import { NutritionRecordCard } from '@/components/NutritionRecordCard';
import { HeaderBar } from '@/components/ui/HeaderBar';
import { Colors } from '@/constants/Colors';
import { useColorScheme } from '@/hooks/useColorScheme';
import { DietRecord, getDietRecords } from '@/services/dietRecords';
import { getMonthDaysZh, getMonthTitleZh, getTodayIndexInMonth } from '@/utils/date';
import { Ionicons } from '@expo/vector-icons';
import dayjs from 'dayjs';
import { router } from 'expo-router';
import React, { useEffect, useRef, useState } from 'react';
import {
  ActivityIndicator,
  FlatList,
  RefreshControl,
  ScrollView,
  StyleSheet,
  Text,
  TouchableOpacity,
  View
} from 'react-native';

type ViewMode = 'daily' | 'all';

export default function NutritionRecordsScreen() {
  const theme = (useColorScheme() ?? 'light') as 'light' | 'dark';
  const colorTokens = Colors[theme];

  // 日期相关状态 - 使用与统计页面相同的日期逻辑
  const days = getMonthDaysZh();
  const [selectedIndex, setSelectedIndex] = useState(getTodayIndexInMonth());
  const monthTitle = getMonthTitleZh();

  // 视图模式：按天查看 vs 全部查看
  const [viewMode, setViewMode] = useState<ViewMode>('daily');

  // 数据状态
  const [records, setRecords] = useState<DietRecord[]>([]);
  const [loading, setLoading] = useState(true);
  const [refreshing, setRefreshing] = useState(false);
  const [hasMoreData, setHasMoreData] = useState(true);
  const [page, setPage] = useState(1);

  // 日期滚动相关
  const daysScrollRef = useRef<ScrollView | null>(null);
  const [scrollWidth, setScrollWidth] = useState(0);
  const DAY_PILL_WIDTH = 60; // 48px width + 12px marginRight = 60px total per item
  const DAY_PILL_SPACING = 0; // spacing is included in the width above

  // 日期滚动控制
  const scrollToIndex = (index: number, animated = true) => {
    if (scrollWidth <= 0) return;

    const itemOffset = index * DAY_PILL_WIDTH;
    const scrollViewCenterX = scrollWidth / 2;
    const itemCenterX = DAY_PILL_WIDTH / 2;
    const centerOffset = Math.max(0, itemOffset - scrollViewCenterX + itemCenterX);

    daysScrollRef.current?.scrollTo({ x: centerOffset, animated });
  };

  // 初始化时滚动到选中位置
  useEffect(() => {
    if (scrollWidth > 0) {
      // 延迟滚动以确保ScrollView已经完全渲染
      setTimeout(() => {
        scrollToIndex(selectedIndex, false);
      }, 100);
    }
  }, [scrollWidth]);

  // 选中日期变化时滚动
  useEffect(() => {
    if (scrollWidth > 0) {
      scrollToIndex(selectedIndex, true);
    }
  }, [selectedIndex]);

  // 加载记录数据
  const loadRecords = async (isRefresh = false, loadMore = false) => {
    try {
      if (isRefresh) {
        setRefreshing(true);
        setPage(1);
      } else if (loadMore) {
        // 加载更多时不显示loading
      } else {
        setLoading(true);
      }

      const currentPage = isRefresh ? 1 : (loadMore ? page + 1 : 1);

      let startDate: string | undefined;
      let endDate: string | undefined;

      if (viewMode === 'daily') {
        // 按天查看时，获取选中日期的数据
        startDate = days[selectedIndex]?.date.startOf('day').toISOString();
        endDate = days[selectedIndex]?.date.endOf('day').toISOString();
      }

      const data = await getDietRecords({
        startDate,
        endDate,
        page: currentPage,
        limit: 10,
      });

      if (isRefresh || currentPage === 1) {
        setRecords(data.records);
      } else {
        setRecords(prev => [...prev, ...data.records]);
      }

      setHasMoreData(data.records.length === 10); // 如果返回的记录数少于limit，说明没有更多数据
      setPage(currentPage);
    } catch (error) {
      console.error('加载营养记录失败:', error);
    } finally {
      setLoading(false);
      setRefreshing(false);
    }
  };

  // 当选中日期或视图模式变化时重新加载数据
  useEffect(() => {
    loadRecords();
  }, [selectedIndex, viewMode]);

  const onRefresh = () => {
    loadRecords(true);
  };

  const loadMoreRecords = () => {
    if (hasMoreData && !loading && !refreshing) {
      loadRecords(false, true);
    }
  };

  // 渲染视图模式切换器
  const renderViewModeToggle = () => (
    <View style={[styles.viewModeContainer, { backgroundColor: colorTokens.pageBackgroundEmphasis }]}>
      <Text style={[styles.monthTitle, { color: colorTokens.text }]}>{monthTitle}</Text>
      <View style={[styles.toggleContainer, { backgroundColor: colorTokens.pageBackgroundEmphasis }]}>
        <TouchableOpacity
          style={[
            styles.toggleButton,
            viewMode === 'daily' && { backgroundColor: colorTokens.primary }
          ]}
          onPress={() => setViewMode('daily')}
        >
          <Text style={[
            styles.toggleText,
            { color: viewMode === 'daily' ? colorTokens.onPrimary : colorTokens.textSecondary }
          ]}>
            按天查看
          </Text>
        </TouchableOpacity>
        <TouchableOpacity
          style={[
            styles.toggleButton,
            viewMode === 'all' && { backgroundColor: colorTokens.primary }
          ]}
          onPress={() => setViewMode('all')}
        >
          <Text style={[
            styles.toggleText,
            { color: viewMode === 'all' ? colorTokens.onPrimary : colorTokens.textSecondary }
          ]}>
            全部记录
          </Text>
        </TouchableOpacity>
      </View>
    </View>
  );

  // 渲染日期选择器（仅在按天查看模式下显示）
  const renderDateSelector = () => {
    if (viewMode !== 'daily') return null;

    return (
      <View style={styles.daysContainer}>
        <ScrollView
          ref={daysScrollRef}
          horizontal
          showsHorizontalScrollIndicator={false}
          contentContainerStyle={styles.daysScrollContainer}
          onLayout={(e) => setScrollWidth(e.nativeEvent.layout.width)}
        >
          {days.map((day, index) => {
            const isSelected = index === selectedIndex;
            const isToday = day.isToday;
            const isDisabled = day.date?.isAfter(dayjs(), 'day') ?? false;

            return (
              <TouchableOpacity
                key={index}
                style={[
                  styles.dayPill,
                  {
                    backgroundColor: isSelected
                      ? colorTokens.primary
                      : colorTokens.surface,
                    borderColor: isToday && !isSelected
                      ? colorTokens.primary
                      : 'transparent',
                    borderWidth: isToday && !isSelected ? 1 : 0,
                    opacity: isDisabled ? 0.4 : 1,
                  },
                ]}
                onPress={() => {
                  if (!isDisabled) {
                    setSelectedIndex(index);
                  }
                }}
                disabled={isDisabled}
              >
                <Text
                  style={[
                    styles.dayNumber,
                    {
                      color: isSelected
                        ? colorTokens.onPrimary
                        : colorTokens.text,
                      fontWeight: isSelected || isToday ? '700' : '600',
                    },
                  ]}
                >
                  {day.date?.date() ?? ''}
                </Text>
                <Text
                  style={[
                    styles.dayLabel,
                    {
                      color: isSelected
                        ? colorTokens.onPrimary
                        : colorTokens.textSecondary,
                      fontWeight: isSelected ? '600' : '500',
                    },
                  ]}
                >
                  {day.dayAbbr}
                </Text>
              </TouchableOpacity>
            );
          })}
        </ScrollView>
      </View>
    );
  };

  const renderEmptyState = () => (
    <View style={styles.emptyContainer}>
      <View style={styles.emptyTimelineContainer}>
        <View style={styles.emptyTimeline}>
          <View style={[styles.emptyTimelineDot, { backgroundColor: colorTokens.primary }]}>
            <Ionicons name="add-outline" size={16} color="#FFFFFF" />
          </View>
        </View>
        <View style={styles.emptyContent}>
          <Ionicons name="restaurant-outline" size={48} color={colorTokens.textSecondary} />
          <Text style={[styles.emptyTitle, { color: colorTokens.text }]}>
            {viewMode === 'daily' ? '今天还没有记录' : '暂无营养记录'}
          </Text>
          <Text style={[styles.emptySubtitle, { color: colorTokens.textSecondary }]}>
            {viewMode === 'daily' ? '开始记录今日营养摄入' : '开始记录你的营养摄入吧'}
          </Text>
        </View>
      </View>
    </View>
  );

  const renderRecord = ({ item, index }: { item: DietRecord; index: number }) => (
    <NutritionRecordCard
      record={item}
      showTimeline={true}
      isFirst={index === 0}
      isLast={index === records.length - 1}
    />
  );

  const renderFooter = () => {
    if (!hasMoreData) {
      return (
        <View style={styles.footerContainer}>
          <Text style={[styles.footerText, { color: colorTokens.textSecondary }]}>
            没有更多数据了
          </Text>
        </View>
      );
    }

    if (viewMode === 'all' && records.length > 0) {
      return (
        <TouchableOpacity style={styles.loadMoreButton} onPress={loadMoreRecords}>
          <Text style={[styles.loadMoreText, { color: colorTokens.primary }]}>
            加载更多
          </Text>
        </TouchableOpacity>
      );
    }

    return null;
  };

  return (
    <View style={[styles.container, { backgroundColor: colorTokens.pageBackgroundEmphasis }]}>
      <HeaderBar
        title="营养记录"
        onBack={() => router.back()}
      />

      {renderViewModeToggle()}
      {renderDateSelector()}

      {loading ? (
        <View style={styles.loadingContainer}>
          <ActivityIndicator size="large" color={colorTokens.primary} />
          <Text style={[styles.loadingText, { color: colorTokens.textSecondary }]}>
            加载中...
          </Text>
        </View>
      ) : (
        <FlatList
          data={records}
          renderItem={({ item, index }) => renderRecord({ item, index })}
          keyExtractor={(item) => item.id.toString()}
          contentContainerStyle={[
            styles.listContainer,
            { paddingBottom: 40, paddingTop: 16 }
          ]}
          showsVerticalScrollIndicator={false}
          refreshControl={
            <RefreshControl
              refreshing={refreshing}
              onRefresh={onRefresh}
              tintColor={colorTokens.primary}
              colors={[colorTokens.primary]}
            />
          }
          ListEmptyComponent={renderEmptyState}
          ListFooterComponent={renderFooter}
          onEndReached={viewMode === 'all' ? loadMoreRecords : undefined}
          onEndReachedThreshold={0.1}
        />
      )}
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
  },
  viewModeContainer: {
    flexDirection: 'row',
    justifyContent: 'space-between',
    alignItems: 'center',
    paddingHorizontal: 16,
    paddingVertical: 12,
    marginBottom: 8,
  },
  monthTitle: {
    fontSize: 22,
    fontWeight: '800',
  },
  toggleContainer: {
    flexDirection: 'row',
    borderRadius: 20,
    padding: 2,
  },
  toggleButton: {
    paddingHorizontal: 16,
    paddingVertical: 8,
    borderRadius: 18,
    minWidth: 80,
    alignItems: 'center',
  },
  toggleText: {
    fontSize: 14,
    fontWeight: '600',
  },
  daysContainer: {
    marginBottom: 12,
  },
  daysScrollContainer: {
    paddingHorizontal: 16,
    paddingVertical: 8,
  },
  dayPill: {
    width: 48,
    height: 48,
    borderRadius: 34,
    marginRight: 12,
    alignItems: 'center',
    justifyContent: 'center',
    shadowColor: '#000',
    shadowOffset: { width: 0, height: 2 },
    shadowOpacity: 0.08,
    shadowRadius: 4,
    elevation: 3,
  },
  dayNumber: {
    fontSize: 18,
    textAlign: 'center',
  },
  dayLabel: {
    fontSize: 12,
    marginTop: 2,
    textAlign: 'center',
  },
  addButton: {
    width: 32,
    height: 32,
    borderRadius: 16,
    alignItems: 'center',
    justifyContent: 'center',
  },
  loadingContainer: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
  },
  loadingText: {
    marginTop: 12,
    fontSize: 16,
    fontWeight: '500',
  },
  listContainer: {
    paddingHorizontal: 16,
    paddingTop: 8,
  },
  emptyContainer: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    paddingVertical: 60,
    paddingHorizontal: 16,
  },
  emptyTimelineContainer: {
    flexDirection: 'row',
    alignItems: 'center',
    maxWidth: 320,
  },
  emptyTimeline: {
    width: 64,
    alignItems: 'center',
    paddingTop: 8,
  },
  emptyTimelineDot: {
    width: 32,
    height: 32,
    borderRadius: 16,
    justifyContent: 'center',
    alignItems: 'center',
    shadowColor: '#000',
    shadowOffset: { width: 0, height: 2 },
    shadowOpacity: 0.1,
    shadowRadius: 4,
    elevation: 2,
  },
  emptyContent: {
    flex: 1,
    alignItems: 'center',
    marginLeft: 16,
  },
  emptyTitle: {
    fontSize: 18,
    fontWeight: '700',
    marginTop: 16,
    marginBottom: 8,
    textAlign: 'center',
  },
  emptySubtitle: {
    fontSize: 14,
    fontWeight: '500',
    textAlign: 'center',
    lineHeight: 20,
  },
  footerContainer: {
    paddingVertical: 20,
    alignItems: 'center',
  },
  footerText: {
    fontSize: 14,
    fontWeight: '500',
  },
  loadMoreButton: {
    paddingVertical: 16,
    alignItems: 'center',
  },
  loadMoreText: {
    fontSize: 16,
    fontWeight: '600',
  },
});