import {
  Component,
  Directive,
  Input,
  Output,
  EventEmitter,
  ChangeDetectionStrategy,
  OnInit,
  OnDestroy,
  Injector,
  Renderer2,
  ComponentRef,
  ElementRef,
  TemplateRef,
  ViewContainerRef,
  ComponentFactoryResolver,
  NgZone
} from '@angular/core';

import {listenToTriggers} from '../util/triggers';
import {positionElements} from '../util/positioning';
import {PopupService} from '../util/popup';
import {Ng2vPopoverConfig} from './popover-config';

let nextId = 0;

@Component({
  selector: 'ng2v-popover-window',
  changeDetection: ChangeDetectionStrategy.OnPush,
  host: {'[class]': '"popover show popover-" + placement', 'role': 'tooltip', '[id]': 'id'},
  template: `
    <h3 class="popover-title">{{title}}</h3><div class="popover-content"><ng-content></ng-content></div>
    `
})
export class Ng2vPopoverWindow {
  @Input() placement: 'top' | 'bottom' | 'left' | 'right' = 'top';
  @Input() title: string;
  @Input() id: string;
}

/**
 * A lightweight, extensible directive for fancy popover creation.
 */
@Directive({selector: '[ng2vPopover]', exportAs: 'ng2vPopover'})
export class Ng2vPopover implements OnInit, OnDestroy {
  /**
   * Content to be displayed as popover.
   */
  @Input() ng2vPopover: string | TemplateRef<any>;
  /**
   * Title of a popover.
   */
  @Input() popoverTitle: string;
  /**
   * Placement of a popover. Accepts: "top", "bottom", "left", "right"
   */
  @Input() placement: 'top' | 'bottom' | 'left' | 'right';
  /**
   * Specifies events that should trigger. Supports a space separated list of event names.
   */
  @Input() triggers: string;
  /**
   * A selector specifying the element the popover should be appended to.
   * Currently only supports "body".
   */
  @Input() container: string;
  /**
   * Emits an event when the popover is shown
   */
  @Output() shown = new EventEmitter();
  /**
   * Emits an event when the popover is hidden
   */
  @Output() hidden = new EventEmitter();

  private _ng2vPopoverWindowId = `ng2v-popover-${nextId++}`;
  private _popupService: PopupService<Ng2vPopoverWindow>;
  private _windowRef: ComponentRef<Ng2vPopoverWindow>;
  private _unregisterListenersFn;
  private _zoneSubscription: any;

  constructor(
      private _elementRef: ElementRef, private _renderer: Renderer2, injector: Injector,
      componentFactoryResolver: ComponentFactoryResolver, viewContainerRef: ViewContainerRef, config: Ng2vPopoverConfig,
      ngZone: NgZone) {
    this.placement = config.placement;
    this.triggers = config.triggers;
    this.container = config.container;
    this._popupService = new PopupService<Ng2vPopoverWindow>(
        Ng2vPopoverWindow, injector, viewContainerRef, _renderer, componentFactoryResolver);

    this._zoneSubscription = ngZone.onStable.subscribe(() => {
      if (this._windowRef) {
        positionElements(
            this._elementRef.nativeElement, this._windowRef.location.nativeElement, this.placement,
            this.container === 'body');
      }
    });
  }

  /**
   * Opens an element’s popover. This is considered a “manual” triggering of the popover.
   * The context is an optional value to be injected into the popover template when it is created.
   */
  open(context?: any) {
    if (!this._windowRef) {
      this._windowRef = this._popupService.open(this.ng2vPopover, context);
      this._windowRef.instance.placement = this.placement;
      this._windowRef.instance.title = this.popoverTitle;
      this._windowRef.instance.id = this._ng2vPopoverWindowId;

      this._renderer.setAttribute(this._elementRef.nativeElement, 'aria-describedby', this._ng2vPopoverWindowId);

      if (this.container === 'body') {
        window.document.querySelector(this.container).appendChild(this._windowRef.location.nativeElement);
      }

      // we need to manually invoke change detection since events registered via
      // Renderer::listen() are not picked up by change detection with the OnPush strategy
      this._windowRef.changeDetectorRef.markForCheck();
      this.shown.emit();
    }
  }

  /**
   * Closes an element’s popover. This is considered a “manual” triggering of the popover.
   */
  close(): void {
    if (this._windowRef) {
      this._renderer.removeAttribute(this._elementRef.nativeElement, 'aria-describedby');
      this._popupService.close();
      this._windowRef = null;
      this.hidden.emit();
    }
  }

  /**
   * Toggles an element’s popover. This is considered a “manual” triggering of the popover.
   */
  toggle(): void {
    if (this._windowRef) {
      this.close();
    } else {
      this.open();
    }
  }

  /**
   * Returns whether or not the popover is currently being shown
   */
  isOpen(): boolean { return this._windowRef != null; }

  ngOnInit() {
    this._unregisterListenersFn = listenToTriggers(
        this._renderer, this._elementRef.nativeElement, this.triggers, this.open.bind(this), this.close.bind(this),
        this.toggle.bind(this));
  }

  ngOnDestroy() {
    this.close();
    this._unregisterListenersFn();
    this._zoneSubscription.unsubscribe();
  }
}