import {
  Component,
  Input,
  OnDestroy,
  OnInit,
  ViewEncapsulation
} from '@angular/core';
import { interval, Subject } from 'rxjs';
import { map, takeUntil } from 'rxjs/operators';
import * as moment from 'moment';

@Component({
  selector: 'fuse-countdown',
  templateUrl: './countdown.component.html',
  styleUrls: ['./countdown.component.scss'],
  encapsulation: ViewEncapsulation.None
})
export class FuseCountdownComponent implements OnInit, OnDestroy {
  // Event date
  @Input('eventDate')
  eventDate;

  countdown: any;

  // Private
  private _unsubscribeAll: Subject<any>;

  /**
   * Constructor
   */
  constructor() {
    // Set the defaults
    this.countdown = {
      days: '',
      hours: '',
      minutes: '',
      seconds: ''
    };

    // Set the private defaults
    this._unsubscribeAll = new Subject();
  }

  // -----------------------------------------------------------------------------------------------------
  // @ Lifecycle hooks
  // -----------------------------------------------------------------------------------------------------

  /**
   * On init
   */
  ngOnInit(): void {
    const currDate = moment();
    const eventDate = moment(this.eventDate);

    // Get the difference in between the current date and event date in seconds
    let diff = eventDate.diff(currDate, 'seconds');

    // Calculate the remaining time for the first time so there will be no
    // delay on the countdown
    this.countdown = this._secondsToRemaining(diff);

    // Create a subscribable interval
    const countDown = interval(1000).pipe(
      map(value => {
        return (diff = diff - 1);
      }),
      map(value => {
        return this._secondsToRemaining(value);
      })
    );

    // Subscribe to the countdown interval
    countDown.pipe(takeUntil(this._unsubscribeAll)).subscribe(value => {
      this.countdown = value;
    });
  }

  /**
   * On destroy
   */
  ngOnDestroy(): void {
    // Unsubscribe from all subscriptions
    this._unsubscribeAll.next();
    this._unsubscribeAll.complete();
  }

  // -----------------------------------------------------------------------------------------------------
  // @ Private methods
  // -----------------------------------------------------------------------------------------------------

  /**
   * Converts given seconds to a remaining time
   *
   * @param seconds
   * @private
   */
  private _secondsToRemaining(seconds): any {
    const timeLeft = moment.duration(seconds, 'seconds');

    return {
      days: timeLeft.asDays().toFixed(0),
      hours: timeLeft.hours(),
      minutes: timeLeft.minutes(),
      seconds: timeLeft.seconds()
    };
  }
}