src/lib/util/flattenPayload.ts

export const flattenPayload = (
    payload: Record<string, unknown> = {},
    parentKey = '',
): Record<string, unknown> =>
    Object.entries(payload).reduce(
        (acc, [key, value]) => {
            const newKey = parentKey ? `${parentKey}.${key}` : key;

            if (
                typeof value === 'object' &&
                value !== null &&
                !Array.isArray(value)
            ) {
                // If it's an object, recurse and merge the results
                Object.assign(
                    acc,
                    flattenPayload(value as Record<string, unknown>, newKey),
                );
            } else if (Array.isArray(value)) {
                // If it's an array, map through it and handle objects and non-objects differently
                value.forEach((item, index) => {
                    if (typeof item === 'object' && item !== null) {
                        Object.assign(
                            acc,
                            flattenPayload(item, `${newKey}[${index}]`),
                        );
                    } else {
                        acc[`${newKey}[${index}]`] = item;
                    }
                });
            } else {
                acc[newKey] = value;
            }

            return acc;
        },
        {} as Record<string, unknown>,
    );