import React, { useRef, useEffect, useCallback } from 'react'
import {
  View,
  Text,
  Pressable,
  ScrollView,
  StyleSheet,
  ViewStyle,
  Dimensions,
  LayoutChangeEvent,
} from 'react-native'
import { DownArrowIcon } from '@/components/icon'

const SCREEN_WIDTH = Dimensions.get('window').width
const ARROW_WIDTH = 48 // 箭头按钮宽度 (padding 8 * 2 + icon ~24 + marginLeft 8)
const HORIZONTAL_PADDING = 16

interface TabNavigationProps {
  tabs: string[]
  activeIndex: number
  onTabPress: (index: number) => void
  showArrow?: boolean
  onArrowPress?: () => void
  isSticky?: boolean
  wrapperStyle?: ViewStyle
  onLayout?: (y: number, height: number) => void
}

export function TabNavigation({
  tabs,
  activeIndex,
  onTabPress,
  showArrow = false,
  onArrowPress,
  isSticky = false,
  wrapperStyle,
  onLayout,
}: TabNavigationProps): JSX.Element {
  const scrollViewRef = useRef<ScrollView>(null)
  const tabLayouts = useRef<{ x: number; width: number }[]>([])

  // 计算可用的滚动区域宽度
  const scrollAreaWidth = SCREEN_WIDTH - HORIZONTAL_PADDING * 2 - (showArrow ? ARROW_WIDTH : 0)

  // 滚动到激活的 tab 使其居中
  const scrollToActiveTab = useCallback((index: number) => {
    const layout = tabLayouts.current[index]
    if (!layout || !scrollViewRef.current) return

    // 计算让 tab 居中需要的滚动位置
    const tabCenter = layout.x + layout.width / 2
    const scrollX = tabCenter - scrollAreaWidth / 2

    scrollViewRef.current.scrollTo({
      x: Math.max(0, scrollX),
      animated: true,
    })
  }, [scrollAreaWidth])

  // 当 activeIndex 变化时滚动
  useEffect(() => {
    // 延迟执行确保布局已完成
    const timer = setTimeout(() => {
      scrollToActiveTab(activeIndex)
    }, 50)
    return () => clearTimeout(timer)
  }, [activeIndex, scrollToActiveTab])

  // 记录每个 tab 的布局
  const handleTabLayout = useCallback((index: number, event: LayoutChangeEvent) => {
    const { x, width } = event.nativeEvent.layout
    tabLayouts.current[index] = { x, width }
  }, [])

  return (
    <View
      testID="tab-navigation"
      style={[
        styles.tabsWrapper,
        isSticky && styles.stickyWrapper,
        wrapperStyle,
      ]}
      onLayout={(e) => {
        const { y, height } = e.nativeEvent.layout
        onLayout?.(y, height)
      }}
    >
      <View style={styles.tabsContainer}>
        <ScrollView
          ref={scrollViewRef}
          horizontal
          showsHorizontalScrollIndicator={false}
          contentContainerStyle={styles.tabsScrollContent}
        >
          {tabs.map((tab, index) => (
            <Pressable
              key={index}
              testID={`tab-${index}`}
              style={[styles.tab, activeIndex === index && styles.activeTab]}
              onPress={() => onTabPress(index)}
              onLayout={(e) => handleTabLayout(index, e)}
            >
              <Text
                style={[
                  styles.tabText,
                  activeIndex === index && styles.activeTabText,
                ]}
              >
                {tab}
              </Text>
            </Pressable>
          ))}
        </ScrollView>
        {showArrow && (
          <Pressable
            testID="tab-arrow"
            style={styles.tabArrow}
            onPress={onArrowPress}
          >
            <DownArrowIcon />
          </Pressable>
        )}
      </View>
    </View>
  )
}

const styles = StyleSheet.create({
  tabsWrapper: {
    paddingHorizontal: 16,
    paddingVertical: 8,
    backgroundColor: '#090A0B',
  },
  stickyWrapper: {
    position: 'absolute',
    top: 0,
    left: 0,
    right: 0,
    zIndex: 100,
  },
  tabsContainer: {
    flexDirection: 'row',
    alignItems: 'center',
  },
  tabsScrollContent: {
    gap: 8,
  },
  tab: {
    paddingHorizontal: 16,
    paddingVertical: 8,
    borderRadius: 20,
    backgroundColor: '#1C1E22',
  },
  activeTab: {
    backgroundColor: '#F5F5F5',
  },
  tabText: {
    color: '#F5F5F5',
    fontSize: 14,
    fontWeight: '500',
  },
  activeTabText: {
    color: '#090A0B',
  },
  tabArrow: {
    marginLeft: 8,
    padding: 8,
    backgroundColor: '#1C1E22',
    borderRadius: 20,
  },
})
