修改代码，左上角管理员的名字时应该时账号登录的用户名      const express = require('express');
const mysql = require('mysql');
const bodyParser = require('body-parser');
const cors = require('cors');

const app = express();
app.use(cors());
app.use(bodyParser.json());

// MySQL数据库连接配置
const db = mysql.createConnection({
    host: 'localhost',
    user: 'root',
    password: '123456', // 替换为你的MySQL密码
    database: 'librarysystem'
});

db.connect(err => {
    if (err) {
        throw err;
    }
    console.log('MySQL connected...');
});

// 登录路由
app.post('/login', (req, res) => {
    const { username, password } = req.body;
    const query = 'SELECT * FROM users WHERE username = ? AND password = ?';
    db.query(query, [username, password], (err, results) => {
        if (err) {
            res.status(500).json({ error: 'Server error' });
        } else if (results.length > 0) {
            console.log("Login successful, sending response:", results[0]);
            res.json(results[0]);
        } else {
            res.status(400).json({ error: 'Invalid login' });
        }
    });
});

// 获取当前管理员信息
app.get('/admin/current', (req, res) => {
    // 假设管理员信息保存在 session 中
    // 或者从数据库中查询并返回
    const adminInfo = { username: '张三' }; // 这里可以找到适合获取当前管理员信息的方式
    res.json(adminInfo);
});
// 注册路由
app.post('/register', (req, res) => {
    const { username, password } = req.body;
    // 检查用户名是否已存在
    const checkUserQuery = 'SELECT * FROM users WHERE username = ?';
    db.query(checkUserQuery, [username], (err, results) => {
        if (err) {
            res.status(500).json({ error: 'Server error' });
        } else if (results.length > 0) {
            // 用户名已存在
            res.status(400).json({ error: 'Username already exists' });
        } else {
            // 用户名不存在，可以注册
            const insertUserQuery = 'INSERT INTO users (username, password, role) VALUES (?, ?, ?)';
            db.query(insertUserQuery, [username, password, 'user'], (err, results) => {
                if (err) {
                    res.status(500).json({ error: 'Failed to register user' });
                } else {
                    res.status(201).send('User registered successfully');
                }
            });
        }
    });
});
// 管理员操作路由
// 添加图书
app.post('/admin/add-book', (req, res) => {
    const { title, author, year_published } = req.body;

    // 在添加之前，先检查书名是否已存在
    const checkBookQuery = 'SELECT * FROM books WHERE title = ?';
    db.query(checkBookQuery, [title], (err, results) => {
        if (err) {
            console.error('Error checking existing book:', err);
            return res.status(500).json({ error: 'Failed to check existing book' });
        }

        if (results.length > 0) {
            return res.status(400).json({ error: 'Book title already exists' }); // 如果书名已存在，则返回错误
        }

        // 如果书名不存在，则继续插入新书
        const query = 'INSERT INTO books (title, author, year_published) VALUES (?, ?, ?)';
        db.query(query, [title, author, year_published], (err, results) => {
            if (err) {
                console.error('Error adding book:', err);
                return res.status(500).json({ error: 'Failed to add book' });
            }
            res.status(200).send('Book added successfully');
        });
    });
});
// 删除图书按ID
app.post('/admin/delete-book', (req, res) => {
    const { id } = req.body;

    // 确保 ID 是有效的数字
    if (!id || isNaN(id)) {
        res.status(400).json({ error: 'Invalid book ID format' });
        return;
    }

    const query = 'DELETE FROM books WHERE id = ?';
    db.query(query, [id], (err, results) => {
        if (err) {
            console.error('Error deleting book:', err);
            res.status(500).json({ error: 'Failed to delete book. Error details: ' + err.message });
        } else {
            // 检查是否有行被删除
            if (results.affectedRows > 0) {
                res.send('Book deleted');
            } else {
                res.status(404).send('No book found with this ID');
            }
        }
    });
});

// 用户操作路由
// 搜索书籍
app.post('/user/search-books', (req, res) => {
    const { keyword } = req.body;
    const query = `
        SELECT * FROM books 
        WHERE id = ? OR title LIKE ? OR author LIKE ?
    `;
    db.query(query, [keyword, `%${keyword}%`, `%${keyword}%`], (err, results) => {
        if (err) {
            res.status(500).send('Server error');
        } else {
            res.json(results);
        }
    });
});
// 添加收藏
// 获取用户的收藏书籍
app.get('/user/favorites/:userId', (req, res) => {
    const { userId } = req.params;
    const query = `
        SELECT b.id, b.title, b.author 
        FROM favorites f 
        JOIN books b ON f.book_id = b.id 
        WHERE f.user_id = ?
    `;
    db.query(query, [userId], (err, results) => {
        if (err) {
            res.status(500).send('Server error');
        } else {
            res.json(results);
        }
    });
});
// 编辑图书
app.post('/admin/edit-book', (req, res) => {
    const { oldTitle, newTitle, newAuthor, newYearPublished } = req.body;

    // 验证每个字段
    if (!oldTitle || !newTitle || !newAuthor || !newYearPublished) {
        return res.status(400).json({ error: '所有字段都需要填写' });
    }

    const query = 'UPDATE books SET title=?, author=?, year_published=? WHERE title=?';
    db.query(query, [newTitle, newAuthor, newYearPublished, oldTitle], (err, results) => {
        if (err) {
            console.error('Error editing book:', err);
            return res.status(500).json({ error: 'Failed to edit book. Error details: ' + err.message });
        }
        // 检查是否有行被更新
        if (results.affectedRows > 0) {
            res.status(200).send('Book edited successfully');
        } else {
            res.status(404).send('No book found with that title for editing');
        }
    });
});
app.post('/admin/edit-book', (req, res) => {
    const { oldTitle, newTitle, newAuthor, newYearPublished } = req.body;

    // 验证每个字段
    if (!oldTitle || !newTitle || !newAuthor || !newYearPublished) {
        return res.status(400).json({ error: '所有字段都需要填写' });
    }

    const query = 'UPDATE books SET title=?, author=?, year_published=? WHERE title=?';
    db.query(query, [newTitle, newAuthor, newYearPublished, oldTitle], (err, results) => {
        if (err) {
            console.error('Error editing book:', err);
            return res.status(500).json({ error: 'Failed to edit book. Error details: ' + err.message });
        }
        // 检查是否有行被更新
        if (results.affectedRows > 0) {
            res.status(200).send('Book edited successfully');
        } else {
            res.status(404).send('No book found with that title for editing');
        }
    });
});

app.get('/admin/get-books', (req, res) => {
    const query = 'SELECT * FROM books';
    db.query(query, (err, results) => {
        if (err) {
            console.error('Error getting books:', err);
            res.status(500).json({ error: 'Failed to get books' });
        } else {
            res.json(results);
        }
    });
});

// 获取所有用户
app.get('/admin/get-users', (req, res) => {
    const query = 'SELECT * FROM users';
    db.query(query, (err, results) => {
        if (err) {
            console.error('Error getting users:', err);
            res.status(500).json({ error: 'Failed to get users' });
        } else {
            res.json(results);
        }
    });
});
// 借阅书籍
app.post('/user/borrow-book', (req, res) => {
    const { userId, bookId } = req.body;
    const query = 'INSERT INTO borrow_records (user_id, book_id, borrow_date) VALUES (?, ?, NOW())';
    db.query(query, [userId, bookId], (err, results) => {
        if (err) {
            console.error('Error borrowing book:', err);
            res.status(500).json({ error: 'Failed to borrow book' });
        } else {
            res.status(200).send('Book borrowed successfully');
        }
    });
});

// 获取借阅历史
app.get('/user/borrow-history/:userId', (req, res) => {
    const { userId } = req.params;
    const query = `
        SELECT b.title, b.author, br.borrow_date 
        FROM borrow_records br 
        JOIN books b ON br.book_id = b.id 
        WHERE br.user_id = ?
        ORDER BY br.borrow_date DESC
    `;
    db.query(query, [userId], (err, results) => {
        if (err) {
            res.status(500).send('Server error');
        } else {
            res.json(results);
        }
    });
});

// 获取所有借阅记录（管理员用）
// 获取所有借阅记录（管理员用）
app.get('/admin/borrow-records', (req, res) => {
    const query = `
        SELECT br.id, u.username, b.title, b.author, br.borrow_date 
        FROM borrow_records br 
        JOIN users u ON br.user_id = u.id 
        JOIN books b ON br.book_id = b.id 
        ORDER BY br.borrow_date DESC
    `;
    db.query(query, (err, results) => {
        if (err) {
            res.status(500).send('Server error');
        } else {
            // Ensure that the ID is included in results
            res.json(results);
        }
    });
});

// 编辑用户
app.post('/admin/edit-user', (req, res) => {
    const { id, username, oldPassword, newPassword, role } = req.body;
 
    // 验证旧密码
    const query = 'SELECT * FROM users WHERE id = ?';
    db.query(query, [id], (err, user) => {
        if (err) {
            console.error('Error fetching user data for password verification:', err);
            return res.status(500).json({ error: 'Failed to verify password' });
        }
        if (!user || user.length === 0 || user[0].password !== oldPassword) {
            // 旧密码不正确
            return res.status(400).json({ error: 'Invalid old password' });
        }
 
        // 更新用户信息
        const updateQuery = 'UPDATE users SET username = ?, password = ?, role = ? WHERE id = ?';
        db.query(updateQuery, [username, newPassword, role, id], (err, results) => {
            if (err) {
                console.error('编辑用户信息出错，编辑的用户ID：', id);
                console.error('错误信息：', err.message);
                console.error('错误堆栈：', err.stack);
                return res.status(500).json({ error: 'Failed to edit user' });
            }
            console.log('用户信息编辑成功，编辑的用户ID：', id);
            res.status(200).send('User edited successfully');
        });
    });
});

// 删除图书
app.post('/admin/delete-book-by-title', (req, res) => {
    const { title } = req.body; // 获取书名

    // 确保书名是有效的字符串
    if (!title || typeof title !== 'string') {
        return res.status(400).json({ error: 'Invalid book title format' });
    }

    // SQL 查询使用书名删除图书
    const query = 'DELETE FROM books WHERE title = ?';
    db.query(query, [title], (err, results) => {
        if (err) {
            console.error('Error deleting book:', err);
            return res.status(500).json({ error: 'Failed to delete book. Error details: ' + err.message });
        } else {
            if (results.affectedRows > 0) {
                res.send('Book deleted');
            } else {
                res.status(404).send('No book found with that title');
            }
        }
    });
});
// 删除用户
app.post('/admin/delete-user', (req, res) => {
    const { id } = req.body;
    db.beginTransaction((err => {
        if (err) {
            console.error('Error starting transaction:', err);
            res.status(500).send('Server error starting transaction');
            return;
        }
        // 先删除 borrow_records 表中与该用户相关的记录
        const deleteBorrowRecordsQuery = 'DELETE FROM borrow_records WHERE user_id =?';
        db.query(deleteBorrowRecordsQuery, [id], (err => {
            if (err) {
                db.rollback(() => {
                    console.error('Error deleting related borrow records, rolling back transaction:', err);
                    res.status(500).send('Server error when deleting related borrow records, transaction rolled back');
                });
                return;
            }
            // 再删除 favorites 表中与该用户相关的记录
            const deleteFavoritesQuery = 'DELETE FROM favorites WHERE user_id =?';
            db.query(deleteFavoritesQuery, [id], (err => {
                if (err) {
                    db.rollback(() => {
                        console.error('Error deleting related favorites, rolling back transaction:', err);
                        res.status(500).send('Server error when deleting related favorites, transaction rolled back');
                    });
                    return;
                }
                // 最后执行删除用户操作
                const query = 'DELETE FROM users WHERE id =?';
                db.query(query, [id], (err, results) => {
                    if (err) {
                        db.rollback(() => {
                            console.error('删除用户出错，要删除的用户ID：', id);
                            console.error('错误信息：', err.message);
                            console.error('错误堆栈：', err.stack);
                            res.status(500).send('Server error, transaction rolled back');
                        });
                    } else {
                        db.commit((err => {
                            if (err) {
                                console.error('Error committing transaction:', err);
                                res.status(500).send('Server error committing transaction');
                                return;
                            }
                            console.log('用户删除成功，删除的用户ID：', id);
                            res.send('User deleted');
                        }));
                    }
                });
            }));
        }));
    }));
});
//获取单个用户
app.get('/admin/get-user/:id', (req, res) => {
    const { id } = req.params;
    const query = 'SELECT * FROM users WHERE id = ?';
    db.query(query, [id], (err, results) => {
        if (err) {
            console.error('Error getting user:', err);
            res.status(500).json({ error: 'Failed to get user' });
        } else if (results.length === 0) {
            res.status(404).json({ error: 'User not found' });
        } else {
            res.json(results[0]);
        }
    });
});
// 编辑借阅记录（注意：通常借阅记录不需要编辑，但这里为了完整性提供示例）
app.post('/admin/edit-borrow-record', (req, res) => {
    const { id, user_id, book_id, borrow_date } = req.body;
    const query = 'UPDATE borrow_records SET user_id = ?, book_id = ?, borrow_date = ? WHERE id = ?';
    db.query(query, [user_id, book_id, borrow_date, id], (err, results) => {
        if (err) {
            console.error('Error editing borrow record:', err);
            res.status(500).json({ error: 'Failed to edit borrow record' });
        } else {
            res.status(200).send('Borrow record edited successfully');
        }
    });
});

// 删除借阅记录
app.post('/admin/delete-borrow-record', (req, res) => {
    const { id } = req.body;

    if (!id || isNaN(id)) {
        return res.status(400).send('无效的借阅记录ID格式');
    }

    const query = 'DELETE FROM borrow_records WHERE id = ?';
    db.query(query, [id], (err, results) => {
        if (err) {
            console.error('Error deleting borrow record:', err);
            return res.status(500).send('服务器错误');
        }
        if (results.affectedRows > 0) {
            res.send('借阅记录删除成功');
        } else {
            res.status(404).send('没有找到该借阅记录');
        }
    });
});
// 获取单个借阅记录详情的路由
app.get('/admin/get-borrow-record/:id', (req, res) => {
    const { id } = req.params;
    // 验证id是否为有效的数字且大于0
    if (!Number.isInteger(Number(id)) || Number(id) <= 0) {
        res.status(400).json({ error: 'Invalid borrow record ID format or value' });
        return;
    }
    const query = `
        SELECT * 
        FROM borrow_records 
        WHERE id =?
    `;
    db.query(query, [id], (err, results) => {
        if (err) {
            console.error('Error getting borrow record:', err);
            res.status(500).json({ error: 'Failed to get borrow record. Error details: ' + err.message });
        } else if (results.length === 0) {
            res.status(404).json({ error: 'Borrow record not found' });
        } else {
            res.json(results[0]);
        }
    });
});
// 添加收藏路由
app.post('/user/add-favorite', (req, res) => {
    const { userId, bookId } = req.body;
    // 先检查该用户是否已经收藏了这本书
    const checkFavoriteQuery = 'SELECT * FROM favorites WHERE user_id =? AND book_id =?';
    db.query(checkFavoriteQuery, [userId, bookId], (err, results) => {
        if (err) {
            res.status(500).json({ error: 'Server error' });
        } else if (results.length > 0) {
            // 已收藏，提示用户
            res.status(400).json({ error: 'This book has already been added to favorites' });
        } else {
            // 可以添加收藏，插入记录到 favorites 表
            const insertFavoriteQuery = 'INSERT INTO favorites (user_id, book_id) VALUES (?,?)';
            db.query(insertFavoriteQuery, [userId, bookId], (err, results) => {
                if (err) {
                    res.status(500).json({ error: 'Failed to add to favorites' });
                } else {
                    // 返回成功的 JSON 响应
                    res.status(200).json({ message: 'Book added to favorites successfully' });
                }
            });
        }
    });
});

// 删除收藏书籍路由
app.post('/user/delete-favorite', (req, res) => {
    const { userId, bookId } = req.body;
    const deleteQuery = 'DELETE FROM favorites WHERE user_id =? AND book_id =?';
    db.query(deleteQuery, [userId, bookId], (err, results) => {
        if (err) {
            res.status(500).json({ error: 'Server error when deleting favorite' });
        } else if (results.affectedRows === 0) {
            // 如果受影响的行数为0，表示没有找到对应的收藏记录，即可能已经不存在该收藏了
            res.status(400).json({ error: 'This book is not in your favorites' });
        } else {
            res.status(200).json({ message: 'Book removed from favorites successfully' });
        }
    });
});

// 从收藏中借阅书籍
app.post('/user/borrow-from-favorite', (req, res) => {
    const { userId, bookId } = req.body;
    // 先从收藏中删除这本书
    const deleteFavoriteQuery = 'DELETE FROM favorites WHERE user_id = ? AND book_id = ?';
    db.query(deleteFavoriteQuery, [userId, bookId], (err, deleteResults) => {
        if (err) {
            console.error('Error deleting favorite before borrowing:', err);
            res.status(500).json({ error: 'Failed to borrow book from favorites' });
            return;
        }
        if (deleteResults.affectedRows === 0) {
            res.status(400).json({ error: 'This book is not in your favorites' });
            return;
        }

        // 然后借阅这本书
        const borrowQuery = 'INSERT INTO borrow_records (user_id, book_id, borrow_date) VALUES (?, ?, NOW())';
        db.query(borrowQuery, [userId, bookId], (err, borrowResults) => {
            if (err) {
                console.error('Error borrowing book:', err);
                res.status(500).json({ error: 'Failed to borrow book' });
            } else {
                // 返回成功的 JSON 响应
                res.status(200).json({ message: 'Book borrowed from favorites successfully' });
            }
        });
    });
});
 

// 监听端口
const PORT = 3000;
app.listen(PORT, () => {
    console.log(`Server running on port ${PORT}`);
});          <!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: left;
    }

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

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

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

    /* 统一复选框样式 */
    input[type="checkbox"] {
        width: 20px;
        /* 统一宽度 */
        height: 20px;
        /* 统一高度 */
        margin-right: 10px;
        /* 右侧间距 */
    }

    .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;
        /* 使用flexbox */
        align-items: center;
        /* 让子元素垂直居中 */
        background-color: #fff;
        padding: 10px;
        border: 1px solid #ddd;
        margin-bottom: 10px;
    }

    .book-item {
        display: flex;
        align-items: center;
        /* 垂直居中 */
        flex-grow: 1;
        /* 占据剩余空间 */
    }

    .book-actions {
        display: flex;
        align-items: center;
        /* 垂直居中 */
        margin-left: 10px;
        /* 按钮与其他内容之间的间距 */
    }

    .book-actions button {

        margin-left: 10px;
        /* 按钮之间的间距 */
    }

    .user-list-container ul {
    list-style-type: none;
    padding: 0;
    width: 100%; /* 允许列表宽度与父容器匹配 */
}

.user-list-container li {
    display: flex; /* 使用 flexbox 进行排列 */
    justify-content: space-between; /* 将项目和按钮分开 */
    align-items: center; /* 垂直居中 */
    background-color: #fff;
    padding: 10px;
    margin-bottom: 10px;
}
</style>

<body>
    <div class="topbar">
        <div id="adminName">管理员：</div> <!-- 这里改为通过 ID 引用 -->
        <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="form-container centered-content" id="formContainer" style="display:none;">
            <!-- 这里将根据需要动态显示表单 -->
        </div>

    </div>
    <script>
        function logout() {
            alert('已退出登录');
            window.location.href = 'login.html'; // 重定向到登录页面
        }
        function showForm(type, id = null) {
            const formContainer = document.getElementById('formContainer');
            formContainer.innerHTML = ''; // 清空之前的内容
            formContainer.style.display = 'block';

            // 根据type动态创建表单
            switch (type) {
                case 'add':
                    formContainer.innerHTML = `
                            <h2 style="text-align: center";>增加图书</h2>
                        <input type="text" placeholder="书名">
                        <input type="text" placeholder="作者">
                        <input type="number" placeholder="出版年份">
                        <button onclick="addBook()">添加</button>
                    `;
                    break;
                case 'delete':
                    formContainer.innerHTML = `
        <h2 style="text-align: center";>删除图书</h2>
        <input type="text" id="bookTitle" placeholder="输入书名" style="width: 200px;" />
        <button onclick="deleteBookByTitle()">删除</button>
    `;
                    break;
                case 'borrowRecords':
                    formContainer.innerHTML = `
                    <h2 style="text-align: center";>借阅记录</h2>
                    <div id="borrowRecordsList"></div>`;
                    loadBorrowRecords();
                    break;
                case 'edit':
                    formContainer.innerHTML = `
                    <h2 style="text-align: center";>修改图书</h2>
        <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">
        <button onclick="editBook()">修改</button>
    `;
                    break;
                case 'search':
                    formContainer.innerHTML = `
                    <h2 style="text-align: center";>查询图书</h2>
                        <input type="text" placeholder="搜索关键词" id="searchKeyword">
                        <button onclick="searchBooks()">查询</button>
                    `;
                    break;
                case 'userManagement':
                    loadUsers().then(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;">
        ${users.map(user => `
            <li style="display: flex; justify-content: space-between; align-items: center; width: 100%;">
                <span style="flex-grow: 1; margin-right: 10px;">${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();  // 正确的位置
                    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('Error fetching user data:', error);
                            alert('Failed to fetch user data: ' + 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';
            }
        }

        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('Network response was not ok');
                    }
                    return response.text();
                })
                .then(data => {
                    console.log('Book deleted:', data);
                    alert('图书删除成功');
                    loadBooks();  // 重新加载图书列表
                })
                .catch(error => {
                    console.error('Error deleting book:', 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;

            // 先检查图书名是否已经存在
            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 => {
                    // 检查书名是否已存在
                    const bookExists = books.some(book => book.title === title);
                    if (bookExists) {
                        alert('书名已经存在，无法添加。');
                        return; // 结束添加逻辑
                    }

                    // 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); // 显示成功消息
                    formContainer.innerHTML = '';
                    formContainer.style.display = 'none';
                    showForm('dataManagement'); // 刷新图书列表
                })
                .catch(error => {
                    console.error('Error adding book:', error);
                    // 在这里可以选择不再显示错误，除非非常重要
                    // alert('添加图书时出错：' + error.message); 
                });
        }

        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('Network response was not ok');
                    }
                    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('Network response was not ok');
                    }
                    return response.json();
                })
                .then(books => {
                    console.log('Loaded books data:', books);
                    displayBooks(books);
                    return Promise.resolve();  // 显式返回一个已解决的Promise，确保外层能正确链式调用
                })
                .catch(error => {
                    console.error('Error loading books:', error);
                    alert('加载图书时出错：' + error.message);
                    return Promise.reject(error);  // 出现错误时返回一个被拒绝的Promise，传播错误
                });
        }

        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>
    `;

            // 绑定全选事件
            const selectAllCheckbox = document.getElementById('selectAllBooks');
            selectAllCheckbox.addEventListener('change', function () {
                const checkboxes = document.querySelectorAll('.bookCheckbox');
                checkboxes.forEach(checkbox => {
                    checkbox.checked = this.checked; // 设置每个复选框的选中状态
                });
            });

            // 绑定小复选框的change事件，以便跟踪选中状态
            const bookCheckboxes = document.querySelectorAll('.bookCheckbox');
            bookCheckboxes.forEach(checkbox => {
                checkbox.addEventListener('change', function () {
                    // 检查所有小复选框是否都被选中
                    const allChecked = Array.from(bookCheckboxes).every(cb => cb.checked);
                    selectAllCheckbox.checked = allChecked; // 更新大全选框的状态
                });
            });
        }

        // 删除选中书籍的函数
        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('Network response was not ok');
                    }
                    return response.json();
                })
                .then(users => {
                    displayUsers(users);
                    return users; // 将处理后的用户数据返回，使得外层能接收到这个 Promise 结果
                })
                .catch(error => {
                    console.error('Error loading users:', error);
                    alert('加载用户时出错：' + error.message);
                    throw error; // 可以选择重新抛出错误，让调用处能进一步处理
                });
        }

        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') // 确保此 API 地址是正确的
                .then(response => {
                    if (!response.ok) {
                        throw new Error('Network response was not ok');
                    }
                    return response.json();
                })
                .then(records => {
                    console.log('Loaded borrow records:', records); // 检查返回的 records
                    displayBorrowRecords(records);
                })
                .catch(error => {
                    console.error('Error loading borrow records:', error);
                    alert('加载借阅记录时出错：' + error.message);
                });
        }

        function displayBorrowRecords(records) {
            console.log('Borrow records:', records); // Debug log - 确保调用时返回记录的结构

            const borrowRecordsList = document.getElementById('borrowRecordsList');
            borrowRecordsList.innerHTML = ''; // 清空之前的内容

            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 => {
                    console.log('Record:', record); // 输出每一条记录
                    const row = document.createElement('tr');
                    row.innerHTML = `
                <td>${record.username}</td>
                <td>${record.title}</td>
                <td>${record.author}</td>
                <td>${record.borrow_date}</td>
                <td>
                    <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('Network response was not ok: ' + response.statusText);
                    }
                    return response.text();
                })
                .then(data => {
                    alert(data);
                    loadUsers(); // 刷新用户列表
                })
                .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'); // 返回用户管理列表
        }

        function editUser(id) {
            const form = document.querySelector(`#editUserForm`);
            if (!form || !(form instanceof HTMLFormElement)) {
                console.error('Invalid form element');
                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('Failed to edit user');
                    }
                    return response.text();
                })
                .then(data => {
                    alert(data); // 显示成功消息
                    loadUsers(); // 刷新用户列表
                })
                .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);
                    }
                    // 保持表单内容不变，以便用户可以继续编辑
                });
        }

        function editBookForm(bookId) {
            fetch(`http://localhost:3000/admin/get-books`)
                .then(response => {
                    if (!response.ok) {
                        throw new Error('Failed to fetch all books data');
                    }
                    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 => {
                    console.error('Error fetching book data:', 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('Network response was not ok');
                    }
                    return response.text();
                })
                .then(data => {
                    console.log('Book deleted:', data);
                    alert('图书删除成功');
                    loadBooks();  // 重新加载图书列表
                })
                .catch(error => {
                    console.error('Error deleting book:', 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();

            // 简单验证输入框是否为空
            if (!newTitle || !newAuthor || !newYearPublished) {
                alert('请填写所有修改信息');
                return;
            }

            const oldTitle = document.getElementById('oldTitle').value; // 注意，没有trim()，因为oldTitle是禁用输入，不应更改

            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('Network response was not ok: ' + 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 => {
                    console.error('Error editing book:', error);
                    alert('修改图书时出错：' + error.message);
                });
        }
        function deleteBorrowRecordConfirm(recordId) {
            console.log('Attempting to delete record with ID:', 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 }) // 发送要删除记录的 ID
            })
                .then(response => {
                    if (!response.ok) {
                        throw new Error('Network response was not ok');
                    }
                    return response.text();
                })
                .then(data => {
                    console.log('Borrow record deleted:', data);
                    alert('借阅记录删除成功');
                    loadBorrowRecords(); // 重新加载借阅记录列表
                })
                .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('Network response was not ok');
            }
            return response.json();
        })
        .then(data => {
            console.log(data);
            
            document.getElementById('adminName').textContent = `管理员：${data.username}`;
        })
        .catch(error => {
            console.error('Error fetching admin name:', error);
            document.getElementById('adminName').textContent = '管理员：未知'; // 出错时处理
        });
}
    </script>
</body>

</html>尽量不要下载npm包