export function buildResponse(statusCode, body, cors = true) {
  const result = {
    statusCode: statusCode || HTTP_STATUS.OK,
  };

  if (cors) {
    result['headers'] = {
      'Access-Control-Allow-Origin': '*',
      Accept: 'application/json',
    };
  }

  if (body) {
    result.body = JSON.stringify(body);
    result.headers['Content-Type'] = 'application/json';
  }

  return result;
}

export function httpRouter(handlerMap) {
  const notFound = async function(event, context, callback) {
    callback(undefined, buildResponse(404));
  };

  return async function(event, context, callback) {
    debug('httpRouter handle event:', readable(event));

    const handler = get(handlerMap, event.httpMethod, notFound);
    if (handler === notFound) {
      debug(
        `Failed to find handler for event: ${readable(
          event,
        )}\nAnd context: ${readable(context)}`,
      );
    }
    return handler(event, context, callback);
  };
}

export function groupedEventHandler(handlers) {
  return async function(event, context, callback) {
    const errors = [];

    for (let handlerName of Object.keys(handlers)) {
      debug(`START EVENT HANDLER: ${handlerName}`);
      const handler = handlers[handlerName];

      try {
        await handler(event, context);
      } catch (err) {
        debug(`ERROR IN EVENT HANDLER: ${handlerName}`);
        debug(err);
        debug(err.stack);
        errors.push(err);
      }
      debug(`  END EVENT HANDLER: ${handlerName}`);
    }

    if (errors.length > 0) {
      callback(errors);
    }

    callback();
  };
}