const ABS = Math.abs
const calcLen = (v) => { // distance between two coordinate
  return Math.sqrt(v.x * v.x + v.y * v.y)
}
const calcAngle = (a, b) => { // angle of the two vectors
  var l = calcLen(a) * calcLen(b); var cosValue; var angle
  if (l) {
    cosValue = (a.x * b.x + a.y * b.y) / l
    angle = Math.acos(Math.min(cosValue, 1))
    angle = a.x * b.y - b.x * a.y > 0 ? -angle : angle
    return angle * 180 / Math.PI
  }
  return 0
}
const generateCanvasId = () => { // generate a random string
  const seeds = 'abcdefghijklmnopqrstuvwxyz'
  const arr = seeds.split('').concat(seeds.toUpperCase().split('')).concat('0123456789'.split(''))
  let m = arr.length; let i
  while (m) {
    i = Math.floor(Math.random() * m--)
    const temp = arr[m]
    arr[m] = arr[i]
    arr[i] = temp
  }
  return arr.slice(0, 16).join('')
}

export default {
  props: {
    width: { // width of the container
      type: [String, Number],
      default: '100%'
    },
    height: { // height of the container
      type: [String, Number],
      default: '100%'
    },
    cutWidth: { // cutter width
      type: [String, Number],
      default: '50%'
    },
    cutHeight: { // cutter height
      type: [String, Number],
      default: 0
    },
    minWidth: { // minWidth of the cutter
      type: Number,
      default: 50
    },
    minHeight: { // minHeight of the cutter
      type: Number,
      default: 50
    },
    center: { // autoCenter
      type: Boolean,
      default: true
    },
    src: String,
    disableScale: Boolean, // disable to zoom
    disableRotate: Boolean,
    disableTranslate: Boolean,
    disableCtrl: Boolean, // disable to resize the cutter
    boundDetect: Boolean, // open boundary detection
    freeBoundDetect: Boolean, // open boundary detection while doing rotation
    keepRatio: Boolean, // keep the ratio of the cutter
    disablePreview: Boolean, // disable preview after cutting
    showCtrlBorder: Boolean, // show cutter border
    resetCut: Boolean, // reset cut while img change
    fit: {
      type: Boolean,
      default: true
    },
    imageCenter: Boolean, // auto center/middle for image
    maxZoom: { // maximum scaling factor
      type: Number,
      default: 10 // can not be Infinity in baidu-MiniProgram
    },
    minZoom: { // minimum scaling factor
      type: Number,
      default: 1
    },
    angle: { // initial angle of rotation
      type: Number,
      default: 0
    },
    zoom: { // initial scaling factor
      type: Number,
      default: 1
    },
    offset: { // initial offset relative to the cutter left border
      type: Array,
      default() {
        return [0, 0]
      }
    },
    background: {
      type: String,
      default: '#000'
    },
    canvasBackground: { // background for the exported image
      type: String,
      default: '#fff'
    },
    canvasZoom: {  // export multiples of the cutter size
      type: Number,
      default: 1
    },
    fileType: {
      type: String,
      default: 'png',
      validator(t) {
        return ['png', 'jpg'].includes(t)
      }
    },
    quality: {
      type: Number,
      default: 1
    },
    maskType: { // type for mask
      type: String,
      default: "shadow"
    },
    circleView: Boolean // circle clip view
  },
  data() {
    return {
      transform: {
        angle: 0,
        translate: {
          x: 0,
          y: 0
        },
        zoom: 1
      },
      corner: {
        left: 50,
        right: 50,
        bottom: 50,
        top: 50
      },
      image: {
        originWidth: 0,
        originHeight: 0,
        width: 0,
        height: 0
      },
      ctrlWidth: 0,
      ctrlHeight: 0,
      view: false,
      canvasId: ''
    }
  },
  computed: {
    transformMeta: function() {
      const transform = this.transform
      return `translate3d(${transform.translate.x}px, ${transform.translate.y}px, 0) rotate(${transform.angle}deg) scale(${transform.zoom})`
    },
    ctrlStyle: function() {
      const corner = this.corner
      let cssStr = `left: ${corner.left}px;top: ${corner.top}px;right: ${corner.right}px;bottom: ${corner.bottom }px;`
      if(this.maskType !== 'outline') {
        cssStr += `box-shadow: 0 0 0 50000rpx rgba(0,0,0, ${this.view ? 0.8 : 0.4})`
      } else {
        cssStr += `outline: rgba(0,0,0, ${this.view ? 0.8 : 0.4}) solid 5000px`
      }
      return cssStr
    }
  },
  watch: {
    src: function() {
      if(this.resetCut) this.resetCutReact()
      this.initImage()
    }
  },
  created() {
    this.canvasId = generateCanvasId()
    uni.getSystemInfo().then(result => {
      result = result[1] || {windowWidth: 375, windowHeight: 736}
      this.ratio = result.windowWidth / 750
      this.windowHeight = result.windowHeight
      this.init()
      this.initCanvas()
    })
  },
  methods: {
    toPx(str) {
      if (str.indexOf('%') !== -1) {
        return Math.floor(Number(str.replace('%', '')) / 100 * this.containerWidth)
      }
      if (str.indexOf('rpx') !== -1) {
        return Math.floor(Number(str.replace('rpx', '')) * this.ratio)
      }
      return Math.floor(Number(str.replace('px', '')))
    },
    initCanvas() {
			// #ifdef MP-ALIPAY
			const context = uni.createSelectorQuery()
			// #endif
			// #ifndef MP-ALIPAY
			const context = uni.createSelectorQuery().in(this)
			// #endif

      // get contianer size
      context.select('.nice-cropper').boundingClientRect()
      context.exec(res => {
        this.containerWidth = res[0].width
        this.containerHeight = res[0].height
        this.initCut()
      })
    },
    resetCutReact() {// init size and position of the cutter
      this.ctrlWidth = Math.min(this.toPx(this.cutWidth), this.containerWidth)
      if (this.cutHeight) {
        this.ctrlHeight = Math.min(this.toPx(this.cutHeight), this.containerHeight)
      } else { // 默认为正方形
        this.ctrlHeight = Math.min(this.ctrlWidth, this.containerHeight)
      }
      const cornerStartX = this.center ? Math.floor((this.containerWidth - this.ctrlWidth) / 2) : 0
      const cornerStartY = this.center ? Math.floor((this.containerHeight - this.ctrlHeight) / 2) : 0
      this.cutRatio = this.ctrlHeight / this.ctrlWidth
      this.corner = {
        left: cornerStartX,
        right: this.containerWidth - this.ctrlWidth - cornerStartX,
        top: cornerStartY,
        bottom: this.containerHeight - this.ctrlHeight - cornerStartY
      }
    },
    initCut() {
      this.resetCutReact()
      this.initImage()
    },
    async initImage() {

      if (!this.src) return

      const [err, res] = await uni.getImageInfo({
        src: this.src
      })

      if(err) {
        this.$emit("error", err)
      } else {
        this.$emit('load', res)
      }
      // init image size
      this.image.originWidth = err ? this.ctrlWidth : res.width
      this.image.originHeight = err ? this.ctrlHeight : res.height
      this.image.width = this.fit ? this.ctrlWidth : this.image.originWidth
      this.image.height = err ? this.ctrlHeight : res.height / res.width * this.image.width
      this.img = res.path

      const offset = [0, 0]
      if(this.imageCenter) {
        offset[0] = (this.ctrlWidth - this.image.width) / 2
        offset[1] = (this.ctrlHeight - this.image.height) / 2
      }
      offset[0] += this.offset[0] || 0
      offset[1] += this.offset[1] || 0

      this.setTranslate(offset)
      this.setZoom(this.zoom)
      this.transform.angle = this.freeBoundDetect || !this.disableRotate ? this.angle : 0

      this.setBoundary() // boundary detect
      this.preview() // preview
      this.draw()
    },
    init() {
      this.pretouch = {}
      this.handles = {}
      this.preVector = {
        x: 0,
        y: 0
      }
      this.distance = 30
      this.touch = {}
      this.movetouch = {}
      this.cutMode = false
      this.params = {
        zoom: 1,
        deltaX: 0,
        deltaY: 0,
        diffX: 0,
        diffY: 0,
        angle: 0
      }
    },
    start(e) {
      if(!this.src) e.preventDefault()
      const point = e.touches ? e.touches[0] : e
      const touch = this.touch
      const now = Date.now()
      touch.startX = point.pageX
      touch.startY = point.pageY
      touch.startTime = now
      this.doubleTap = false
      this.view = false
      clearTimeout(this.previewTimer)
      if (e.touches.length > 1) {
        var point2 = e.touches[1]
        this.preVector = {
          x: point2.pageX - this.touch.startX,
          y: point2.pageY - this.touch.startY
        }
        this.startDistance = calcLen(this.preVector)
      } else {
        let pretouch = this.pretouch
        this.doubleTap = this.pretouch.time && now - this.pretouch.time < 300 && ABS(touch.startX - pretouch.startX) < 30 && ABS(touch.startY - pretouch.startY) < 30 && ABS(touch.startTime - pretouch.time) < 300
        pretouch = { // reserve the last touch
          startX: this.touch.startX,
          startY: this.touch.startY,
          time: this.touch.startTime
        }
      }
    },
    move(e) {
      if(!this.src) return
      const point = e.touches ? e.touches[0] : e
      if (e.touches.length > 1) { // multi touch
        const point2 = e.touches[1]
        const v = {
          x: point2.pageX - point.pageX,
          y: point2.pageY - point.pageY
        }

        if (this.preVector.x !== null) {
          if (this.startDistance) { // zoom
            const len = calcLen(v)
            this.params.zoom = calcLen(v) / this.startDistance
            this.startDistance = len
            this.cutMode && !this.disableCtrl ? this.setCut() : !this.disableScale && this.pinch()
          }
          // rotate
          this.params.angle = calcAngle(v, this.preVector)
          this.cutMode && !this.disableCtrl ? this.setCut() : !this.disableRotate && this.rotate()
        }
        this.preVector.x = v.x
        this.preVector.y = v.y
      } else { // translate
        const diffX = point.pageX - this.touch.startX
        const diffY = point.pageY - this.touch.startY
        this.params.diffY = diffY
        this.params.diffX = diffX
        if (this.movetouch.x) {
          this.params.deltaX = point.pageX - this.movetouch.x
          this.params.deltaY = point.pageY - this.movetouch.y
        } else {
          this.params.deltaX = this.params.deltaY = 0
        }
        if (ABS(diffX) > 30 || ABS(diffY) > 30) {
          this.doubleTap = false
        }
        this.cutMode && !this.disableCtrl ? this.setCut() : !this.disableTranslate && this.translate()
        this.movetouch.x = point.pageX
        this.movetouch.y = point.pageY
      }
      !this.cutMode && this.setBoundary()
      if (e.touches.length > 1) {
        e.preventDefault()
      }
    },
    end() {
      this.doubleTap && this.$emit('doubleTap')
      this.cutMode && this.setBoundary()
      this.init()
      !this.disablePreview && this.preview()
      this.draw()
    },
    translate() {
      const transform = this.transform.translate
      const meta = this.params
      transform.x += meta.deltaX
      transform.y += meta.deltaY
    },
    pinch() {
      this.transform.zoom *= this.params.zoom
    },
    rotate() {
      this.transform.angle += this.params.angle
    },
    setZoom(scale) {
      scale = Math.min(Math.max(Number(scale) || 1, this.minZoom), this.maxZoom)
      this.transform.zoom = scale
    },
    setTranslate(offset) {
      if(Array.isArray(offset)) {
        const x = Number(offset[0])
        const y = Number(offset[1])
        this.transform.translate.x = isNaN(x) ? this.transform.translate.x : this.corner.left + x
        this.transform.translate.y = isNaN(y) ? this.transform.translate.y : this.corner.top + y
      }
    },
    setRotate(angle) {
      this.transform.angle = Number(angle) || 0
    },
    setTransform(x, y, angle, scale) {
      this.setTranslate([x, y])
      this.setZoom(scale)
      this.setRotate(angle)
    },
    setCutMode(type) {
      if(!this.src) return
      this.cutMode = true
      this.cutDirection = type
    },
    setCut() {
      const corner = this.corner
      const meta = this.params
      this.setMeta(this.cutDirection, meta) // correct cutter position
      if (this.keepRatio) {
        if (this.cutDirection === 'lt' || this.cutDirection === 'rb') {
          meta.deltaY = meta.deltaX * this.cutRatio
        } else {
          meta.deltaX = meta.deltaY / this.cutRatio
        }
      }
      switch (this.cutDirection) {
        case 'lt':
          corner.top += meta.deltaY
          corner.left += meta.deltaX
          break
        case 'rt':
          corner.top += meta.deltaY
          corner.right -= this.keepRatio ? -meta.deltaX : meta.deltaX
          break
        case 'rb':
          corner.right -= meta.deltaX
          corner.bottom -= meta.deltaY
          break
        case 'lb':
          corner.bottom -= meta.deltaY
          corner.left += this.keepRatio ? -meta.deltaX : meta.deltaX
          break
      }
      this.ctrlWidth = this.containerWidth - corner.left - corner.right
      this.ctrlHeight = this.containerHeight - corner.top - corner.bottom
    },
    setMeta(direction, meta) {
      const {ctrlWidth, ctrlHeight, minWidth, minHeight } = this
      switch(direction) {
        case 'lt':
          if(meta.deltaX > 0 || meta.deltaY > 0) {
            meta.deltaX = Math.min(meta.deltaX, ctrlWidth - minWidth)
            meta.deltaY = Math.min(meta.deltaY, ctrlHeight - minHeight)
          }
          break
        case 'rt':
          if(meta.deltaX < 0 || meta.deltaY > 0) {
            meta.deltaX = Math.max(meta.deltaX, minWidth - ctrlWidth)
            meta.deltaY = Math.min(meta.deltaY, ctrlHeight - minHeight)
          }
          break
        case 'rb':
          if(meta.deltaX < 0 || meta.deltaY < 0) {
            meta.deltaX = Math.max(meta.deltaX, minWidth - ctrlWidth)
            meta.deltaY = Math.max(meta.deltaY, minHeight - ctrlHeight)
          }
          break
        case 'lb':
          if(meta.deltaX > 0 || meta.deltaY < 0) {
            meta.deltaX = Math.min(meta.deltaX, ctrlWidth - minWidth)
            meta.deltaY = Math.max(meta.deltaY, minHeight - ctrlHeight)
          }
          break
      }

    },
    setBoundary() {
      let zoom = this.transform.zoom
      zoom = zoom < this.minZoom ? this.minZoom : (zoom > this.maxZoom ? this.maxZoom : zoom)
      this.transform.zoom = zoom
      if (!this.boundDetect || !this.disableRotate && !this.freeBoundDetect) return true
      const translate = this.transform.translate
      const corner = this.corner
      const minX = corner.left - this.image.width + this.ctrlWidth - this.image.width * (zoom - 1) / 2
      const maxX = corner.left + this.image.width * (zoom - 1) / 2
      const minY = corner.top - this.image.height + this.ctrlHeight - this.image.height * (zoom - 1) / 2
      const maxY = corner.top + this.image.height * (zoom - 1) / 2
      translate.x = Math.floor(translate.x < minX ? minX : (translate.x > maxX ? maxX : translate.x))
      translate.y = Math.floor(translate.y < minY ? minY : (translate.y > maxY ? maxY : translate.y))
    },
    preview() {
      clearTimeout(this.previewTimer)
      this.previewTimer = setTimeout(() => {
        this.view = true
      }, 500)
    },
    draw() {
      // #ifdef MP-ALIPAY
      const context = uni.createCanvasContext(this.canvasId)
      // #endif
      // #ifndef MP-ALIPAY
      const context = uni.createCanvasContext(this.canvasId, this)
      // #endif
      const transform = this.transform
      const corner = this.corner
      const canvasZoom = this.canvasZoom
      const img = this.image
      context.save()
      context.setFillStyle(this.canvasBackground)
      this.$emit('beforeDraw', context, transform) // beforeDraw hook

      const zoom = transform.zoom
      context.fillRect(0, 0, this.ctrlWidth * canvasZoom, this.ctrlHeight * canvasZoom) // clear canvas
      context.translate((transform.translate.x - corner.left + img.width / 2) *canvasZoom, (transform.translate.y - corner.top + img.height / 2) * canvasZoom) // translate the canvas's orgin to the image center
      context.rotate(transform.angle * Math.PI / 180)
      context.translate(-img.width * zoom * 0.5 * canvasZoom, -img.height * zoom * 0.5 * canvasZoom)
      context.drawImage(this.img, 0, 0, img.width * zoom * canvasZoom, img.height * zoom * canvasZoom)
      context.restore()
      this.$emit('afterDraw', context, {
        width: this.ctrlWidth * canvasZoom,
        height: this.ctrlHeight * canvasZoom
      }) // afterDraw hook
      context.draw(false, () => {
        uni.canvasToTempFilePath({
          canvasId: this.canvasId,
          quality: this.quality || 1,
          fileType: this.fileType,
          success: (res) => {
            this.$emit('cropped', res.tempFilePath, {
              originWidth: this.image.originWidth,
              originHeight: this.image.originHeight,
              width: this.ctrlWidth * canvasZoom,
              height: this.ctrlHeight * canvasZoom,
              scale: zoom,
              translate: {
                x: transform.translate.x,
                y: transform.translate.y
              },
              rotate: transform.angle
            }) // draw callback
          }
        }, this)
      })
    }
  }
}