import { getDbClient } from '@/app/lib/dbClient';
import { BillingLocation } from '@/app/lib/db-types';
import { notFound } from 'next/navigation';
import { extractShareId, validateShareChecksum } from '@/app/lib/shareChecksum';

export async function GET(_request: Request, { params: { id } }: { params: { id: string } }) {
    // Parse shareId-billID format
    // shareId = 40 chars (locationId 24 + checksum 16)
    const shareId = id.substring(0, 40);
    const billID = id.substring(41); // Skip the '-' separator

    if (!shareId || !billID) {
        notFound();
    }

    // Validate shareId and extract locationId
    const extracted = extractShareId(shareId);
    if (!extracted) {
        notFound();
    }

    const { locationId: locationID, checksum } = extracted;

    // Validate checksum
    if (!validateShareChecksum(locationID, checksum)) {
        notFound();
    }

    const dbClient = await getDbClient();
    const location = await dbClient.collection<BillingLocation>("lokacije")
        .findOne({ _id: locationID }, {
            projection: {
                // Don't load bill attachments, only proof of payment and shareTTL
                "bills._id": 1,
                "bills.proofOfPayment": 1,
                "shareTTL": 1,
            }
        });

    if (!location) {
        notFound();
    }

    // Check if sharing is active and not expired
    if (!location.shareTTL || new Date() > location.shareTTL) {
        notFound();
    }

    // Find the specific bill
    const bill = location.bills.find(b => b._id === billID);

    if(!bill?.proofOfPayment) {
        notFound();
    }

    // Convert fileContentsBase64 from Base64 string to binary
    const fileContentsBuffer = Buffer.from(bill.proofOfPayment.fileContentsBase64, 'base64');

    // Convert fileContentsBuffer to format that can be sent to the client
    const fileContents = new Uint8Array(fileContentsBuffer);

    return new Response(fileContents, {
        status: 200,
        headers: {
            'Content-Type': 'application/pdf',
            'Content-Disposition': `attachment; filename="${bill.proofOfPayment.fileName}"`,
            'Last-Modified': `${bill.proofOfPayment.fileLastModified}`
        }
    });
}
