import debounce from 'lodash/debounce'
import classnames from 'classnames'
import Vue from 'vue'
import ref from 'vue-ref'
import { getStyle } from '../../_util/props-util'
import BaseMixin from '../../_util/BaseMixin'
import defaultProps from './default-props'
import initialState from './initial-state'
import {
  getOnDemandLazySlides,
  extractObject,
  initializedState,
  getHeight,
  canGoNext,
  slideHandler,
  changeSlide,
  keyHandler,
  swipeStart,
  swipeMove,
  swipeEnd,
  getPreClones,
  getPostClones,
  getTrackLeft,
  getTrackCSS,
} from './utils/innerSliderUtils'
import Track from './track'
import Dots from './dots'
import { PrevArrow, NextArrow } from './arrows'
import ResizeObserver from 'resize-observer-polyfill'

Vue.use(ref, { name: 'ant-ref' })

function noop () {}

export default {
  props: {
    ...defaultProps,
  },
  mixins: [BaseMixin],
  data () {
    this.preProps = { ...this.$props }
    this.list = null
    this.track = null
    this.callbackTimers = []
    this.clickable = true
    this.debouncedResize = null
    return {
      ...initialState,
      currentSlide: this.initialSlide,
      slideCount: this.children.length,
    }
  },
  methods: {
    listRefHandler (ref) {
      this.list = ref
    },
    trackRefHandler (ref) {
      this.track = ref
    },
    adaptHeight () {
      if (this.adaptiveHeight && this.list) {
        const elem = this.list.querySelector(
          `[data-index="${this.currentSlide}"]`
        )
        this.list.style.height = getHeight(elem) + 'px'
      }
    },
    onWindowResized (setTrackStyle) {
      if (this.debouncedResize) this.debouncedResize.cancel()
      this.debouncedResize = debounce(() => this.resizeWindow(setTrackStyle), 50)
      this.debouncedResize()
    },
    resizeWindow (setTrackStyle = true) {
      if (!this.track) return
      const spec = {
        listRef: this.list,
        trackRef: this.track,
        children: this.children,
        ...this.$props,
        ...this.$data,
      }
      this.updateState(spec, setTrackStyle, () => {
        if (this.autoplay) {
          this.handleAutoPlay('update')
        } else {
          this.pause('paused')
        }
      })
      // animating state should be cleared while resizing, otherwise autoplay stops working
      this.setState({
        animating: false,
      })
      clearTimeout(this.animationEndCallback)
      delete this.animationEndCallback
    },
    updateState (spec, setTrackStyle, callback) {
      const updatedState = initializedState(spec)
      spec = { ...spec, ...updatedState, slideIndex: updatedState.currentSlide }
      const targetLeft = getTrackLeft(spec)
      spec = { ...spec, left: targetLeft }
      const trackStyle = getTrackCSS(spec)
      if (
        setTrackStyle ||
        this.children.length !==
        spec.children.length
      ) {
        updatedState['trackStyle'] = trackStyle
      }
      this.setState(updatedState, callback)
    },
    ssrInit () {
      const children = this.children
      if (this.variableWidth) {
        let trackWidth = 0
        let trackLeft = 0
        const childrenWidths = []
        const preClones = getPreClones({
          ...this.$props,
          ...this.$data,
          slideCount: children.length,
        })
        const postClones = getPostClones({
          ...this.$props,
          ...this.$data,
          slideCount: children.length,
        })
        children.forEach(child => {
          const childWidth = getStyle(child).width.split('px')[0]
          childrenWidths.push(childWidth)
          trackWidth += childWidth
        })
        for (let i = 0; i < preClones; i++) {
          trackLeft += childrenWidths[childrenWidths.length - 1 - i]
          trackWidth += childrenWidths[childrenWidths.length - 1 - i]
        }
        for (let i = 0; i < postClones; i++) {
          trackWidth += childrenWidths[i]
        }
        for (let i = 0; i < this.currentSlide; i++) {
          trackLeft += childrenWidths[i]
        }
        const trackStyle = {
          width: trackWidth + 'px',
          left: -trackLeft + 'px',
        }
        if (this.centerMode) {
          const currentWidth = `${childrenWidths[this.currentSlide]}px`
          trackStyle.left = `calc(${
            trackStyle.left
          } + (100% - ${currentWidth}) / 2 ) `
        }
        this.setState({
          trackStyle,
        })
        return
      }
      const childrenCount = children.length
      const spec = { ...this.$props, ...this.$data, slideCount: childrenCount }
      const slideCount = getPreClones(spec) + getPostClones(spec) + childrenCount
      const trackWidth = 100 / this.slidesToShow * slideCount
      const slideWidth = 100 / slideCount
      let trackLeft =
        -slideWidth *
        (getPreClones(spec) + this.currentSlide) *
        trackWidth /
        100
      if (this.centerMode) {
        trackLeft += (100 - slideWidth * trackWidth / 100) / 2
      }
      const trackStyle = {
        width: trackWidth + '%',
        left: trackLeft + '%',
      }
      this.setState({
        slideWidth: slideWidth + '%',
        trackStyle: trackStyle,
      })
    },
    checkImagesLoad () {
      const images = document.querySelectorAll('.slick-slide img')
      const imagesCount = images.length
      let loadedCount = 0
      Array.prototype.forEach.call(images, image => {
        const handler = () =>
          ++loadedCount && loadedCount >= imagesCount && this.onWindowResized()
        if (!image.onclick) {
          image.onclick = () => image.parentNode.focus()
        } else {
          const prevClickHandler = image.onclick
          image.onclick = () => {
            prevClickHandler()
            image.parentNode.focus()
          }
        }
        if (!image.onload) {
          if (this.$props.lazyLoad) {
            image.onload = () => {
              this.adaptHeight()
              this.callbackTimers.push(
                setTimeout(this.onWindowResized, this.speed)
              )
            }
          } else {
            image.onload = handler
            image.onerror = () => {
              handler()
              this.$emit('lazyLoadError')
            }
          }
        }
      })
    },
    progressiveLazyLoad () {
      const slidesToLoad = []
      const spec = { ...this.$props, ...this.$data }
      for (
        let index = this.currentSlide;
        index < this.slideCount + getPostClones(spec);
        index++
      ) {
        if (this.lazyLoadedList.indexOf(index) < 0) {
          slidesToLoad.push(index)
          break
        }
      }
      for (
        let index = this.currentSlide - 1;
        index >= -getPreClones(spec);
        index--
      ) {
        if (this.lazyLoadedList.indexOf(index) < 0) {
          slidesToLoad.push(index)
          break
        }
      }
      if (slidesToLoad.length > 0) {
        this.setState(state => ({
          lazyLoadedList: state.lazyLoadedList.concat(slidesToLoad),
        }))
        this.$emit('lazyLoad', slidesToLoad)
      } else {
        if (this.lazyLoadTimer) {
          clearInterval(this.lazyLoadTimer)
          delete this.lazyLoadTimer
        }
      }
    },
    slideHandler (index, dontAnimate = false) {
      const {
        asNavFor,
        currentSlide,
        beforeChange,
        speed,
        afterChange,
      } = this.$props
      const { state, nextState } = slideHandler({
        index,
        ...this.$props,
        ...this.$data,
        trackRef: this.track,
        useCSS: this.useCSS && !dontAnimate,
      })
      if (!state) return
      beforeChange && beforeChange(currentSlide, state.currentSlide)
      const slidesToLoad = state.lazyLoadedList.filter(
        value => this.lazyLoadedList.indexOf(value) < 0
      )
      if (this.$listeners.lazyLoad && slidesToLoad.length > 0) {
        this.$emit('lazyLoad', slidesToLoad)
      }
      this.setState(state, () => {
        asNavFor &&
          asNavFor.innerSlider.currentSlide !== currentSlide &&
          asNavFor.innerSlider.slideHandler(index)
        if (!nextState) return
        this.animationEndCallback = setTimeout(() => {
          const { animating, ...firstBatch } = nextState
          this.setState(firstBatch, () => {
            this.callbackTimers.push(
              setTimeout(() => this.setState({ animating }), 10)
            )
            afterChange && afterChange(state.currentSlide)
            delete this.animationEndCallback
          })
        }, speed)
      })
    },
    changeSlide (options, dontAnimate = false) {
      const spec = { ...this.$props, ...this.$data }
      const targetSlide = changeSlide(spec, options)
      if (targetSlide !== 0 && !targetSlide) return
      if (dontAnimate === true) {
        this.slideHandler(targetSlide, dontAnimate)
      } else {
        this.slideHandler(targetSlide)
      }
    },
    clickHandler (e) {
      if (this.clickable === false) {
        e.stopPropagation()
        e.preventDefault()
      }
      this.clickable = true
    },
    keyHandler (e) {
      const dir = keyHandler(e, this.accessibility, this.rtl)
      dir !== '' && this.changeSlide({ message: dir })
    },
    selectHandler (options) {
      this.changeSlide(options)
    },
    disableBodyScroll () {
      const preventDefault = e => {
        e = e || window.event
        if (e.preventDefault) e.preventDefault()
        e.returnValue = false
      }
      window.ontouchmove = preventDefault
    },
    enableBodyScroll () {
      window.ontouchmove = null
    },
    swipeStart (e) {
      if (this.verticalSwiping) {
        this.disableBodyScroll()
      }
      const state = swipeStart(e, this.swipe, this.draggable)
      state !== '' && this.setState(state)
    },
    swipeMove (e) {
      const state = swipeMove(e, {
        ...this.$props,
        ...this.$data,
        trackRef: this.track,
        listRef: this.list,
        slideIndex: this.currentSlide,
      })
      if (!state) return
      if (state['swiping']) {
        this.clickable = false
      }
      this.setState(state)
    },
    swipeEnd (e) {
      const state = swipeEnd(e, {
        ...this.$props,
        ...this.$data,
        trackRef: this.track,
        listRef: this.list,
        slideIndex: this.currentSlide,
      })
      if (!state) return
      const triggerSlideHandler = state['triggerSlideHandler']
      delete state['triggerSlideHandler']
      this.setState(state)
      if (triggerSlideHandler === undefined) return
      this.slideHandler(triggerSlideHandler)
      if (this.$props.verticalSwiping) {
        this.enableBodyScroll()
      }
    },
    slickPrev () {
      // this and fellow methods are wrapped in setTimeout
      // to make sure initialize setState has happened before
      // any of such methods are called
      this.callbackTimers.push(
        setTimeout(() => this.changeSlide({ message: 'previous' }), 0)
      )
    },
    slickNext () {
      this.callbackTimers.push(
        setTimeout(() => this.changeSlide({ message: 'next' }), 0)
      )
    },
    slickGoTo (slide, dontAnimate = false) {
      slide = Number(slide)
      if (isNaN(slide)) return ''
      this.callbackTimers.push(
        setTimeout(
          () =>
            this.changeSlide(
              {
                message: 'index',
                index: slide,
                currentSlide: this.currentSlide,
              },
              dontAnimate
            ),
          0
        )
      )
    },
    play () {
      let nextIndex
      if (this.rtl) {
        nextIndex = this.currentSlide - this.slidesToScroll
      } else {
        if (canGoNext({ ...this.$props, ...this.$data })) {
          nextIndex = this.currentSlide + this.slidesToScroll
        } else {
          return false
        }
      }

      this.slideHandler(nextIndex)
    },
    handleAutoPlay (playType) {
      if (this.autoplayTimer) {
        clearInterval(this.autoplayTimer)
      }
      const autoplaying = this.autoplaying
      if (playType === 'update') {
        if (
          autoplaying === 'hovered' ||
          autoplaying === 'focused' ||
          autoplaying === 'paused'
        ) {
          return
        }
      } else if (playType === 'leave') {
        if (autoplaying === 'paused' || autoplaying === 'focused') {
          return
        }
      } else if (playType === 'blur') {
        if (autoplaying === 'paused' || autoplaying === 'hovered') {
          return
        }
      }
      this.autoplayTimer = setInterval(this.play, this.autoplaySpeed + 50)
      this.setState({ autoplaying: 'playing' })
    },
    pause (pauseType) {
      if (this.autoplayTimer) {
        clearInterval(this.autoplayTimer)
        this.autoplayTimer = null
      }
      const autoplaying = this.autoplaying
      if (pauseType === 'paused') {
        this.setState({ autoplaying: 'paused' })
      } else if (pauseType === 'focused') {
        if (autoplaying === 'hovered' || autoplaying === 'playing') {
          this.setState({ autoplaying: 'focused' })
        }
      } else {
        // pauseType  is 'hovered'
        if (autoplaying === 'playing') {
          this.setState({ autoplaying: 'hovered' })
        }
      }
    },
    onDotsOver () {
      this.autoplay && this.pause('hovered')
    },
    onDotsLeave () {
      this.autoplay &&
      this.autoplaying === 'hovered' &&
      this.handleAutoPlay('leave')
    },
    onTrackOver () {
      this.autoplay && this.pause('hovered')
    },
    onTrackLeave () {
      this.autoplay &&
      this.autoplaying === 'hovered' &&
      this.handleAutoPlay('leave')
    },
    onSlideFocus () {
      this.autoplay && this.pause('focused')
    },
    onSlideBlur () {
      this.autoplay &&
      this.autoplaying === 'focused' &&
      this.handleAutoPlay('blur')
    },
    customPaging ({ i }) {
      return <button>{i + 1}</button>
    },
    appendDots ({ dots }) {
      return <ul style={{ display: 'block' }}>{dots}</ul>
    },
  },
  beforeMount () {
    this.ssrInit()
    this.$emit('init')
    if (this.lazyLoad) {
      const slidesToLoad = getOnDemandLazySlides({
        ...this.$props,
        ...this.$data,
      })
      if (slidesToLoad.length > 0) {
        this.setState(prevState => ({
          lazyLoadedList: prevState.lazyLoadedList.concat(slidesToLoad),
        }))
        this.$emit('lazyLoad', slidesToLoad)
      }
    }
  },
  mounted () {
    this.$nextTick(() => {
      const spec = {
        listRef: this.list,
        trackRef: this.track,
        children: this.children,
        ...this.$props,
      }
      this.updateState(spec, true, () => {
        this.adaptHeight()
        this.autoplay && this.handleAutoPlay('update')
      })
      if (this.lazyLoad === 'progressive') {
        this.lazyLoadTimer = setInterval(this.progressiveLazyLoad, 1000)
      }
      this.ro = new ResizeObserver(() => {
        if (this.animating) {
          this.onWindowResized(false) // don't set trackStyle hence don't break animation
          this.callbackTimers.push(
            setTimeout(() => this.onWindowResized(), this.speed)
          )
        } else {
          this.onWindowResized()
        }
      })
      this.ro.observe(this.list)
      Array.prototype.forEach.call(
        document.querySelectorAll('.slick-slide'),
        slide => {
          slide.onfocus = this.$props.pauseOnFocus ? this.onSlideFocus : null
          slide.onblur = this.$props.pauseOnFocus ? this.onSlideBlur : null
        }
      )
      // To support server-side rendering
      if (!window) {
        return
      }
      if (window.addEventListener) {
        window.addEventListener('resize', this.onWindowResized)
      } else {
        window.attachEvent('onresize', this.onWindowResized)
      }
    })
  },
  beforeDestroy () {
    if (this.animationEndCallback) {
      clearTimeout(this.animationEndCallback)
    }
    if (this.lazyLoadTimer) {
      clearInterval(this.lazyLoadTimer)
    }
    if (this.callbackTimers.length) {
      this.callbackTimers.forEach(timer => clearTimeout(timer))
      this.callbackTimers = []
    }
    if (window.addEventListener) {
      window.removeEventListener('resize', this.onWindowResized)
    } else {
      window.detachEvent('onresize', this.onWindowResized)
    }
    if (this.autoplayTimer) {
      clearInterval(this.autoplayTimer)
    }
  },
  updated () {
    this.checkImagesLoad()
    this.$emit('reInit')
    if (this.lazyLoad) {
      const slidesToLoad = getOnDemandLazySlides({
        ...this.$props,
        ...this.$data,
      })
      if (slidesToLoad.length > 0) {
        this.setState(prevState => ({
          lazyLoadedList: prevState.lazyLoadedList.concat(slidesToLoad),
        }))
        this.$emit('lazyLoad')
      }
    }
    // if (this.props.onLazyLoad) {
    //   this.props.onLazyLoad([leftMostSlide])
    // }
    this.adaptHeight()
  },
  watch: {
    __propsSymbol__ () {
      const nextProps = this.$props
      const spec = {
        listRef: this.list,
        trackRef: this.track,
        ...nextProps,
        ...this.$data,
      }
      let setTrackStyle = false
      for (const key of Object.keys(this.preProps)) {
        if (!nextProps.hasOwnProperty(key)) {
          setTrackStyle = true
          break
        }
        if (
          typeof nextProps[key] === 'object' ||
          typeof nextProps[key] === 'function' ||
          typeof nextProps[key] === 'symbol'
        ) {
          continue
        }
        if (nextProps[key] !== this.preProps[key]) {
          setTrackStyle = true
          break
        }
      }
      this.updateState(spec, setTrackStyle, () => {
        if (this.currentSlide >= nextProps.children.length) {
          this.changeSlide({
            message: 'index',
            index: nextProps.children.length - nextProps.slidesToShow,
            currentSlide: this.currentSlide,
          })
        }
        if (nextProps.autoplay) {
          this.handleAutoPlay('update')
        } else {
          this.pause('paused')
        }
      })
      this.preProps = { ...nextProps }
    },
  },
  render () {
    const className = classnames('slick-slider', {
      'slick-vertical': this.vertical,
      'slick-initialized': true,
    })
    const spec = { ...this.$props, ...this.$data }
    let trackProps = extractObject(spec, [
      'fade',
      'cssEase',
      'speed',
      'infinite',
      'centerMode',
      'focusOnSelect',
      'currentSlide',
      'lazyLoad',
      'lazyLoadedList',
      'rtl',
      'slideWidth',
      'slideHeight',
      'listHeight',
      'vertical',
      'slidesToShow',
      'slidesToScroll',
      'slideCount',
      'trackStyle',
      'variableWidth',
      'unslick',
      'centerPadding',
    ])
    const { pauseOnHover } = this.$props
    trackProps = {
      props: {
        ...trackProps,
        focusOnSelect: this.focusOnSelect ? this.selectHandler : null,
      },
      directives: [{
        name: 'ant-ref',
        value: this.trackRefHandler,
      }],
      on: {
        mouseenter: pauseOnHover ? this.onTrackOver : noop,
        mouseleave: pauseOnHover ? this.onTrackLeave : noop,
        mouseover: pauseOnHover ? this.onTrackOver : noop,
      },
    }

    let dots
    if (
      this.dots === true &&
      this.slideCount >= this.slidesToShow
    ) {
      let dotProps = extractObject(spec, [
        'dotsClass',
        'slideCount',
        'slidesToShow',
        'currentSlide',
        'slidesToScroll',
        'clickHandler',
        'children',
        'infinite',
        'appendDots',
      ])
      dotProps.customPaging = this.customPaging
      dotProps.appendDots = this.appendDots
      const { customPaging, appendDots } = this.$scopedSlots
      if (customPaging) {
        dotProps.customPaging = customPaging
      }
      if (appendDots) {
        dotProps.appendDots = appendDots
      }
      const { pauseOnDotsHover } = this.$props
      dotProps = {
        props: {
          ...dotProps,
          clickHandler: this.changeSlide,
        },
        on: {
          mouseenter: pauseOnDotsHover ? this.onDotsLeave : noop,
          mouseover: pauseOnDotsHover ? this.onDotsOver : noop,
          mouseleave: pauseOnDotsHover ? this.onDotsLeave : noop,
        },
      }
      dots = <Dots {...dotProps} />
    }

    let prevArrow, nextArrow
    const arrowProps = extractObject(spec, [
      'infinite',
      'centerMode',
      'currentSlide',
      'slideCount',
      'slidesToShow',
    ])
    arrowProps.clickHandler = this.changeSlide
    const { prevArrow: prevArrowCustom, nextArrow: nextArrowCustom } = this.$scopedSlots
    if (prevArrowCustom) {
      arrowProps.prevArrow = prevArrowCustom
    }
    if (nextArrowCustom) {
      arrowProps.nextArrow = nextArrowCustom
    }
    if (this.arrows) {
      prevArrow = <PrevArrow {...{ props: arrowProps }} />
      nextArrow = <NextArrow {...{ props: arrowProps }} />
    }
    let verticalHeightStyle = null

    if (this.vertical) {
      verticalHeightStyle = {
        height: typeof this.listHeight === 'number' ? `${this.listHeight}px` : this.listHeight,
      }
    }

    let centerPaddingStyle = null

    if (this.vertical === false) {
      if (this.centerMode === true) {
        centerPaddingStyle = {
          padding: '0px ' + this.centerPadding,
        }
      }
    } else {
      if (this.centerMode === true) {
        centerPaddingStyle = {
          padding: this.centerPadding + ' 0px',
        }
      }
    }

    const listStyle = { ...verticalHeightStyle, ...centerPaddingStyle }
    const touchMove = this.touchMove
    let listProps = {
      directives: [{
        name: 'ant-ref',
        value: this.listRefHandler,
      }],
      class: 'slick-list',
      style: listStyle,
      on: {
        click: this.clickHandler,
        mousedown: touchMove ? this.swipeStart : noop,
        mousemove: this.dragging && touchMove ? this.swipeMove : noop,
        mouseup: touchMove ? this.swipeEnd : noop,
        mouseleave: this.dragging && touchMove ? this.swipeEnd : noop,
        touchstart: touchMove ? this.swipeStart : noop,
        touchmove: this.dragging && touchMove ? this.swipeMove : noop,
        touchend: touchMove ? this.swipeEnd : noop,
        touchcancel: this.dragging && touchMove ? this.swipeEnd : noop,
        keydown: this.accessibility ? this.keyHandler : noop,
      },
    }

    let innerSliderProps = {
      class: className,
      props: {
        dir: 'ltr',
      },
    }

    if (this.unslick) {
      listProps = {
        class: 'slick-list',
        directives: [{
          name: 'ant-ref',
          value: this.listRefHandler,
        }],
      }
      innerSliderProps = { class: className }
    }
    return (
      <div {...innerSliderProps}>
        {!this.unslick ? prevArrow : ''}
        <div {...listProps}>
          <Track {...trackProps}>
            {this.children}
          </Track>
        </div>
        {!this.unslick ? nextArrow : ''}
        {!this.unslick ? dots : ''}
      </div>
    )
  },
}