/**
 * EGroupware Custom Html Elements - pdf player Web Components
 *
 * @license http://opensource.org/licenses/gpl-license.php GPL - GNU General Public License
 * @package etemplate
 * @subpackage api
 * @link https://www.egroupware.org
 * @author Hadi Nategh <hn[at]egroupware.org>
 * @copyright EGroupware GmbH
 */

import pdfjs from "@bundled-es-modules/pdfjs-dist/build/pdf";

/*
	This web component allows to display and play pdf file like a video player widget/element. Its attributes and
	methodes are mostley identical as video html. No controls attribute supported yet.
*/
pdfjs.GlobalWorkerOptions.workerSrc = 'node_modules/@bundled-es-modules/pdfjs-dist/build/pdf.worker.js';

/**
 *
 */
type PdfViewArray = {
	pdf: any,
	zoom: number,
	currentPage: number
};

// Create a class for the element
class pdf_player extends HTMLElement {

	/**
	 * shadow dom container
	 * @private
	 */
	private readonly _shadow = null;
	/**
	 * wrapper container holds canvas
	 * @private
	 */
	private readonly _wrapper : HTMLDivElement;
	/**
	 * Canvas element to render pdf
	 * @private
	 */
	private _canvas : HTMLCanvasElement;
	/**
	 * Styling contianer
	 * @private
	 */
	private readonly _style : HTMLStyleElement;
	/**
	 * keeps duration time internally
	 * @private
	 */
	private _duration : number = 0;
	/**
	 * keeps currentTime internally
	 * @private
	 */
	private _currentTime : number = 0;
	/**
	 * Keeps playing state internally
	 * @private
	 */
	private __playing: boolean = false;
	/**
	 * keeps playing interval id
	 * @private
	 */
	private __playingInterval : number = 0;
	/**
	 * keeps play back rate
	 * @private
	 */
	private _playBackRate : number = 1000;
	/**
	 * keeps ended state of playing pdf
	 * @private
	 */
	private _ended : boolean = false;
	/**
	 * keep paused state
	 * @private
	 */
	private _paused : boolean = false;
	/**
	 * keeps pdf doc states
	 * @private
	 */
	private __pdfViewState : PdfViewArray = {
		pdf: null,
		currentPage: 1,
		zoom: 1
	};

	constructor() {

		super();

		// Create a shadow root
		this._shadow = this.attachShadow({mode: 'open'});

		// Create wrapper
		this._wrapper = document.createElement('div');
		this._wrapper.setAttribute('class','wrapper');

		// Create some CSS to apply to the shadow dom
		this._style = document.createElement('style');

		this._style.textContent = '.wrapper {' +
			'width: 100%;' +
			'height: auto;' +
			'display: block;' +
			'}'+
			'.wrapper canvas {' +
			'width: 100%;'+
			'height: auto;'+
			'}';

		// attach to the shadow dom
		this._shadow.appendChild(this._style);
		this._shadow.appendChild(this._wrapper);
	}

	/**
	 * set observable attributes
	 * @return {string[]}
	 */
	static get observedAttributes() {
		return ['src', 'type'];
	}

	/**
	 * Gets called on observable attributes changes
	 * @param name attribute name
	 * @param _
	 * @param newVal new value
	 */
	attributeChangedCallback(name, _, newVal) {
		switch(name)
		{
			case 'src':
				this.__buildPDFView(newVal);
				break;
			case 'type':
				// do nothing
				break;
		}
	}

	/**
	 * init/update pdf tag
	 * @param _value
	 * @private
	 */
	private __buildPDFView(_value)
	{
		this._canvas = document.createElement('canvas');
		this._wrapper.appendChild(this._canvas);
		let longTask = pdfjs.getDocument(_value);
		longTask.promise.then((pdf) => {

			this.__pdfViewState.pdf = pdf;
			this._duration = this.__pdfViewState.pdf._pdfInfo.numPages;

			// initiate the pdf file viewer for the first time after loading
			this.__render(1).then(_ =>{
				this.__pushEvent('loadedmetadata');
			});
		});
	}

	/**
	 * Render given page from pdf into the canvas container
	 *
	 * @param _page
	 * @private
	 */
	private __render(_page)
	{
		if (!this.__pdfViewState.pdf) return;
		let p = _page || this.__pdfViewState.currentPage;
		let self = this;
		return this.__pdfViewState.pdf.getPage(p).then((page) => {
			let canvasContext = self._canvas.getContext('2d');
			let viewport = page.getViewport({scale:self.__pdfViewState.zoom});
			self._canvas.width = viewport.width;
			self._canvas.height = viewport.height;
			// don't ty to render if page is under proccess
			if (typeof page.intentStates.display == 'undefined')
			{
				page.render({
					canvasContext: canvasContext,
					viewport: viewport
				});
			}
		});
	}

	/**
	 * Creates event and dispatches it
	 * @param _name
	 */
	private __pushEvent(_name: string)
	{
		let event = document.createEvent("Event");
		event.initEvent(_name, true, true);
		this.dispatchEvent(event);
	}

	/**************************** PUBLIC ATTRIBUTES & METHODES *************************************************/

	/****************************** ATTRIBUTES **************************************/

	/**
	 * set src
	 * @param _value
	 */
	set src(_value)
	{
		this._wrapper.children.forEach(_ch=>{
			_ch.remove();
		});
		this.__buildPDFView(_value);
	}

	/**
	 * get src
	 * @return string returns comma separated sources
	 */
	get src ()
	{
		return this.src;
	}

	/**
	 * currentTime
	 * @param _time
	 */
	set currentTime(_time : number)
	{
		let time = Math.floor(_time < 1 ? 1 : _time);

		if (time>this._duration)
		{
			// set ended state to true as it's the last page of pdf
			this._ended = true;
			// don't go further because it's litterally the last page
			return;
		}

		// set ended state to false as it's not the end of the pdf
		this._ended = false;
		this._currentTime = time;
		this.__pdfViewState.currentPage = time;
		this.__render(time);
	}

	/**
	 * get currentTime
	 * @return {number}
	 */
	get currentTime()
	{
		return this._currentTime;
	}

	/**
	 * get duration time
	 */
	get duration()
	{
		return this._duration;
	}

	/**
	 * get paused attribute
	 */
	get paused()
	{
		return this._paused;
	}

	/**
	 * set muted attribute
	 * @param _value
	 */
	set muted(_value: boolean)
	{
		return;
	}

	/**
	 * get muted attribute
	 */
	get muted()
	{
		return true;
	}

	set ended (_value : boolean)
	{
		this._ended = _value;
	}

	/**
	 * get ended attribute
	 */
	get ended()
	{
		return this._ended;
	}

	/**
	 * set playbackRate
	 * @param _value
	 */
	set playbackRate(_value: number)
	{
		this._playBackRate = _value*1000;
	}

	/**
	 * get playbackRate
	 */
	get playbackRate()
	{
		return this._playBackRate;
	}

	/**
	 * set volume
	 */
	set volume(_value: number)
	{
		return;
	}

	/**
	 * get volume
	 */
	get volume()
	{
		return 0;
	}


	/************************************************* METHODES ******************************************/

	/**
	 * Play
	 */
	play()
	{
		this.__playing = true;
		let self = this;
		return new Promise(function(_resolve, _reject){
			self.__playingInterval = window.setInterval(_=>{
				if (self.currentTime >= self._duration)
				{
					self.ended = true;
					self.pause();
				}
				self.currentTime +=1;
				self.__pushEvent('timeupdate');
			}, self._playBackRate);
			_resolve();
		});
	}

	/**
	 * pause
	 */
	pause()
	{
		this.__playing = false;
		this._paused = true;
		window.clearInterval(this.__playingInterval);
	}

	/**
	 * seek previous page
	 */
	prevPage()
	{
		this.currentTime -=1;
	}

	/**
	 * seek next page
	 */
	nextPage()
	{
		this.currentTime +=1;
	}
}

// Define pdf-player element
customElements.define('pdf-player', pdf_player);