Checkmate/server/middleware/responseHandler.js

/**
 * Middleware that adds standardized response methods to the Express response object.
 * This allows for consistent API responses throughout the application.
 *
 * @param {import('express').Request} req - Express request object
 * @param {import('express').Response} res - Express response object
 * @param {import('express').NextFunction} next - Express next middleware function
 */
const responseHandler = (req, res, next) => {
	/**
	 * Sends a standardized success response
	 *
	 * @param {Object} options - Success response options
	 * @param {number} [options.status=200] - HTTP status code
	 * @param {string} [options.msg="OK"] - Success message
	 * @param {*} [options.data=null] - Response data payload
	 * @returns {Object} Express response object
	 */
	res.success = ({ status = 200, msg = "OK", data = null, headers = {} }) => {
		// Set custom headers if provided
		Object.entries(headers).forEach(([key, value]) => {
			res.set(key, value);
		});

		return res.status(status).json({
			success: true,
			msg: msg,
			data: data,
		});
	};

	/**
	 * Sends a standardized error response
	 *
	 * @param {Object} options - Error response options
	 * @param {number} [options.status=500] - HTTP status code
	 * @param {string} [options.msg="Internal server error"] - Error message
	 * @param {*} [options.data=null] - Additional error data (if any)
	 * @returns {Object} Express response object
	 */
	res.error = ({ status = 500, msg = "Internal server error", data = null }) => {
		return res.status(status).json({
			success: false,
			msg,
			data,
		});
	};

	/**
	 * Sends a raw file response (for CSV, PDF, etc.)
	 * @param {Object} options
	 * @param {Buffer|string} options.data - The file content
	 * @param {Object} options.headers - Headers to set (e.g. Content-Type, Content-Disposition)
	 * @param {number} [options.status=200] - HTTP status code
	 */
	res.file = ({ data, headers = {}, status = 200 }) => {
		Object.entries(headers).forEach(([key, value]) => {
			res.setHeader(key, value);
		});
		return res.status(status).send(data);
	};

	next();
};

export { responseHandler };