/**
 * @file utils.js
 * @description Utility functions for making API requests and handling responses.
 */

"use strict";

/**
 * Fetches a resource from the server with authentication token.
 *
 * @async
 * @param {string} url - The URL of the resource to fetch.
 * @param {Object} options - Options for the fetch request (e.g. method, body).
 * @returns {Promise<Object>} A promise resolving to the response data.
 */
async function fetchWithToken(url, options) {
    const authToken = localStorage.getItem('token');
    return await fetch(url, {...options, headers: {
            'Authorization': `Bearer ${authToken}`,
            'Content-Type': 'application/json',
            'Cache-Control': 'no-cache, no-store',
        }});
}

/**
 * Fetches a resource from the server without authentication token.
 *
 * @async
 * @param {string} url - The URL of the resource to fetch.
 * @param {Object} options - Options for the fetch request (e.g. method, body).
 * @returns {Promise<Object>} A promise resolving to the response data.
 */
async function fetchRegular(url, options) {
    return await fetch(url, {...options, headers: {
            'Content-Type': 'application/json',
            'Cache-Control': 'no-cache, no-store',
        }});
}

/**
 * Formats a time as HH:MM string.
 *
 * @param {Date} date - The date to format.
 * @returns {string} The formatted time string (e.g. "09:00").
 */
function formatTime(date) {
    const hours = date.getHours().toString().padStart(2, '0');
    const minutes = date.getMinutes().toString().padStart(2, '0');
    return `${hours}:${minutes}`;
}

/**
 * Gets the time span between two dates.
 *
 * @param {Date} start - The start date.
 * @param {Date} end - The end date.
 * @returns {string} The time span string (e.g. "09:00 to 10:00").
 */
function getTimeSpan(start, end) {
    return `${formatTime(new Date(start))} to ${formatTime(new Date(end))}`;
}

/**
 * Parses the response data and redirects if necessary.
 *
 * @async
 * @param {Response} response - The server response.
 * @returns {Promise<Object>} A promise resolving to the parsed response data, or null if a redirect was taken.
 */
async function parseOrRedirect(response) {
    if (response.status === 401) {
        // Handle unauthorized request (redirect to login page)
        window.location.replace("/html/auth.html");
        return;
    }

    if (response.status === 410) {
        // Handle deprecated resource (redirect to deprecated page)
        window.location.replace("/html/410.html");
        return;
    }

    const js = await response.json();
    if (!response.ok) {
        // Handle non-200 status code (redirect to error page)
        window.location.replace("/html/404.html");
    }

    return js;
}

export { fetchWithToken, getTimeSpan, parseOrRedirect, fetchRegular };