/**
 * 认证模块管理器
 * 处理登录、注册、注销及权限检查
 */
class AuthManager {
    constructor() {
        this.apiBase = '/api';
        this.init();
    }
    
    init() {
        this.createNotificationContainer();
        this.initEventListeners();
        this.checkAuthStatus();
    }
    
    /**
     * 创建通知容器
     */
    createNotificationContainer() {
        if (!document.getElementById('notification-container')) {
            const container = document.createElement('div');
            container.id = 'notification-container';
            container.style.cssText = `
                position: fixed;
                top: 20px;
                right: 20px;
                z-index: 9999;
                display: flex;
                flex-direction: column;
                gap: 10px;
            `;
            document.body.appendChild(container);
        }
    }
    
    /**
     * 检查用户认证状态
     */
    async checkAuthStatus() {
        // 如果当前是公共页面，可以选择不检查，或者检查后更新UI
        const currentPath = window.location.pathname;
        const isAuthPage = currentPath.includes('/login') || currentPath.includes('/register');
        
        try {
            const response = await fetch(`${this.apiBase}/auth/me`);
            const data = await response.json();
            
            if (data.success && data.user) {
                // 用户已登录
                const redirectUrl = this.getDashboardUrl(data.user.role);
                
                // 如果在登录/注册页，跳转到仪表板
                if (isAuthPage || currentPath === '/') {
                    window.location.href = redirectUrl;
                }
            } else {
                // 用户未登录，如果在受保护页面，跳转到登录页
                // 注意：后端通常已经处理了重定向，这里是前端的额外保障
                if (!isAuthPage && currentPath !== '/') {
                    // 可以在这里添加逻辑，但通常交给后端控制
                }
            }
        } catch (error) {
            console.error('Auth check failed:', error);
        }
    }
    
    getDashboardUrl(role) {
        switch(role) {
            case 'student': return '/student/dashboard';
            case 'teacher': return '/teacher/dashboard';
            case 'admin': return '/admin/dashboard';
            default: return '/dashboard';
        }
    }
    
    initEventListeners() {
        // 登录表单
        const loginForm = document.getElementById('loginForm');
        if (loginForm) {
            loginForm.addEventListener('submit', (e) => this.handleLogin(e));
        }
        
        // 注册表单
        const registerForm = document.getElementById('registerForm');
        if (registerForm) {
            registerForm.addEventListener('submit', (e) => this.handleRegister(e));
            
            // 角色选择联动
            const roleSelect = document.getElementById('role');
            if (roleSelect) {
                roleSelect.addEventListener('change', (e) => this.handleRoleChange(e));
            }
        }
        
        // 注销按钮 (可能有多个，例如在导航栏)
        document.querySelectorAll('.btn-logout, #logoutBtn').forEach(btn => {
            btn.addEventListener('click', (e) => this.handleLogout(e));
        });
    }
    
    handleRoleChange(e) {
        const role = e.target.value;
        const classField = document.getElementById('classField');
        const classInput = document.getElementById('class');
        
        if (classField && classInput) {
            if (role === 'student' || role === 'teacher') {
                classField.style.display = 'block';
                classInput.required = true;
            } else {
                classField.style.display = 'none';
                classInput.required = false;
                classInput.value = ''; // 清空值
            }
        }
    }
    
    async handleLogin(e) {
        e.preventDefault();
        const form = e.target;
        const submitBtn = form.querySelector('button[type="submit"]');
        
        if (this.setLoading(submitBtn, true, '登录中...')) {
            try {
                const formData = new FormData(form);
                const data = Object.fromEntries(formData.entries());
                
                const response = await fetch(`${this.apiBase}/auth/login`, {
                    method: 'POST',
                    headers: { 'Content-Type': 'application/json' },
                    body: JSON.stringify(data)
                });
                
                const result = await response.json();
                
                if (result.success) {
                    this.showNotification('登录成功，正在跳转...', 'success');
                    setTimeout(() => {
                        window.location.href = this.getDashboardUrl(result.user.role);
                    }, 1000);
                } else {
                    this.showNotification(result.message || '登录失败', 'error');
                    this.setLoading(submitBtn, false);
                }
            } catch (error) {
                console.error('Login error:', error);
                this.showNotification('网络错误，请稍后重试', 'error');
                this.setLoading(submitBtn, false);
            }
        }
    }
    
    async handleRegister(e) {
        e.preventDefault();
        const form = e.target;
        const submitBtn = form.querySelector('button[type="submit"]');
        
        // 获取数据
        const formData = new FormData(form);
        const data = Object.fromEntries(formData.entries());
        
        // 简单验证
        if (data.password !== data.confirmPassword) {
            this.showNotification('两次输入的密码不一致', 'error');
            return;
        }
        
        if (this.setLoading(submitBtn, true, '注册中...')) {
            try {
                const response = await fetch(`${this.apiBase}/auth/register`, {
                    method: 'POST',
                    headers: { 'Content-Type': 'application/json' },
                    body: JSON.stringify(data)
                });
                
                const result = await response.json();
                
                if (result.success) {
                    this.showNotification('注册成功，请登录', 'success');
                    setTimeout(() => {
                        window.location.href = '/login';
                    }, 1500);
                } else {
                    this.showNotification(result.message || '注册失败', 'error');
                    this.setLoading(submitBtn, false);
                }
            } catch (error) {
                console.error('Register error:', error);
                this.showNotification('网络错误，请稍后重试', 'error');
                this.setLoading(submitBtn, false);
            }
        }
    }
    
    async handleLogout(e) {
        e.preventDefault();
        
        if (confirm('确定要退出登录吗？')) {
            try {
                const response = await fetch(`${this.apiBase}/auth/logout`, {
                    method: 'POST'
                });
                
                const result = await response.json();
                
                if (result.success) {
                    this.showNotification('已退出登录', 'success');
                    setTimeout(() => {
                        window.location.href = '/login';
                    }, 1000);
                }
            } catch (error) {
                console.error('Logout error:', error);
                // 即使出错也强制跳转到登录页
                window.location.href = '/login';
            }
        }
    }
    
    /**
     * 设置按钮加载状态
     * @param {HTMLElement} btn 按钮元素
     * @param {boolean} isLoading 是否正在加载
     * @param {string} text 加载时的文本
     * @returns {boolean} true表示状态设置成功
     */
    setLoading(btn, isLoading, text = '') {
        if (!btn) return false;
        
        if (isLoading) {
            if (btn.dataset.loading) return false; // 防止重复提交
            btn.dataset.loading = 'true';
            btn.dataset.originalText = btn.innerHTML;
            btn.innerHTML = `<i class="fas fa-spinner fa-spin"></i> ${text}`;
            btn.disabled = true;
        } else {
            btn.innerHTML = btn.dataset.originalText || btn.innerHTML;
            delete btn.dataset.loading;
            btn.disabled = false;
        }
        return true;
    }
    
    /**
     * 显示通知
     * @param {string} message 消息内容
     * @param {string} type 消息类型 'success' | 'error' | 'info'
     */
    showNotification(message, type = 'info') {
        const container = document.getElementById('notification-container');
        if (!container) return;
        
        const notification = document.createElement('div');
        notification.className = `notification ${type}`;
        
        let icon = 'info-circle';
        if (type === 'success') icon = 'check-circle';
        if (type === 'error') icon = 'exclamation-circle';
        
        notification.innerHTML = `
            <i class="fas fa-${icon}"></i>
            <span class="notification-content">${message}</span>
        `;
        
        container.appendChild(notification);
        
        // 动画显示
        requestAnimationFrame(() => {
            notification.classList.add('show');
        });
        
        // 自动消失
        setTimeout(() => {
            notification.classList.remove('show');
            notification.addEventListener('transitionend', () => {
                notification.remove();
            });
        }, 3000);
    }
}

// 初始化
document.addEventListener('DOMContentLoaded', () => {
    window.authManager = new AuthManager();
});