import http from 'node:http';

export function startControlApi({
  host = '0.0.0.0',
  port = 8081,
  logger = null,
  service = 'service',
  namespace = 'unrip',
  stateProvider = null,
  healthProvider = null,
  routes = [],
} = {}) {
  const routeMap = new Map(routes.map((route) => [`${route.method} ${route.path}`, route]));

  const server = http.createServer(async (req, res) => {
    try {
      if (req.method === 'GET' && req.url === '/healthz') {
        return sendJson(res, 200, {
          ok: true,
          service,
          namespace,
          ...(await healthProvider?.getHealth?.()),
        });
      }

      if (req.method === 'GET' && req.url === '/state') {
        return sendJson(res, 200, {
          service,
          namespace,
          ...(await stateProvider?.getState?.()),
        });
      }

      const route = routeMap.get(`${req.method} ${req.url}`);
      if (!route) {
        return sendJson(res, 404, {
          error: 'not_found',
        });
      }

      const body = route.readBody === false ? null : await readJsonBody(req);
      const result = await route.handler({
        req,
        res,
        body: body || {},
      });

      if (result == null) return;
      if (result.statusCode != null) {
        return sendJson(res, result.statusCode, result.payload ?? {});
      }
      return sendJson(res, 200, result);
    } catch (error) {
      logger?.error('control_api_request_failed', {
        details: {
          method: req.method,
          path: req.url,
          error: error.message,
        },
      });
      return sendJson(res, 500, {
        error: error.message,
      });
    }
  });

  server.listen(port, host, () => {
    logger?.info('control_api_started', {
      details: {
        host,
        port,
      },
    });
  });

  return {
    close() {
      return new Promise((resolve, reject) => {
        server.close((error) => {
          if (error) reject(error);
          else resolve();
        });
      });
    },
  };
}

export function sendJson(res, statusCode, payload) {
  const body = JSON.stringify(payload, null, 2);
  res.statusCode = statusCode;
  res.setHeader('content-type', 'application/json; charset=utf-8');
  res.end(`${body}\n`);
}

export function readJsonBody(req) {
  return new Promise((resolve, reject) => {
    let raw = '';

    req.on('data', (chunk) => {
      raw += chunk;
      if (raw.length > 64 * 1024) {
        reject(new Error('request body too large'));
      }
    });

    req.on('end', () => {
      if (!raw.trim()) {
        resolve({});
        return;
      }

      try {
        resolve(JSON.parse(raw));
      } catch {
        reject(new Error('invalid_json'));
      }
    });

    req.on('error', reject);
  });
}