修改代码，再用户管理中，当点击删除按钮后，在弹出的删除框中，加一个取消按钮，点击取消不删除，类似图书管理的删除一样<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>管理员页面</title>
    <link href="./css/admin.css" rel="stylesheet" type="text/css">
</head>
<style>
    li {
        list-style-type: none;
    }

    table {
        width: 100%;
        border-collapse: collapse;
        margin-top: 20px;
    }

    th,
    td {
        border: 1px solid #ddd;
        padding: 12px;
        text-align: center;
    }

    th {
        background-color: #f2f2f2;
        font-weight: bold;
    }

    .book-list-container {
        margin-top: 20px;
    }

    .book-list-container h2 {
        margin-bottom: 20px;
    }

    input[type="checkbox"] {
        width: 20px;
        height: 20px;
        margin-right: 10px;
    }

    .book-list-header {
        display: flex;
        align-items: center;
        margin-bottom: 10px;
    }

    .book-list-header input[type="checkbox"] {
        margin-right: 10px;
    }

    .book-list-container ul {
        list-style-type: none;
        padding: 0;
    }

    .book-list-container li {
        display: flex;
        align-items: center;
        background-color: #fff;
        padding: 10px;
        border: 1px solid #ddd;
        margin-bottom: 10px;
    }

    .book-item {
        display: flex;
        align-items: center;
        flex-grow: 1;
    }

    .book-actions {
        display: flex;
        align-items: center;
        margin-left: 10px;
    }

    .book-actions button {

        margin-left: 18px;
    }

    .user-list-container ul {
        list-style-type: none;
        padding: 0;
        width: 100%;
    }

    .user-list-container li {
        display: flex;
        justify-content: space-between;
        align-items: center;
        background-color: #fff;
        padding: 10px;
        margin-bottom: 10px;
    }
</style>

<body>
    <div class="topbar">
        <div id="adminName">管理员：</div>
        <button onclick="logout()">退出</button>
    </div>
    <div class="sidebar">
        <h1>管理员菜单</h1>
        <button onclick="showForm('add')">增加图书</button>
        <button onclick="showForm('delete')">删除图书</button>
        <button onclick="showForm('edit')">修改图书</button>
        <button onclick="showForm('search')">查询图书</button>
        <button onclick="showForm('userManagement')">用户管理</button>
        <button onclick="showForm('dataManagement')">图书管理</button>
        <button onclick="showForm('borrowRecords')">借阅记录</button>
    </div>
    <div class="main-content">
        <div class="welcome-message" id="welcomeMessage">
            <h1 style="text-align: center;">欢迎进入管理系统</h1>
        </div>
        <div class="form-container centered-content" id="formContainer" style="display:none;">

        </div>

    </div>
    <script>
        function logout() {
            alert('已退出登录');
            window.location.href = 'login.html';
        }
        function showForm(type, id = null) {

            const formContainer = document.getElementById('formContainer');
            const welcomeMessage = document.getElementById('welcomeMessage');
            formContainer.innerHTML = '';
            formContainer.style.display = 'block';
            welcomeMessage.style.display = 'none';
            switch (type) {
                case 'add':
                    formContainer.innerHTML = `
                        <h1 style="text-align: center";>增加图书</h1>
                        <input type="text" placeholder="书名">
                        <input type="text" placeholder="作者">
                        <input type="number" placeholder="出版年份">
                        <div style="text-align: center;">
                        <button style="padding: 10px 20px; font-size: 16px;" onclick="addBook()">添加</button>
                    `;
                    break;
                case 'delete':
                    formContainer.innerHTML = `
                        <h1 style="text-align: center";>删除图书</h1>
                        <input type="text" id="bookTitle" placeholder="输入书名" style="width: 96%;" />
                        <div style="text-align: center;">
                        <button style="padding: 10px 20px; font-size: 16px;" onclick="deleteBookByTitle()">删除</button>
                    `;
                    break;
                case 'borrowRecords':
                    formContainer.innerHTML = `
                        <div style="text-align: center;">
                        <h1 style="text-align: center";>借阅记录</h1>
                        <div id="borrowRecordsList"></div>`;
                    loadBorrowRecords();
                    break;
                case 'edit':
                    formContainer.innerHTML = `
                        <h1 style="text-align: center";>修改图书</h1>
                        <input type="text" placeholder="旧书名" id="oldTitle">
                        <input type="text" placeholder="新书名" id="newTitle">
                        <input type="text" placeholder="新作者" id="newAuthor">
                        <input type="number" placeholder="新出版年份" id="newYearPublished">
                        <div style="text-align: center;">
                        <button style="padding: 10px 20px; font-size: 16px;" onclick="editBook()">修改</button>
                    `;
                    break;
                case 'search':
                    formContainer.innerHTML = `
                        <div style="text-align: center;">
                        <h1 style="text-align: center";>查询图书</h1>
                        <input type="text" placeholder="搜索关键词" id="searchKeyword">
                        <button style="padding: 10px 20px; font-size: 16px;" onclick="searchBooks()">查询</button>
                    `;
                    break;
                case 'userManagement':
                    loadUsers().then(users => {
                        const formContainer = document.getElementById('formContainer');
                        formContainer.innerHTML = `
                        <h1 style="text-align: center;">用户管理</h1>
                        <div class="user-list-container" style="display: flex; flex-direction: column; align-items: center;">
                        <ul style="list-style-type: none; padding: 0;">
                    ${users.map(user => `
                        <li style="display: flex; justify-content: space-between; align-items: center; width: 100%;">
                    <span style="flex-grow: 1; margin-right: 10px;">${user.username}</span>
                    <div class="book-actions">
                    <button onclick="editUserForm('${user.id}')">编辑</button>
                    <button onclick="deleteUser('${user.id}')">删除</button>
                </div>
                </li>`).join("")}
    </ul>
</div>
            `;
                    });
                    break;
                case 'dataManagement':
                    formContainer.innerHTML = `
                        <h2>数据管理</h2>
                        <!-- 这里可以添加数据管理的相关表单或内容 -->
                    `;
                    loadBooks(); 
                    break;
                case 'borrowRecords':
                    formContainer.innerHTML = `
                    <h2 style="text-align: center";>借阅记录</h2>
                        <!-- 这里可以添加借阅记录的相关表单或内容 -->
                    `;
                    break;
                case 'editUser':
                    fetch(`http://localhost:3000/admin/get-user/${id}`)
                        .then(response => {
                            if (!response.ok) {
                                throw new Error('Failed to fetch user data');
                            }
                            return response.json();
                        })
                        .then(user => {
                            const formContainer = document.getElementById('formContainer');
                            formContainer.innerHTML = `
                <input type="hidden" value="${id}" name="id">
                <input type="text" placeholder="用户名" value="${user.username}" name="username">
                <input type="password" placeholder="密码" name="password">
                <select name="role">
                    <option value="user" ${user.role === 'user' ? 'selected' : ''}>用户</option>
                    <option value="admin" ${user.role === 'admin' ? 'selected' : ''}>管理员</option>
                </select>
                <button onclick="editUser(${id})">保存</button>
            `;
                        })
                        .catch(error => {
                            console.error('获取用户数据出错:', error);
                            alert('获取用户数据失败: ' + error.message);
                        });
                    break;
                case 'deleteUser':
                    if (confirm(`确定要删除用户ID为${id}的用户吗？此操作不可撤销！`)) {
                        deleteUser(id);
                    }
                    break;
                default:
                    formContainer.style.display = 'none';
                    welcomeMessage.style.display = 'block'; // 默认显示欢迎消息
            }
        }

        function deleteBookByTitle() {
            const bookTitle = document.getElementById('bookTitle').value; // 获取书名

            if (!bookTitle) {
                alert('请输入书名以进行删除');
                return;
            }

            fetch('http://localhost:3000/admin/delete-book-by-title', {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json',
                    'user-type': 'admin'
                },
                body: JSON.stringify({ title: bookTitle }) // 传递书名
            })
                .then(response => {
                    if (!response.ok) {
                        throw new Error('网络响应不正常');
                    }
                    return response.text();
                })
                .then(data => {
                    alert('图书删除成功');
                    loadBooks();  // 重新加载图书列表
                })
                .catch(error => {
                    alert('删除图书时出错：' + error.message);
                });
        }
        function addBook() {
            const formContainer = document.getElementById('formContainer');
            const title = formContainer.querySelector('input[placeholder="书名"]').value;
            const author = formContainer.querySelector('input[placeholder="作者"]').value;
            const year_published = formContainer.querySelector('input[placeholder="出版年份"]').value;

            fetch('http://localhost:3000/admin/get-books') // 获取所有书籍的数组
                .then(response => {
                    if (!response.ok) {
                        throw new Error('无法加载书籍');
                    }
                    return response.json();
                })
                .then(books => {
                    const bookExists = books.some(book => book.title === title);
                    if (bookExists) {
                        alert('书名已经存在，无法添加。');
                        return; 
                    }

                    // 发送增加图书的请求
                    return fetch('http://localhost:3000/admin/add-book', {
                        method: 'POST',
                        headers: {
                            'Content-Type': 'application/json',
                            'user-type': 'admin'
                        },
                        body: JSON.stringify({ title, author, year_published })
                    });
                })
                .then(response => {
                    // 前端处理整个响应
                    if (!response.ok) {
                        return response.json().then(err => {
                            alert(err.error || '添加图书时出错'); // 不再抛出异常
                        });
                    }

                    return response.text();
                })
                .then(data => {
                    alert('图书添加成功：' + data); 
                    formContainer.innerHTML = '';
                    formContainer.style.display = 'none';
                    showForm('dataManagement');
                })
                .catch(error => {
                    console.error('Error adding book:', error);
                });
        }

        function searchBooks() {
            const searchKeyword = document.getElementById('searchKeyword').value;

            fetch('http://localhost:3000/user/search-books', {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json'
                },
                body: JSON.stringify({ keyword: searchKeyword })
            })
                .then(response => {
                    if (!response.ok) {
                        throw new Error('网络响应不正常');
                    }
                    return response.json();
                })
                .then(data => {
                    displaySearchResults(data);
                })
                .catch(error => {
                    console.error('Error searching books:', error);
                    alert('搜索图书时出错：' + error.message);
                });
        }

        function displaySearchResults(books) {
            const formContainer = document.getElementById('formContainer');
            formContainer.innerHTML = `
        <div>
            <button onclick="showForm('search')">返回继续搜索</button>
        </div>
        <h2>搜索结果</h2>
    `;

            if (books.length === 0) {
                formContainer.innerHTML += '<p>未找到图书。</p>';
            } else {
                const resultsList = document.createElement('ul');
                books.forEach(book => {
                    const listItem = document.createElement('li');
                    listItem.textContent = `${book.title} by ${book.author} (${book.year_published})`;
                    resultsList.appendChild(listItem);
                });
                formContainer.appendChild(resultsList);
            }
        }

        function loadBooks() {
            console.log('Starting to load books...');
            return fetch('http://localhost:3000/admin/get-books')
                .then(response => {
                    console.log('Received response from get-books:', response);
                    if (!response.ok) {
                        throw new Error('网络响应不正常');
                    }
                    return response.json();
                })
                .then(books => {
                    console.log('Loaded books data:', books);
                    displayBooks(books);
                    return Promise.resolve();  
                })
                .catch(error => {
                    console.error('Error loading books:', error);
                    alert('加载图书时出错：' + error.message);
                    return Promise.reject(error); 
                });
        }

        function displayBooks(books) {
            const formContainer = document.getElementById('formContainer');
            formContainer.innerHTML = `
        <h2 style="text-align: center;">图书管理</h2>
        <div class="book-list-container">
            <div class="book-list-header">
                <input type="checkbox" id="selectAllBooks"> 全选
                <button onclick="deleteSelectedBooks()">删除选中</button>
            </div>
            <ul id="bookList">
    `;
            books.forEach(book => {
                formContainer.innerHTML += `
            <li style="display: flex; align-items: center;">
                <div class="book-item" style="flex-grow: 1; display: flex; align-items: center;">
                    <input type="checkbox" class="bookCheckbox" value="${book.id}">
                    <strong>书名:</strong> ${book.title} &nbsp;&nbsp;
                    <strong>作者:</strong> ${book.author} &nbsp;&nbsp;
                    <strong>出版年份:</strong> ${book.year_published}
                </div>
                <div class="book-actions">
                    <button onclick="editBookForm('${book.id}')">编辑</button>
                    <button onclick="deleteBookConfirm('${book.id}')">删除</button>
                </div>
            </li>
        `;
            });
            formContainer.innerHTML += `
            </ul>
        </div>
    `;

            const selectAllCheckbox = document.getElementById('selectAllBooks');
            selectAllCheckbox.addEventListener('change', function () {
                const checkboxes = document.querySelectorAll('.bookCheckbox');
                checkboxes.forEach(checkbox => {
                    checkbox.checked = this.checked; 
                });
            });
            const bookCheckboxes = document.querySelectorAll('.bookCheckbox');
            bookCheckboxes.forEach(checkbox => {
                checkbox.addEventListener('change', function () {
                    const allChecked = Array.from(bookCheckboxes).every(cb => cb.checked);
                    selectAllCheckbox.checked = allChecked; 
                });
            });
        }

        function deleteSelectedBooks() {
            const checkboxes = document.querySelectorAll('.bookCheckbox:checked');
            const bookIds = Array.from(checkboxes).map(checkbox => checkbox.value);

            if (bookIds.length === 0) {
                alert('没有选中任何书籍。');
                return;
            }

            if (confirm('确定要删除选中的书籍吗？此操作不可撤销！')) {
                bookIds.forEach(id => {
                    deleteBook(id);
                });
            }
        }


        function loadUsers() {
            return fetch('http://localhost:3000/admin/get-users')
                .then(response => {
                    if (!response.ok) {
                        throw new Error('网络响应不正常');
                    }
                    return response.json();
                })
                .then(users => {
                    displayUsers(users);
                    return users; 
                })
                .catch(error => {
                    console.error('Error loading users:', error);
                    alert('加载用户时出错：' + error.message);
                    throw error; 
                });
        }

        function displayUsers(users) {
            const formContainer = document.getElementById('formContainer');
            formContainer.innerHTML = `
        <h2 style="text-align: center;">用户管理</h2>
        <div class="user-list-container" style="display: flex; flex-direction: column; align-items: center;">
            <ul style="list-style-type: none; padding: 0;">
        `;
            users.forEach(user => {
                formContainer.innerHTML += `
            <li style="margin: 10px 0;">
                ${user.username}
                <button onclick="editUserForm('${user.id}')">编辑</button>
                <button onclick="deleteUserConfirm('${user.id}')">删除</button>
            </li>
        `;
            });
            formContainer.innerHTML += `
            </ul>
        </div>
    `;
        }

        function loadBorrowRecords() {
            fetch('http://localhost:3000/admin/borrow-records') 
                .then(response => {
                    if (!response.ok) {
                        throw new Error('网络响应不正常');
                    }
                    return response.json();
                })
                .then(records => {
                    displayBorrowRecords(records);
                })
                .catch(error => {
                    alert('加载借阅记录时出错：' + error.message);
                });
        }

        function displayBorrowRecords(records) {
            const borrowRecordsList = document.getElementById('borrowRecordsList');
            borrowRecordsList.innerHTML = ''; 

            if (records.length === 0) {
                borrowRecordsList.innerHTML = '<p>无借阅记录。</p>';
            } else {
                const table = document.createElement('table');
                table.innerHTML = `
            <tr>
                <th>用户名</th>
                <th>书名</th>
                <th>作者</th>
                <th>借阅日期</th>
                <th>操作</th>
            </tr>
        `;
                records.forEach(record => {
                    const borrowDate = new Date(record.borrow_date);
                    const options = { year: 'numeric', month: '2-digit', day: '2-digit' };
                    const formattedDate = borrowDate.toLocaleDateString('zh-CN', options).replace(/\//g, '-');
                    const row = document.createElement('tr');
                    row.innerHTML = `
                <td>${record.username}</td>
                <td>${record.title}</td>
                <td>${record.author}</td>
                <td>${formattedDate}</td>
                <td style="text-align: center;">
                    <button onclick="deleteBorrowRecordConfirm(${record.id})">删除</button>
                </td>
            `;
                    table.appendChild(row);
                });
                borrowRecordsList.appendChild(table);
            }
        }


        function deleteUser(id) {
            fetch(`http://localhost:3000/admin/delete-user`, {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify({ id })
            })
                .then(response => {
                    if (!response.ok) {
                        throw new Error('网络响应不正常: ' + response.statusText);
                    }
                    return response.text();
                })
                .then(data => {
                    alert(data);
                    loadUsers(); 
                })
                .catch(error => {
                    console.error('Error deleting user:', error);
                    alert('删除用户时出现错误：' + error.message);
                });
        }
        function editUserForm(id) {
            fetch(`http://localhost:3000/admin/get-user/${id}`)
                .then(response => {
                    if (!response.ok) {
                        throw new Error('获取用户信息失败，状态码：' + response.status);
                    }
                    return response.json();
                })
                .then(user => {
                    const formContainer = document.getElementById('formContainer');
                    formContainer.innerHTML = `
                <form id="editUserForm">
                    <input type="hidden" value="${id}" name="id">
                    <input type="text" placeholder="用户名" value="${user.username}" name="username">
                    <input type="password" placeholder="旧密码" name="oldPassword" required>
                    <input type="password" placeholder="新密码" name="newPassword">
                    <select name="role">
                        <option value="user" ${user.role === 'user' ? 'selected' : ''}>用户</option>
                        <option value="admin" ${user.role === 'admin' ? 'selected' : ''}>管理员</option>
                    </select>
                    <button type="button" onclick="editUser(${id})">保存</button>
                    <button type="button" onclick="cancelEditUser()">取消</button>
                </form>
            `;
                })
                .catch(error => {
                    console.error('编辑用户信息获取出错：', error);
                    alert('获取用户信息失败，请稍后重试：' + error.message);
                });
        }

        function cancelEditUser() {
            showForm('userManagement'); 
        }

        function editUser(id) {
            const form = document.querySelector(`#editUserForm`);
            if (!form || !(form instanceof HTMLFormElement)) {
                return;
            }
            const formData = new FormData(form);
            const data = Object.fromEntries(formData.entries());

            // Simple validation for required fields
            if (!data.username || !data.oldPassword || !data.newPassword || !data.role) {
                alert('请填写所有必填字段');
                return;
            }

            fetch(`http://localhost:3000/admin/edit-user`, {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify(data)
            })
                .then(response => {
                    if (!response.ok) {
                        throw new Error('编辑用户失败');
                    }
                    return response.text();
                })
                .then(data => {
                    alert(data);
                    loadUsers(); 
                })
                .catch(error => {
                    console.error('Error editing user:', error);
                    if (error.response && error.response.status === 400) {
                        error.response.json().then(data => {
                            alert('编辑用户信息时出错：' + data.error);
                        });
                    } else {
                        alert('编辑用户信息时出错，请稍后重试：' + error.message);
                    }
                });
        }

        function editBookForm(bookId) {
            fetch(`http://localhost:3000/admin/get-books`)
                .then(response => {
                    if (!response.ok) {
                        throw new Error('未能获取所有图书数据');
                    }
                    return response.json();
                })
                .then(allBooks => {
                    const targetBook = allBooks.find(book => book.id === Number(bookId));
                    if (!targetBook) {
                        alert('未找到对应图书信息，请确认图书ID是否正确');
                        return;
                    }

                    const formContainer = document.getElementById('formContainer');
                    formContainer.innerHTML = `
                        <h2>修改图书</h2>
                        <input type="hidden" value="${bookId}" id="bookId">
                        <input type="text" placeholder="旧书名" id="oldTitle" value="${targetBook.title}" disabled>
                        <input type="text" placeholder="新书名" id="newTitle" value="${targetBook.title}">
                        <input type="text" placeholder="新作者" id="newAuthor" value="${targetBook.author}">
                        <input type="number" placeholder="新出版年份" id="newYearPublished" value="${targetBook.year_published}">
                        <button onclick="editBook()">保存</button>
                        <button onclick="cancelEditBook()">取消</button>
                    `;
                })
                .catch(error => {
                    alert('获取图书信息失败，请稍后重试：' + error.message);
                });
        }

        function cancelEditBook() {
            const bookId = document.getElementById('bookId').value;
            if (bookId) {
                showForm('dataManagement'); // 返回图书管理列表
            }
        }

        function deleteBookConfirm(bookId) {
            if (!bookId) {
                alert('无效的图书ID');
                return;
            }
            if (confirm(`确定要删除图书ID为${bookId}的图书吗？此操作不可撤销！`)) {
                deleteBook(bookId);
            }
        }

        function deleteBook(bookId) {
            if (!bookId) {
                alert('无效的图书ID');
                return;
            }

            fetch('http://localhost:3000/admin/delete-book', {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json',
                    'user-type': 'admin'
                },
                body: JSON.stringify({ id: bookId })  // 使用书籍 ID
            })
                .then(response => {
                    if (!response.ok) {
                        throw new Error('网络响应不正常');
                    }
                    return response.text();
                })
                .then(data => {
                    alert('图书删除成功');
                    loadBooks();  // 重新加载图书列表
                })
                .catch(error => {
                    alert('删除图书时出错：' + error.message);
                });
        }

        function editBook() {
            const newTitle = document.getElementById('newTitle').value.trim();
            const newAuthor = document.getElementById('newAuthor').value.trim();
            const newYearPublished = document.getElementById('newYearPublished').value.trim();

            if (!newTitle || !newAuthor || !newYearPublished) {
                alert('请填写所有修改信息');
                return;
            }

            const oldTitle = document.getElementById('oldTitle').value; 
            fetch('http://localhost:3000/admin/edit-book', {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json',
                    'user-type': 'admin'
                },
                body: JSON.stringify({ oldTitle, newTitle, newAuthor, newYearPublished })
            })
                .then(response => {
                    if (!response.ok) {
                        throw new Error('网络响应不正常: ' + response.statusText);
                    }
                    return response.text();
                })
                .then(data => {
                    console.log('Book edited:', data);
                    alert('图书修改成功');
                    showForm('dataManagement'); // 返回数据管理界面
                })
                .catch(error => {
                    alert('修改图书时出错：' + error.message);
                });
        }
        function deleteBorrowRecordConfirm(recordId) {
            if (!recordId) {
                alert('无效的借阅记录ID');
                return;
            }
            if (confirm(`确定要删除借阅记录ID为${recordId}的记录吗？此操作不可撤销！`)) {
                deleteBorrowRecord(recordId);
            }
        }
        function deleteBorrowRecord(recordId) {
            fetch('http://localhost:3000/admin/delete-borrow-record', {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json'
                },
                body: JSON.stringify({ id: recordId }) 
            })
                .then(response => {
                    if (!response.ok) {
                        throw new Error('网络响应不正常');
                    }
                    return response.text();
                })
                .then(data => {
                    alert('借阅记录删除成功');
                    loadBorrowRecords(); 
                })
                .catch(error => {
                    console.error('Error deleting borrow record:', error);
                    alert('删除借阅记录时出错：' + error.message);
                });
        }
        document.addEventListener('DOMContentLoaded', () => {
            fetchCurrentAdmin();
        });

        // 获取当前管理员信息
        function fetchCurrentAdmin() {
            fetch('http://localhost:3000/admin/current')
                .then(response => {
                    if (!response.ok) {
                        throw new Error('网络响应不正常');
                    }
                    return response.json();
                })
                .then(data => {
                    console.log(data);

                    document.getElementById('adminName').textContent = `管理员：${data.username}`;
                })
                .catch(error => {
                    console.error('获取管理员名错误:', error);
                    document.getElementById('adminName').textContent = '管理员：未知'; // 出错时处理
                });
        }
    </script>
</body>

</html>