import React, { useState } from 'react';
import { View, Text, TextInput, TouchableOpacity, StyleSheet, ActivityIndicator, Alert } from 'react-native';
import { SafeAreaView } from 'react-native-safe-area-context';
import { theme } from '../theme';
import * as API from '../api';

interface LoginScreenProps {
  onLoginSuccess: () => void;
  onBack: () => void;
}

export const LoginScreen: React.FC<LoginScreenProps> = ({ onLoginSuccess, onBack }) => {
  const [username, setUsername] = useState('');
  const [password, setPassword] = useState('');
  const [loading, setLoading] = useState(false);

  const handleLogin = async () => {
    if (!username.trim() || !password.trim()) {
      Alert.alert('提示', '请输入账号和密码');
      return;
    }

    setLoading(true);
    try {
      const result = await API.login(username.trim(), password);
      if (result.ok) {
        Alert.alert('登录成功', `欢迎，${result.username}`, [
          { text: '好的', onPress: onLoginSuccess }
        ]);
      } else {
        Alert.alert('登录失败', result.error || '账号或密码错误');
      }
    } catch (error) {
      Alert.alert('错误', '登录请求失败，请检查网络');
    } finally {
      setLoading(false);
    }
  };

  return (
    <SafeAreaView style={styles.container}>
      <View style={styles.header}>
        <TouchableOpacity onPress={onBack} style={styles.backBtn}>
          <Text style={styles.backText}>← 返回</Text>
        </TouchableOpacity>
        <Text style={styles.title}>观空禅音</Text>
      </View>

      <View style={styles.form}>
        <Text style={styles.label}>账号</Text>
        <TextInput
          style={styles.input}
          value={username}
          onChangeText={setUsername}
          placeholder="请输入账号"
          placeholderTextColor={theme.colors.textSecondary}
          autoCapitalize="none"
          autoComplete="off"
        />

        <Text style={styles.label}>密码</Text>
        <TextInput
          style={styles.input}
          value={password}
          onChangeText={setPassword}
          placeholder="请输入密码"
          placeholderTextColor={theme.colors.textSecondary}
          secureTextEntry
          autoComplete="off"
        />

        <TouchableOpacity
          style={[styles.loginBtn, loading && styles.loginBtnDisabled]}
          onPress={handleLogin}
          disabled={loading}
        >
          {loading ? (
            <ActivityIndicator size="small" color="#fff" />
          ) : (
            <Text style={styles.loginBtnText}>登录</Text>
          )}
        </TouchableOpacity>

        <Text style={styles.hint}>
          登录后可同步歌单选择、播放进度等配置到云端，跨设备使用。
        </Text>
      </View>
    </SafeAreaView>
  );
};

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: theme.colors.background,
  },
  header: {
    flexDirection: 'row',
    alignItems: 'center',
    paddingHorizontal: theme.spacing.md,
    paddingVertical: theme.spacing.sm,
  },
  backBtn: {
    padding: theme.spacing.xs,
  },
  backText: {
    fontSize: 15,
    color: theme.colors.primary,
  },
  title: {
    flex: 1,
    textAlign: 'center',
    fontSize: 18,
    fontWeight: '600',
    color: theme.colors.text,
    marginRight: 40,
  },
  form: {
    paddingHorizontal: theme.spacing.xl,
    paddingTop: theme.spacing.xl,
  },
  label: {
    fontSize: 14,
    color: theme.colors.textSecondary,
    marginBottom: 6,
  },
  input: {
    backgroundColor: theme.colors.surface,
    borderRadius: 8,
    paddingHorizontal: theme.spacing.md,
    paddingVertical: theme.spacing.sm,
    fontSize: 16,
    color: theme.colors.text,
    marginBottom: theme.spacing.md,
    borderWidth: 1,
    borderColor: theme.colors.border,
  },
  loginBtn: {
    backgroundColor: theme.colors.primary,
    borderRadius: 8,
    paddingVertical: theme.spacing.sm,
    alignItems: 'center',
    marginTop: theme.spacing.md,
  },
  loginBtnDisabled: {
    opacity: 0.6,
  },
  loginBtnText: {
    fontSize: 16,
    fontWeight: '600',
    color: '#fff',
  },
  hint: {
    fontSize: 13,
    color: theme.colors.textSecondary,
    marginTop: theme.spacing.lg,
    textAlign: 'center',
    lineHeight: 20,
  },
});