function showAuthModal() {
    const el = document.getElementById("auth-modal");
    if (el) el.classList.remove("hidden");
}

function hideAuthModal() {
    const el = document.getElementById("auth-modal");
    if (el) el.classList.add("hidden");
}

async function handleLogin(e) {
    if (e && e.preventDefault) e.preventDefault();
    
    const usernameInput = document.getElementById("auth-username-input");
    const passwordInput = document.getElementById("auth-password-input");
    const errorEl = document.getElementById("auth-error");

    if (!usernameInput || !passwordInput) return;

    const username = usernameInput.value.trim();
    const password = passwordInput.value;

    if (!username || !password) return;

    if (errorEl) errorEl.classList.add("hidden");

    try {
        const res = await fetch("/api/v1/auth/login", {
            method: "POST",
            headers: { "Content-Type": "application/json" },
            body: JSON.stringify({ username, password })
        });

        const data = await res.json();

        if (res.status === 200) {
            // Используем прямой строковый ключ, чтобы избежать ошибки ReferenceError
            API_TOKEN = data.token;
            CURRENT_USERNAME = data.username;
            IS_ADMIN = data.is_admin;
            IS_GUEST = false;

            localStorage.setItem("scud_api_auth_token", data.token);
            localStorage.setItem("scud_username", data.username);
            localStorage.setItem("scud_is_admin", data.is_admin ? "true" : "false");
            localStorage.removeItem("scud_is_guest");

            hideAuthModal();
            updateUIState();
            
            if (typeof loadTasks === 'function') {
                loadTasks();
            }
        } else {
            if (errorEl) {
                errorEl.innerText = data.detail || "Ошибка авторизации";
                errorEl.classList.remove("hidden");
            }
        }
    } catch (err) {
        console.error("[Auth Error]", err);
        if (errorEl) {
            errorEl.innerText = "Ошибка соединения с сервером";
            errorEl.classList.remove("hidden");
        }
    }
}

function enableGuestMode() {
    IS_GUEST = true;
    API_TOKEN = "";
    CURRENT_USERNAME = "Гость";
    IS_ADMIN = false;
    localStorage.setItem("scud_is_guest", "true");
    hideAuthModal();
    updateUIState();
}

function logout() {
    localStorage.removeItem("scud_api_auth_token");
    localStorage.removeItem("scud_username");
    localStorage.removeItem("scud_is_admin");
    localStorage.removeItem("scud_is_guest");
    API_TOKEN = "";
    CURRENT_USERNAME = "";
    IS_ADMIN = false;
    IS_GUEST = false;
    showAuthModal();
}

function updateUIState() {
    const tasksBtn = document.getElementById("tasks-drawer-btn");
    const adminBtn = document.getElementById("admin-users-btn");
    const changePwdBtn = document.getElementById("change-pwd-btn");
    const guestBadge = document.getElementById("guest-badge");
    const usernameBadge = document.getElementById("username-badge");

    if (typeof IS_GUEST !== 'undefined' && IS_GUEST) {
        if (tasksBtn) tasksBtn.classList.add("hidden");
        if (adminBtn) adminBtn.classList.add("hidden");
        if (changePwdBtn) changePwdBtn.classList.add("hidden");
        if (guestBadge) guestBadge.classList.remove("hidden");
        if (usernameBadge) usernameBadge.classList.add("hidden");
    } else {
        if (tasksBtn) tasksBtn.classList.remove("hidden");
        if (changePwdBtn) changePwdBtn.classList.remove("hidden");
        if (guestBadge) guestBadge.classList.add("hidden");

        if (usernameBadge) {
            usernameBadge.innerText = (typeof CURRENT_USERNAME !== 'undefined' && CURRENT_USERNAME) ? CURRENT_USERNAME : "User";
            usernameBadge.classList.remove("hidden");
        }

        if (adminBtn) {
            const isAdminUser = (typeof IS_ADMIN !== 'undefined' && IS_ADMIN) || (typeof CURRENT_USERNAME !== 'undefined' && CURRENT_USERNAME === "puh");
            if (isAdminUser) {
                adminBtn.classList.remove("hidden");
            } else {
                adminBtn.classList.add("hidden");
            }
        }
    }
}

function openChangePasswordModal() {
    const el = document.getElementById("change-pwd-modal");
    if (el) el.classList.remove("hidden");
}

function closeChangePasswordModal() {
    const el = document.getElementById("change-pwd-modal");
    if (el) el.classList.add("hidden");
    
    const err = document.getElementById("pwd-error");
    const succ = document.getElementById("pwd-success");
    if (err) err.classList.add("hidden");
    if (succ) succ.classList.add("hidden");
    
    document.getElementById("old-pwd-input").value = "";
    document.getElementById("new-pwd-input").value = "";
    const confirmInput = document.getElementById("confirm-pwd-input");
    if (confirmInput) confirmInput.value = "";
}

async function handleChangePassword(e) {
    if (e && e.preventDefault) e.preventDefault();
    const old_password = document.getElementById("old-pwd-input").value;
    const new_password = document.getElementById("new-pwd-input").value;
    const confirmInput = document.getElementById("confirm-pwd-input");
    const confirm_password = confirmInput ? confirmInput.value : new_password;
    const errorEl = document.getElementById("pwd-error");
    const successEl = document.getElementById("pwd-success");

    if (errorEl) errorEl.classList.add("hidden");
    if (successEl) successEl.classList.add("hidden");

    if (new_password !== confirm_password) {
        if (errorEl) {
            errorEl.innerText = "Новые пароли не совпадают";
            errorEl.classList.remove("hidden");
        }
        return;
    }

    try {
        const token = typeof API_TOKEN !== 'undefined' ? API_TOKEN : localStorage.getItem("scud_api_auth_token");
        const res = await fetch("/api/v1/auth/change-password", {
            method: "POST",
            headers: {
                "Content-Type": "application/json",
                "Authorization": "Bearer " + token
            },
            body: JSON.stringify({ old_password, new_password })
        });

        const data = await res.json();

        if (res.status === 200) {
            if (successEl) {
                successEl.innerText = "Пароль успешно изменен!";
                successEl.classList.remove("hidden");
            }
            setTimeout(closeChangePasswordModal, 1500);
        } else {
            if (errorEl) {
                errorEl.innerText = data.detail || "Ошибка при смене пароля";
                errorEl.classList.remove("hidden");
            }
        }
    } catch (err) {
        if (errorEl) {
            errorEl.innerText = "Ошибка соединения с сервером";
            errorEl.classList.remove("hidden");
        }
    }
}

function openAdminModal() {
    const el = document.getElementById("admin-modal");
    if (el) el.classList.remove("hidden");
    loadUsersList();
}

function closeAdminModal() {
    const el = document.getElementById("admin-modal");
    if (el) el.classList.add("hidden");
}

async function loadUsersList() {
    const listEl = document.getElementById("admin-users-list");
    if (!listEl) return;
    listEl.innerHTML = '<div class="text-xs text-slate-400 py-4 text-center">Загрузка пользователей...</div>';

    try {
        const token = typeof API_TOKEN !== 'undefined' ? API_TOKEN : localStorage.getItem("scud_api_auth_token");
        const res = await fetch("/api/v1/admin/users", {
            headers: { "Authorization": "Bearer " + token }
        });
        const users = await res.json();

        if (res.status === 200) {
            listEl.innerHTML = users.map(u => {
                const adminTag = u.is_admin ? '<span class="ml-1.5 text-[9px] bg-indigo-100 text-indigo-700 px-1.5 py-0.5 rounded font-bold">ADMIN</span>' : '<span class="ml-1.5 text-[9px] bg-slate-100 text-slate-600 px-1.5 py-0.5 rounded">USER</span>';
                const fullNameHtml = u.full_name ? `<div class="text-[11px] text-slate-500 font-normal">${u.full_name}</div>` : '';
                const dateStr = u.created_at ? u.created_at.split(' ')[0] : '—';
                const deleteBtn = u.username !== CURRENT_USERNAME ? `<button type="button" onclick="deleteUser(${u.id}, '${u.username}')" class="text-red-500 hover:text-red-700 p-1"><i class="fa-solid fa-trash-can"></i></button>` : '<span class="text-[10px] text-slate-400">Вы</span>';
                
                return `
                    <div class="flex justify-between items-center bg-slate-50 border border-slate-200 p-2.5 rounded-xl text-xs">
                        <div>
                            <div class="flex items-center">
                                <span class="font-bold text-slate-800">${u.username}</span>
                                ${adminTag}
                            </div>
                            ${fullNameHtml}
                            <div class="text-[10px] text-slate-400 mt-0.5">Создан: ${dateStr}</div>
                        </div>
                        ${deleteBtn}
                    </div>
                `;
            }).join("");
        } else {
            listEl.innerHTML = `<div class="text-xs text-red-500 py-2">${users.detail}</div>`;
        }
    } catch (err) {
        listEl.innerHTML = '<div class="text-xs text-red-500 py-2">Ошибка загрузки пользователей</div>';
    }
}

async function handleCreateUser(e) {
    if (e && e.preventDefault) e.preventDefault();
    const username = document.getElementById("new-user-name").value.trim();
    const password = document.getElementById("new-user-pwd").value;
    const fullNameInput = document.getElementById("new-user-fullname");
    const full_name = fullNameInput ? fullNameInput.value.trim() : "";
    const adminCheckbox = document.getElementById("new-user-is-admin");
    const is_admin = adminCheckbox ? adminCheckbox.checked : false;
    const msgEl = document.getElementById("admin-msg");

    if (msgEl) msgEl.classList.add("hidden");

    try {
        const token = typeof API_TOKEN !== 'undefined' ? API_TOKEN : localStorage.getItem("scud_api_auth_token");
        const res = await fetch("/api/v1/admin/users", {
            method: "POST",
            headers: {
                "Content-Type": "application/json",
                "Authorization": "Bearer " + token
            },
            body: JSON.stringify({ username, password, full_name, is_admin })
        });

        const data = await res.json();

        if (res.status === 200) {
            document.getElementById("new-user-name").value = "";
            document.getElementById("new-user-pwd").value = "";
            if (fullNameInput) fullNameInput.value = "";
            if (adminCheckbox) adminCheckbox.checked = false;
            loadUsersList();
        } else {
            if (msgEl) {
                msgEl.innerText = data.detail || "Ошибка";
                msgEl.classList.remove("hidden");
            }
        }
    } catch (err) {
        if (msgEl) {
            msgEl.innerText = "Ошибка связи с сервером";
            msgEl.classList.remove("hidden");
        }
    }
}

async function deleteUser(userId, username) {
    if (!confirm("Удалить пользователя " + username + "?")) return;

    try {
        const token = typeof API_TOKEN !== 'undefined' ? API_TOKEN : localStorage.getItem("scud_api_auth_token");
        await fetch("/api/v1/admin/users/" + userId, {
            method: "DELETE",
            headers: { "Authorization": "Bearer " + token }
        });
        loadUsersList();
    } catch (err) {
        alert("Ошибка при удалении");
    }
}