/*
简单使用时：
<template>
  <div class="relic-list">
    <div
      ref="listEl"
      class="the-list"
    >
      <button @click="onClickBtn"></button>
      <div class="content">
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      </div>
    </div>
  </div>
</template>

<script setup>
import { ref, computed, watch, watchEffect, onMounted } from "vue"
import useSmoothSwipe from '@/useFunctions/useSmoothSwipe.js'
import { useWindowSize } from '@vueuse/core'

const listEl = ref(null)
const { width: windowWidth, height: windowHeight } = useWindowSize()
const { haveSwipedThisTime, translateLength } = useSmoothSwipe({
  scrollTargetRef: listEl,
  viewportWidth: windowWidth,
})

function onClickBtn(e) {
  if (!haveSwipedThisTime.value) {
    console.log('button click!')
  }
}
</script>
*/
import { ref, unref, watch, watchEffect, onMounted, onBeforeUnmount } from 'vue'

export default function useSmoothSwipe({
  scrollTargetRef,
  maxTranslateLength,
  viewportWidth = document.documentElement.clientWidth,
  speedFactor = 1,
  damping = 0.003,
  enableAutoMoving = false
} = {}) {
  const isOperating = ref(false)
  const haveSwipedThisTime = ref(false)
  let haveSwipedThisTimeTimeoutId = null
  let lastMoveEventTimeStamp = 0
  let lastCursorPos = 0
  let moveSpeed = ref(0)
  let translateLength = ref(0)
  let maxTranslateLengthInner = Infinity
  let isAutoMoving = ref(false)
  let beginAutoMoveIntervalId = null
  let lastAnimationTimeStamp = 0
  let animationFrameId = null

  //
  watch(moveSpeed, (v) => {
    if (!haveSwipedThisTime.value && v) {
      haveSwipedThisTime.value = true
    }
  })
  watch(isOperating, (v) => {
    if (v) {
      clearTimeout(haveSwipedThisTimeTimeoutId)
      haveSwipedThisTime.value = false
    } else {
      clearTimeout(haveSwipedThisTimeTimeoutId)
      haveSwipedThisTimeTimeoutId = setTimeout(() => {
        haveSwipedThisTime.value = false
      }, 333)
    }
  })

  // compute maxTranslateLengthInner
  watchEffect(() => {
    if (maxTranslateLength) {
      maxTranslateLengthInner = unref(maxTranslateLength) - unref(viewportWidth)
      if (maxTranslateLengthInner < 0) {
        maxTranslateLengthInner = 0
      }
    }
  })

  function computeMaxTranslateLengthInnerByScrollTarget() {
    maxTranslateLengthInner = scrollTargetRef.value.scrollWidth - unref(viewportWidth)
  }

  function onWheel(e) {
    moveSpeed.value += e.deltaY / 200
  }

  function speedUp(v) {
    console.log('sdf')
    moveSpeed.value += v
  }

  /**
   * swipe begin
   */
  function onMouseDown(e) {
    isOperating.value = true
    moveSpeed.value = 0
    lastMoveEventTimeStamp = 0
    lastAnimationTimeStamp = Date.now()
    lastCursorPos = e.clientX
    if (beginAutoMoveIntervalId) {
      clearInterval(beginAutoMoveIntervalId)
      beginAutoMoveIntervalId = null
    }
    if (isAutoMoving.value) {
      isAutoMoving.value = false
    }
  }
  function onTouchStart(e) {
    isOperating.value = true
    moveSpeed.value = 0
    lastMoveEventTimeStamp = 0
    lastAnimationTimeStamp = Date.now()
    lastCursorPos = e.changedTouches[0].clientX
    if (beginAutoMoveIntervalId) {
      clearInterval(beginAutoMoveIntervalId)
      beginAutoMoveIntervalId = null
    }
    if (isAutoMoving.value) {
      isAutoMoving.value = false
    }
  }

  /**
   * swiping
   */
  function onMouseMove(e) {
    if (isOperating.value) {
      // 疯狂操作的极端情况下两个时间戳之间的时差会不合理，甚至为0
      if (lastMoveEventTimeStamp && (e.timeStamp - lastMoveEventTimeStamp > 1)) {
        // 更新speed
        const currentMoveSpeed = - (e.clientX - lastCursorPos) / (e.timeStamp - lastMoveEventTimeStamp) * unref(speedFactor)
        moveSpeed.value = moveSpeed.value * 0.9 + currentMoveSpeed * 0.1
        lastCursorPos = e.clientX
      }
      lastMoveEventTimeStamp = e.timeStamp
    }
  }

  function onTouchMove(e) {
    if (isOperating.value && e.changedTouches.length === 1) {
      // 疯狂操作的极端情况下两个时间戳之间的时差会不合理，甚至为0
      if (lastMoveEventTimeStamp && (e.timeStamp - lastMoveEventTimeStamp > 1)) {
        // 更新speed
        const currentMoveSpeed = - (e.changedTouches[0].clientX - lastCursorPos) / (e.timeStamp - lastMoveEventTimeStamp) * unref(speedFactor)
        moveSpeed.value = moveSpeed.value * 0.9 + currentMoveSpeed * 0.1
        lastCursorPos = e.changedTouches[0].clientX
      }
      lastMoveEventTimeStamp = e.timeStamp
    }
  }

  /**
   * swipe end
   */
  function onMouseUp(e) {
    isOperating.value = false
    e.stopPropagation()
    beginAutoMoveIntervalId = setInterval(() => {
      if (moveSpeed.value === 0 && unref(enableAutoMoving)) {
        isAutoMoving.value = true
      }
    }, 2000)
  }
  function onTouchEnd(e) {
    isOperating.value = false
    beginAutoMoveIntervalId = setInterval(() => {
      if (moveSpeed.value === 0 && unref(enableAutoMoving)) {
        isAutoMoving.value = true
      }
    }, 2000)
  }
  function onMouseLeave() {
    isOperating.value = false
    beginAutoMoveIntervalId = setInterval(() => {
      if (moveSpeed.value === 0 && unref(enableAutoMoving)) {
        isAutoMoving.value = true
      }
    }, 2000)
  }

  function onTouchCancel() {
    isOperating.value = false
    beginAutoMoveIntervalId = setInterval(() => {
      if (moveSpeed.value === 0 && unref(enableAutoMoving)) {
        isAutoMoving.value = true
      }
    }, 2000)
  }

  beginAutoMoveIntervalId = setInterval(() => {
    if (moveSpeed.value === 0 && unref(enableAutoMoving)) {
      isAutoMoving.value = true
    }
  }, 2000)

  watch(isAutoMoving, (vNew) => {
    if (vNew) {
      moveSpeed.value = 0.03
    } else {
      moveSpeed.value = 0
    }
  })
  onBeforeUnmount(() => {
    clearInterval(beginAutoMoveIntervalId)
  })

  // 在每一帧更新镜头速度、位置
  function animationFrameTask() {
    const timeStamp = Date.now()
    const timeElapsed = timeStamp - lastAnimationTimeStamp
    if (!isAutoMoving.value) {
      // 速度减慢
      if (moveSpeed.value > 0) {
        moveSpeed.value -= unref(damping) * timeElapsed
        if (moveSpeed.value < 0) {
          moveSpeed.value = 0
        }
      } else if (moveSpeed.value < 0) {
        moveSpeed.value += unref(damping) * timeElapsed
        if (moveSpeed.value > 0) {
          moveSpeed.value = 0
        }
      }
    }

    // 根据速度更新位置
    translateLength.value += moveSpeed.value * timeElapsed
    if (translateLength.value < 0) {
      translateLength.value = 0
      moveSpeed.value = 0
    } else if (translateLength.value > maxTranslateLengthInner) {
      if (isAutoMoving.value) {
        translateLength.value = 0
      } else {
        translateLength.value = maxTranslateLengthInner
        moveSpeed.value = 0
      }
    }
    lastAnimationTimeStamp = timeStamp
    animationFrameId = requestAnimationFrame(animationFrameTask)
  }
  onMounted(() => {
    animationFrameId = requestAnimationFrame(animationFrameTask)
  })
  onBeforeUnmount(() => {
    cancelAnimationFrame(animationFrameId)
  })

  if (scrollTargetRef) {
    watch(scrollTargetRef, (v) => {
      if (v) {
        v.addEventListener('wheel', onWheel)
        v.addEventListener('mousedown', onMouseDown)
        v.addEventListener('mouseleave', onMouseLeave)
        v.addEventListener('mousemove', onMouseMove)
        v.addEventListener('mouseup', onMouseUp)
        // v.addEventListener('touchstart', onTouchStart)
        // v.addEventListener('touchmove', onTouchMove)
        // v.addEventListener('touchend', onTouchEnd)
        // v.addEventListener('touchcancel', onTouchCancel)
      }
    }, {
      immediate: true,
    })

    watch(translateLength, (v) => {
      scrollTargetRef.value && (scrollTargetRef.value.scrollLeft = v)
    })
  }

  return {
    onWheel,
    onMouseDown,
    onMouseLeave,
    onMouseMove,
    onMouseUp,
    onTouchStart,
    onTouchMove,
    onTouchEnd,
    onTouchCancel,
    translateLength,
    haveSwipedThisTime,
    computeMaxTranslateLengthInnerByScrollTarget,
    speedUp
  }
}