import React, { useState, useEffect, useRef } from 'react'
import { View, Text, ScrollView } from '@tarojs/components'
import { CommonPopup } from '../index'
import styles from './index.module.scss'

export interface TimePickerProps {
  visible: boolean
  onClose: () => void
  onConfirm: (year: number, month: number) => void
  defaultYear?: number
  defaultMonth?: number
  minYear?: number
  maxYear?: number
}

const TimePicker: React.FC<TimePickerProps> = ({
  visible,
  onClose,
  onConfirm,
  defaultYear = new Date().getFullYear(),
  defaultMonth = new Date().getMonth() + 1,
  minYear = 2020,
  maxYear = 2030
}) => {
  const [selectedYear, setSelectedYear] = useState(defaultYear)
  const [selectedMonth, setSelectedMonth] = useState(defaultMonth)
  const [yearScrollTop, setYearScrollTop] = useState(0)
  const [monthScrollTop, setMonthScrollTop] = useState(0)
  
  const yearScrollRef = useRef<any>(null)
  const monthScrollRef = useRef<any>(null)
  
  // 计算当前选项在数组中的索引
  const getYearIndex = (year: number) => year - minYear
  const getMonthIndex = (month: number) => month - 1

  // 生成选择器的选项数据
  const yearOptions = Array.from({ length: maxYear - minYear + 1 }, (_, index) => ({
    text: `${minYear + index}年`,
    value: minYear + index
  }))
  
  const monthOptions = Array.from({ length: 12 }, (_, index) => ({
    text: `${index + 1}月`,
    value: index + 1
  }))

  // 计算滚动位置 - 确保每次只显示一个选项
  const calculateScrollTop = (index: number) => {
    const itemHeight = 48 // 每个选项的高度
    const containerHeight = 216 // 容器高度
    const centerOffset = (containerHeight - itemHeight) / 2
    return index * itemHeight - centerOffset
  }

  // 获取当前可见的选项数量
  const getVisibleItemCount = () => {
    const containerHeight = 216
    const itemHeight = 48
    return Math.floor(containerHeight / itemHeight)
  }

  useEffect(() => {
    if (visible) {
      setSelectedYear(defaultYear)
      setSelectedMonth(defaultMonth)
      
      // 设置初始滚动位置
      const yearScrollTop = calculateScrollTop(getYearIndex(defaultYear))
      const monthScrollTop = calculateScrollTop(getMonthIndex(defaultMonth))
      setYearScrollTop(yearScrollTop)
      setMonthScrollTop(monthScrollTop)
    }
  }, [visible, defaultYear, defaultMonth])

  // 处理年份滚动
  const handleYearScroll = (event: any) => {
    const scrollTop = event.detail.scrollTop
    const itemHeight = 48
    const containerHeight = 216
    const centerOffset = (containerHeight - itemHeight) / 2
    
    // 计算当前选中的年份索引
    const currentIndex = Math.round((scrollTop + centerOffset) / itemHeight)
    const clampedIndex = Math.max(0, Math.min(currentIndex, yearOptions.length - 1))
    const newYear = minYear + clampedIndex
    
    if (newYear !== selectedYear) {
      setSelectedYear(newYear)
    }
  }

  // 处理年份滚动结束，自动对齐
  const handleYearScrollEnd = () => {
    const yearIndex = getYearIndex(selectedYear)
    const alignedScrollTop = calculateScrollTop(yearIndex)
    // 使用setTimeout确保滚动动画完成后再对齐
    setTimeout(() => {
      setYearScrollTop(alignedScrollTop)
    }, 100)
  }

  // 处理月份滚动
  const handleMonthScroll = (event: any) => {
    const scrollTop = event.detail.scrollTop
    const itemHeight = 48
    const containerHeight = 216
    const centerOffset = (containerHeight - itemHeight) / 2
    
    // 计算当前选中的月份索引
    const currentIndex = Math.round((scrollTop + centerOffset) / itemHeight)
    const clampedIndex = Math.max(0, Math.min(currentIndex, monthOptions.length - 1))
    const newMonth = clampedIndex + 1
    
    if (newMonth !== selectedMonth) {
      setSelectedMonth(newMonth)
    }
  }

  // 处理月份滚动结束，自动对齐
  const handleMonthScrollEnd = () => {
    const monthIndex = getMonthIndex(selectedMonth)
    const alignedScrollTop = calculateScrollTop(monthIndex)
    // 使用setTimeout确保滚动动画完成后再对齐
    setTimeout(() => {
      setMonthScrollTop(alignedScrollTop)
    }, 100)
  }

  const handleConfirm = () => {
    onConfirm(selectedYear, selectedMonth)
    onClose()
  }

  if (!visible) return null

  return (
    <CommonPopup
      visible={visible}
      onClose={onClose}
      onConfirm={handleConfirm}
      showHeader={false}
      hideFooter={false}
      cancelText="返回"
      confirmText="完成"
      position="bottom"
      round={true}
      className={styles['time-picker-popup']}
    >
      {/* 拖拽手柄 */}
      <View className={styles['popup-handle']} />
      
      {/* 时间选择器 */}
      <View className={styles['picker-container']}>
        {/* 自定义多列选择器 */}
        <View className={styles['picker-wrapper']}>
          <View className={styles['custom-picker']}>
            {/* 选中项指示器 */}
            <View className={styles['picker-indicator']} />
            
            {/* 年份列 */}
            <View className={styles['picker-column']}>
              <ScrollView
                ref={yearScrollRef}
                scrollY
                scrollTop={yearScrollTop}
                onScroll={handleYearScroll}
                onTouchEnd={handleYearScrollEnd}
                onScrollToLower={handleYearScrollEnd}
                onScrollToUpper={handleYearScrollEnd}
                className={styles['picker-scroll']}
                scrollWithAnimation={true}
                enhanced={true}
                showScrollbar={false}
                bounces={false}
                fastDeceleration={true}
              >
                <View className={styles['picker-padding']} />
                {yearOptions.map((option, index) => (
                  <View 
                    key={option.value} 
                    className={`${styles['picker-item']} ${
                      option.value === selectedYear ? styles['picker-item-active'] : ''
                    }`}
                    data-value={option.value}
                  >
                    <Text className={styles['picker-item-text']}>{option.text}</Text>
                  </View>
                ))}
                <View className={styles['picker-padding']} />
              </ScrollView>
            </View>
            
            {/* 月份列 */}
            <View className={styles['picker-column']}>
              <ScrollView
                ref={monthScrollRef}
                scrollY
                scrollTop={monthScrollTop}
                onScroll={handleMonthScroll}
                onTouchEnd={handleMonthScrollEnd}
                onScrollToLower={handleMonthScrollEnd}
                onScrollToUpper={handleMonthScrollEnd}
                className={styles['picker-scroll']}
                scrollWithAnimation={true}
                enhanced={true}
                showScrollbar={false}
                bounces={false}
                fastDeceleration={true}
              >
                <View className={styles['picker-padding']} />
                {monthOptions.map((option, index) => (
                  <View 
                    key={option.value} 
                    className={`${styles['picker-item']} ${
                      option.value === selectedMonth ? styles['picker-item-active'] : ''
                    }`}
                    data-value={option.value}
                  >
                    <Text className={styles['picker-item-text']}>{option.text}</Text>
                  </View>
                ))}
                <View className={styles['picker-padding']} />
              </ScrollView>
            </View>
          </View>
        </View>
      </View>
    </CommonPopup>
  )
}

export default TimePicker