import { getArea } from '@/services/address';
import React, { useEffect, useState } from 'react';
import {
    ActivityIndicator,
    Dimensions,
    Modal,
    ScrollView,
    StyleSheet,
    Text,
    TouchableOpacity,
    View,
} from 'react-native';

interface AreaItem {
  id: string;
  name: string;
  pid?: number;
}

interface RegionPickerProps {
  visible: boolean;
  onClose: () => void;
  onSelect: (province: string, city: string, district: string) => void;
}

const { width, height } = Dimensions.get('window');

export const RegionPicker: React.FC<RegionPickerProps> = ({
  visible,
  onClose,
  onSelect,
}) => {
  const [loading, setLoading] = useState(false);
  const [tabs, setTabs] = useState(['请选择', '', '']);
  const [activeTab, setActiveTab] = useState(0);

  const [provinces, setProvinces] = useState<AreaItem[]>([]);
  const [cities, setCities] = useState<AreaItem[]>([]);
  const [districts, setDistricts] = useState<AreaItem[]>([]);

  const [selectedProvince, setSelectedProvince] = useState<AreaItem | null>(null);
  const [selectedCity, setSelectedCity] = useState<AreaItem | null>(null);
  // District selection ends the flow

  useEffect(() => {
    if (visible && provinces.length === 0) {
      loadProvinces();
    }
  }, [visible]);

  const loadProvinces = async () => {
    setLoading(true);
    try {
      // 省级节点的 pid 通常为 1（中国节点），先尝试 1，空则回退 0
      let list = await getArea(1);
      if (!list || list.length === 0) {
        list = await getArea(0);
      }
      setProvinces(list || []);
    } catch (e) {
      console.error('加载省份数据失败:', e);
    }
    setLoading(false);
  };

  const handleSelect = async (item: AreaItem) => {
    if (activeTab === 0) {
      // Province selected
      setSelectedProvince(item);
      setTabs([item.name, '请选择', '']);
      setActiveTab(1);
      setLoading(true);
      const list = await getArea(Number(item.id));
      setCities(list || []);
      setLoading(false);
    } else if (activeTab === 1) {
      // City selected
      setSelectedCity(item);
      setTabs([selectedProvince!.name, item.name, '请选择']);
      setActiveTab(2);
      setLoading(true);
      const list = await getArea(Number(item.id));
      setDistricts(list || []);
      setLoading(false);
    } else {
      // District selected
      onSelect(selectedProvince!.name, selectedCity!.name, item.name);
      onClose();
    }
  };

  const handleTabPress = (index: number) => {
    // Only allow going back to previous tabs if data exists
    if (index < activeTab) {
      setActiveTab(index);
    }
  };

  const renderList = () => {
    let data : AreaItem[] = [];
    if (activeTab === 0) data = provinces;
    else if (activeTab === 1) data = cities;
    else data = districts;

    // Filter out invalid items if strictly needed, but let's trust API
    return (
      <ScrollView contentContainerStyle={styles.listContent}>
        {data.map((item) => {
            const isSelected = 
                (activeTab === 0 && item.id === selectedProvince?.id) ||
                (activeTab === 1 && item.id === selectedCity?.id);
            
            return (
          <TouchableOpacity
            key={item.id}
            style={styles.item}
            onPress={() => handleSelect(item)}
          >
            <Text style={[styles.itemText, isSelected && styles.itemTextActive]}>
              {item.name}
            </Text>
            {isSelected && <Text style={styles.checkIcon}>✓</Text>}
          </TouchableOpacity>
        )})}
      </ScrollView>
    );
  };

  return (
    <Modal
      visible={visible}
      transparent
      animationType="slide"
      onRequestClose={onClose}
    >
      <View style={styles.mask}>
        <TouchableOpacity style={styles.maskClickable} onPress={onClose} />
        <View style={styles.container}>
          <View style={styles.header}>
            <Text style={styles.title}>配送至</Text>
            <TouchableOpacity onPress={onClose} style={styles.closeBtn}>
              <Text style={styles.closeText}>✕</Text>
            </TouchableOpacity>
          </View>

          <View style={styles.tabs}>
            {tabs.map((tab, index) => (
              tab ? (
              <TouchableOpacity
                key={index}
                onPress={() => handleTabPress(index)}
                style={[styles.tabItem, activeTab === index && styles.tabItemActive]}
                disabled={!tab || (index > activeTab)} 
              >
                <Text style={[styles.tabText, activeTab === index && styles.tabTextActive]}>
                  {tab}
                </Text>
                {activeTab === index && <View style={styles.tabLine} />}
              </TouchableOpacity>
              ) : null
            ))}
          </View>

          {loading ? (
            <View style={styles.loadingBox}>
                <ActivityIndicator size="small" color="#e79018" />
            </View>
          ) : (
            renderList()
          )}
        </View>
      </View>
    </Modal>
  );
};

const styles = StyleSheet.create({
  mask: {
    flex: 1,
    backgroundColor: 'rgba(0,0,0,0.5)',
    justifyContent: 'flex-end',
  },
  maskClickable: {
    flex: 1,
  },
  container: {
    height: height * 0.7, // 70% height
    backgroundColor: '#fff',
    borderTopLeftRadius: 16,
    borderTopRightRadius: 16,
  },
  header: {
    flexDirection: 'row',
    alignItems: 'center',
    justifyContent: 'center', // Title centered
    height: 50,
    borderBottomWidth: 1,
    borderBottomColor: '#eee',
    position: 'relative',
  },
  title: {
    fontSize: 16,
    fontWeight: 'bold',
    color: '#333',
  },
  closeBtn: {
    position: 'absolute',
    right: 15,
    top: 0,
    bottom: 0,
    justifyContent: 'center',
    paddingHorizontal: 10,
  },
  closeText: {
    fontSize: 18,
    color: '#999',
  },
  tabs: {
    flexDirection: 'row',
    borderBottomWidth: 1,
    borderBottomColor: '#eee',
    paddingHorizontal: 15,
  },
  tabItem: {
    marginRight: 25,
    height: 44,
    justifyContent: 'center',
    position: 'relative',
  },
  tabItemActive: {},
  tabText: {
    fontSize: 14,
    color: '#333',
  },
  tabTextActive: {
    color: '#e79018',
    fontWeight: 'bold',
  },
  tabLine: {
    position: 'absolute',
    bottom: 0,
    left: '10%',
    width: '80%',
    height: 2,
    backgroundColor: '#e79018',
  },
  loadingBox: {
      flex: 1,
      justifyContent: 'center',
      alignItems: 'center',
  },
  listContent: {
      paddingBottom: 40,
  },
  item: {
    flexDirection: 'row',
    alignItems: 'center',
    justifyContent: 'space-between',
    paddingVertical: 14,
    paddingHorizontal: 15,
    borderBottomWidth: StyleSheet.hairlineWidth,
    borderBottomColor: '#f5f5f5',
  },
  itemText: {
    fontSize: 14,
    color: '#333',
  },
  itemTextActive: {
    color: '#e79018',
  },
  checkIcon: {
      color: '#e79018',
      fontSize: 16,
  },
});