import { Injectable, NgZone, OnDestroy } from '@angular/core';
import { BehaviorSubject, fromEvent, Subject, Subscription } from 'rxjs';
import { map, share, tap } from 'rxjs/operators';
import { gadgets } from '@reveldigital/gadget-types';


// So that TypeScript doesn't complain, we're going to augment the GLOBAL / WINDOW 
// name-space definition to include the Tracker API. This also provides us with a place
// to actually DOCUMENT the API so that our developers aren't guessing about what's
// available on the library.

/** @ignore */
declare global {
  var Client: Client;
}

/** @ignore */
export interface Client {

  callback(...args: any[]): void;

  getDeviceTime(date?: Date): Promise<string>;

  getDeviceTimeZoneName(): Promise<string>;

  getDeviceTimeZoneID(): Promise<string>;

  getDeviceTimeZoneOffset(): Promise<number>;

  getLanguageCode(): Promise<string>;

  getDeviceKey(): Promise<string>;

  sendCommand(name: string, arg: string): void;

  sendRemoteCommand(deviceKeys: string[], name: string, arg: string): void;

  track(eventName: string, properties?: string): void;

  timeEvent(eventName: string): void;

  newEventSession(id?: string): void;

  getRevelRoot(): Promise<string>;

  getCommandMap(): Promise<string>;

  finish(): void;
}

export interface EventProperties {
  [key: string]: any;
}

export interface Command {
  name: string;
  arg: string;
}

@Injectable({
  providedIn: 'root'
})
export class PlayerClientService implements OnDestroy {

  /** @ignore */
  private clientPromise: Promise<Client> | null;

  /**
   * Commands sent to this player.
   */
  public onCommand$ = new Subject<Command>();
  /**
   * Signals the gadget has been loaded and is ready to start.
   */
  public onReady$ = new BehaviorSubject(false);
  /**
   * Signals the gadget has been started by the player.
   */
  public onStart$ = new Subject();
  /**
   * Signals the gadgets has been stopped by the player.
   */
  public onStop$ = new Subject();

  //
  // Two methods available for calling into the library:
  //
  // 1) Using dispatchEvent() with the following custom events
  // 2) Using the window scoped RevelDigital object as defined in the constructor
  //
  /** @ignore */
  private onStartSub: Subscription;
  /** @ignore */
  private onStartEvt$ = fromEvent(document, 'RevelDigital.Start').pipe(
    share(),
    tap(this.onStart$)
  );
  /** @ignore */
  private onStopSub: Subscription;
  /** @ignore */
  private onStopEvt$ = fromEvent(document, 'RevelDigital.Stop').pipe(
    share(),
    tap(this.onStop$)
  );
  /** @ignore */
  private onCommandSub: Subscription;
  /** @ignore */
  private onCommandEvt$ = fromEvent<Command>(document, 'RevelDigital.Command').pipe(
    map((e: any) => { return { name: e.detail.name, arg: e.detail.arg } as Command }),
    share(),
    tap(this.onCommand$)
  );

  // private onPostMessageSub: Subscription;
  // private onPostMessageEvt$ = fromEvent(window, 'message').pipe(
  //   filter((messageEvent: MessageEvent) =>
  //     messageEvent.source !== window.parent &&
  //     typeof messageEvent.data === 'string' &&
  //     messageEvent.data.startsWith('reveldigital:')),
  //   map((e: any) => { return JSON.parse(e.substring(13)) as Command }),
  //   share(),
  //   tap(this.onCommand$)
  // );

  /** @ignore */
  constructor(zone: NgZone) {

    let self = this;
    (window as any).RevelDigital = {
      Controller: {
        onCommand: function (name: string, arg: string) {
          zone.run(() => {
            self.onCommand$.next({ name: name, arg: arg });
          });
        },
        onStart: function () {
          zone.run(() => {
            self.onStart$.next(null);
          });
        },
        onStop: function () {
          zone.run(() => {
            self.onStop$.next(null);
          });
        }
      }
    }

    this.onStartSub = this.onStartEvt$.subscribe(() => { });
    this.onStopSub = this.onStopEvt$.subscribe(() => { });
    this.onCommandSub = this.onCommandEvt$.subscribe(() => { });

    this.clientPromise = null;

    this.onReady$.next(true);
  }

  /** @ignore */
  ngOnDestroy(): void {

    this.onStartSub?.unsubscribe();
    this.onStopSub?.unsubscribe();
    this.onCommandSub?.unsubscribe();

    this.onReady$.next(false);
  }

  /** @ignore */
  public static init(data: any) {

    console.log(
      '%c⚙️ Initializing Revel Digital client library',
      'background-color:blue; color:yellow;'
    );
  }

  /**
   * This method allows the gadget to communicate with player scripting.
   * If the appropriate scripting is in place in the currently running template, calling this method
   * will initiate a callback which can be acted upon in player script.
   * 
   * @example
   * client.callback('test', 'this');
   * 
   * @param args variable number of arguments
   */
  public callback(...args: any[]): void {

    this.getClient().then((client) => {

      switch (args.length) {
        case 0:
          client.callback();
          break;
        case 1:
          client.callback(args[0]);
          break;
        case 2:
          client.callback(args[1]);
          break;
        case 3:
          client.callback(args[2]);
          break;
        case 4:
          client.callback(args[3]);
          break;
        case 5:
          client.callback(args[4]);
          break;
      }
    })
  }

  /**
   * Accessor method for the user preferences interface exposed by the Gadgets API.
   * 
   * See {@link https://developers.google.com/gadgets/docs/basic} for more details on the Gadgets API.
   * 
   * @example
   * constructor(public client: PlayerClientService) {
   *            let prefs = client.getPrefs();
   *            let myString = prefs.getString('myStringPref');
   * }
   * @returns {gadgets.Prefs} Gadget API Prefs object
   */
  public getPrefs(): gadgets.Prefs {

    return new window['gadgets']['Prefs']();
  }

  /**
   * Returns the current device time in ISO8601 format.
   * Current device time is determined by the device timezone assigned to the device in the CMS.
   * 
   * @param date Optional. If supplied will translate the supplied date/time to device time based on respective timezones.
   * @returns Date/time in ISO8601 format
   */
  public async getDeviceTime(date?: Date): Promise<string> {

    const client = await this.getClient();

    if (date !== undefined) {
      return client.getDeviceTime(date);
    }
    return client.getDeviceTime();
  }

  /**
   * Returns the timezone name currently assigned to the device.
   * 
   * @returns Timezone Name
   */
  public async getDeviceTimeZoneName(): Promise<string> {

    const client = await this.getClient();

    return client.getDeviceTimeZoneName();
  }

  /**
   * Returns the timezone ID currently assigned to the device.
   * 
   * @returns Timezone ID
   */
  public async getDeviceTimeZoneID(): Promise<string> {

    const client = await this.getClient();

    return client.getDeviceTimeZoneID();
  }

  /**
   * Returns the numerical offset from GMT of the timezone currently assigned to the device.
   * 
   * @returns Timezone offset
   */
  public async getDeviceTimeZoneOffset(): Promise<number> {

    const client = await this.getClient();

    return client.getDeviceTimeZoneOffset();
  }

  /**
   * Returns the language code of the language currently assigned to the device.
   * 
   * @returns Language code
   */
  public async getLanguageCode(): Promise<string> {

    const client = await this.getClient();

    return client.getLanguageCode();
  }

  /**
   * Returns the unique Revel Digital device key associated with the device.
   * 
   * @returns Device key
   */
  public async getDeviceKey(): Promise<string> {

    const client = await this.getClient();

    return client.getDeviceKey();
  }

  /**
   * Send a command to the player device.
   * 
   * @param name Command name
   * @param arg Command argument
   */
  public sendCommand(name: string, arg: string): void {

    this.getClient().then((client) => {
      client.sendCommand(name, arg);
    })
  }

  /**
   * Send a command to any remote player with the supplied device key(s).
   * Note: Remote commands can only be delivered to devices within the same account as the sender device.
   * 
   * @param deviceKeys Array of remote device keys
   * @param name Command name
   * @param arg Command arg
   */
  public sendRemoteCommand(deviceKeys: string[], name: string, arg: string): void {

    this.getClient().then((client) => {
      client.sendRemoteCommand(deviceKeys, name, arg);
    });
  }

  /**
   * Log an event for use with AdHawk analytics.
   * Events are used for tracking various metrics including usage statistics, player condition, state changes, etc.
   * 
   * @param eventName Unique name for this event
   * @param properties A map of user defined properties to associate with this event
   */
  public track(eventName: string, properties?: EventProperties): void {

    this.getClient().then((client) => {
      client.track(eventName, JSON.stringify(properties));
    })
  }

  /**
   * Method for initiating a timed event.
   * Timed events are useful for tracking the duration of an event and must be proceeded with a call to track().
   * 
   * @example
   * client.timeEvent('testEvent');
   * client.track("test", { "a": "b" });
   * @param eventName Unique name for this event
   */
  public timeEvent(eventName: string): void {

    this.getClient().then((client) => {
      client.timeEvent(eventName);
    })
  }

  /**
   * A session is a way of grouping events together. Each event has an associated session ID.
   * Session ID's are randomly generated and reset by subsequent calls to newEventSession().
   * 
   * Each call to track() will utilize the same session ID, until another call to newEventSession().
   * @param id Optional. User supplied session ID. If not supplied a random session ID will be generated.
   */
  public newEventSession(id?: string): void {

    this.getClient().then((client) => {
      if (id !== undefined) {
        client.newEventSession();
      } else {
        client.newEventSession(id);
      }
    })
  }

  /**
   * Returns the root folder utilized by this player device.
   * 
   * @returns Path to the root folder
   */
  public async getRevelRoot(): Promise<string> {

    const client = await this.getClient();

    return client.getRevelRoot();
  }

  /**
   * Returns a map of commands currently active for this device.
   * 
   * @returns Map of commands currently active for this device.
   */
  public async getCommandMap(): Promise<any> {

    const client = await this.getClient();

    return JSON.parse(await client.getCommandMap());
  }

  /**
   * Indicate to the player that this gadget has finished it's visualization.
   * This allows the player to proceed with the next item in a playlist if applicable.
   */
  public finish(): void {

    this.getClient().then((client) => {

      client.finish();
    })
  }

  /**
   * Check is the gadget is running in preview mode. Preview mode is enabled when the gadget is
   * being edited in the CMS, or otherwise not running in a normal player environment.
   * 
   * @returns True if the gadget is running in preview mode, false otherwise.
   */
  public async isPreviewMode(): Promise<boolean> {

    const client = await this.getClient();

    return client instanceof NoopClient;
  }

    
  // ---
  // PRIVATE METHODS.
  // ---
  /** @ignore */
  private getClient(): Promise<Client> {

    if (this.clientPromise) {

      return (this.clientPromise);
    }

    if (window.Client) {

      return (this.clientPromise = Promise.resolve(window.Client));
    }

    // A "complete" status indicates that the "load" event has been fired on the
    // window; and, that all sub-resources such as Scripts, Images, and Frames have
    // been loaded.
    if (window.document.readyState === "complete") {

      // If this event has fired AND the 3rd-party script isn't available (see IF-
      // condition BEFORE this one), it means that the 3rd-party script either
      // failed on the network or was BLOCKED by an ad-blocker. As such, we have to
      // fall-back to using a mock API.
      return (this.clientPromise = Promise.resolve(new NoopClient()));
    }

    // ASSERT: If we made it this far, the document has not completed loading (but it
    // may be in an "interactive" state which is when I believe that the Angular app
    // gets bootstrapped). As such, we need bind to the LOAD event to wait for our
    // third-party scripts to load (or fail to load, or be blocked).
    this.clientPromise = new Promise<Client>(
      (resolve) => {

        window.addEventListener(
          "load",
          function handleWindowLoad() {

            // At this point, the 3rd-party library is either available or
            // it's not - there's no further loading to do. If it's not
            // present on the global scope, we're going to fall-back to using
            // a mock API.
            resolve(window.Client || new NoopClient());
          }
        );

      }
    );

    return (this.clientPromise);
  }

}



// ----------------------------------------------------------------------------------- //
// ----------------------------------------------------------------------------------- //

// I provide a mock API for the 3rd-party script. This just allows the consuming code to
// act as though the library is available even if it failed to load (example, it was
// blocked by an ad-blocker).

/** @ignore */
class NoopClient implements Client {

  constructor() {

    console.log(
      '%cClient API not available, falling back to mock API',
      'background-color:blue; color:yellow;'
    );
  }

  public callback(...args: any[]): void {

    // NOOP implement, nothing to do....
  }

  public getDeviceTime(date?: Date): Promise<string> {

    return Promise.resolve(new Date().toISOString());
  }

  public async getDeviceTimeZoneName(): Promise<string> {

    return Promise.resolve(null);
  }

  public async getDeviceTimeZoneID(): Promise<string> {

    return Promise.resolve(null);
  }

  public async getDeviceTimeZoneOffset(): Promise<number> {

    return Promise.resolve(null);
  }

  public async getLanguageCode(): Promise<string> {

    return Promise.resolve(null);
  }

  public async getDeviceKey(): Promise<string> {

    return Promise.resolve(null);
  }

  public sendCommand(name: string, arg: string): void {

    // NOOP implement, nothing to do....
  }

  public sendRemoteCommand(deviceKeys: string[], name: string, arg: string) {

    // NOOP implement, nothing to do....
  }

  public track(eventName: string, properties?: string): void {

    // NOOP implement, nothing to do....
  }

  public timeEvent(eventName: string): void {

    // NOOP implement, nothing to do....
  }

  public newEventSession(id?: string): void {

    // NOOP implement, nothing to do....
  }

  public async getRevelRoot(): Promise<string> {

    return Promise.resolve(null);
  }

  public async getCommandMap(): Promise<string> {

    return Promise.resolve('{}');
  }

  public finish(): void {

    // NOOP implement, nothing to do....
  }
}