/** @typedef {import('koa').Context} Context */
/** @typedef {import('koa').Next} Next */
/** @typedef {import('koa').Middleware} Middleware */

/**
 * Koa middleware generator for checking the presence and type of a field in the request body.
 *
 * @param {string} field_name - The name of the field to be checked.
 * @param {string} field_type - The expected type of the field.
 * @returns {Middleware} Koa middleware function.
 */
export function syllableRequired(field_name, field_type) {
	/**
	 * @param {Context} ctx - Koa context object.
	 * @param {Next} next - Next middleware function.
	 */
	return async (ctx, next) => {
		const fieldValue = ctx.request.body[field_name];

		if (fieldValue === undefined || typeof fieldValue !== field_type) {
			ctx.status = 400; // 400 Bad Request
			ctx.body = {
				error: `Field '${field_name}' is required and must be of type '${field_type}'.`,
			};
			return;
		}

		await next();
	};
}