import React, { useState, useEffect, useCallback } from 'react';
import {
    View,
    Text,
    StyleSheet,
    TouchableOpacity,
    ActivityIndicator,
    Alert,
    Platform,
} from 'react-native';
import { SafeAreaView } from 'react-native-safe-area-context';
import { router, useLocalSearchParams } from 'expo-router';
import { Ionicons } from '@expo/vector-icons';
// import { usePaymentSheet } from '@stripe/stripe-react-native'; // Removed for web
import { AppColors, Spacing, BorderRadius, FontSizes, FontWeights, Shadows } from '@/constants/theme';
import { useAuth } from '@/contexts/AuthContext';
import { api } from '@/services/api';
import { LoadingSpinner } from '@/components/ui/LoadingSpinner';
import { hasBeneficiaryDevices } from '@/services/BeneficiaryDetailController';

// const STRIPE_API_URL = 'https://wellnuo.smartlaunchhub.com/api/stripe';

const STARTER_KIT = {
    name: 'WellNuo Starter Kit',
    price: '$249',
    priceValue: 249,
};

export default function PurchaseScreen() {
    const params = useLocalSearchParams<{ lovedOneName?: string; beneficiaryId?: string }>();
    const lovedOneName = params.lovedOneName || '';
    const beneficiaryId = params.beneficiaryId;

    const [isProcessing, setIsProcessing] = useState(false);
    const [isLoading, setIsLoading] = useState(true);
    const [step, setStep] = useState<'purchase' | 'order_placed'>('purchase');
    const { user } = useAuth();

    // const { initPaymentSheet, presentPaymentSheet } = usePaymentSheet(); // Removed for web

    // Check if equipment is already ordered - redirect to equipment-status
    const checkEquipmentStatus = useCallback(async () => {
        if (!beneficiaryId) {
            setIsLoading(false);
            return;
        }

        try {
            const response = await api.getWellNuoBeneficiary(parseInt(beneficiaryId, 10));
            if (response.ok && response.data) {
                // If user already has devices - go to main screen
                if (hasBeneficiaryDevices(response.data)) {
                    router.replace(`/(tabs)/beneficiaries/${beneficiaryId}`);
                    return;
                }

                // If equipment is ordered/shipped/delivered - go to equipment-status
                const status = response.data.equipmentStatus;
                if (status && ['ordered', 'shipped', 'delivered'].includes(status)) {
                    router.replace(`/(tabs)/beneficiaries/${beneficiaryId}/equipment-status`);
                    return;
                }
            }
        } catch (error) {
            console.warn('[Purchase] Failed to check equipment status:', error);
        }

        setIsLoading(false);
    }, [beneficiaryId]);

    useEffect(() => {
        checkEquipmentStatus();
    }, [checkEquipmentStatus]);

    const handlePurchase = async () => {
        alert('Purchases are currently only available in the mobile app.');
    };

    const handleAlreadyHaveSensors = () => {
        router.replace({
            pathname: '/(auth)/activate',
            params: { beneficiaryId, lovedOneName },
        });
    };

    const handleGoToEquipmentStatus = () => {
        if (beneficiaryId) {
            router.replace(`/(tabs)/beneficiaries/${beneficiaryId}/equipment-status`);
        } else {
            router.replace('/(tabs)');
        }
    };

    // Loading state - checking equipment status
    if (isLoading) {
        return <LoadingSpinner fullScreen message="Loading..." />;
    }

    // Order Placed Screen
    if (step === 'order_placed') {
        return (
            <SafeAreaView style={styles.container} edges={['top', 'bottom']}>
                <View style={styles.orderPlacedContainer}>
                    <View style={styles.successIcon}>
                        <Ionicons name="checkmark" size={64} color={AppColors.white} />
                    </View>

                    <Text style={styles.orderPlacedTitle}>Order Placed!</Text>
                    <Text style={styles.orderPlacedSubtitle}>
                        Thank you for your purchase
                    </Text>

                    <View style={styles.orderInfoCard}>
                        <View style={styles.orderInfoRow}>
                            <Text style={styles.orderInfoLabel}>Item</Text>
                            <Text style={styles.orderInfoValue}>{STARTER_KIT.name}</Text>
                        </View>
                        <View style={styles.orderInfoRow}>
                            <Text style={styles.orderInfoLabel}>For</Text>
                            <Text style={styles.orderInfoValue}>{lovedOneName || 'Your loved one'}</Text>
                        </View>
                        <View style={[styles.orderInfoRow, { borderBottomWidth: 0 }]}>
                            <Text style={styles.orderInfoLabel}>Total</Text>
                            <Text style={[styles.orderInfoValue, styles.orderInfoPrice]}>{STARTER_KIT.price}</Text>
                        </View>
                    </View>

                    <TouchableOpacity style={styles.primaryButton} onPress={handleGoToEquipmentStatus}>
                        <Text style={styles.primaryButtonText}>Track My Order</Text>
                    </TouchableOpacity>
                </View>
            </SafeAreaView>
        );
    }

    return (
        <SafeAreaView style={styles.container} edges={['top', 'bottom']}>
            <View style={styles.content}>
                {/* Header */}
                <View style={styles.header}>
                    <TouchableOpacity
                        style={styles.backButton}
                        onPress={() => router.canGoBack() ? router.back() : router.replace('/(tabs)')}
                    >
                        <Ionicons name="arrow-back" size={24} color={AppColors.textPrimary} />
                    </TouchableOpacity>
                    <Text style={styles.title}>Get Started</Text>
                    <View style={styles.placeholder} />
                </View>

                {/* Product Card */}
                <View style={styles.productCard}>
                    <View style={styles.productIcon}>
                        <Ionicons name="hardware-chip" size={48} color={AppColors.primary} />
                    </View>

                    <Text style={styles.productName}>{STARTER_KIT.name}</Text>
                    <Text style={styles.productPrice}>{STARTER_KIT.price}</Text>

                    <Text style={styles.productDescription}>
                        4 smart sensors that easily plug into any outlet and set up through the app in minutes
                    </Text>

                    {/* Security Badge */}
                    <View style={styles.securityBadge}>
                        <Ionicons name="shield-checkmark" size={16} color={AppColors.success} />
                        <Text style={styles.securityText}>Secure payment powered by Stripe</Text>
                    </View>
                </View>

                {/* Bottom Actions */}
                <View style={styles.bottomActions}>
                    <TouchableOpacity
                        style={[styles.purchaseButton, isProcessing && styles.buttonDisabled]}
                        onPress={handlePurchase}
                        disabled={isProcessing}
                    >
                        {isProcessing ? (
                            <ActivityIndicator color={AppColors.white} />
                        ) : (
                            <>
                                <Ionicons name="card" size={20} color={AppColors.white} />
                                <Text style={styles.purchaseButtonText}>Buy Now - {STARTER_KIT.price}</Text>
                            </>
                        )}
                    </TouchableOpacity>

                    <TouchableOpacity style={styles.skipButton} onPress={handleAlreadyHaveSensors}>
                        <Text style={styles.skipButtonText}>I already have sensors</Text>
                    </TouchableOpacity>

                    <View style={{ marginTop: 20, padding: 10, backgroundColor: '#f0f9ff', borderRadius: 8 }}>
                        <Text style={{ textAlign: 'center', color: '#0066cc', fontSize: 14 }}>
                            Web version: Please use mobile app for purchases.
                        </Text>
                    </View>
                </View>
            </View>
        </SafeAreaView>
    );
}

const styles = StyleSheet.create({
    container: {
        flex: 1,
        backgroundColor: AppColors.background,
    },
    content: {
        flex: 1,
        padding: Spacing.lg,
        justifyContent: 'space-between',
    },
    header: {
        flexDirection: 'row',
        alignItems: 'center',
        justifyContent: 'space-between',
    },
    backButton: {
        padding: Spacing.sm,
        marginLeft: -Spacing.sm,
    },
    title: {
        fontSize: FontSizes.xl,
        fontWeight: FontWeights.bold,
        color: AppColors.textPrimary,
    },
    placeholder: {
        width: 40,
    },
    productCard: {
        backgroundColor: AppColors.white,
        borderRadius: BorderRadius.xl,
        padding: Spacing.xl,
        alignItems: 'center',
        borderWidth: 2,
        borderColor: AppColors.primary,
        ...Shadows.md,
    },
    productIcon: {
        width: 80,
        height: 80,
        borderRadius: 40,
        backgroundColor: `${AppColors.primary}15`,
        alignItems: 'center',
        justifyContent: 'center',
        marginBottom: Spacing.lg,
    },
    productName: {
        fontSize: FontSizes.xl,
        fontWeight: FontWeights.bold,
        color: AppColors.textPrimary,
        textAlign: 'center',
        marginBottom: Spacing.xs,
    },
    productPrice: {
        fontSize: FontSizes['3xl'],
        fontWeight: FontWeights.bold,
        color: AppColors.primary,
        marginBottom: Spacing.lg,
    },
    productDescription: {
        fontSize: FontSizes.base,
        color: AppColors.textSecondary,
        textAlign: 'center',
        lineHeight: 22,
        marginBottom: Spacing.lg,
    },
    securityBadge: {
        flexDirection: 'row',
        alignItems: 'center',
        gap: Spacing.xs,
        paddingVertical: Spacing.sm,
        paddingHorizontal: Spacing.md,
        backgroundColor: `${AppColors.success}10`,
        borderRadius: BorderRadius.lg,
    },
    securityText: {
        fontSize: FontSizes.sm,
        color: AppColors.success,
    },
    bottomActions: {
        gap: Spacing.md,
    },
    purchaseButton: {
        flexDirection: 'row',
        alignItems: 'center',
        justifyContent: 'center',
        gap: Spacing.sm,
        backgroundColor: AppColors.primary,
        paddingVertical: Spacing.lg,
        borderRadius: BorderRadius.lg,
        ...Shadows.primary,
    },
    buttonDisabled: {
        opacity: 0.7,
    },
    purchaseButtonText: {
        fontSize: FontSizes.lg,
        fontWeight: FontWeights.semibold,
        color: AppColors.white,
    },
    skipButton: {
        alignItems: 'center',
        paddingVertical: Spacing.sm,
    },
    skipButtonText: {
        fontSize: FontSizes.base,
        color: AppColors.textSecondary,
        textDecorationLine: 'underline',
    },
    // Order Placed Screen
    orderPlacedContainer: {
        flex: 1,
        padding: Spacing.lg,
        alignItems: 'center',
        justifyContent: 'center',
    },
    successIcon: {
        width: 100,
        height: 100,
        borderRadius: 50,
        backgroundColor: AppColors.success,
        alignItems: 'center',
        justifyContent: 'center',
        marginBottom: Spacing.xl,
        ...Shadows.lg,
    },
    orderPlacedTitle: {
        fontSize: FontSizes['2xl'],
        fontWeight: FontWeights.bold,
        color: AppColors.textPrimary,
        marginBottom: Spacing.xs,
    },
    orderPlacedSubtitle: {
        fontSize: FontSizes.base,
        color: AppColors.textSecondary,
        marginBottom: Spacing.xl,
    },
    orderInfoCard: {
        width: '100%',
        backgroundColor: AppColors.surface,
        borderRadius: BorderRadius.lg,
        padding: Spacing.lg,
        marginBottom: Spacing.xl,
        ...Shadows.sm,
    },
    orderInfoRow: {
        flexDirection: 'row',
        justifyContent: 'space-between',
        alignItems: 'center',
        paddingVertical: Spacing.sm,
        borderBottomWidth: 1,
        borderBottomColor: AppColors.border,
    },
    orderInfoLabel: {
        fontSize: FontSizes.sm,
        color: AppColors.textSecondary,
    },
    orderInfoValue: {
        fontSize: FontSizes.base,
        fontWeight: FontWeights.medium,
        color: AppColors.textPrimary,
    },
    orderInfoPrice: {
        color: AppColors.primary,
        fontWeight: FontWeights.bold,
    },
    primaryButton: {
        width: '100%',
        backgroundColor: AppColors.primary,
        paddingVertical: Spacing.lg,
        borderRadius: BorderRadius.lg,
        alignItems: 'center',
        ...Shadows.primary,
    },
    primaryButtonText: {
        fontSize: FontSizes.base,
        fontWeight: FontWeights.semibold,
        color: AppColors.white,
    },
});