import {
  AfterViewInit,
  ChangeDetectorRef,
  Component,
  ContentChildren,
  ElementRef, EventEmitter,
  Input, OnDestroy, Output,
  QueryList,
  ViewChild
} from "@angular/core";
import {SliderTabComponent} from "./slider-tab.component";
import {ActivatedRoute, Router} from "@angular/router";
import {Subscription} from "rxjs";
import Timeout = NodeJS.Timeout;

declare var UIkit;

@Component({
  selector: 'slider-tabs',
  template: `
    <div #sliderElement class="uk-position-relative" [class.uk-slider]="position === 'horizontal'"
         [ngClass]="customClass">
      <div [class.uk-slider-container-tabs]="position === 'horizontal'">
        <ul #tabsElement class="uk-tab" [class.uk-flex-nowrap]="position === 'horizontal'"
            [class.uk-slider-items]="position === 'horizontal'"
            [class.uk-tab-left]="position === 'left'" [class.uk-tab-right]="position === 'right'"
            [attr.uk-tab]="type === 'static'?('connect:' + connect):null"
            [ngClass]="'uk-flex-' + flexPosition">
          <ng-container *ngIf="type === 'static'">
            <li *ngFor="let tab of tabs.toArray()" class="uk-text-capitalize">
              <a>{{tab.title}}</a>
            </li>
          </ng-container>
          <ng-container *ngIf="type === 'scrollable'">
            <li *ngFor="let tab of tabs.toArray()" class="uk-text-capitalize" [class.uk-active]="tab.active">
              <a routerLink="./" [fragment]="tab.id">{{tab.title}}</a>
            </li>
          </ng-container>
        </ul>
      </div>
      <a *ngIf="position === 'horizontal'" class="uk-position-center-left uk-blur-background" uk-slider-item="previous"><span
          uk-icon="chevron-left"></span></a>
      <a *ngIf="position === 'horizontal'" class="uk-position-center-right uk-blur-background" uk-slider-item="next"><span
          uk-icon="chevron-right"></span></a>
    </div>
  `,
})
export class SliderTabsComponent implements AfterViewInit, OnDestroy {
  //TODO now it works only for scrollable and static, to be extended for dynamic
  /**
   * Type of tabs: Static = Uikit tabs with @connect class or selector, Dynamic = Active is defined by tabComponent.active input,
   * Scrollable = Active is defined by the active fragment of URL and position of scroll
   * */
  @Input()
  public type: 'static' | 'dynamic' | 'scrollable' = 'static';
  /**
   * Connect selector in static type. Default: .uk-switcher
   * */
  @Input()
  public connect = '.uk-switcher';
  /**
   * Threshold between 0.0 to 1.0 for Intersection Observer
   * */
  @Input()
  public scrollThreshold = 0.1;
  /**
   * Tabs view: Horizontal is the default.
   * */
  @Input()
  public position: 'horizontal' | 'left' | 'right' = 'horizontal';
  /**
   * Tabs flex position: Left is the default.
   * */
  @Input()
  public flexPosition: 'center' | 'left' | 'right' = 'left';
  /**
   * Tabs custom class
   * */
  @Input()
  public customClass: string;
  @ContentChildren(SliderTabComponent) tabs: QueryList<SliderTabComponent>;
  @ViewChild('sliderElement') sliderElement: ElementRef;
  @ViewChild('tabsElement') tabsElement: ElementRef;
  /**
   * Notify regarding new active element
   * */
  @Output() activeEmitter: EventEmitter<string> = new EventEmitter<string>();
  private activeIndex: number = 0;
  private subscriptions: any[] = [];
  private observer: IntersectionObserver;
  private timeout: Timeout;
  
  constructor(private route: ActivatedRoute,
              private router: Router,
              private cdr: ChangeDetectorRef) {
  }
  
  ngAfterViewInit() {
    if (typeof document !== 'undefined' && this.tabs.length > 0) {
      setTimeout(() => {
        if (this.position === 'horizontal') {
          let slider = UIkit.slider(this.sliderElement.nativeElement, {finite: true});
          slider.clsActive = 'uk-slider-active';
          slider.updateActiveClasses();
          slider.slides.forEach(item => {
            item.classList.remove('uk-active');
          });
          if (this.type === 'static') {
            let tabs = UIkit.tab(this.tabsElement.nativeElement, {connect: this.connect});
            tabs.show(this.activeIndex);
            if (this.connect.includes('#')) {
              this.scrollToStart();
            }
          } else if (this.type === 'scrollable') {
            this.scrollable(slider);
          }
        } else {
          this.scrollable();
        }
      });
    }
  }
  
  private scrollToStart() {
    this.subscriptions.push(UIkit.util.on(this.connect, 'shown', (event): void => {
      let index = event.detail[0].index();
      if (index !== this.activeIndex) {
        this.activeIndex = index;
        this.router.navigate(['./'], {relativeTo: this.route, fragment: this.connect.replace('#', '')});
      }
    }));
  }
  
  private scrollable(slider = null) {
    this.activeFragment(this.route.snapshot.fragment, slider);
    this.subscriptions.push(this.route.fragment.subscribe(fragment => {
      this.activeFragment(fragment, slider);
    }));
    this.setObserver();
  }
  
  private setObserver() {
    if (this.observer) {
      this.observer.disconnect();
    }
    this.observer = new IntersectionObserver((entries) => {
      entries.forEach(entry => {
        if (entry.isIntersecting) {
          if (this.timeout) {
            clearTimeout(this.timeout);
          }
          this.timeout = setTimeout(() => {
            this.router.navigate(['./'], {
              fragment: entry.target.id,
              relativeTo: this.route,
              state: {disableScroll: true}
            });
          }, 200);
        }
      });
    }, {threshold: 0.1});
    this.tabs.forEach(tab => {
      let element = document.getElementById(tab.id);
      if (element) {
        this.observer.observe(element);
      }
    });
  }
  
  private activeFragment(fragment, slider) {
    let index = 0;
    if (fragment) {
      index = this.tabs.toArray().findIndex(item => item.id == fragment);
    }
    if (slider) {
      slider.show(index);
    }
    this.tabs.forEach((tab, i) => {
      if (index === i) {
        tab.active = true;
        this.activeEmitter.emit(tab.id);
      } else {
        tab.active = false;
      }
    });
    this.cdr.detectChanges();
  }
  
  ngOnDestroy() {
    this.subscriptions.forEach(subscription => {
      if (subscription instanceof Subscription) {
        subscription.unsubscribe();
      } else if (subscription instanceof Function) {
        subscription();
      }
    });
    if (this.observer) {
      this.observer.disconnect();
    }
  }
}