import './jigsaw.css'

let w = 310 // canvas宽度
let h = 155 // canvas高度
const l = 42 // 滑块边长
const r = 9 // 滑块半径
const PI = Math.PI
const L = l + r * 2 + 3 // 滑块实际边长

function getRandomNumberByRange(start, end) {
    return Math.round(Math.random() * (end - start) + start)
}

function createCanvas(width, height) {
    const canvas = document.createElement('canvas')
    canvas.width = width
    canvas.height = height
    return canvas
}

function createImg(onload) {
    const img = new Image()
    img.crossOrigin = 'Anonymous'
    img.onload = onload
    img.onerror = () => {
        img.setSrc(getRandomImgSrc())
    }

    img.setSrc = function (src) {
        const isIE = window.navigator.userAgent.indexOf('Trident') > -1
        if (isIE) { // IE浏览器无法通过img.crossOrigin跨域，使用ajax获取图片blob然后转为dataURL显示
            const xhr = new XMLHttpRequest()
            xhr.onloadend = function (e) {
                const file = new FileReader() // FileReader仅支持IE10+
                file.readAsDataURL(e.target.response)
                file.onloadend = function (e) {
                    img.src = e.target.result
                }
            }
            xhr.open('GET', src)
            xhr.responseType = 'blob'
            xhr.send()
        } else img.src = src
    }

    img.setSrc(getRandomImgSrc())
    return img
}

function createElement(tagName, className) {
    const elment = document.createElement(tagName)
    elment.className = className
    return elment
}

function addClass(tag, className) {
    tag.classList.add(className)
}

function removeClass(tag, className) {
    tag.classList.remove(className)
}

function getRandomImgSrc() {
    return `https://picsum.photos/${w}/${h}/?image=${getRandomNumberByRange(0, 1084)}`
}

function draw(ctx, x, y, operation) {
    ctx.beginPath()
    ctx.moveTo(x, y)
    ctx.arc(x + l / 2, y - r + 2, r, 0.72 * PI, 2.26 * PI)
    ctx.lineTo(x + l, y)
    ctx.arc(x + l + r - 2, y + l / 2, r, 1.21 * PI, 2.78 * PI)
    ctx.lineTo(x + l, y + l)
    ctx.lineTo(x, y + l)
    ctx.arc(x + r - 2, y + l / 2, r + 0.4, 2.76 * PI, 1.24 * PI, true)
    ctx.lineTo(x, y)
    ctx.lineWidth = 2
    ctx.fillStyle = 'rgba(255, 255, 255, 0.7)'
    ctx.strokeStyle = 'rgba(255, 255, 255, 0.7)'
    ctx.stroke()
    ctx[operation]()
    ctx.globalCompositeOperation = 'destination-over'
}

function sum(x, y) {
    return x + y
}

function square(x) {
    return x * x
}

class jigsaw {
    constructor({el, width = 310, height = 155, onSuccess, onFail, onRefresh}) {
        w = width
        h = height
        el.style.position = 'relative';
        el.style.width = w + 'px'
        Object.assign(el.style, {
            position: 'relative',
            width: w + 'px',
            margin: '0 auto'
        })
        this.el = el
        this.onSuccess = onSuccess
        this.onFail = onFail
        this.onRefresh = onRefresh
    }

    init() {
        this.initDOM()
        this.initImg()
        this.bindEvents()
    }

    initDOM() {
        const canvas = createCanvas(w, h) // 画布
        const block = canvas.cloneNode(true) // 滑块
        const sliderContainer = createElement('div', 'sliderContainer')
        sliderContainer.style.width = w + 'px'
        const refreshIcon = createElement('div', 'refreshIcon')
        const sliderMask = createElement('div', 'sliderMask')
        const slider = createElement('div', 'slider')
        const sliderIcon = createElement('span', 'sliderIcon')
        const text = createElement('span', 'sliderText')

        block.className = 'block'
        text.innerHTML = '向右滑动填充拼图'

        const el = this.el
        el.appendChild(canvas)
        el.appendChild(refreshIcon)
        el.appendChild(block)
        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.draw()
            this.canvasCtx.drawImage(img, 0, 0, w, h)
            this.blockCtx.drawImage(img, 0, 0, w, h)
            const y = this.y - r * 2 - 1
            const ImageData = this.blockCtx.getImageData(this.x - 3, 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, this.x, this.y, 'fill')
        draw(this.blockCtx, this.x, this.y, 'clip')
    }

    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()
            typeof this.onRefresh === 'function' && this.onRefresh()
        }

        let originX, originY, trail = [], isMouseDown = false

        const handleDragStart = function (e) {
            originX = e.clientX || e.touches[0].clientX
            originY = e.clientY || e.touches[0].clientY
            isMouseDown = true
        }

        const handleDragMove = (e) => {
            if (!isMouseDown) return false
            const eventX = e.clientX || e.touches[0].clientX
            const eventY = e.clientY || e.touches[0].clientY
            const moveX = eventX - originX
            const moveY = eventY - originY
            if (moveX < 0 || moveX + 38 >= w) return false
            this.slider.style.left = moveX + 'px'
            const 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)
        }

        const handleDragEnd = (e) => {
            if (!isMouseDown) return false
            isMouseDown = false
            const eventX = e.clientX || e.changedTouches[0].clientX
            if (eventX === originX) return false
            removeClass(this.sliderContainer, 'sliderContainer_active')
            this.trail = trail
            const {spliced, verified} = this.verify()
            if (spliced) {
                if (verified) {
                    addClass(this.sliderContainer, 'sliderContainer_success')
                    typeof this.onSuccess === 'function' && this.onSuccess()
                } else {
                    addClass(this.sliderContainer, 'sliderContainer_fail')
                    this.text.innerHTML = '请再试一次'
                    this.reset()
                }
            } else {
                addClass(this.sliderContainer, 'sliderContainer_fail')
                typeof this.onFail === 'function' && this.onFail()
                setTimeout(() => {
                    this.reset()
                }, 1000)
            }
        }
        this.slider.addEventListener('mousedown', handleDragStart)
        this.slider.addEventListener('touchstart', handleDragStart)
        this.block.addEventListener('mousedown', handleDragStart)
        this.block.addEventListener('touchstart', handleDragStart)
        document.addEventListener('mousemove', handleDragMove)
        document.addEventListener('touchmove', handleDragMove)
        document.addEventListener('mouseup', handleDragEnd)
        document.addEventListener('touchend', handleDragEnd)
    }

    verify() {
        const arr = this.trail // 拖动时y轴的移动距离
        const average = arr.reduce(sum) / arr.length
        const deviations = arr.map(x => x - average)
        const stddev = Math.sqrt(deviations.map(square).reduce(sum) / arr.length)
        const left = parseInt(this.block.style.left)
        return {
            spliced: Math.abs(left - this.x) < 10,
            verified: stddev !== 0 // 简单验证拖动轨迹，为零时表示Y轴上下没有波动，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.setSrc(getRandomImgSrc())
    }
}

window.jigsaw = {
    init: function (opts) {
        let $jigsaw = new jigsaw(opts)
        $jigsaw.init();
        return $jigsaw;
    }
}