class Swiper {
	constructor() {
		this.isInitialized = false;
		this.initSubscribers();
		this.initHandlers();
		this.swipe = {
			startX: null,
			endX: null,
			startY: null,
			endY: null,
			minSwipe: 50
		};

		this.pinch = {
			active: false,
			startDistance: 0,
			lastDistance: 0,
			scale: 1
		};
	}

	/*********************************************************************
	 LISTENERS
	 *********************************************************************/
	initHandlers() {
		this.touchStartHandler 	= this.handleTouchStart.bind(this);
		this.touchMoveHandler 	= this.handleTouchMove.bind(this);
		this.touchEndHandler 	= this.handleTouchEnd.bind(this);
	}
	initListeners() {
		if (this.isInitialized) {
			return;
		}
		this.isInitialized = true;
		document.addEventListener('touchstart', this.touchStartHandler);
		document.addEventListener('touchmove', this.touchMoveHandler);
		document.addEventListener('touchend', this.touchEndHandler);
	}
	cleanupListeners() {
		if (this.subscribers.size > 0) return;
		this.isInitialized = false;
		document.removeEventListener('touchstart', this.touchStartHandler);
		document.removeEventListener('touchmove', this.touchMoveHandler);
		document.removeEventListener('touchend', this.touchEndHandler);
	}
	handleTouchStart(e) {
		if (e.touches.length === 2) {
			// Two-finger pinch start
			const dx = e.touches[0].clientX - e.touches[1].clientX;
			const dy = e.touches[0].clientY - e.touches[1].clientY;
			const distance = Math.sqrt(dx*dx + dy*dy);

			this.pinch.active = true;
			this.pinch.startDistance = this.pinch.lastDistance = distance;
			this.notify('pinch-start', { distance });

			return; // Don't treat this as a swipe
		}

		this.swipe.startX = e.touches[0].clientX;
		this.swipe.startY = e.touches[0].clientY;
	}
	handleTouchMove(e) {
		if (this.pinch.active && e.touches.length === 2) {
			const dx = e.touches[0].clientX - e.touches[1].clientX;
			const dy = e.touches[0].clientY - e.touches[1].clientY;
			const distance = Math.sqrt(dx*dx + dy*dy);

			const scale = distance / this.pinch.startDistance;

			this.pinch.lastDistance = distance;
			this.pinch.scale = scale;

			this.notify('pinch-move', { e, distance, scale });

			// Direction
			if (distance > this.pinch.startDistance) {
				this.notify('pinch-out', { scale });
			} else {
				this.notify('pinch-in', { scale });
			}

			return; // Do not fire swipe logic
		}
		this.swipe.endX = e.touches[0].clientX;
		this.swipe.endY = e.touches[0].clientY;
	}
	handleTouchEnd(e) {
		// Finish pinch
		if (this.pinch.active) {
			this.notify('pinch-end', {
				finalScale: this.pinch.scale
			});
			this.pinch.active = false;
			return;
		}

		if ((!this.swipe.startX || !this.swipe.endX) ||(!this.swipe.startY || !this.swipe.endY)) return;

		const distanceX = this.swipe.startX - this.swipe.endX;
		const distanceY = this.swipe.startY - this.swipe.endY;

		if (Math.abs(distanceX) > this.swipe.minSwipe) {
			let direction = distanceX > 0 ? 'swipe-right' : 'swipe-left';
			this.notify(direction);
		}
		if (Math.abs(distanceY) > this.swipe.minSwipe) {
			let direction = distanceY > 0 ? 'swipe-up' : 'swipe-down';
			this.notify(direction);
		}
		this.swipe.startX = this.swipe.startY = this.swipe.endX = this.swipe.endY = null;
	}
	/*********************************************************************
	 SUBSCRIBERS
	 *********************************************************************/
	initSubscribers() {
		this.subscribers = new Set();
	}

	subscribe(callback) {
		if (!this.isInitialized) {
			this.initListeners();
		}
		this.subscribers.add(callback);
		return () => this.subscribers.delete(callback);
	}
	unsubscribe(callback) {
		this.subscribers.delete(callback);
		if (this.subscribers.size === 0) {
			this.cleanupListeners();
		}
	}

	notify(event, data = {}) {
		this.subscribers.forEach( callback => {
			try {
				callback(event, data);
			} catch (error) {
				console.error('Subscriber error:', error);
			}
		});
	}

	/******************************************************************
	 CLEANUP
	 ******************************************************************/

	destroy() {
		this.subscribers.clear();
		this.cleanupListeners();
	}
}

window.jvbSwiper = new Swiper();