/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import {AnimationEvent} from '@angular/animations';
import {
  BasePortalOutlet,
  CdkPortalOutlet,
  ComponentPortal,
  TemplatePortal,
} from '@angular/cdk/portal';
import {
  ChangeDetectionStrategy,
  ChangeDetectorRef,
  Component,
  ComponentRef,
  ElementRef,
  EmbeddedViewRef,
  NgZone,
  OnDestroy,
  ViewChild,
  ViewEncapsulation,
} from '@angular/core';
import {Observable, Subject} from 'rxjs';
import {take} from 'rxjs/operators';
import {matSnackBarAnimations} from './snack-bar-animations';
import {MatSnackBarConfig} from './snack-bar-config';


/**
 * Internal component that wraps user-provided snack bar content.
 * @docs-private
 */
@Component({
  moduleId: module.id,
  selector: 'snack-bar-container',
  templateUrl: 'snack-bar-container.html',
  styleUrls: ['snack-bar-container.css'],
  // In Ivy embedded views will be change detected from their declaration place, rather than
  // where they were stamped out. This means that we can't have the snack bar container be OnPush,
  // because it might cause snack bars that were opened from a template not to be out of date.
  // tslint:disable-next-line:validate-decorators
  changeDetection: ChangeDetectionStrategy.Default,
  encapsulation: ViewEncapsulation.None,
  animations: [matSnackBarAnimations.snackBarState],
  host: {
    '[attr.role]': '_role',
    'class': 'mat-snack-bar-container',
    '[@state]': '_animationState',
    '(@state.done)': 'onAnimationEnd($event)'
  },
})
export class MatSnackBarContainer extends BasePortalOutlet implements OnDestroy {
  /** Whether the component has been destroyed. */
  private _destroyed = false;

  /** The portal outlet inside of this container into which the snack bar content will be loaded. */
  @ViewChild(CdkPortalOutlet, {static: true}) _portalOutlet: CdkPortalOutlet;

  /** Subject for notifying that the snack bar has exited from view. */
  readonly _onExit: Subject<any> = new Subject();

  /** Subject for notifying that the snack bar has finished entering the view. */
  readonly _onEnter: Subject<any> = new Subject();

  /** The state of the snack bar animations. */
  _animationState = 'void';

  /** ARIA role for the snack bar container. */
  _role: 'alert' | 'status' | null;

  constructor(
    private _ngZone: NgZone,
    private _elementRef: ElementRef<HTMLElement>,
    private _changeDetectorRef: ChangeDetectorRef,
    /** The snack bar configuration. */
    public snackBarConfig: MatSnackBarConfig) {

    super();

    // Based on the ARIA spec, `alert` and `status` roles have an
    // implicit `assertive` and `polite` politeness respectively.
    if (snackBarConfig.politeness === 'assertive' && !snackBarConfig.announcementMessage) {
      this._role = 'alert';
    } else if (snackBarConfig.politeness === 'off') {
      this._role = null;
    } else {
      this._role = 'status';
    }
  }

  /** Attach a component portal as content to this snack bar container. */
  attachComponentPortal<T>(portal: ComponentPortal<T>): ComponentRef<T> {
    this._assertNotAttached();
    this._applySnackBarClasses();
    return this._portalOutlet.attachComponentPortal(portal);
  }

  /** Attach a template portal as content to this snack bar container. */
  attachTemplatePortal<C>(portal: TemplatePortal<C>): EmbeddedViewRef<C> {
    this._assertNotAttached();
    this._applySnackBarClasses();
    return this._portalOutlet.attachTemplatePortal(portal);
  }

  /** Handle end of animations, updating the state of the snackbar. */
  onAnimationEnd(event: AnimationEvent) {
    const {fromState, toState} = event;

    if ((toState === 'void' && fromState !== 'void') || toState === 'hidden') {
      this._completeExit();
    }

    if (toState === 'visible') {
      // Note: we shouldn't use `this` inside the zone callback,
      // because it can cause a memory leak.
      const onEnter = this._onEnter;

      this._ngZone.run(() => {
        onEnter.next();
        onEnter.complete();
      });
    }
  }

  /** Begin animation of snack bar entrance into view. */
  enter(): void {
    if (!this._destroyed) {
      this._animationState = 'visible';
      this._changeDetectorRef.detectChanges();
    }
  }

  /** Begin animation of the snack bar exiting from view. */
  exit(): Observable<void> {
    // Note: this one transitions to `hidden`, rather than `void`, in order to handle the case
    // where multiple snack bars are opened in quick succession (e.g. two consecutive calls to
    // `MatSnackBar.open`).
    this._animationState = 'hidden';
    return this._onExit;
  }

  /** Makes sure the exit callbacks have been invoked when the element is destroyed. */
  ngOnDestroy() {
    this._destroyed = true;
    this._completeExit();
  }

  /**
   * Waits for the zone to settle before removing the element. Helps prevent
   * errors where we end up removing an element which is in the middle of an animation.
   */
  private _completeExit() {
    this._ngZone.onMicrotaskEmpty.asObservable().pipe(take(1)).subscribe(() => {
      this._onExit.next();
      this._onExit.complete();
    });
  }

  /** Applies the various positioning and user-configured CSS classes to the snack bar. */
  private _applySnackBarClasses() {
    const element: HTMLElement = this._elementRef.nativeElement;
    const panelClasses = this.snackBarConfig.panelClass;

    if (panelClasses) {
      if (Array.isArray(panelClasses)) {
        // Note that we can't use a spread here, because IE doesn't support multiple arguments.
        panelClasses.forEach(cssClass => element.classList.add(cssClass));
      } else {
        element.classList.add(panelClasses);
      }
    }

    if (this.snackBarConfig.horizontalPosition === 'center') {
      element.classList.add('mat-snack-bar-center');
    }

    if (this.snackBarConfig.verticalPosition === 'top') {
      element.classList.add('mat-snack-bar-top');
    }
  }

  /** Asserts that no content is already attached to the container. */
  private _assertNotAttached() {
    if (this._portalOutlet.hasAttached()) {
      throw Error('Attempting to attach snack bar content after content is already attached');
    }
  }
}