import { NextRequest, NextResponse } from 'next/server';
import fs from 'fs';
import path from 'path';
import serverConfig from '@lifetracker/shared/config';

// Define paths for uploaded files and the production DB
const UPLOAD_DIR = path.join(process.cwd(), 'uploads');
const DB_PATH = path.join(serverConfig.dataDir, 'lifetracker.db');

// Ensure upload directory exists
if (!fs.existsSync(UPLOAD_DIR)) {
    fs.mkdirSync(UPLOAD_DIR, { recursive: true });
}

export async function POST(req: NextRequest) {
    try {
        const contentType = req.headers.get('content-type') || '';
        if (!contentType.includes('multipart/form-data')) {
            return NextResponse.json({ message: 'Invalid content type. Please upload a file.' }, { status: 400 });
        }

        // Create a writable stream for saving the uploaded file
        const formBoundary = contentType.split('boundary=')[1];
        const formData = req.body;

        // Parse and save the uploaded file
        const chunks: Buffer[] = [];
        for await (const chunk of formData) {
            chunks.push(chunk);
        }

        const bodyBuffer = Buffer.concat(chunks);
        const start = bodyBuffer.indexOf(`\r\n\r\n`) + 4;
        const end = bodyBuffer.indexOf(`\r\n--${formBoundary}`, start);
        const fileContent = bodyBuffer.slice(start, end);

        // Save the uploaded file to the upload directory
        const uploadedFilePath = path.join(UPLOAD_DIR, 'uploaded.db');
        fs.writeFileSync(uploadedFilePath, fileContent);

        // Validate the uploaded file extension
        if (!uploadedFilePath.endsWith('.db')) {
            return NextResponse.json({ message: 'Invalid file type. Please upload a .db file.' }, { status: 400 });
        }

        // Backup the current production database
        const backupPath = path.join(
            serverConfig.dataDir,
            `backup_${Date.now()}.db`
        );
        if (fs.existsSync(DB_PATH)) {
            fs.copyFileSync(DB_PATH, backupPath);
        }

        // Replace the production database with the uploaded file
        fs.renameSync(uploadedFilePath, DB_PATH);

        return NextResponse.json({ message: 'Database uploaded and replaced successfully!' }, { status: 200 });
    } catch (error) {
        console.error('Error handling the uploaded file:', error);
        return NextResponse.json({ message: 'Error processing upload.' }, { status: 500 });
    }
}