import fs from 'node:fs/promises';
import path from 'node:path';
import { defineConfig } from 'vite';
import react from '@vitejs/plugin-react';

const databasePath = path.resolve(process.cwd(), 'data', 'flow-db.json');

async function readDatabase() {
  try {
    const raw = await fs.readFile(databasePath, 'utf8');
    return JSON.parse(raw);
  } catch (error) {
    if (error.code === 'ENOENT') return null;
    throw error;
  }
}

async function writeDatabase(data) {
  await fs.mkdir(path.dirname(databasePath), { recursive: true });
  await fs.writeFile(databasePath, JSON.stringify({
    ...data,
    updatedAt: new Date().toISOString()
  }, null, 2));
}

function readRequestBody(request) {
  return new Promise((resolve, reject) => {
    let body = '';

    request.on('data', (chunk) => {
      body += chunk;
      if (body.length > 5_000_000) {
        reject(new Error('Request body is too large'));
        request.destroy();
      }
    });

    request.on('end', () => resolve(body));
    request.on('error', reject);
  });
}

function sendJson(response, statusCode, payload) {
  response.statusCode = statusCode;
  response.setHeader('Content-Type', 'application/json; charset=utf-8');
  response.end(JSON.stringify(payload));
}

function serverDatabasePlugin() {
  return {
    name: 'flow-server-database',
    configureServer(server) {
      server.middlewares.use('/api/state', async (request, response) => {
        try {
          if (request.method === 'GET') {
            const data = await readDatabase();
            if (!data) {
              sendJson(response, 404, { error: 'Database is empty' });
              return;
            }
            sendJson(response, 200, data);
            return;
          }

          if (request.method === 'PUT' || request.method === 'PATCH') {
            const current = request.method === 'PATCH' ? (await readDatabase()) ?? {} : {};
            const body = await readRequestBody(request);
            const payload = body ? JSON.parse(body) : {};
            const nextData = {
              ...current,
              ...payload
            };
            await writeDatabase(nextData);
            sendJson(response, 200, nextData);
            return;
          }

          response.statusCode = 405;
          response.end();
        } catch (error) {
          sendJson(response, 500, { error: error.message });
        }
      });
    }
  };
}

export default defineConfig({
  plugins: [react(), serverDatabasePlugin()]
});