} -> '{"a":1,"b":2}'
     *
     * @param obj Object to stringify.
     * @return Stringified object.
     */
    sortAndStringify(obj: object): string {
        return JSON.stringify(this.sortProperties(obj));
    }

    /**
     * Given an object, sort its properties and the properties of all the nested objects.
     *
     * @param obj The object to sort. If it isn't an object, the original value will be returned.
     * @return Sorted object.
     */
    sortProperties(obj: object): object {
        if (obj != null && typeof obj == 'object' && !Array.isArray(obj)) {
            // It's an object, sort it.
            return Object.keys(obj).sort().reduce((accumulator, key) => {
                // Always call sort with the value. If it isn't an object, the original value will be returned.
                accumulator[key] = this.sortProperties(obj[key]);

                return accumulator;
            }, {});
        } else {
            return obj;
        }
    }

    /**
     * Given an object, sort its values. Values need to be primitive values, it cannot have subobjects.
     *
     * @param obj The object to sort. If it isn't an object, the original value will be returned.
     * @return Sorted object.
     */
    sortValues(obj: object): object {
        if (typeof obj == 'object' && !Array.isArray(obj)) {
            // It's an object, sort it. Convert it to an array to be able to sort it and then convert it back to object.
            const array = this.objectToArrayOfObjects(obj, 'name', 'value', false, true);

            return this.objectToKeyValueMap(array, 'name', 'value');
        } else {
            return obj;
        }
    }

    /**
     * Sum the filesizes from a list of files checking if the size will be partial or totally calculated.
     *
     * @param files List of files to sum its filesize.
     * @return File size and a boolean to indicate if it is the total size or only partial.
     * @deprecated since 3.8.0. Use CorePluginFileDelegate.getFilesSize instead.
     */
    sumFileSizes(files: any[]): { size: number, total: boolean } {
        const result = {
            size: 0,
            total: true
        };

        files.forEach((file) => {
            if (typeof file.filesize == 'undefined') {
                // We don't have the file size, cannot calculate its total size.
                result.total = false;
            } else {
                result.size += file.filesize;
            }
        });

        return result;
    }

    /**
     * Set a timeout to a Promise. If the time passes before the Promise is resolved or rejected, it will be automatically
     * rejected.
     *
     * @param promise The promise to timeout.
     * @param time Number of milliseconds of the timeout.
     * @return Promise with the timeout.
     */
    timeoutPromise<T>(promise: Promise<T>, time: number): Promise<T> {
        return new Promise((resolve, reject): void => {
            const timeout = setTimeout(() => {
                reject({timeout: true});
            }, time);

            promise.then(resolve).catch(reject).finally(() => {
                clearTimeout(timeout);
            });
        });
    }

    /**
     * Converts locale specific floating point/comma number back to standard PHP float value.
     * Do NOT try to do any math operations before this conversion on any user submitted floats!
     * Based on Moodle's unformat_float function.
     *
     * @param localeFloat Locale aware float representation.
     * @param strict If true, then check the input and return false if it is not a valid number.
     * @return False if bad format, empty string if empty value or the parsed float if not.
     */
    unformatFloat(localeFloat: any, strict?: boolean): any {
        // Bad format on input type number.
        if (typeof localeFloat == 'undefined') {
            return false;
        }

        // Empty (but not zero).
        if (localeFloat == null) {
            return '';
        }

        // Convert float to string.
        localeFloat += '';
        localeFloat = localeFloat.trim();

        if (localeFloat == '') {
            return '';
        }

        localeFloat = localeFloat.replace(' ', ''); // No spaces - those might be used as thousand separators.
        localeFloat = localeFloat.replace(Translate.instance.instant('core.decsep'), '.');

        const parsedFloat = parseFloat(localeFloat);

        // Bad format.
        if (strict && (!isFinite(localeFloat) || isNaN(parsedFloat))) {
            return false;
        }

        return parsedFloat;
    }

    /**
     * Return an array without duplicate values.
     *
     * @param array The array to treat.
     * @param [key] Key of the property that must be unique. If not specified, the whole entry.
     * @return Array without duplicate values.
     */
    uniqueArray(array: any[], key?: string): any[] {
        const filtered = [];
        const unique = {}; // Use an object to make it faster to check if it's duplicate.

        array.forEach((entry) => {
            const value = key ? entry[key] : entry;

            if (!unique[value]) {
                unique[value] = true;
                filtered.push(entry);
            }
        });

        return filtered;
    }

    /**
     * Debounce a function so consecutive calls are ignored until a certain time has passed since the last call.
     *
     * @param context The context to apply to the function.
     * @param fn Function to debounce.
     * @param delay Time that must pass until the function is called.
     * @return Debounced function.
     */
    debounce(fn: (...args: any[]) => any, delay: number): (...args: any[]) => void {

        let timeoutID: number;

        const debounced = (...args: any[]): void => {
            clearTimeout(timeoutID);

            timeoutID = window.setTimeout(() => {
                fn.apply(null, args);
            }, delay);
        };

        return debounced;
    }

    /**
     * Check whether the app can scan QR codes.
     *
     * @return Whether the app can scan QR codes.
     */
    canScanQR(): boolean {
        return CoreApp.instance.isMobile();
    }

    /**
     * Open a modal to scan a QR code.
     *
     * @param title Title of the modal. Defaults to "QR reader".
     * @return Promise resolved with the captured text or undefined if cancelled or error.
     */
    scanQR(title?: string): Promise<string> {
        return new Promise((resolve, reject): void => {
            // @todo
        });
    }

    /**
     * Start scanning for a QR code.
     *
     * @return Promise resolved with the QR string, rejected if error or cancelled.
     */
    startScanQR(): Promise<string> {
        if (!CoreApp.instance.isMobile()) {
            return Promise.reject('QRScanner isn\'t available in desktop apps.');
        }

        // Ask the user for permission to use the camera.
        // The scan method also does this, but since it returns an Observable we wouldn't be able to detect if the user denied.
        return QRScanner.instance.prepare().then((status) => {

            if (!status.authorized) {
                // No access to the camera, reject. In android this shouldn't happen, denying access passes through catch.
                return Promise.reject('The user denied camera access.');
            }

            if (this.qrScanData && this.qrScanData.deferred) {
                // Already scanning.
                return this.qrScanData.deferred.promise;
            }

            // Start scanning.
            this.qrScanData = {
                deferred: this.promiseDefer(),
                observable: QRScanner.instance.scan().subscribe((text) => {

                    // Text received, stop scanning and return the text.
                    this.stopScanQR(text, false);
                })
            };

            // Show the camera.
            return QRScanner.instance.show().then(() => {
                document.body.classList.add('core-scanning-qr');

                return this.qrScanData.deferred.promise;
            }, (err) => {
                this.stopScanQR(err, true);

                return Promise.reject(err);
            });

        }).catch((err) => {
            err.message = err.message || err._message;

            return Promise.reject(err);
        });
    }

    /**
     * Stop scanning for QR code. If no param is provided, the app will consider the user cancelled.
     *
     * @param data If success, the text of the QR code. If error, the error object or message. Undefined for cancelled.
     * @param error True if the data belongs to an error, false otherwise.
     */
    stopScanQR(data?: any, error?: boolean): void {

        if (!this.qrScanData) {
            // Not scanning.
            return;
        }

        // Hide camera preview.
        document.body.classList.remove('core-scanning-qr');
        QRScanner.instance.hide();
        QRScanner.instance.destroy();

        this.qrScanData.observable.unsubscribe(); // Stop scanning.

        if (error) {
            this.qrScanData.deferred.reject(data);
        } else if (typeof data != 'undefined') {
            this.qrScanData.deferred.resolve(data);
        } else {
            this.qrScanData.deferred.reject(CoreDomUtils.instance.createCanceledError());
        }

        delete this.qrScanData;
    }

    /**
     * Ignore errors from a promise.
     *
     * @param promise Promise to ignore errors.
     * @return Promise with ignored errors.
     */
    async ignoreErrors<T>(promise: Promise<T>): Promise<T | undefined> {
        try {
            const result = await promise;

            return result;
        } catch (error) {
            // Ignore errors.
        }
    }

    /**
     * Wait some time.
     *
     * @param milliseconds Number of milliseconds to wait.
     * @return Promise resolved after the time has passed.
     */
    wait(milliseconds: number): Promise<void> {
        return new Promise((resolve, reject): void => {
            setTimeout(resolve, milliseconds);
        });
    }
}

export class CoreUtils extends makeSingleton(CoreUtilsProvider) {}

/**
 * Deferred promise. It's similar to the result of $q.defer() in AngularJS.
 */
export type PromiseDefer<T> = {
    /**
     * The promise.
     */
    promise?: Promise<T>;

    /**
     * Function to resolve the promise.
     *
     * @param value The resolve value.
     */
    resolve?: (value?: T) => void; // Function to resolve the promise.

    /**
     * Function to reject the promise.
     *
     * @param reason The reject param.
     */
    reject?: (reason?: any) => void;
};