class Gesture {
	private element: HTMLElement
	private istouch: boolean = false
	private initX: number = 0
	private initY: number = 0
	private lastDistance: number = 0
	private scale: number = 1
	private minScale: number = 0.5 // 最小缩放比例
	private maxScale: number = 2 // 最大缩放比例
	private elementW: number = 375 // 容器宽高
	private elementH: number = 500

	constructor(element: HTMLElement) {
		this.element = element
		this.elementW = element.offsetWidth
		this.elementH = element.offsetHeight
		this.attachEventListeners()
	}
	// 监听触摸事件
	private attachEventListeners() {
		this.element.addEventListener('touchstart', this.handleTouchStart.bind(this), false)
		this.element.addEventListener('touchmove', this.handleTouchMove.bind(this), false)
		this.element.addEventListener('touchend', this.handleTouchEnd.bind(this), false)
	}

	private handleTouchStart(event: TouchEvent) {
		// 可以根据需要初始化平移或缩放所需的数据
		this.istouch = true
		if (event.touches.length === 1) {
			// 记录初始触摸点
			const touch = event.touches[0]
			this.initX = touch.clientX
			this.initY = touch.clientY
		} else if (event.touches.length === 2) {
			// 记录当前缩放比例
			this.lastDistance = this.getDistance(event)
		}
	}

	private handleTouchMove(event: TouchEvent) {
		if (event.touches.length === 1 && this.istouch) {
			// 处理平移
			this.pan(event)
		} else if (event.touches.length === 2 && this.istouch) {
			// 处理缩放
			this.zoom(event)
		}
	}

	private handleTouchEnd() {
		// 处理触摸结束后的逻辑
		this.istouch = false
	}
	// 平移
	private pan(event: TouchEvent) {
		const touch = event.touches[0]
		const deltaX = touch.clientX - this.initX
		const deltaY = touch.clientY - this.initY

		// 计算新的位置
		const style = window.getComputedStyle(this.element)
		// WebKitCSSMatrix是用于操作矩阵的函数。m41就是translateX值，其中4代表第4列，1代表第一行。translateY的值，就用m42
		const matrix = new WebKitCSSMatrix(style.transform)
		let newX = matrix.m41 + deltaX,
			newY = matrix.m42 + deltaY

		// 定义安全边界（可以根据需要调整）
		const safeMarginX = this.elementW / 3,
			safeMarginY = this.elementH / 3 // 安全边界大小

		// 确保元素不会移出窗口边界
		newX = Math.min(Math.max(safeMarginX - this.elementW, newX), this.elementW - safeMarginX)
		newY = Math.min(Math.max(safeMarginY - this.elementH, newY), this.elementH - safeMarginY)

		// 应用平移（同时保留当前的缩放比例）
		this.element.style.transform = `translate(${newX}px, ${newY}px) scale(${this.scale})`
		// 平移结束后更新初始坐标
		this.initX = touch.clientX
		this.initY = touch.clientY
	}
	// 缩放
	private zoom(event: TouchEvent) {
		// 计算两点间的距离
		const distance = this.getDistance(event)

		if (this.lastDistance) {
			const scaleChange = distance / this.lastDistance
			// 计算新的缩放比例时基于初始缩放比例
			const newScale = Math.min(Math.max(this.scale * scaleChange, this.minScale), this.maxScale)
			// 更新缩放比例
			this.scale = newScale

			// 应用缩放
			const style = window.getComputedStyle(this.element)
			const matrix = new WebKitCSSMatrix(style.transform)
			this.element.style.transform = `translate(${matrix.m41}px, ${matrix.m42}px) scale(${this.scale})`
		}
		// 更新距离用于下一次计算
		this.lastDistance = distance
	}
	// 计算两点间的距离
	private getDistance(evt: TouchEvent) {
		const dx = evt.touches[0].clientX - evt.touches[1].clientX
		const dy = evt.touches[0].clientY - evt.touches[1].clientY
		return Math.sqrt(dx * dx + dy * dy)
	}
}

export default Gesture