import classnames from 'classnames'
import { cloneElement } from '../../_util/vnode'
import { getStyle, getClass } from '../../_util/props-util'
import {
  lazyStartIndex,
  lazyEndIndex,
  getPreClones,
} from './utils/innerSliderUtils'

// given specifications/props for a slide, fetch all the classes that need to be applied to the slide
const getSlideClasses = spec => {
  let slickActive, slickCenter
  let centerOffset, index

  if (spec.rtl) {
    index = spec.slideCount - 1 - spec.index
  } else {
    index = spec.index
  }
  const slickCloned = index < 0 || index >= spec.slideCount
  if (spec.centerMode) {
    centerOffset = Math.floor(spec.slidesToShow / 2)
    slickCenter = (index - spec.currentSlide) % spec.slideCount === 0
    if (
      index > spec.currentSlide - centerOffset - 1 &&
      index <= spec.currentSlide + centerOffset
    ) {
      slickActive = true
    }
  } else {
    slickActive =
      spec.currentSlide <= index &&
      index < spec.currentSlide + spec.slidesToShow
  }
  const slickCurrent = index === spec.currentSlide
  return {
    'slick-slide': true,
    'slick-active': slickActive,
    'slick-center': slickCenter,
    'slick-cloned': slickCloned,
    'slick-current': slickCurrent, // dubious in case of RTL
  }
}

const getSlideStyle = function (spec) {
  const style = {}

  if (spec.variableWidth === undefined || spec.variableWidth === false) {
    style.width = spec.slideWidth + (typeof spec.slideWidth === 'number' ? 'px' : '')
  }

  if (spec.fade) {
    style.position = 'relative'
    if (spec.vertical) {
      style.top = -spec.index * parseInt(spec.slideHeight) + 'px'
    } else {
      style.left = -spec.index * parseInt(spec.slideWidth) + 'px'
    }
    style.opacity = spec.currentSlide === spec.index ? 1 : 0
    style.transition =
      'opacity ' +
      spec.speed +
      'ms ' +
      spec.cssEase +
      ', ' +
      'visibility ' +
      spec.speed +
      'ms ' +
      spec.cssEase
    style.WebkitTransition =
      'opacity ' +
      spec.speed +
      'ms ' +
      spec.cssEase +
      ', ' +
      'visibility ' +
      spec.speed +
      'ms ' +
      spec.cssEase
  }

  return style
}

const getKey = (child, fallbackKey) => child.key || (child.key === 0 && '0') || fallbackKey

const renderSlides = function (spec, children, createElement) {
  let key
  const slides = []
  const preCloneSlides = []
  const postCloneSlides = []
  const childrenCount = children.length
  const startIndex = lazyStartIndex(spec)
  const endIndex = lazyEndIndex(spec)

  children.forEach((elem, index) => {
    let child
    const childOnClickOptions = {
      message: 'children',
      index: index,
      slidesToScroll: spec.slidesToScroll,
      currentSlide: spec.currentSlide,
    }

    // in case of lazyLoad, whether or not we want to fetch the slide
    if (
      !spec.lazyLoad ||
      (spec.lazyLoad && spec.lazyLoadedList.indexOf(index) >= 0)
    ) {
      child = elem
    } else {
      child = createElement('div')
    }
    const childStyle = getSlideStyle({ ...spec, index })
    const slideClass = getClass(child.context) || ''
    let slideClasses = getSlideClasses({ ...spec, index })
    // push a cloned element of the desired slide
    slides.push(
      cloneElement(child, {
        key: 'original' + getKey(child, index),
        attrs: {
          tabIndex: '-1',
          'data-index': index,
          'aria-hidden': !slideClasses['slick-active'],
        },
        class: classnames(slideClasses, slideClass),
        style: { outline: 'none', ...(getStyle(child.context) || {}), ...childStyle },
        on: {
          click: e => {
            // child.props && child.props.onClick && child.props.onClick(e)
            if (spec.focusOnSelect) {
              spec.focusOnSelect(childOnClickOptions)
            }
          },
        },
      }, true)
    )

    // if slide needs to be precloned or postcloned
    if (spec.infinite && spec.fade === false) {
      const preCloneNo = childrenCount - index
      if (
        preCloneNo <= getPreClones(spec) &&
        childrenCount !== spec.slidesToShow
      ) {
        key = -preCloneNo
        if (key >= startIndex) {
          child = elem
        }
        slideClasses = getSlideClasses({ ...spec, index: key })
        preCloneSlides.push(
          cloneElement(child, {
            key: 'precloned' + getKey(child, key),
            class: classnames(slideClasses, slideClass),
            attrs: {
              tabIndex: '-1',
              'data-index': key,
              'aria-hidden': !slideClasses['slick-active'],
            },
            style: { ...(getStyle(child.context) || {}), ...childStyle },
            on: {
              click: e => {
                // child.props && child.props.onClick && child.props.onClick(e)
                if (spec.focusOnSelect) {
                  spec.focusOnSelect(childOnClickOptions)
                }
              },
            },
          })
        )
      }

      if (childrenCount !== spec.slidesToShow) {
        key = childrenCount + index
        if (key < endIndex) {
          child = elem
        }
        slideClasses = getSlideClasses({ ...spec, index: key })
        postCloneSlides.push(
          cloneElement(child, {
            key: 'postcloned' + getKey(child, key),
            attrs: {
              tabIndex: '-1',
              'data-index': key,
              'aria-hidden': !slideClasses['slick-active'],
            },
            class: classnames(slideClasses, slideClass),
            style: { ...(getStyle(child.context) || {}), ...childStyle },
            on: {
              click: e => {
                // child.props && child.props.onClick && child.props.onClick(e)
                if (spec.focusOnSelect) {
                  spec.focusOnSelect(childOnClickOptions)
                }
              },
            },
          })
        )
      }
    }
  })
  if (spec.rtl) {
    return preCloneSlides.concat(slides, postCloneSlides).reverse()
  } else {
    return preCloneSlides.concat(slides, postCloneSlides)
  }
}

export default {
  functional: true,
  render (createElement, context) {
    const { props, listeners, children, data } = context
    const slides = renderSlides(props, children, createElement)
    const { mouseenter, mouseover, mouseleave } = listeners
    const mouseEvents = { mouseenter, mouseover, mouseleave }
    const trackProps = {
      class: 'slick-track',
      style: props.trackStyle,
      on: {
        ...mouseEvents,
      },
      directives: data.directives,
    }
    return (
      <div
        {...trackProps}
      >
        {slides}
      </div>
    )
  },
}