const loginForm = document.getElementById("loginForm");
const loginButton = document.getElementById("loginButton");
const userInput = document.getElementById("user");
const passwordInput = document.getElementById("pwd");
const loginError = document.getElementById("err");
let loginPending = false;

function showLoginError(message){
    loginError.textContent = message;
    loginError.hidden = false;
}

async function login(){
    if(loginPending) return;
    const username = userInput.value.trim();
    const password = passwordInput.value;
    userInput.setAttribute("aria-invalid", String(!username));
    passwordInput.setAttribute("aria-invalid", String(!password));
    if(!username || !password){
        showLoginError("请输入客服账号和登录密码");
        (!username ? userInput : passwordInput).focus();
        return;
    }
    loginPending = true;
    loginError.hidden = true;
    loginButton.disabled = true;
    loginButton.textContent = "正在登录…";
    loginForm.setAttribute("aria-busy", "true");
    try{
        const response = await fetch("/admin/login", {
            method: "POST", headers: {"Content-Type": "application/json"},
            body: JSON.stringify({username: username, password: password})
        });
        if(response.ok){
            location.href = "/admin/dashboard";
            return;
        }
        showLoginError(response.status === 401 ? "账号或密码不正确，请重新输入" : "暂时无法登录，请稍后重试");
    }catch(error){
        showLoginError("网络连接失败，请检查网络后重试");
    }finally{
        loginPending = false;
        loginButton.disabled = false;
        loginButton.textContent = "登录工作台 →";
        loginForm.removeAttribute("aria-busy");
    }
}

loginForm.addEventListener("submit", function(event){
    event.preventDefault();
    login();
});
[userInput, passwordInput].forEach(function(input){
    input.addEventListener("input", function(){
        loginError.hidden = true;
        input.removeAttribute("aria-invalid");
    });
});