import React, { useState } from 'react';
import { 
  View, 
  Text, 
  TextInput, 
  TouchableOpacity, 
  StyleSheet, 
  KeyboardAvoidingView,
  Platform,
  Alert
} from 'react-native';
import { useRouter } from 'expo-router';
import { register } from '../../services/auth';
import { colors, spacing, borderRadius } from '../../constants/theme';

export default function RegisterScreen() {
  const router = useRouter();
  const [username, setUsername] = useState('');
  const [password, setPassword] = useState('');
  const [confirmPassword, setConfirmPassword] = useState('');
  const [isLoading, setIsLoading] = useState(false);

  const handleRegister = async () => {
    if (!username || !password || !confirmPassword) {
      Alert.alert('Error', 'Por favor completa todos los campos');
      return;
    }

    if (password !== confirmPassword) {
      Alert.alert('Error', 'Las contraseñas no coinciden');
      return;
    }

    setIsLoading(true);
    try {
      await register(username, password);
      router.replace('/(tabs)');
    } catch (error) {
      Alert.alert('Error', 'No se pudo crear la cuenta');
    } finally {
      setIsLoading(false);
    }
  };

  return (
    <KeyboardAvoidingView
      style={styles.container}
      behavior={Platform.OS === 'ios' ? 'padding' : 'height'}
    >
      <View style={styles.form}>
        <Text style={styles.title}>Crear Cuenta</Text>
        <Text style={styles.subtitle}>Regístrate para empezar</Text>

        <View style={styles.inputContainer}>
          <Text style={styles.label}>Usuario</Text>
          <TextInput
            style={styles.input}
            value={username}
            onChangeText={setUsername}
            placeholder="Elige un usuario"
            placeholderTextColor={colors.textSecondary}
            autoCapitalize="none"
            autoCorrect={false}
          />
        </View>

        <View style={styles.inputContainer}>
          <Text style={styles.label}>Contraseña</Text>
          <TextInput
            style={styles.input}
            value={password}
            onChangeText={setPassword}
            placeholder="Elige una contraseña"
            placeholderTextColor={colors.textSecondary}
            secureTextEntry
          />
        </View>

        <View style={styles.inputContainer}>
          <Text style={styles.label}>Confirmar Contraseña</Text>
          <TextInput
            style={styles.input}
            value={confirmPassword}
            onChangeText={setConfirmPassword}
            placeholder="Repite la contraseña"
            placeholderTextColor={colors.textSecondary}
            secureTextEntry
          />
        </View>

        <TouchableOpacity
          style={[styles.button, isLoading && styles.buttonDisabled]}
          onPress={handleRegister}
          disabled={isLoading}
        >
          <Text style={styles.buttonText}>
            {isLoading ? 'Creando cuenta...' : 'Crear Cuenta'}
          </Text>
        </TouchableOpacity>

        <TouchableOpacity
          style={styles.linkButton}
          onPress={() => router.back()}
        >
          <Text style={styles.linkText}>¿Ya tienes cuenta? Inicia sesión</Text>
        </TouchableOpacity>
      </View>
    </KeyboardAvoidingView>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: colors.background,
  },
  form: {
    flex: 1,
    justifyContent: 'center',
    padding: spacing.xl,
  },
  title: {
    fontSize: 28,
    fontWeight: 'bold',
    color: colors.text,
    marginBottom: spacing.sm,
  },
  subtitle: {
    fontSize: 16,
    color: colors.textSecondary,
    marginBottom: spacing.xl,
  },
  inputContainer: {
    marginBottom: spacing.md,
  },
  label: {
    fontSize: 14,
    fontWeight: '500',
    color: colors.text,
    marginBottom: spacing.xs,
  },
  input: {
    backgroundColor: colors.card,
    borderRadius: borderRadius.md,
    padding: spacing.md,
    fontSize: 16,
    color: colors.text,
  },
  button: {
    backgroundColor: colors.primary,
    borderRadius: borderRadius.md,
    padding: spacing.md,
    alignItems: 'center',
    marginTop: spacing.md,
  },
  buttonDisabled: {
    opacity: 0.6,
  },
  buttonText: {
    color: colors.textInverse,
    fontSize: 16,
    fontWeight: '600',
  },
  linkButton: {
    marginTop: spacing.lg,
    alignItems: 'center',
  },
  linkText: {
    color: colors.primary,
    fontSize: 14,
  },
});