import { Component, OnInit, AfterViewChecked, ViewEncapsulation, ViewChild, AfterContentInit, AfterViewInit } from '@angular/core';
import { UserGuideService } from '@app/core/services/user-guide/user-guide.service';
import { BaseComponent } from '@common/base/base.component';
import { takeUntil } from 'rxjs/internal/operators/takeUntil';
import { DomSanitizer, SafeResourceUrl } from '@angular/platform-browser';
import { LanguageService } from '@app/core/services/language/language.service';
import { HttpClient } from '@angular/common/http';
import { MatomoService } from '@app/core/services/matomo/matomo-service';
import { ElementRef } from '@angular/core';
import { interval, Subject } from 'rxjs';
import { ConfigurationService } from '@app/core/services/configuration/configuration.service';

@Component({
	selector: 'app-user-guide-content',
	templateUrl: './user-guide-content.component.html',
	styleUrls: ['./user-guide-content.component.scss']
})
export class UserGuideContentComponent extends BaseComponent implements OnInit {
	readonly useInnerHTML: boolean = false; //GK: Change for TESTING PURPOSES ONLY

	guideHTML: any;
	guideHTMLUrl: SafeResourceUrl;
	sanitizedGuideUrl: any;
	private scrollEvent: EventListener;
	private tocScrollEvent: EventListener;
	private _transformed: Subject<boolean> = new Subject();
	private _parsed: Subject<boolean> = new Subject();

	@ViewChild('guide', {static: false}) guide: ElementRef;

	constructor(
		private userGuideService: UserGuideService,
		private sanitizer: DomSanitizer,
		private languageService: LanguageService,
		private httpClient: HttpClient,
		private matomoService: MatomoService,
		private configurationService: ConfigurationService
	) { super(); }

	ngOnInit() {
		this.matomoService.trackPageView('User Guide Content');
		this.scrollEvent = ((ev) => this.scroll(ev));
		this.tocScrollEvent = ((ev) => {
			this.activeToc(ev);
			this.scroll(ev);
		});
		this.userGuideService.getUserGuide(this.languageService.getCurrentLanguage())
			.pipe(takeUntil(this._destroyed))
			.subscribe(response => {
				const blob = new Blob([response.body], { type: 'text/html' });
				if (this.useInnerHTML) {
					this.readBlob(blob);
				} else {
					this.guideHTMLUrl = this.sanitizer.bypassSecurityTrustResourceUrl((window.URL ? URL : webkitURL).createObjectURL(blob));
					//GK: In case the app is in localhost (dev/debug build) apply the following transformation
					//in order to show the user guide's images
					if (this.guideHTMLUrl && this.configurationService.app.includes('localhost')) {
						interval(1000).pipe(takeUntil(this._transformed)).subscribe(() => this.transform());
					}
				}

				// this.guideHTML = this.sanitizer.sanitize(SecurityContext.HTML, blob);
				// this.sanitizedGuideUrl = this.sanitizer.sanitize(SecurityContext.URL, this.guideHTMLUrl);
				// console.log(this.guideHTMLUrl);
			});
	}

	readBlob(blob: Blob) {
		const fr = new FileReader();
		fr.onload = ev => {
			const HTMLstring = fr.result as string;
			this.guideHTML = this.sanitizer.bypassSecurityTrustHtml(HTMLstring);
			this.addScripts(HTMLstring);
			if (this.guideHTML) {
				interval(1000).pipe(takeUntil(this._transformed)).subscribe(() => this.transform());
				interval(1000).pipe(takeUntil(this._parsed)).subscribe(() => this.parse());
			}
		};
		fr.readAsText(blob);
	}

	activeToc(ev: Event) {
		const current = document.getElementsByClassName('active');
		if (current.length > 0) {
			current[0].classList.remove('active');
		}
		(ev.currentTarget as Element).classList.add('active');
	}

	scroll(ev: Event) {
		document.getElementById((ev.currentTarget as Element).getAttribute('path')).scrollIntoView({ behavior: 'smooth', block: 'start' });
	}

	private parse() {
		const specialElements: HTMLCollection = document.getElementsByTagName('a');
		for (let i = 0; i < specialElements.length; i++) {
			const element = specialElements.item(i) as  HTMLAnchorElement;
			if(element.href.includes('#')) {
				this.hrefToPath(element);
				element.removeEventListener('click', this.scrollEvent);
				element.addEventListener('click', this.scrollEvent);
			}
			if (!this._parsed.isStopped) {
				this._parsed.next(true);
				this._parsed.complete();
			}
		}

	}

	private addScripts(HTMLString: string) {
		const fragment = document.createRange().createContextualFragment(HTMLString);
		this.guide.nativeElement.appendChild(fragment);
	}

	transform() {
		if (this.useInnerHTML) {
			const tocElements = document.getElementsByClassName('nav-link');
			for (let i = 0; i < tocElements.length; i++) {
				const href = (tocElements[i] as HTMLAnchorElement).href;
				if (href.includes('#')) {
					this.hrefToPath(tocElements[i] as HTMLAnchorElement);
					tocElements[i].addEventListener('click', this.tocScrollEvent);
					tocElements[i].classList.add('tocElement');
					if (!this._transformed.isStopped) {
						this._transformed.next(true);
						this._transformed.complete();
					}
				}
			}
		} else {
			const userguide = document.getElementById('userguide') as HTMLIFrameElement;
			const images = userguide.contentWindow.document.getElementsByTagName('img');
			for (let i = 0; i < images.length; i++) {
				const image = images[i];
				image.src = `${this.configurationService.app}${image.src}`;
				if (!this._transformed.isStopped) {
					this._transformed.next(true);
					this._transformed.complete();
				}
			}
		}
	}

	private hrefToPath(element: HTMLAnchorElement) {
		const href = element.href;
		const hashtagIndex = href.lastIndexOf('#');
		element.removeAttribute('href');
		element.setAttribute('path', href.slice(hashtagIndex + 1));
	}

}