// (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 } from '@angular/core';
import { Params } from '@angular/router';
import { Connection } from '@ionic-native/network/ngx';

import { CoreDB } from '@services/db';
import { CoreEvents } from '@singletons/events';
import { CoreUtils, PromiseDefer } from '@services/utils/utils';
import { SQLiteDB, SQLiteDBTableSchema } from '@classes/sqlitedb';

import { makeSingleton, Keyboard, Network, StatusBar, Platform, Device } from '@singletons';
import { CoreLogger } from '@singletons/logger';
import { CoreColors } from '@singletons/colors';
import { DBNAME, SCHEMA_VERSIONS_TABLE_NAME, SCHEMA_VERSIONS_TABLE_SCHEMA, SchemaVersionsDBEntry } from '@services/database/app';
import { CoreNavHelper } from './nav-helper';

/**
 * Object responsible of managing schema versions.
 */
type SchemaVersionsManager = {
    get(schemaName: string): Promise<number>;
    set(schemaName: string, version: number): Promise<void>;
};

/**
 * Factory to provide some global functionalities, like access to the global app database.
 *
 * @description
 * Each service or component should be responsible of creating their own database tables. Example:
 *
 * ```ts
 * constructor(appProvider: CoreAppProvider) {
 *     this.appDB = appProvider.getDB();
 *     this.appDB.createTableFromSchema(this.tableSchema);
 * }
 * ```
 */
@Injectable({ providedIn: 'root' })
export class CoreAppProvider {

    protected db: SQLiteDB;
    protected logger: CoreLogger;
    protected ssoAuthenticationDeferred?: PromiseDefer<void>;
    protected isKeyboardShown = false;
    protected keyboardOpening = false;
    protected keyboardClosing = false;
    protected backActions: {callback: () => boolean; priority: number}[] = [];
    protected forceOffline = false;

    // Variables for DB.
    protected schemaVersionsManager: Promise<SchemaVersionsManager>;
    protected resolveSchemaVersionsManager!: (schemaVersionsManager: SchemaVersionsManager) => void;

    constructor() {
        this.schemaVersionsManager = new Promise(resolve => this.resolveSchemaVersionsManager = resolve);
        this.db = CoreDB.instance.getDB(DBNAME);
        this.logger = CoreLogger.getInstance('CoreAppProvider');

        // @todo
        // this.platform.registerBackButtonAction(() => {
        //     this.backButtonAction();
        // }, 100);
    }

    /**
     * Returns whether the user agent is controlled by automation. I.e. Behat testing.
     *
     * @return True if the user agent is controlled by automation, false otherwise.
     */
    static isAutomated(): boolean {
        return !!navigator.webdriver;
    }

    /**
     * Initialize database.
     */
    async initializeDatabase(): Promise<void> {
        await this.db.createTableFromSchema(SCHEMA_VERSIONS_TABLE_SCHEMA);

        this.resolveSchemaVersionsManager({
            get: async name => {
                try {
                    // Fetch installed version of the schema.
                    const entry = await this.db.getRecord<SchemaVersionsDBEntry>(SCHEMA_VERSIONS_TABLE_NAME, { name });

                    return entry.version;
                } catch (error) {
                    // No installed version yet.
                    return  0;
                }
            },
            set: async (name, version) => {
                await this.db.insertRecord(SCHEMA_VERSIONS_TABLE_NAME, { name, version });
            },
        });
    }

    /**
     * Check if the browser supports mediaDevices.getUserMedia.
     *
     * @return Whether the function is supported.
     */
    canGetUserMedia(): boolean {
        return !!(navigator && navigator.mediaDevices && navigator.mediaDevices.getUserMedia);
    }

    /**
     * Check if the browser supports MediaRecorder.
     *
     * @return Whether the function is supported.
     */
    canRecordMedia(): boolean {
        return !!window.MediaRecorder;
    }

    /**
     * Closes the keyboard.
     */
    closeKeyboard(): void {
        if (this.isMobile()) {
            Keyboard.instance.hide();
        }
    }

    /**
     * Install and upgrade a certain schema.
     *
     * @param schema The schema to create.
     * @return Promise resolved when done.
     */
    async createTablesFromSchema(schema: CoreAppSchema): Promise<void> {
        this.logger.debug(`Apply schema to app DB: ${schema.name}`);

        const schemaVersionsManager = await this.schemaVersionsManager;
        const oldVersion = await schemaVersionsManager.get(schema.name);

        if (oldVersion >= schema.version) {
            // Version already installed, nothing else to do.
            return;
        }

        this.logger.debug(`Migrating schema '${schema.name}' of app DB from version ${oldVersion} to ${schema.version}`);

        if (schema.tables) {
            await this.db.createTablesFromSchema(schema.tables);
        }
        if (schema.migrate) {
            await schema.migrate(this.db, oldVersion);
        }

        // Set installed version.
        schemaVersionsManager.set(schema.name, schema.version);
    }

    /**
     * Get the application global database.
     *
     * @return App's DB.
     */
    getDB(): SQLiteDB {
        return this.db;
    }

    /**
     * Get an ID for a main menu.
     *
     * @return Main menu ID.
     * @deprecated since 3.9.5. Use CoreNavHelperService.getMainMenuId instead.
     */
    getMainMenuId(): number {
        return CoreNavHelper.instance.getMainMenuId();
    }

    /**
     * Get app store URL.
     *
     * @param  storesConfig Config params to send the user to the right place.
     * @return Store URL.
     */
    getAppStoreUrl(storesConfig: CoreStoreConfig): string | undefined {
        if (this.isIOS() && storesConfig.ios) {
            return 'itms-apps://itunes.apple.com/app/' + storesConfig.ios;
        }

        if (this.isAndroid() && storesConfig.android) {
            return 'market://details?id=' + storesConfig.android;
        }

        if (this.isMobile() && storesConfig.mobile) {
            return storesConfig.mobile;
        }

        return storesConfig.default;
    }

    /**
     * Get platform major version number.
     */
    getPlatformMajorVersion(): number {
        if (!this.isMobile()) {
            return 0;
        }

        return Number(Device.instance.version?.split('.')[0]);
    }

    /**
     * Checks if the app is running in a 64 bits desktop environment (not browser).
     *
     * @return false.
     * @deprecated since 3.9.5 Desktop support has been removed.
     */
    is64Bits(): boolean {
        return false;
    }

    /**
     * Checks if the app is running in an Android mobile or tablet device.
     *
     * @return Whether the app is running in an Android mobile or tablet device.
     */
    isAndroid(): boolean {
        return this.isMobile() && Platform.instance.is('android');
    }

    /**
     * Checks if the app is running in a desktop environment (not browser).
     *
     * @return false.
     * @deprecated since 3.9.5 Desktop support has been removed.
     */
    isDesktop(): boolean {
        return false;
    }

    /**
     * Checks if the app is running in an iOS mobile or tablet device.
     *
     * @return Whether the app is running in an iOS mobile or tablet device.
     */
    isIOS(): boolean {
        return this.isMobile() && !Platform.instance.is('android');
    }

    /**
     * Check if the keyboard is closing.
     *
     * @return Whether keyboard is closing (animating).
     */
    isKeyboardClosing(): boolean {
        return this.keyboardClosing;
    }

    /**
     * Check if the keyboard is being opened.
     *
     * @return Whether keyboard is opening (animating).
     */
    isKeyboardOpening(): boolean {
        return this.keyboardOpening;
    }

    /**
     * Check if the keyboard is visible.
     *
     * @return Whether keyboard is visible.
     */
    isKeyboardVisible(): boolean {
        return this.isKeyboardShown;
    }

    /**
     * Check if the app is running in a Linux environment.
     *
     * @return false.
     * @deprecated since 3.9.5 Desktop support has been removed.
     */
    isLinux(): boolean {
        return false;
    }

    /**
     * Check if the app is running in a Mac OS environment.
     *
     * @return false.
     * @deprecated since 3.9.5 Desktop support has been removed.
     */
    isMac(): boolean {
        return false;
    }

    /**
     * Check if the main menu is open.
     *
     * @return Whether the main menu is open.
     * @deprecated since 3.9.5. Use CoreNavHelperService.isMainMenuOpen instead.
     */
    isMainMenuOpen(): boolean {
        return CoreNavHelper.instance.isMainMenuOpen();
    }

    /**
     * Checks if the app is running in a mobile or tablet device (Cordova).
     *
     * @return Whether the app is running in a mobile or tablet device.
     */
    isMobile(): boolean {
        return Platform.instance.is('cordova');
    }

    /**
     * Checks if the current window is wider than a mobile.
     *
     * @return Whether the app the current window is wider than a mobile.
     */
    isWide(): boolean {
        return Platform.instance.width() > 768;
    }

    /**
     * Returns whether we are online.
     *
     * @return Whether the app is online.
     */
    isOnline(): boolean {
        if (this.forceOffline) {
            return false;
        }

        let online = Network.instance.type !== null && Number(Network.instance.type) != Connection.NONE &&
            Number(Network.instance.type) != Connection.UNKNOWN;
        // Double check we are not online because we cannot rely 100% in Cordova APIs. Also, check it in browser.
        if (!online && navigator.onLine) {
            online = true;
        }

        return online;
    }

    /**
     * Check if device uses a limited connection.
     *
     * @return Whether the device uses a limited connection.
     */
    isNetworkAccessLimited(): boolean {
        const type = Network.instance.type;
        if (type === null) {
            // Plugin not defined, probably in browser.
            return false;
        }

        const limited = [Connection.CELL_2G, Connection.CELL_3G, Connection.CELL_4G, Connection.CELL];

        return limited.indexOf(Number(type)) > -1;
    }

    /**
     * Check if device uses a wifi connection.
     *
     * @return Whether the device uses a wifi connection.
     */
    isWifi(): boolean {
        return this.isOnline() && !this.isNetworkAccessLimited();
    }

    /**
     * Check if the app is running in a Windows environment.
     *
     * @return false.
     * @deprecated since 3.9.5 Desktop support has been removed.
     */
    isWindows(): boolean {
        return false;
    }

    /**
     * Open the keyboard.
     */
    openKeyboard(): void {
        // Open keyboard is not supported in desktop and in iOS.
        if (this.isAndroid()) {
            Keyboard.instance.show();
        }
    }

    /**
     * Notify that Keyboard has been shown.
     *
     * @param keyboardHeight Keyboard height.
     */
    onKeyboardShow(keyboardHeight: number): void {
        document.body.classList.add('keyboard-is-open');
        this.setKeyboardShown(true);
        // Error on iOS calculating size.
        // More info: https://github.com/ionic-team/ionic-plugin-keyboard/issues/276 .
        CoreEvents.trigger(CoreEvents.KEYBOARD_CHANGE, keyboardHeight);
    }

    /**
     * Notify that Keyboard has been hidden.
     */
    onKeyboardHide(): void {
        document.body.classList.remove('keyboard-is-open');
        this.setKeyboardShown(false);
        CoreEvents.trigger(CoreEvents.KEYBOARD_CHANGE, 0);
    }

    /**
     * Notify that Keyboard is about to be shown.
     */
    onKeyboardWillShow(): void {
        this.keyboardOpening = true;
        this.keyboardClosing = false;
    }

    /**
     * Notify that Keyboard is about to be hidden.
     */
    onKeyboardWillHide(): void {
        this.keyboardOpening = false;
        this.keyboardClosing = true;
    }

    /**
     * Set keyboard shown or hidden.
     *
     * @param Whether the keyboard is shown or hidden.
     */
    protected setKeyboardShown(shown: boolean): void {
        this.isKeyboardShown = shown;
        this.keyboardOpening = false;
        this.keyboardClosing = false;
    }

    /**
     * Set a main menu as open or not.
     *
     * @param id Main menu ID.
     * @param open Whether it's open or not.
     * @deprecated since 3.9.5. Use CoreNavHelperService.setMainMenuOpen instead.
     */
    setMainMenuOpen(id: number, open: boolean): void {
        CoreNavHelper.instance.setMainMenuOpen(id, open);
    }

    /**
     * Start an SSO authentication process.
     * Please notice that this function should be called when the app receives the new token from the browser,
     * NOT when the browser is opened.
     */
    startSSOAuthentication(): void {
        this.ssoAuthenticationDeferred = CoreUtils.instance.promiseDefer<void>();

        // Resolve it automatically after 10 seconds (it should never take that long).
        const cancelTimeout = setTimeout(() => this.finishSSOAuthentication(), 10000);

        // If the promise is resolved because finishSSOAuthentication is called, stop the cancel promise.
        // eslint-disable-next-line promise/catch-or-return
        this.ssoAuthenticationDeferred.promise.then(() => clearTimeout(cancelTimeout));
    }

    /**
     * Finish an SSO authentication process.
     */
    finishSSOAuthentication(): void {
        if (this.ssoAuthenticationDeferred) {
            this.ssoAuthenticationDeferred.resolve();
            this.ssoAuthenticationDeferred = undefined;
        }
    }

    /**
     * Check if there's an ongoing SSO authentication process.
     *
     * @return Whether there's a SSO authentication ongoing.
     */
    isSSOAuthenticationOngoing(): boolean {
        return !!this.ssoAuthenticationDeferred;
    }

    /**
     * Returns a promise that will be resolved once SSO authentication finishes.
     *
     * @return Promise resolved once SSO authentication finishes.
     */
    async waitForSSOAuthentication(): Promise<void> {
        const promise = this.ssoAuthenticationDeferred?.promise;

        await promise;
    }

    /**
     * Wait until the application is resumed.
     *
     * @param timeout Maximum time to wait, use null to wait forever.
     */
    async waitForResume(timeout: number | null = null): Promise<void> {
        let deferred: PromiseDefer<void> | null = CoreUtils.instance.promiseDefer<void>();

        const stopWaiting = () => {
            if (!deferred) {
                return;
            }

            deferred.resolve();
            resumeSubscription.unsubscribe();
            timeoutId && clearTimeout(timeoutId);

            deferred = null;
        };

        const resumeSubscription = Platform.instance.resume.subscribe(stopWaiting);
        const timeoutId = timeout ? setTimeout(stopWaiting, timeout) : false;

        await deferred.promise;
    }

    /**
     * Retrieve redirect data.
     *
     * @return Object with siteid, state, params and timemodified.
     */
    getRedirect(): CoreRedirectData {
        if (localStorage?.getItem) {
            try {
                const paramsJson = localStorage.getItem('CoreRedirectParams');
                const data: CoreRedirectData = {
                    siteId: localStorage.getItem('CoreRedirectSiteId') || undefined,
                    page: localStorage.getItem('CoreRedirectState')  || undefined,
                    timemodified: parseInt(localStorage.getItem('CoreRedirectTime') || '0', 10),
                };

                if (paramsJson) {
                    data.params = JSON.parse(paramsJson);
                }

                return data;
            } catch (ex) {
                this.logger.error('Error loading redirect data:', ex);
            }
        }

        return {};
    }

    /**
     * Store redirect params.
     *
     * @param siteId Site ID.
     * @param page Page to go.
     * @param params Page params.
     */
    storeRedirect(siteId: string, page: string, params: Params): void {
        if (localStorage && localStorage.setItem) {
            try {
                localStorage.setItem('CoreRedirectSiteId', siteId);
                localStorage.setItem('CoreRedirectState', page);
                localStorage.setItem('CoreRedirectParams', JSON.stringify(params));
                localStorage.setItem('CoreRedirectTime', String(Date.now()));
            } catch (ex) {
                // Ignore errors.
            }
        }
    }

    /**
     * The back button event is triggered when the user presses the native
     * platform's back button, also referred to as the "hardware" back button.
     * This event is only used within Cordova apps running on Android and
     * Windows platforms. This event is not fired on iOS since iOS doesn't come
     * with a hardware back button in the same sense an Android or Windows device
     * does.
     *
     * Registering a hardware back button action and setting a priority allows
     * apps to control which action should be called when the hardware back
     * button is pressed. This method decides which of the registered back button
     * actions has the highest priority and should be called.
     *
     * @param callback Called when the back button is pressed, if this registered action has the highest priority.
     * @param priority Set the priority for this action. All actions sorted by priority will be executed since one of
     *                 them returns true.
     *                 - Priorities higher or equal than 1000 will go before closing modals
     *                 - Priorities lower than 500 will only be executed if you are in the first state of the app (before exit).
     * @return A function that, when called, will unregister the back button action.
     */
    registerBackButtonAction(callback: () => boolean, priority: number = 0): () => boolean {
        const action = { callback, priority };

        this.backActions.push(action);

        this.backActions.sort((a, b) => b.priority - a.priority);

        return (): boolean => {
            const index = this.backActions.indexOf(action);

            return index >= 0 && !!this.backActions.splice(index, 1);
        };
    }

    /**
     * Set StatusBar color depending on platform.
     *
     * @param color RGB color to use as status bar background. If not set the css variable will be read.
     */
    setStatusBarColor(color?: string): void {
        if (!color) {
            // Get the default color to reset it.
            color = getComputedStyle(document.documentElement).getPropertyValue('--ion-statusbar-background').trim();
        }

        // Make darker on Android.
        if (this.isAndroid()) {
            color = CoreColors.darker(color);
        }

        const useLightText = CoreColors.isWhiteContrastingBetter(color);
        const statusBar = StatusBar.instance;
        statusBar.backgroundColorByHexString(color);
        useLightText ? statusBar.styleLightContent() : statusBar.styleDefault();

        this.isIOS() && statusBar.overlaysWebView(false);
    }

    /**
     * Reset StatusBar color if any was set.
     *
     * @deprecated Use setStatusBarColor passing the color of the new statusbar color loaded on remote theme or no color to reset.
     */
    resetStatusBarColor(): void {
        this.setStatusBarColor();
    }

    /**
     * Set value of forceOffline flag. If true, the app will think the device is offline.
     *
     * @param value Value to set.
     */
    setForceOffline(value: boolean): void {
        this.forceOffline = !!value;
    }

}

export class CoreApp extends makeSingleton(CoreAppProvider) {}

/**
 * Data stored for a redirect to another page/site.
 */
export type CoreRedirectData = {
    /**
     * ID of the site to load.
     */
    siteId?: string;

    /**
     * Name of the page to redirect to.
     */
    page?: string;

    /**
     * Params to pass to the page.
     */
    params?: Params;

    /**
     * Timestamp when this redirect was last modified.
     */
    timemodified?: number;
};

/**
 * Store config data.
 */
export type CoreStoreConfig = {
    /**
     * ID of the Apple store where the mobile iOS app is uploaded.
     */
    ios?: string;

    /**
     * ID of the Google play store where the android app is uploaded.
     */
    android?: string;

    /**
     * Fallback URL when the mobile options is not set.
     */
    mobile?: string;

    /**
     * Fallback URL when the other fallbacks options are not set.
     */
    default?: string;
};

/**
 * App DB schema and migration function.
 */
export type CoreAppSchema = {
    /**
     * Name of the schema.
     */
    name: string;

    /**
     * Latest version of the schema (integer greater than 0).
     */
    version: number;

    /**
     * Tables to create when installing or upgrading the schema.
     */
    tables?: SQLiteDBTableSchema[];

    /**
     * Migrates the schema to the latest version.
     *
     * Called when installing and upgrading the schema, after creating the defined tables.
     *
     * @param db The affected DB.
     * @param oldVersion Old version of the schema or 0 if not installed.
     * @return Promise resolved when done.
     */
    migrate?(db: SQLiteDB, oldVersion: number): Promise<void>;
};