// Copyright Epic Games, Inc. All Rights Reserved.

import { CoordinateConverter } from '../Util/CoordinateConverter';
import { StreamMessageController } from '../UeInstanceMessage/StreamMessageController';
import { VideoPlayer } from '../VideoPlayer/VideoPlayer';
import { ITouchController } from './ITouchController';
import { MouseButton } from './MouseButtons';
import { EventListenerTracker } from '../Util/EventListenerTracker';

/**
 * Allows for the usage of fake touch events and implements ITouchController
 * @param dataChannelController - The controller for the Data channel
 * @param videoElementParent - The video player DOM element
 */
export class FakeTouchController implements ITouchController {
    fakeTouchFinger: FakeTouchFinger;
    toStreamerMessagesProvider: StreamMessageController;
    videoElementProvider: VideoPlayer;
    coordinateConverter: CoordinateConverter;
    videoElementParentClientRect: DOMRect;

    // Utility for keeping track of event handlers and unregistering them
    private touchEventListenerTracker = new EventListenerTracker();

    /**
     * @param toStreamerMessagesProvider - Stream message instance
     * @param videoElementProvider - Video element instance
     * @param coordinateConverter - A coordinate converter instance
     */
    constructor(
        toStreamerMessagesProvider: StreamMessageController,
        videoElementProvider: VideoPlayer,
        coordinateConverter: CoordinateConverter
    ) {
        this.toStreamerMessagesProvider = toStreamerMessagesProvider;
        this.videoElementProvider = videoElementProvider;
        this.coordinateConverter = coordinateConverter;
        const ontouchstart = (ev: TouchEvent) => this.onTouchStart(ev);
        const ontouchend = (ev: TouchEvent) => this.onTouchEnd(ev);
        const ontouchmove = (ev: TouchEvent) => this.onTouchMove(ev);
        document.addEventListener('touchstart', ontouchstart, { passive: false });
        document.addEventListener('touchend', ontouchend, { passive: false });
        document.addEventListener('touchmove', ontouchmove, { passive: false });
        this.touchEventListenerTracker.addUnregisterCallback(
            () => document.removeEventListener('touchstart', ontouchstart)
        );
        this.touchEventListenerTracker.addUnregisterCallback(
            () => document.removeEventListener('touchend', ontouchend)
        );
        this.touchEventListenerTracker.addUnregisterCallback(
            () => document.removeEventListener('touchmove', ontouchmove)
        );
    }

    /**
     * Unregister all touch events
     */
    unregisterTouchEvents() {
        this.touchEventListenerTracker.unregisterAll();
    }

    /**
     * Sets the video Element Parent Client Rect numbers for this class
     * @param videoElementParentClientRect - a html ElementParentClientRect object
     */
    setVideoElementParentClientRect(videoElementParentClientRect: DOMRect) {
        this.videoElementParentClientRect = videoElementParentClientRect;
    }

    /**
     * When a touch event begins
     * @param touch - the activating touch event
     */
    onTouchStart(touch: TouchEvent): void {
        if (!this.videoElementProvider.isVideoReady() || touch.target !== this.videoElementProvider.getVideoElement()) {
            return;
        }
        if (this.fakeTouchFinger == null) {
            const first_touch = touch.changedTouches[0];
            this.fakeTouchFinger = new FakeTouchFinger(
                first_touch.identifier,
                first_touch.clientX - this.videoElementParentClientRect.left,
                first_touch.clientY - this.videoElementParentClientRect.top
            );

            const videoElementParent =
                this.videoElementProvider.getVideoParentElement() as HTMLDivElement;
            const mouseEvent = new MouseEvent('mouseenter', first_touch);
            videoElementParent.dispatchEvent(mouseEvent);

            const coord = this.coordinateConverter.normalizeAndQuantizeUnsigned(
                this.fakeTouchFinger.x,
                this.fakeTouchFinger.y
            );
            const toStreamerHandlers =
                this.toStreamerMessagesProvider.toStreamerHandlers;
            toStreamerHandlers.get('MouseDown')([
                MouseButton.mainButton,
                coord.x,
                coord.y
            ]);
        }
        touch.preventDefault();
    }

    /**
     * When a touch event ends
     * @param touchEvent - the activating touch event
     */
    onTouchEnd(touchEvent: TouchEvent): void {
        if (!this.videoElementProvider.isVideoReady() || this.fakeTouchFinger == null) {
            return;
        }
        const videoElementParent =
            this.videoElementProvider.getVideoParentElement();
        const toStreamerHandlers =
            this.toStreamerMessagesProvider.toStreamerHandlers;

        for (let t = 0; t < touchEvent.changedTouches.length; t++) {
            const touch = touchEvent.changedTouches[t];
            if (touch.identifier === this.fakeTouchFinger.id) {
                const x =
                    touch.clientX - this.videoElementParentClientRect.left;
                const y = touch.clientY - this.videoElementParentClientRect.top;
                const coord =
                    this.coordinateConverter.normalizeAndQuantizeUnsigned(x, y);
                toStreamerHandlers.get('MouseUp')([
                    MouseButton.mainButton,
                    coord.x,
                    coord.y
                ]);

                const mouseEvent = new MouseEvent('mouseleave', touch);
                videoElementParent.dispatchEvent(mouseEvent);
                this.fakeTouchFinger = null;
                break;
            }
        }
        touchEvent.preventDefault();
    }

    /**
     * On a Move touch event
     * @param touchEvent - the activating touch event
     */
    onTouchMove(touchEvent: TouchEvent): void {
        if (!this.videoElementProvider.isVideoReady() || this.fakeTouchFinger == null) {
            return;
        }
        const toStreamerHandlers =
            this.toStreamerMessagesProvider.toStreamerHandlers;

        for (let t = 0; t < touchEvent.touches.length; t++) {
            const touch = touchEvent.touches[t];
            if (touch.identifier === this.fakeTouchFinger.id) {
                const x =
                    touch.clientX - this.videoElementParentClientRect.left;
                const y = touch.clientY - this.videoElementParentClientRect.top;
                const coord =
                    this.coordinateConverter.normalizeAndQuantizeUnsigned(x, y);
                const delta =
                    this.coordinateConverter.normalizeAndQuantizeSigned(
                        x - this.fakeTouchFinger.x,
                        y - this.fakeTouchFinger.y
                    );
                toStreamerHandlers.get('MouseMove')([
                    coord.x,
                    coord.y,
                    delta.x,
                    delta.y
                ]);
                this.fakeTouchFinger.x = x;
                this.fakeTouchFinger.y = y;
                break;
            }
        }
        touchEvent.preventDefault();
    }
}

/**
 * The interface for finger position mapping
 */
export class FakeTouchFinger {
    id: number;
    x: number;
    y: number;

    /**
     * @param id - the button id
     * @param x - the x axis value
     * @param y - the y axis value
     */
    constructor(id: number, x: number, y: number) {
        this.id = id;
        this.x = x;
        this.y = y;
    }
}