import { NextRequest, NextResponse } from 'next/server';
import { cookies } from 'next/headers';
import { db } from '@/lib/db';

// Reserved subdomains that cannot be used
const RESERVED_SUBDOMAINS = [
    'www', 'app', 'api', 'admin', 'mail', 'email',
    'ftp', 'smtp', 'pop', 'imap', 'dns', 'ns1', 'ns2',
    'blog', 'shop', 'store', 'help', 'support', 'dashboard',
    'login', 'signup', 'auth', 'cdn', 'static', 'assets',
    'dev', 'staging', 'test', 'demo', 'beta', 'alpha'
];

// Validate subdomain format
function isValidSubdomain(subdomain: string): { valid: boolean; error?: string } {
    if (!subdomain) {
        return { valid: false, error: 'Subdomain is required' };
    }

    // Must be lowercase
    if (subdomain !== subdomain.toLowerCase()) {
        return { valid: false, error: 'Subdomain must be lowercase' };
    }

    // Length check
    if (subdomain.length < 3 || subdomain.length > 30) {
        return { valid: false, error: 'Subdomain must be 3-30 characters' };
    }

    // Alphanumeric and hyphens only, no leading/trailing hyphens
    if (!/^[a-z0-9]([a-z0-9-]*[a-z0-9])?$/.test(subdomain)) {
        return { valid: false, error: 'Only lowercase letters, numbers, and hyphens allowed' };
    }

    // No consecutive hyphens
    if (/--/.test(subdomain)) {
        return { valid: false, error: 'No consecutive hyphens allowed' };
    }

    // Check reserved
    if (RESERVED_SUBDOMAINS.includes(subdomain)) {
        return { valid: false, error: 'This subdomain is reserved' };
    }

    return { valid: true };
}

// GET /api/user/subdomain - Get current subdomain
export async function GET() {
    try {
        const userId = cookies().get('userId')?.value;
        if (!userId) {
            return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
        }

        const user = await db.user.findUnique({
            where: { id: userId },
            select: { subdomain: true },
        });

        if (!user) {
            return NextResponse.json({ error: 'User not found' }, { status: 404 });
        }

        return NextResponse.json({ subdomain: user.subdomain });
    } catch (error) {
        console.error('Error fetching subdomain:', error);
        return NextResponse.json({ error: 'Internal server error' }, { status: 500 });
    }
}

// POST /api/user/subdomain - Set subdomain
export async function POST(request: NextRequest) {
    try {
        const userId = cookies().get('userId')?.value;
        if (!userId) {
            return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
        }

        const body = await request.json();
        const subdomain = body.subdomain?.trim().toLowerCase();

        // Validate
        const validation = isValidSubdomain(subdomain);
        if (!validation.valid) {
            return NextResponse.json({ error: validation.error }, { status: 400 });
        }

        // Check if already taken by another user
        const existing = await db.user.findFirst({
            where: {
                subdomain,
                NOT: { id: userId },
            },
        });

        if (existing) {
            return NextResponse.json({ error: 'This subdomain is already taken' }, { status: 409 });
        }

        // Update user
        try {
            const updatedUser = await db.user.update({
                where: { id: userId },
                data: { subdomain },
                select: { subdomain: true } // Only select needed fields
            });

            return NextResponse.json({
                success: true,
                subdomain: updatedUser.subdomain,
                url: `https://${updatedUser.subdomain}.qrmaster.net`
            });
        } catch (error: any) {
            if (error.code === 'P2025') {
                return NextResponse.json({ error: 'User not found' }, { status: 404 });
            }
            throw error;
        }
    } catch (error) {
        console.error('Error setting subdomain:', error);
        return NextResponse.json({ error: 'Internal server error' }, { status: 500 });
    }
}

// DELETE /api/user/subdomain - Remove subdomain
export async function DELETE() {
    try {
        const userId = cookies().get('userId')?.value;
        if (!userId) {
            return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
        }

        await db.user.update({
            where: { id: userId },
            data: { subdomain: null },
        });

        return NextResponse.json({ success: true });
    } catch (error) {
        console.error('Error removing subdomain:', error);
        return NextResponse.json({ error: 'Internal server error' }, { status: 500 });
    }
}