text: (function (window) {
    const l = 42, // 滑块边长
        r = 10, // 滑块半径
        w = 310, // canvas宽度
        h = 155, // canvas高度
        PI = Math.PI
    const L = l + r * 2 // 滑块实际边长
  
    function getRandomNumberByRange(start, end) {
        return Math.round(Math.random() * (end - start) + start)
    }
  
    function createCanvas(width, height) {
        const canvas = createElement('canvas')
        canvas.width = width
        canvas.height = height
        return canvas
    }
  
    function createImg(onload) {
        const img = createElement('img')
        img.crossOrigin = "Anonymous"
        img.onload = onload
        img.onerror = () => {
            img.src = getRandomImg()
        }
        img.src = getRandomImg()
        return img
    }
  
    function createElement(tagName) {
        return document.createElement(tagName)
    }
  
    function addClass(tag, className) {
        tag.classList.add(className)
    }
  
    function removeClass(tag, className) {
        tag.classList.remove(className)
    }
  
    function getRandomImg() {
        return 'https://picsum.photos/300/150/?image=' + getRandomNumberByRange(0, 1084)
    }
  
    function draw(ctx, operation, x, y) {
        ctx.beginPath()
        ctx.moveTo(x, y)
        ctx.lineTo(x + l / 2, y)
        ctx.arc(x + l / 2, y - r + 2, r, 0, 2 * PI)
        ctx.lineTo(x + l / 2, y)
        ctx.lineTo(x + l, y)
        ctx.lineTo(x + l, y + l / 2)
        ctx.arc(x + l + r - 2, y + l / 2, r, 0, 2 * PI)
        ctx.lineTo(x + l, y + l / 2)
        ctx.lineTo(x + l, y + l)
        ctx.lineTo(x, y + l)
        ctx.lineTo(x, y)
        ctx.fillStyle = '#fff'
        ctx[operation]()
        ctx.beginPath()
        ctx.arc(x, y + l / 2, r, 1.5 * PI, 0.5 * PI)
        ctx.globalCompositeOperation = "xor"
        ctx.fill()
    }
  
    function sum(x, y) {
        return x + y
    }
  
    function square(x) {
        return x * x
    }
  
    class SlidingVerificationCode {
        constructor(el, success, fail) {
            this.el = el
            this.success = success
            this.fail = fail
        }
  
        init() {
            this.initDOM()
            this.initImg()
            this.draw()
            this.bindEvents()
        }
  
        initDOM() {
            const fathers = createElement('div')//父级
            const canvas = createCanvas(w, h) // 画布
            const block = canvas.cloneNode(true) // 滑块
            const sliderContainer = createElement('div')
            const refreshIcon = createElement('div')
            const sliderMask = createElement('div')
            const slider = createElement('div')
            const sliderIcon = createElement('span')
            const text = createElement('span')
  
            fathers.className='fatherBox';
            fathers.style='';
            canvas.className='myCanvas';
            block.className = 'block';
            sliderContainer.className = 'sliderContainer';
            refreshIcon.className = 'refreshIcon';
            sliderMask.className = 'sliderMask';
            slider.className = 'slider';
            sliderIcon.className = 'sliderIcon';
            text.innerHTML = '向右滑动滑块填充拼图';
            text.className = 'sliderText';
            const el = this.el;
            //el.appendChild(canvas)
            //el.appendChild(refreshIcon)
            //el.appendChild(block)
            fathers.appendChild(canvas)
            fathers.appendChild(refreshIcon)
            fathers.appendChild(block)
            el.appendChild(fathers)
            slider.appendChild(sliderIcon)
            sliderMask.appendChild(slider)
            sliderContainer.appendChild(sliderMask)
            sliderContainer.appendChild(text)
            el.appendChild(sliderContainer)
  
            Object.assign(this, {
                canvas,
                block,
                sliderContainer,
                refreshIcon,
                slider,
                sliderMask,
                sliderIcon,
                text,
                canvasCtx: canvas.getContext('2d'),
                blockCtx: block.getContext('2d')
            })
        }
  
        initImg() {
            const img = createImg(() => {
                this.canvasCtx.drawImage(img, 0, 0, w, h)
                this.blockCtx.drawImage(img, 0, 0, w, h)
                const y = this.y - r * 2 + 2
                const ImageData = this.blockCtx.getImageData(this.x, y, L, L)
                this.block.width = L
                this.blockCtx.putImageData(ImageData, 0, y)
            })
            this.img = img
        }
  
        draw() {
            // 随机创建滑块的位置
            this.x = getRandomNumberByRange(L + 10, w - (L + 10))
            this.y = getRandomNumberByRange(10 + r * 2, h - (L + 10))
            draw(this.canvasCtx, 'fill', this.x, this.y)
            draw(this.blockCtx, 'clip', this.x, this.y)
        }
  
        clean() {
            this.canvasCtx.clearRect(0, 0, w, h)
            this.blockCtx.clearRect(0, 0, w, h)
            this.block.width = w
        }
  
        bindEvents() {
            this.el.onselectstart = () => false
            this.refreshIcon.onclick = () => {
                this.reset()
            }
  
            let originX, originY, trail = [], isMouseDown = false
            this.slider.addEventListener('touchstart', function (e) {
  
              if (e.targetTouches.length == 1) { 
                  var touch = e.targetTouches[0]; 
                  originX = touch.pageX, originY = touch.pageY
                  isMouseDown = true
              }
  
                
            })
            document.addEventListener('touchmove', (e) => {
                if (!isMouseDown) return false
                if (e.targetTouches.length == 1) { 
                  var touch = e.targetTouches[0]; 
                  const moveX = touch.pageX - originX
                  const moveY = touch.pageY - originY
                  if (moveX < 0 || moveX + 38 >= w) return false
                  this.slider.style.left = moveX + 'px'
                  var blockLeft = (w - 40 - 20) / (w - 40) * moveX
                  this.block.style.left = blockLeft + 'px'
  
                  addClass(this.sliderContainer, 'sliderContainer_active')
                  this.sliderMask.style.width = moveX + 'px'
                  trail.push(moveY)
                }
            })
            document.addEventListener('touchend', (e) => {
                if (!isMouseDown) return false
                isMouseDown = false
                if (e.x == originX) return false
                removeClass(this.sliderContainer, 'sliderContainer_active')
                this.trail = trail
                const {spliced, TuringTest} = this.verify()
                if (spliced) {
                    if (TuringTest) {
                        addClass(this.sliderContainer, 'sliderContainer_success')
                        this.success && this.success()
                    } else {
                        addClass(this.sliderContainer, 'sliderContainer_fail')
                        this.text.innerHTML = '再试一次'
                        this.reset()
                    }
                } else {
                    addClass(this.sliderContainer, 'sliderContainer_fail')
                    this.fail && this.fail()
                    setTimeout(() => {
                        this.reset()
                    }, 1000)
                }
            })
        }
  
        verify() {
            const arr = this.trail // 拖动时y轴的移动距离
            const average = arr.reduce(sum) / arr.length // 平均值
            const deviations = arr.map(x => x - average) // 偏差数组
            const stddev = Math.sqrt(deviations.map(square).reduce(sum) / arr.length) // 标准差
            const left = parseInt(this.block.style.left)
            return {
                spliced: Math.abs(left - this.x) < 10,
                TuringTest: average !== stddev, // 只是简单的验证拖动轨迹，相等时一般为0，表示可能非人为操作
            }
        }
  
        reset() {
            this.sliderContainer.className = 'sliderContainer'
            this.slider.style.left = 0
            this.block.style.left = 0
            this.sliderMask.style.width = 0
            this.clean()
            this.img.src = getRandomImg()
            this.draw()
        }
  
    }
  
    window.SlidingVerificationCode = {
        init: function (el, success, fail) {
            new SlidingVerificationCode(el, success, fail).init()
        }
    }
  }(window))