import { Button } from '@/components/ui/Button';
import { ErrorMessage } from '@/components/ui/ErrorMessage';
import { Input } from '@/components/ui/Input';
import { AppColors, FontSizes, Spacing } from '@/constants/theme';
import { useAuth } from '@/contexts/AuthContext';
import { router } from 'expo-router';
import React, { useEffect, useState } from 'react';
import {
  Image,
  KeyboardAvoidingView,
  Platform,
  ScrollView,
  StyleSheet,
  Text,
  TouchableOpacity,
  View,
} from 'react-native';
import { Ionicons } from '@expo/vector-icons';

export default function LoginScreen() {
  const { checkEmail, requestOtp, isLoading, error, clearError } = useAuth();
  const [email, setEmail] = useState('');
  const [inviteCode, setInviteCode] = useState('');
  const [showInviteCode, setShowInviteCode] = useState(false);
  const [validationError, setValidationError] = useState<string | null>(null);

  // Clear errors on mount
  useEffect(() => {
    clearError();
  }, []);

  const validateEmail = (email: string): boolean => {
    const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
    return emailRegex.test(email);
  };

  const handleContinue = async () => {
    // Clear previous errors
    clearError();
    setValidationError(null);

    const trimmedEmail = email.trim().toLowerCase();

    // Validate email
    if (!trimmedEmail) {
      setValidationError('Email is required');
      return;
    }

    if (!validateEmail(trimmedEmail)) {
      setValidationError('Please enter a valid email address');
      return;
    }

    // Check if email exists in database
    const result = await checkEmail(trimmedEmail);

    // Direct OTP Flow (Streamlined)
    const otpResult = await requestOtp(trimmedEmail);

    if (otpResult.success) {
      router.push({
        pathname: '/(auth)/verify-otp',
        params: {
          email: trimmedEmail,
          isNewUser: result.exists ? '0' : '1',
          inviteCode: inviteCode.trim() || undefined,
        }
      });
    } else {
      setValidationError('Failed to send verification code. Please try again.');
    }
  };

  const displayError = validationError || error?.message;

  return (
    <KeyboardAvoidingView
      style={styles.container}
      behavior={Platform.OS === 'ios' ? 'padding' : 'padding'}
      keyboardVerticalOffset={Platform.OS === 'ios' ? 0 : 20}
    >
      <ScrollView
        contentContainerStyle={styles.scrollContent}
        keyboardShouldPersistTaps="handled"
        showsVerticalScrollIndicator={false}
        bounces={false}
      >
        <View style={styles.logoContainer}>
          <Image
            source={require('@/assets/logo.png')}
            style={styles.logo}
            resizeMode="contain"
          />
        </View>

        <View style={styles.header}>
          <Text style={styles.title}>Welcome to WellNuo</Text>
          <Text style={styles.subtitle}>
            Enter your email to sign in or create an account
          </Text>
        </View>

        <View style={styles.form}>
          {displayError && (
            <ErrorMessage
              message={displayError}
              onDismiss={() => {
                clearError();
                setValidationError(null);
              }}
            />
          )}

          <Input
            label="Email"
            placeholder="Enter your email"
            leftIcon="mail-outline"
            value={email}
            onChangeText={(text) => {
              setEmail(text);
              setValidationError(null);
            }}
            autoCapitalize="none"
            autoCorrect={false}
            keyboardType="email-address"
            editable={!isLoading}
            returnKeyType="next"
          />

          {/* Invite Code Toggle */}
          {!showInviteCode ? (
            <TouchableOpacity
              style={styles.inviteCodeToggle}
              onPress={() => setShowInviteCode(true)}
            >
              <Ionicons name="gift-outline" size={18} color={AppColors.primary} />
              <Text style={styles.inviteCodeToggleText}>I have an invite code</Text>
            </TouchableOpacity>
          ) : (
            <Input
              label="Invite Code"
              placeholder="Enter 5-digit code"
              leftIcon="gift-outline"
              value={inviteCode}
              onChangeText={(text) => {
                // Only allow digits, max 5
                const code = text.replace(/\D/g, '').slice(0, 5);
                setInviteCode(code);
              }}
              keyboardType="number-pad"
              maxLength={5}
              editable={!isLoading}
              onSubmitEditing={handleContinue}
              returnKeyType="done"
            />
          )}

          <Button
            title="Continue"
            onPress={handleContinue}
            loading={isLoading}
            fullWidth
            size="lg"
            style={styles.button}
          />
        </View>

        <View style={styles.infoContainer}>
          <Text style={styles.infoText}>
            We'll send you a verification code to confirm your email
          </Text>
        </View>

        <Text style={styles.version}>WellNuo v1.0.0</Text>
      </ScrollView>
    </KeyboardAvoidingView>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: AppColors.background,
  },
  scrollContent: {
    flexGrow: 1,
    paddingHorizontal: Spacing.lg,
    paddingTop: Platform.OS === 'android' ? Spacing.xl : Spacing.xxl + Spacing.xl,
    paddingBottom: Spacing.xl,
  },
  logoContainer: {
    alignItems: 'center',
    marginBottom: Platform.OS === 'android' ? Spacing.md : Spacing.xl,
  },
  logo: {
    width: Platform.OS === 'android' ? 80 : 120,
    height: Platform.OS === 'android' ? 80 : 120,
  },
  header: {
    alignItems: 'center',
    marginBottom: Spacing.xl,
  },
  title: {
    fontSize: FontSizes['2xl'],
    fontWeight: '700',
    color: AppColors.textPrimary,
    marginBottom: Spacing.xs,
  },
  subtitle: {
    fontSize: FontSizes.base,
    color: AppColors.textSecondary,
    textAlign: 'center',
    paddingHorizontal: Spacing.md,
  },
  form: {
    marginBottom: Spacing.md,
  },
  button: {
    marginTop: Spacing.md,
  },
  infoContainer: {
    alignItems: 'center',
    marginTop: Spacing.lg,
    marginBottom: Spacing.xl,
  },
  infoText: {
    fontSize: FontSizes.sm,
    color: AppColors.textMuted,
    textAlign: 'center',
  },
  version: {
    textAlign: 'center',
    fontSize: FontSizes.xs,
    color: AppColors.textMuted,
    marginTop: 'auto',
  },
  inviteCodeToggle: {
    flexDirection: 'row',
    alignItems: 'center',
    justifyContent: 'center',
    paddingVertical: Spacing.sm,
    marginTop: Spacing.xs,
    gap: Spacing.xs,
  },
  inviteCodeToggleText: {
    fontSize: FontSizes.sm,
    color: AppColors.primary,
    fontWeight: '500',
  },
});