import { CircularRing } from '@/components/CircularRing';
import { FastingStartPickerModal } from '@/components/fasting/FastingStartPickerModal';
import { Colors } from '@/constants/Colors';
import { FASTING_PLANS, FastingPlan, getPlanById, getRecommendedStart } from '@/constants/Fasting';
import { ROUTES } from '@/constants/Routes';
import { useAppDispatch, useAppSelector } from '@/hooks/redux';
import { useColorScheme } from '@/hooks/useColorScheme';
import {
  rescheduleActivePlan,
  scheduleFastingPlan,
  selectActiveFastingSchedule,
} from '@/store/fastingSlice';
import { buildDisplayWindow, calculateFastingWindow, savePreferredPlanId } from '@/utils/fasting';
import { Ionicons } from '@expo/vector-icons';
import { GlassView, isLiquidGlassAvailable } from 'expo-glass-effect';
import { LinearGradient } from 'expo-linear-gradient';
import { useLocalSearchParams, useRouter } from 'expo-router';
import React, { useEffect, useMemo, useState } from 'react';
import { ScrollView, StyleSheet, Text, TouchableOpacity, View } from 'react-native';
import { useSafeAreaInsets } from 'react-native-safe-area-context';

type InfoTab = 'fit' | 'avoid' | 'intro';

const TAB_LABELS: Record<InfoTab, string> = {
  fit: '适合人群',
  avoid: '不适合人群',
  intro: '计划介绍',
};

export default function FastingPlanDetailScreen() {
  const router = useRouter();
  const insets = useSafeAreaInsets();
  const theme = useColorScheme() ?? 'light';
  const colors = Colors[theme];
  const dispatch = useAppDispatch();
  const activeSchedule = useAppSelector(selectActiveFastingSchedule);

  const { planId } = useLocalSearchParams<{ planId: string }>();
  const fallbackPlan = FASTING_PLANS[0];
  const plan: FastingPlan = useMemo(
    () => (planId ? getPlanById(planId) ?? fallbackPlan : fallbackPlan),
    [planId, fallbackPlan]
  );

  useEffect(() => {
    void savePreferredPlanId(plan.id);
  }, [plan.id]);

  const [infoTab, setInfoTab] = useState<InfoTab>('fit');
  const [showPicker, setShowPicker] = useState(false);
  const glassAvailable = isLiquidGlassAvailable();

  const recommendedStart = useMemo(() => getRecommendedStart(plan), [plan]);
  const window = calculateFastingWindow(recommendedStart, plan.fastingHours);
  const displayWindow = buildDisplayWindow(window.start, window.end);

  const handleStartWithRecommended = () => {
    dispatch(scheduleFastingPlan({ planId: plan.id, start: recommendedStart.toISOString(), origin: 'recommended' }));
    router.replace(ROUTES.TAB_FASTING);
  };

  const handleOpenPicker = () => {
    setShowPicker(true);
  };

  const handleConfirmPicker = (date: Date) => {
    if (activeSchedule?.planId === plan.id) {
      dispatch(rescheduleActivePlan({ start: date.toISOString(), origin: 'manual' }));
    } else {
      dispatch(scheduleFastingPlan({ planId: plan.id, start: date.toISOString(), origin: 'manual' }));
    }
    setShowPicker(false);
    router.replace(ROUTES.TAB_FASTING);
  };

  const renderInfoList = () => {
    let items: string[] = [];
    if (infoTab === 'fit') items = plan.audienceFit;
    if (infoTab === 'avoid') items = plan.audienceAvoid;
    if (infoTab === 'intro') items = [plan.description, ...plan.nutritionTips];

    return (
      <View style={styles.infoList}>
        {items.map((item) => (
          <View key={item} style={styles.infoItem}>
            <View style={[styles.infoDot, { backgroundColor: plan.theme.accent }]} />
            <Text style={styles.infoText}>{item}</Text>
          </View>
        ))}
      </View>
    );
  };

  const fastingRatio = plan.fastingHours / 24;

  return (
    <View style={[styles.safeArea, { backgroundColor: '#ffffff' }]}>
      {/* 固定悬浮的返回按钮 */}
      <View style={[styles.backButtonContainer, { paddingTop: insets.top + 12 }]}>
        <TouchableOpacity style={styles.backButton} onPress={router.back} activeOpacity={0.8}>
          {glassAvailable ? (
            <GlassView
              style={styles.backButtonGlass}
              glassEffectStyle="regular"
              tintColor="rgba(255,255,255,0.4)"
              isInteractive={true}
            >
              <Ionicons name="chevron-back" size={24} color="#2E3142" />
            </GlassView>
          ) : (
            <View style={styles.backButtonFallback}>
              <Ionicons name="chevron-back" size={24} color="#2E3142" />
            </View>
          )}
        </TouchableOpacity>
      </View>

      <ScrollView contentContainerStyle={{ paddingBottom: 40 }}>
        <LinearGradient
          colors={[plan.theme.accentSecondary, plan.theme.backdrop]}
          style={[styles.hero, { paddingTop: insets.top + 12 }]}
        >
          <View style={{
            paddingTop: insets.top + 12
          }}>
            <View style={styles.heroHeader}>
              <Text style={styles.planId}>{plan.id}</Text>
              {plan.badge && (
                <View style={[styles.heroBadge, { backgroundColor: `${plan.theme.accent}2B` }]}>
                  <Text style={[styles.heroBadgeText, { color: plan.theme.accent }]}>{plan.badge}</Text>
                </View>
              )}
            </View>
            <Text style={styles.heroTitle}>{plan.title}</Text>
            <Text style={styles.heroSubtitle}>{plan.subtitle}</Text>

            <View style={styles.tagRow}>
              <View style={[styles.tagChip, { backgroundColor: `${plan.theme.accent}22` }]}>
                <Text style={[styles.tagChipText, { color: plan.theme.accent }]}>
                  断食 {plan.fastingHours} 小时
                </Text>
              </View>
              <View style={[styles.tagChip, { backgroundColor: `${plan.theme.accent}22` }]}>
                <Text style={[styles.tagChipText, { color: plan.theme.accent }]}>
                  进食 {plan.eatingHours} 小时
                </Text>
              </View>
            </View>
          </View>
        </LinearGradient>

        <View style={styles.body}>
          <View style={styles.chartCard}>
            <CircularRing
              size={190}
              strokeWidth={18}
              progress={fastingRatio}
              progressColor={plan.theme.accent}
              trackColor={plan.theme.ringTrack}
              showCenterText={false}
            />
            <View style={styles.chartContent}>
              <Text style={styles.chartTitle}>每日节奏</Text>
              <Text style={styles.chartValue}>{plan.fastingHours} h 断食</Text>
              <Text style={styles.chartSubtitle}>进食窗口 {plan.eatingHours} h</Text>
            </View>
            <View style={styles.legendRow}>
              <View style={styles.legendItem}>
                <View style={[styles.legendDot, { backgroundColor: plan.theme.accent }]} />
                <Text style={styles.legendText}>断食期</Text>
              </View>
              <View style={styles.legendItem}>
                <View style={[styles.legendDot, { backgroundColor: plan.theme.ringTrack }]} />
                <Text style={styles.legendText}>进食期</Text>
              </View>
            </View>
          </View>

          <View style={styles.windowCard}>
            <Text style={styles.windowLabel}>推荐开始时间</Text>
            <View style={styles.windowRow}>
              <View style={styles.windowCell}>
                <Text style={styles.windowTitle}>开始</Text>
                <Text style={styles.windowDay}>{displayWindow.startDayLabel}</Text>
                <Text style={[styles.windowTime, { color: plan.theme.accent }]}>
                  {displayWindow.startTimeLabel}
                </Text>
              </View>
              <View style={styles.windowDivider} />
              <View style={styles.windowCell}>
                <Text style={styles.windowTitle}>结束</Text>
                <Text style={styles.windowDay}>{displayWindow.endDayLabel}</Text>
                <Text style={[styles.windowTime, { color: plan.theme.accent }]}>
                  {displayWindow.endTimeLabel}
                </Text>
              </View>
            </View>
            <Text style={styles.windowHint}>
              推荐在晚餐后约 2 小时开始，保证进食期覆盖早餐至午后。
            </Text>
          </View>

          <View style={styles.tabContainer}>
            {(Object.keys(TAB_LABELS) as InfoTab[]).map((tabKey) => {
              const isActive = infoTab === tabKey;
              return (
                <TouchableOpacity
                  key={tabKey}
                  style={[
                    styles.tabButton,
                    isActive && { backgroundColor: plan.theme.accent },
                  ]}
                  onPress={() => setInfoTab(tabKey)}
                  activeOpacity={0.9}
                >
                  <Text
                    style={[
                      styles.tabButtonText,
                      { color: isActive ? '#fff' : colors.textSecondary },
                    ]}
                  >
                    {TAB_LABELS[tabKey]}
                  </Text>
                </TouchableOpacity>
              );
            })}
          </View>

          {renderInfoList()}

          <View style={styles.actionBlock}>
            <TouchableOpacity
              style={[styles.secondaryAction, { borderColor: plan.theme.accent }]}
              onPress={handleOpenPicker}
              activeOpacity={0.85}
            >
              <Text style={[styles.secondaryActionText, { color: plan.theme.accent }]}>
                自定义开始时间
              </Text>
            </TouchableOpacity>
            <TouchableOpacity
              style={[styles.primaryAction, { backgroundColor: plan.theme.accent }]}
              onPress={handleStartWithRecommended}
              activeOpacity={0.9}
            >
              <Text style={styles.primaryActionText}>
                开始轻断食
              </Text>
            </TouchableOpacity>
          </View>
        </View>
      </ScrollView>

      <FastingStartPickerModal
        visible={showPicker}
        onClose={() => setShowPicker(false)}
        initialDate={recommendedStart}
        recommendedDate={recommendedStart}
        onConfirm={handleConfirmPicker}
      />
    </View>
  );
}

const styles = StyleSheet.create({
  safeArea: {
    flex: 1,
  },
  hero: {
    paddingHorizontal: 24,
    paddingBottom: 32,
    borderBottomLeftRadius: 32,
    borderBottomRightRadius: 32,
  },
  backButtonContainer: {
    position: 'absolute',
    top: 0,
    left: 24,
    zIndex: 10,
  },
  backButton: {
    width: 44,
    height: 44,
    borderRadius: 22,
    alignItems: 'center',
    justifyContent: 'center',
    shadowColor: '#000',
    shadowOffset: {
      width: 0,
      height: 4,
    },
    shadowOpacity: 0.15,
    shadowRadius: 8,
    elevation: 8,
  },
  backButtonGlass: {
    width: 44,
    height: 44,
    borderRadius: 22,
    alignItems: 'center',
    justifyContent: 'center',
    borderWidth: 1,
    borderColor: 'rgba(255,255,255,0.3)',
    overflow: 'hidden',
  },
  backButtonFallback: {
    width: 44,
    height: 44,
    borderRadius: 22,
    alignItems: 'center',
    justifyContent: 'center',
    backgroundColor: 'rgba(255,255,255,0.85)',
    borderWidth: 1,
    borderColor: 'rgba(255,255,255,0.5)',
  },
  heroContent: {
  },
  heroHeader: {
    flexDirection: 'row',
    alignItems: 'center',
    marginBottom: 14,
  },
  planId: {
    fontSize: 18,
    fontWeight: '700',
    color: '#2E3142',
    marginRight: 12,
  },
  heroBadge: {
    paddingHorizontal: 12,
    paddingVertical: 6,
    borderRadius: 16,
  },
  heroBadgeText: {
    fontSize: 12,
    fontWeight: '600',
  },
  heroTitle: {
    fontSize: 26,
    fontWeight: '800',
    color: '#2E3142',
    marginBottom: 8,
  },
  heroSubtitle: {
    fontSize: 14,
    color: '#5B6572',
    marginBottom: 16,
  },
  tagRow: {
    flexDirection: 'row',
  },
  tagChip: {
    marginRight: 10,
    paddingHorizontal: 14,
    paddingVertical: 8,
    borderRadius: 18,
  },
  tagChipText: {
    fontSize: 12,
    fontWeight: '600',
  },
  body: {
    paddingHorizontal: 24,
    paddingTop: 28,
  },
  chartCard: {
    alignItems: 'center',
    marginBottom: 24,
  },
  chartContent: {
    position: 'absolute',
    top: 70,
    alignItems: 'center',
  },
  chartTitle: {
    fontSize: 14,
    color: '#6F7D87',
    marginBottom: 6,
  },
  chartValue: {
    fontSize: 20,
    fontWeight: '700',
    color: '#2E3142',
  },
  chartSubtitle: {
    fontSize: 12,
    color: '#6F7D87',
    marginTop: 4,
  },
  legendRow: {
    flexDirection: 'row',
    justifyContent: 'center',
    marginTop: 20,
  },
  legendItem: {
    flexDirection: 'row',
    alignItems: 'center',
    marginHorizontal: 12,
  },
  legendDot: {
    width: 12,
    height: 12,
    borderRadius: 6,
    marginRight: 6,
  },
  legendText: {
    fontSize: 12,
    color: '#5B6572',
  },
  windowCard: {
    borderRadius: 20,
    backgroundColor: '#FFFFFF',
    padding: 20,
    marginBottom: 24,
    shadowColor: '#000',
    shadowOpacity: 0.04,
    shadowRadius: 12,
    shadowOffset: { width: 0, height: 10 },
    elevation: 3,
  },
  windowLabel: {
    fontSize: 16,
    fontWeight: '700',
    color: '#2E3142',
    marginBottom: 12,
  },
  windowRow: {
    flexDirection: 'row',
    alignItems: 'center',
  },
  windowCell: {
    flex: 1,
    alignItems: 'center',
  },
  windowTitle: {
    fontSize: 12,
    color: '#778290',
    marginBottom: 6,
  },
  windowDay: {
    fontSize: 16,
    fontWeight: '600',
    color: '#2E3142',
  },
  windowTime: {
    fontSize: 24,
    fontWeight: '700',
    marginTop: 6,
  },
  windowDivider: {
    width: 1,
    height: 60,
    backgroundColor: 'rgba(95,105,116,0.2)',
  },
  windowHint: {
    fontSize: 12,
    color: '#6F7D87',
    marginTop: 16,
    lineHeight: 18,
  },
  tabContainer: {
    flexDirection: 'row',
    marginBottom: 20,
    borderRadius: 20,
    backgroundColor: '#F2F3F5',
    padding: 4,
  },
  tabButton: {
    flex: 1,
    borderRadius: 16,
    paddingVertical: 12,
    alignItems: 'center',
  },
  tabButtonText: {
    fontSize: 13,
    fontWeight: '600',
  },
  infoList: {
    marginBottom: 28,
  },
  infoItem: {
    flexDirection: 'row',
    alignItems: 'flex-start',
    marginBottom: 12,
  },
  infoDot: {
    width: 6,
    height: 6,
    borderRadius: 3,
    marginRight: 10,
    marginTop: 7,
  },
  infoText: {
    flex: 1,
    fontSize: 14,
    color: '#4A5460',
    lineHeight: 21,
  },
  actionBlock: {
    flexDirection: 'row',
    alignItems: 'center',
    marginBottom: 50,
  },
  secondaryAction: {
    flex: 1,
    borderWidth: 1.4,
    borderRadius: 24,
    paddingVertical: 14,
    alignItems: 'center',
    marginRight: 12,
    backgroundColor: '#FFFFFF',
  },
  secondaryActionText: {
    fontSize: 14,
    fontWeight: '600',
  },
  primaryAction: {
    flex: 1,
    borderRadius: 24,
    paddingVertical: 14,
    alignItems: 'center',
  },
  primaryActionText: {
    fontSize: 16,
    fontWeight: '700',
    color: '#FFFFFF',
  },
});