import { NextFunction, Request, Response } from 'express';

/**
 * Middleware to parse JSON data from form data
 * This middleware expects the request body to contain a 'data' field with a JSON string.
 * It parses the JSON string and replaces req.body with the parsed object.
 * 
 * @param req - Express Request object
 * @param res - Express Response object
 * @param next - Express NextFunction
 */
const formDataToSetJSONformatData = (
  req: Request,
  res: Response,
  next: NextFunction
): void => {
  try {
    // Check if the data field exists in the request body
    if (!req.body || !req.body.data) {
      throw new Error('Missing required field: data');
    }
    
    // Parse the JSON string from the data field
    const parsedData = JSON.parse(req.body.data);
    
    // Replace the entire request body with the parsed data
    req.body = parsedData;
    
    // Continue to the next middleware
    next();
  } catch (error) {
    // Handle JSON parsing errors or missing data field
    res.status(400).json({
      success: false,
      message: 'Invalid JSON data provided',
      error: error instanceof Error ? error.message : 'Unknown error'
    });
  }
};

export default formDataToSetJSONformatData;