function isObject(value) {
	return value === Object(value);
}

function isArray(value) {
	return Array.isArray(value);
}

function isFile(value) {
	return value instanceof File;
}

function makeArrayKey(key) {
	return key;
}

function objectToFormData(obj, fd, pre) {
	fd = fd || new FormData();

	Object.keys(obj).forEach(function(prop) {
		var key = pre ? pre + '[' + prop + ']' : prop;

		if (isObject(obj[prop]) && !isArray(obj[prop]) && !isFile(obj[prop])) {
			objectToFormData(obj[prop], fd, key);
		} else if (isArray(obj[prop])) {
			obj[prop].forEach(function(value) {
				var arrayKey = makeArrayKey(key);

				if (isObject(value) && !isFile(value)) {
					objectToFormData(value, fd, arrayKey);
				} else {
					fd.append(arrayKey, value);
				}
			});
		} else {
			if (obj[prop] != null) fd.append(key, obj[prop]);
		}
	});

	return fd;
}

export default objectToFormData;