export async function postData(url, data, token = null) {
    const elements = url.split("/");
    const end = elements[elements.length - 1];

    const res = await fetch(end, token == null ? {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify(data)
    } : {
        method: "POST",
        headers: {
            "Content-Type": "application/json",
            "Authorization" : "Bearer " + token
        },
        body: JSON.stringify(data)
    });

    const resultObject = await res.json();

    if (resultObject.logout === true) {
        alert("Session expired; please log in again.");
        window.location.href = "login.html";
        return resultObject;
    }

    return resultObject;
}

export async function verifyLogin() {
    let token = null;
    try {
        token = JSON.stringify(localStorage.getItem("token"));
    } catch (error) {
        alert("You are not logged in.");
        window.location.href = "login.html";
        console.log("Error encountered: " + error);
        return false;
    }
    if (!token) {
        alert("You are not logged in.");
        window.location.href = "login.html";
        console.log("Token was null");
        return false;
    }

    return true;
}

export async function verifyRole(role) {
    if (!verifyLogin()) return;

    return postData("/getInfo", {}, localStorage.getItem("token")).Role === role;
}