import React, { useEffect } from 'react';
import { useParams, useNavigate, Link } from 'react-router-dom';
import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
import { ArrowLeft, Play, Pause, XCircle, RefreshCw, Calendar, User, Package, CreditCard, Clock, FileText } from 'lucide-react';
import { Button } from '@/components/ui/button';
import { Badge } from '@/components/ui/badge';
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
import {
    Table,
    TableBody,
    TableCell,
    TableHead,
    TableHeader,
    TableRow,
} from '@/components/ui/table';
import {
    AlertDialog,
    AlertDialogAction,
    AlertDialogCancel,
    AlertDialogContent,
    AlertDialogDescription,
    AlertDialogFooter,
    AlertDialogHeader,
    AlertDialogTitle,
} from '@/components/ui/alert-dialog';
import { Skeleton } from '@/components/ui/skeleton';
import { usePageHeader } from '@/contexts/PageHeaderContext';
import { __ } from '@/lib/i18n';
import { toast } from 'sonner';
import { api } from '@/lib/api';

interface SubscriptionOrder {
    id: number;
    subscription_id: number;
    order_id: number;
    order_type: 'parent' | 'renewal' | 'switch' | 'resubscribe';
    order_status: string;
    created_at: string;
}

interface Subscription {
    id: number;
    user_id: number;
    order_id: number;
    product_id: number;
    variation_id: number | null;
    product_name: string;
    product_image: string;
    user_name: string;
    user_email: string;
    status: string;
    billing_period: string;
    billing_interval: number;
    billing_schedule: string;
    recurring_amount: string;
    start_date: string;
    trial_end_date: string | null;
    next_payment_date: string | null;
    end_date: string | null;
    last_payment_date: string | null;
    payment_method: string;
    payment_method_title?: string;
    pause_count: number;
    failed_payment_count: number;
    cancel_reason: string | null;
    created_at: string;
    can_pause: boolean;
    can_resume: boolean;
    can_cancel: boolean;
    orders: SubscriptionOrder[];
}

const statusColors: Record<string, string> = {
    'pending': 'bg-yellow-100 text-yellow-800',
    'active': 'bg-green-100 text-green-800',
    'on-hold': 'bg-blue-100 text-blue-800',
    'cancelled': 'bg-gray-100 text-gray-800',
    'expired': 'bg-red-100 text-red-800',
    'pending-cancel': 'bg-orange-100 text-orange-800',
    'draft': 'bg-gray-100 text-gray-600',
};

const statusLabels: Record<string, string> = {
    'pending': __('Pending'),
    'active': __('Active'),
    'on-hold': __('On Hold'),
    'cancelled': __('Cancelled'),
    'expired': __('Expired'),
    'pending-cancel': __('Pending Cancel'),
    'draft': __('Draft'),
};

const orderTypeLabels: Record<string, string> = {
    'parent': __('Initial Order'),
    'renewal': __('Renewal'),
    'switch': __('Plan Switch'),
    'resubscribe': __('Resubscribe'),
};

const formatPrice = (amount: string | number) => {
    const val = typeof amount === 'string' ? parseFloat(amount) : amount;
    if (isNaN(val)) return amount;

    // Simple formatting using browser's locale but keeping currency from store
    try {
        return new Intl.NumberFormat(window.WNW_STORE?.locale || 'en-US', {
            style: 'currency',
            currency: window.WNW_STORE?.currency || 'USD',
            minimumFractionDigits: window.WNW_STORE?.decimals || 2,
        }).format(val);
    } catch (e) {
        return (window.WNW_STORE?.currency_symbol || '$') + val;
    }
};

async function fetchSubscription(id: string) {
    const res = await api.get(`/subscriptions/${id}`);
    return res;
}

async function subscriptionAction(id: number, action: string, reason?: string) {
    const res = await api.post(`/subscriptions/${id}/${action}`, { reason });
    return res;
}

export default function SubscriptionDetail() {
    const { id } = useParams<{ id: string }>();
    const navigate = useNavigate();
    const queryClient = useQueryClient();
    const { setPageHeader, clearPageHeader } = usePageHeader();
    const [showCancelDialog, setShowCancelDialog] = React.useState(false);

    const { data: subscription, isLoading, error } = useQuery<Subscription>({
        queryKey: ['subscription', id],
        queryFn: () => fetchSubscription(id!),
        enabled: !!id,
    });

    useEffect(() => {
        if (subscription) {
            setPageHeader(__('Subscription') + ' #' + subscription.id);
        }
        return () => clearPageHeader();
    }, [subscription, setPageHeader, clearPageHeader]);

    const actionMutation = useMutation({
        mutationFn: ({ action, reason }: { action: string; reason?: string }) =>
            subscriptionAction(parseInt(id!), action, reason),
        onSuccess: (_, { action }) => {
            queryClient.invalidateQueries({ queryKey: ['subscription', id] });
            queryClient.invalidateQueries({ queryKey: ['subscriptions'] });
            toast.success(__(`Subscription ${action}d successfully`));
            setShowCancelDialog(false);
        },
        onError: (error: Error) => {
            toast.error(error.message);
            setShowCancelDialog(false);
        },
    });

    const handleAction = (action: string) => {
        if (action === 'cancel') {
            setShowCancelDialog(true);
            return;
        }
        actionMutation.mutate({ action });
    };

    const confirmCancel = () => {
        actionMutation.mutate({ action: 'cancel' });
    };

    if (isLoading) {
        return (
            <div className="space-y-6">
                <Skeleton className="h-8 w-64" />
                <div className="grid gap-6 md:grid-cols-2">
                    <Skeleton className="h-48" />
                    <Skeleton className="h-48" />
                </div>
                <Skeleton className="h-64" />
            </div>
        );
    }

    if (error || !subscription) {
        return (
            <div className="text-center py-12">
                <p className="text-red-500">{__('Failed to load subscription')}</p>
                <Button variant="outline" className="mt-4" onClick={() => navigate('/subscriptions')}>
                    <ArrowLeft className="w-4 h-4 mr-2" />
                    {__('Back to Subscriptions')}
                </Button>
            </div>
        );
    }

    return (
        <div className="space-y-6">
            {/* Back button and actions */}
            <div className="flex items-center justify-between">
                <Button variant="ghost" onClick={() => navigate('/subscriptions')}>
                    <ArrowLeft className="w-4 h-4 mr-2" />
                    {__('Back')}
                </Button>

                <div className="flex items-center gap-2">
                    {subscription.can_pause && (
                        <Button
                            variant="outline"
                            onClick={() => handleAction('pause')}
                            disabled={actionMutation.isPending}
                        >
                            <Pause className="w-4 h-4 mr-2" />
                            {__('Pause')}
                        </Button>
                    )}
                    {subscription.can_resume && (
                        <Button
                            variant="outline"
                            onClick={() => handleAction('resume')}
                            disabled={actionMutation.isPending}
                        >
                            <Play className="w-4 h-4 mr-2" />
                            {__('Resume')}
                        </Button>
                    )}
                    {subscription.status === 'active' && (
                        <Button
                            variant="outline"
                            onClick={() => handleAction('renew')}
                            disabled={actionMutation.isPending}
                        >
                            <RefreshCw className="w-4 h-4 mr-2" />
                            {__('Renew Now')}
                        </Button>
                    )}
                    {subscription.can_cancel && (
                        <Button
                            variant="destructive"
                            onClick={() => handleAction('cancel')}
                            disabled={actionMutation.isPending}
                        >
                            <XCircle className="w-4 h-4 mr-2" />
                            {__('Cancel')}
                        </Button>
                    )}
                </div>
            </div>

            {/* Status and product info */}
            <div className="grid gap-6 md:grid-cols-2">
                {/* Subscription Info */}
                <Card>
                    <CardHeader>
                        <div className="flex items-center justify-between">
                            <CardTitle>{__('Subscription Details')}</CardTitle>
                            <Badge className={statusColors[subscription.status] || 'bg-gray-100'}>
                                {statusLabels[subscription.status] || subscription.status}
                            </Badge>
                        </div>
                    </CardHeader>
                    <CardContent className="space-y-4">
                        <div className="flex items-start gap-4">
                            {subscription.product_image ? (
                                <img
                                    src={subscription.product_image}
                                    alt={subscription.product_name}
                                    className="w-16 h-16 object-cover rounded"
                                />
                            ) : (
                                <div className="w-16 h-16 bg-muted rounded flex items-center justify-center">
                                    <Package className="w-8 h-8 text-muted-foreground" />
                                </div>
                            )}
                            <div>
                                <h3 className="font-medium">{subscription.product_name}</h3>
                                <p className="text-sm text-muted-foreground">
                                    {subscription.billing_schedule}
                                </p>
                                <p className="text-lg font-semibold mt-1">
                                    {formatPrice(subscription.recurring_amount)}
                                </p>
                            </div>
                        </div>

                        <div className="grid grid-cols-2 gap-4 pt-4 border-t">
                            <div>
                                <div className="text-sm text-muted-foreground">{__('Start Date')}</div>
                                <div>{new Date(subscription.start_date).toLocaleDateString()}</div>
                            </div>
                            {subscription.next_payment_date && (
                                <div>
                                    <div className="text-sm text-muted-foreground">{__('Next Payment')}</div>
                                    <div>{new Date(subscription.next_payment_date).toLocaleDateString()}</div>
                                </div>
                            )}
                            {subscription.trial_end_date && (
                                <div>
                                    <div className="text-sm text-muted-foreground">{__('Trial End')}</div>
                                    <div>{new Date(subscription.trial_end_date).toLocaleDateString()}</div>
                                </div>
                            )}
                            {subscription.end_date && (
                                <div>
                                    <div className="text-sm text-muted-foreground">{__('End Date')}</div>
                                    <div>{new Date(subscription.end_date).toLocaleDateString()}</div>
                                </div>
                            )}
                        </div>

                        {subscription.cancel_reason && (
                            <div className="pt-4 border-t">
                                <div className="text-sm text-muted-foreground">{__('Cancel Reason')}</div>
                                <div className="text-red-600">{subscription.cancel_reason}</div>
                            </div>
                        )}
                    </CardContent>
                </Card>

                {/* Customer Info */}
                <Card>
                    <CardHeader>
                        <CardTitle>{__('Customer')}</CardTitle>
                    </CardHeader>
                    <CardContent className="space-y-4">
                        <div className="flex items-center gap-3">
                            <div className="w-10 h-10 bg-muted rounded-full flex items-center justify-center">
                                <User className="w-5 h-5 text-muted-foreground" />
                            </div>
                            <div>
                                <div className="font-medium">{subscription.user_name}</div>
                                <div className="text-sm text-muted-foreground">{subscription.user_email}</div>
                            </div>
                        </div>

                        <div className="grid grid-cols-2 gap-4 pt-4 border-t">
                            <div>
                                <div className="text-sm text-muted-foreground">{__('Payment Method')}</div>
                                <div className="flex items-center gap-2">
                                    <CreditCard className="w-4 h-4" />
                                    {subscription.payment_method_title || subscription.payment_method || __('Not set')}
                                </div>
                            </div>
                            <div>
                                <div className="text-sm text-muted-foreground">{__('Pause Count')}</div>
                                <div>{subscription.pause_count}</div>
                            </div>
                            <div>
                                <div className="text-sm text-muted-foreground">{__('Failed Payments')}</div>
                                <div className={subscription.failed_payment_count > 0 ? 'text-red-600' : ''}>
                                    {subscription.failed_payment_count}
                                </div>
                            </div>
                            <div>
                                <div className="text-sm text-muted-foreground">{__('Parent Order')}</div>
                                <Link
                                    to={`/orders/${subscription.order_id}`}
                                    className="text-primary hover:underline"
                                >
                                    #{subscription.order_id}
                                </Link>
                            </div>
                        </div>
                    </CardContent>
                </Card>
            </div>

            {/* Related Orders */}
            <Card>
                <CardHeader>
                    <CardTitle>{__('Related Orders')}</CardTitle>
                    <CardDescription>{__('All orders associated with this subscription')}</CardDescription>
                </CardHeader>
                <CardContent>
                    <Table>
                        <TableHeader>
                            <TableRow>
                                <TableHead>{__('Order')}</TableHead>
                                <TableHead>{__('Type')}</TableHead>
                                <TableHead>{__('Status')}</TableHead>
                                <TableHead>{__('Date')}</TableHead>
                            </TableRow>
                        </TableHeader>
                        <TableBody>
                            {subscription.orders?.length === 0 ? (
                                <TableRow>
                                    <TableCell colSpan={4} className="text-center py-8 text-muted-foreground">
                                        {__('No orders found')}
                                    </TableCell>
                                </TableRow>
                            ) : (
                                subscription.orders?.map((order) => {
                                    const rawStatus = order.order_status?.replace('wc-', '') || 'pending';
                                    return (
                                        <TableRow key={order.id}>
                                            <TableCell>
                                                <Link
                                                    to={`/orders/${order.order_id}`}
                                                    className="text-primary hover:underline font-medium"
                                                >
                                                    #{order.order_id}
                                                </Link>
                                            </TableCell>
                                            <TableCell>
                                                <Badge variant="outline">
                                                    {orderTypeLabels[order.order_type] || order.order_type}
                                                </Badge>
                                            </TableCell>
                                            <TableCell>
                                                <span className="capitalize">{statusLabels[rawStatus] || rawStatus}</span>
                                            </TableCell>
                                            <TableCell>
                                                {new Date(order.created_at).toLocaleDateString()}
                                            </TableCell>
                                        </TableRow>
                                    );
                                })
                            )}
                        </TableBody>
                    </Table>
                </CardContent>
            </Card>

            {/* Cancel Confirmation Dialog (replaces native confirm()) */}
            <AlertDialog open={showCancelDialog} onOpenChange={setShowCancelDialog}>
                <AlertDialogContent>
                    <AlertDialogHeader>
                        <AlertDialogTitle>{__('Cancel Subscription')}</AlertDialogTitle>
                        <AlertDialogDescription>
                            {__('Are you sure you want to cancel this subscription?')}
                            <br />
                            <span className="text-red-600 font-medium">{__('This action cannot be undone.')}</span>
                        </AlertDialogDescription>
                    </AlertDialogHeader>
                    <AlertDialogFooter>
                        <AlertDialogCancel
                            onClick={() => setShowCancelDialog(false)}
                            disabled={actionMutation.isPending}
                        >
                            {__('Keep Subscription')}
                        </AlertDialogCancel>
                        <AlertDialogAction
                            onClick={confirmCancel}
                            disabled={actionMutation.isPending}
                            className="bg-destructive text-destructive-foreground hover:bg-destructive/90"
                        >
                            {actionMutation.isPending ? __('Cancelling...') : __('Cancel Subscription')}
                        </AlertDialogAction>
                    </AlertDialogFooter>
                </AlertDialogContent>
            </AlertDialog>
        </div>
    );
}
