const loginSection = document.getElementById("login-section");
const mainSection = document.getElementById("main-section");
const settingsSection = document.getElementById("settings-section");
const loginForm = document.getElementById("login-form");
const loginError = document.getElementById("login-error");
const welcomeUser = document.getElementById("welcome-user");
const settingsForm = document.getElementById("settings-form");
const settingsError = document.getElementById("settings-error");
const settingsSuccess = document.getElementById("settings-success");
const form = document.getElementById("start-form");
const urlInput = document.getElementById("url-input");
const startBtn = document.getElementById("start-btn");
const errorMsg = document.getElementById("error-msg");

function show(el) {
  el.classList.remove("hidden");
}

function hide(el) {
  el.classList.add("hidden");
}

function showPanelError(el, message) {
  el.textContent = message;
  show(el);
}

function hidePanelError(el) {
  hide(el);
}

function showMain(username) {
  hide(loginSection);
  hide(settingsSection);
  show(mainSection);
  welcomeUser.textContent = `当前用户：${username}`;
  document.getElementById("cur-user").value = username;
  urlInput.focus();
}

function showLogin() {
  hide(mainSection);
  hide(settingsSection);
  show(loginSection);
}

async function init() {
  const user = await AUTH.me();
  if (user) {
    showMain(user.username);
  } else {
    showLogin();
  }
}

loginForm.addEventListener("submit", async (e) => {
  e.preventDefault();
  hidePanelError(loginError);
  const username = document.getElementById("login-user").value.trim();
  const password = document.getElementById("login-pass").value;
  try {
    const data = await AUTH.login(username, password);
    showMain(data.username);
  } catch (err) {
    showPanelError(loginError, err.message);
  }
});

document.getElementById("btn-logout").addEventListener("click", async () => {
  await AUTH.logout();
  showLogin();
});

document.getElementById("btn-settings").addEventListener("click", () => {
  hide(mainSection);
  hidePanelError(settingsError);
  hide(settingsSuccess);
  show(settingsSection);
});

document.getElementById("btn-settings-cancel").addEventListener("click", () => {
  const user = welcomeUser.textContent.replace("当前用户：", "");
  showMain(user);
});

settingsForm.addEventListener("submit", async (e) => {
  e.preventDefault();
  hidePanelError(settingsError);
  hide(settingsSuccess);
  try {
    const data = await AUTH.changeCredentials({
      current_username: document.getElementById("cur-user").value.trim(),
      current_password: document.getElementById("cur-pass").value,
      new_username: document.getElementById("new-user").value.trim(),
      new_password: document.getElementById("new-pass").value,
    });
    document.getElementById("cur-pass").value = "";
    document.getElementById("new-pass").value = "";
    settingsSuccess.textContent = "账号已更新，请使用新凭据登录";
    show(settingsSuccess);
    setTimeout(async () => {
      await AUTH.logout();
      showLogin();
    }, 1500);
    welcomeUser.textContent = `当前用户：${data.username}`;
  } catch (err) {
    showPanelError(settingsError, err.message);
  }
});

function showError(message) {
  errorMsg.textContent = message;
  show(errorMsg);
}

function hideError() {
  hide(errorMsg);
}

form.addEventListener("submit", async (event) => {
  event.preventDefault();
  hideError();

  const url = urlInput.value.trim();
  if (!url) {
    showError("请输入网址");
    return;
  }

  startBtn.disabled = true;
  startBtn.textContent = "启动中...";

  try {
    const response = await fetch("/api/session", {
      method: "POST",
      credentials: "include",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ url }),
    });

    const data = await response.json().catch(() => ({}));

    if (response.status === 401) {
      showLogin();
      showPanelError(loginError, "登录已过期，请重新登录");
      return;
    }

    if (!response.ok) {
      showError(data.detail || "创建会话失败");
      return;
    }

    window.location.href = `/view/${data.session_id}`;
  } catch (err) {
    showError("网络错误，请稍后重试");
  } finally {
    startBtn.disabled = false;
    startBtn.textContent = "进入";
  }
});

init();