import type { IncomingMessage, ServerResponse } from 'node:http';

export function sendJson(res: ServerResponse, status: number, body: unknown) {
  res.writeHead(status, { 'content-type': 'application/json; charset=utf-8' });
  res.end(JSON.stringify(body));
}

export function readJsonBody(req: IncomingMessage): Promise<unknown> {
  return new Promise((resolveBody, reject) => {
    let body = '';
    req.setEncoding('utf8');
    req.on('data', (chunk) => {
      body += chunk;
      if (body.length > 2_000_000) {
        req.destroy();
        reject(new Error('Request body too large'));
      }
    });
    req.on('end', () => {
      try {
        resolveBody(body ? JSON.parse(body) : {});
      } catch {
        reject(new Error('Invalid JSON body'));
      }
    });
    req.on('error', reject);
  });
}

export function isPlainObject(value: unknown): value is Record<string, unknown> {
  return typeof value === 'object' && value !== null && !Array.isArray(value);
}

export function errorMessage(error: unknown): string {
  return error instanceof Error ? error.message : String(error);
}