// 文件传输服务 - 前端JavaScript

class FileShareApp {
    constructor() {
        this.baseURL = window.location.origin;
        this.init();
    }

    init() {
        this.setupEventListeners();
        this.setupTabSwitching();
        this.setupDragAndDrop();
    }

    // 设置事件监听器
    setupEventListeners() {
        // 文件选择
        const fileInput = document.getElementById('fileInput');
        const selectBtn = document.querySelector('.select-btn');
        
        selectBtn?.addEventListener('click', () => fileInput?.click());
        fileInput?.addEventListener('change', (e) => this.handleFileSelect(e.target.files[0]));

        // 文本分享
        const shareTextBtn = document.getElementById('shareTextBtn');
        shareTextBtn?.addEventListener('click', () => this.handleTextShare());

        // 下载文件
        const downloadBtn = document.getElementById('downloadBtn');
        const downloadCode = document.getElementById('downloadCode');
        
        downloadBtn?.addEventListener('click', () => this.handleDownloadInfo());
        downloadCode?.addEventListener('keypress', (e) => {
            if (e.key === 'Enter') this.handleDownloadInfo();
        });

        // 重置按钮
        window.resetUpload = () => this.resetUploadSection();
        window.resetText = () => this.resetTextSection();

        // 复制功能
        window.copyCode = (elementId) => this.copyToClipboard(elementId);
        window.copyText = (text) => this.copyTextToClipboard(text);
    }

    // 设置选项卡切换
    setupTabSwitching() {
        const tabBtns = document.querySelectorAll('.tab-btn');
        const tabContents = document.querySelectorAll('.tab-content');

        tabBtns.forEach(btn => {
            btn.addEventListener('click', () => {
                const targetTab = btn.getAttribute('data-tab');
                
                // 更新按钮状态
                tabBtns.forEach(b => b.classList.remove('active'));
                btn.classList.add('active');

                // 更新内容显示
                tabContents.forEach(content => {
                    content.classList.remove('active');
                });
                
                const targetContent = document.getElementById(`${targetTab}-tab`);
                if (targetContent) {
                    targetContent.classList.add('active');
                }
            });
        });
    }

    // 设置拖拽上传
    setupDragAndDrop() {
        const dropZone = document.getElementById('dropZone');
        
        if (!dropZone) return;

        ['dragenter', 'dragover', 'dragleave', 'drop'].forEach(eventName => {
            dropZone.addEventListener(eventName, this.preventDefaults, false);
        });

        ['dragenter', 'dragover'].forEach(eventName => {
            dropZone.addEventListener(eventName, () => dropZone.classList.add('dragover'), false);
        });

        ['dragleave', 'drop'].forEach(eventName => {
            dropZone.addEventListener(eventName, () => dropZone.classList.remove('dragover'), false);
        });

        dropZone.addEventListener('drop', (e) => {
            const files = e.dataTransfer.files;
            if (files.length > 0) {
                this.handleFileSelect(files[0]);
            }
        }, false);
    }

    preventDefaults(e) {
        e.preventDefault();
        e.stopPropagation();
    }

    // 处理文件选择
    async handleFileSelect(file) {
        if (!file) return;

        // 检查文件大小
        const maxSize = 100 * 1024 * 1024; // 100MB
        if (file.size > maxSize) {
            this.showToast('文件太大，最大支持100MB', 'error');
            return;
        }

        try {
            // 显示进度界面
            this.showProgress();
            
            // 创建FormData
            const formData = new FormData();
            formData.append('file', file);

            // 上传文件
            const response = await fetch(`${this.baseURL}/api/upload`, {
                method: 'POST',
                body: formData,
                onUploadProgress: (progressEvent) => {
                    const percentCompleted = Math.round((progressEvent.loaded * 100) / progressEvent.total);
                    this.updateProgress(percentCompleted);
                }
            });

            if (!response.ok) {
                throw new Error(`上传失败: ${response.statusText}`);
            }

            const result = await response.json();
            this.showUploadResult(result);
            this.showToast('文件上传成功！', 'success');

        } catch (error) {
            console.error('Upload error:', error);
            this.showToast(error.message || '上传失败', 'error');
            this.hideProgress();
        }
    }

    // 处理文本分享
    async handleTextShare() {
        const content = document.getElementById('textContent').value.trim();
        const filename = document.getElementById('textFilename').value.trim() || 'shared_text.txt';

        if (!content) {
            this.showToast('请输入要分享的文本内容', 'warning');
            return;
        }

        try {
            const shareBtn = document.getElementById('shareTextBtn');
            shareBtn.classList.add('loading');
            shareBtn.disabled = true;

            const response = await fetch(`${this.baseURL}/api/share-text`, {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json',
                },
                body: JSON.stringify({
                    content: content,
                    filename: filename
                })
            });

            if (!response.ok) {
                throw new Error(`分享失败: ${response.statusText}`);
            }

            const result = await response.json();
            this.showTextResult(result);
            this.showToast('文本分享成功！', 'success');

        } catch (error) {
            console.error('Text share error:', error);
            this.showToast(error.message || '分享失败', 'error');
        } finally {
            const shareBtn = document.getElementById('shareTextBtn');
            shareBtn.classList.remove('loading');
            shareBtn.disabled = false;
        }
    }

    // 处理下载信息获取
    async handleDownloadInfo() {
        const code = document.getElementById('downloadCode').value.trim().toUpperCase();
        
        if (!code) {
            this.showToast('请输入分享码', 'warning');
            return;
        }

        if (code.length !== 8) {
            this.showToast('分享码格式错误，应为8位字符', 'warning');
            return;
        }

        try {
            const downloadBtn = document.getElementById('downloadBtn');
            downloadBtn.classList.add('loading');
            downloadBtn.disabled = true;

            const response = await fetch(`${this.baseURL}/api/info/${code}`);

            if (response.status === 404) {
                throw new Error('分享码不存在');
            }

            if (response.status === 410) {
                throw new Error('分享已过期');
            }

            if (!response.ok) {
                throw new Error(`获取信息失败: ${response.statusText}`);
            }

            const fileInfo = await response.json();
            this.showFileInfo(fileInfo);

        } catch (error) {
            console.error('Download info error:', error);
            this.showToast(error.message || '获取文件信息失败', 'error');
            this.hideFileInfo();
        } finally {
            const downloadBtn = document.getElementById('downloadBtn');
            downloadBtn.classList.remove('loading');
            downloadBtn.disabled = false;
        }
    }

    // 处理文件下载
    handleFileDownload(code) {
        const downloadUrl = `${this.baseURL}/api/download/${code}`;
        
        // 创建隐藏的下载链接
        const link = document.createElement('a');
        link.href = downloadUrl;
        link.style.display = 'none';
        document.body.appendChild(link);
        link.click();
        document.body.removeChild(link);

        this.showToast('开始下载文件...', 'success');
    }

    // 显示上传进度
    showProgress() {
        const progressSection = document.getElementById('progressSection');
        const uploadResult = document.getElementById('uploadResult');
        const dropZone = document.getElementById('dropZone');
        
        dropZone.style.display = 'none';
        uploadResult.style.display = 'none';
        progressSection.style.display = 'block';
        
        this.updateProgress(0);
    }

    // 更新进度条
    updateProgress(percent) {
        const progressFill = document.getElementById('progressFill');
        const progressText = document.getElementById('progressText');
        
        if (progressFill) {
            progressFill.style.width = `${percent}%`;
        }
        
        if (progressText) {
            progressText.textContent = `上传中... ${percent}%`;
        }
    }

    // 隐藏进度条
    hideProgress() {
        const progressSection = document.getElementById('progressSection');
        const dropZone = document.getElementById('dropZone');
        
        progressSection.style.display = 'none';
        dropZone.style.display = 'block';
    }

    // 显示上传结果
    showUploadResult(result) {
        const progressSection = document.getElementById('progressSection');
        const uploadResult = document.getElementById('uploadResult');
        const uploadCode = document.getElementById('uploadCode');
        const uploadLink = document.getElementById('uploadLink');
        const uploadExpire = document.getElementById('uploadExpire');
        
        progressSection.style.display = 'none';
        uploadResult.style.display = 'block';
        
        uploadCode.textContent = result.code;
        uploadLink.textContent = `${this.baseURL}${result.download_url}`;
        
        const expireTime = new Date(result.expires_at);
        const now = new Date();
        const diffMinutes = Math.ceil((expireTime - now) / (1000 * 60));
        uploadExpire.textContent = `${diffMinutes}分钟后过期`;

        // 设置下载按钮
        const downloadFileBtn = document.getElementById('downloadFileBtn');
        if (downloadFileBtn) {
            downloadFileBtn.onclick = () => this.handleFileDownload(result.code);
        }
    }

    // 显示文本分享结果
    showTextResult(result) {
        const textResult = document.getElementById('textResult');
        const textCode = document.getElementById('textCode');
        const textLink = document.getElementById('textLink');
        const textExpire = document.getElementById('textExpire');
        
        textResult.style.display = 'block';
        
        textCode.textContent = result.code;
        textLink.textContent = `${this.baseURL}${result.download_url}`;
        
        const expireTime = new Date(result.expires_at);
        const now = new Date();
        const diffMinutes = Math.ceil((expireTime - now) / (1000 * 60));
        textExpire.textContent = `${diffMinutes}分钟后过期`;

        // 隐藏输入区域
        document.querySelector('.text-input-area').style.display = 'none';
    }

    // 显示文件信息
    showFileInfo(fileInfo) {
        const fileInfoDiv = document.getElementById('fileInfo');
        const fileName = document.getElementById('fileName');
        const fileSize = document.getElementById('fileSize');
        const fileType = document.getElementById('fileType');
        const fileExpire = document.getElementById('fileExpire');
        const downloadFileBtn = document.getElementById('downloadFileBtn');
        
        fileInfoDiv.style.display = 'block';
        
        fileName.textContent = fileInfo.filename;
        fileSize.textContent = this.formatFileSize(fileInfo.size);
        fileType.textContent = fileInfo.file_type;
        
        if (fileInfo.is_expired) {
            fileExpire.textContent = '已过期';
            fileExpire.style.color = 'var(--error-color)';
            downloadFileBtn.disabled = true;
            downloadFileBtn.textContent = '文件已过期';
        } else {
            const expireTime = new Date(fileInfo.expires_at);
            const now = new Date();
            const diffMinutes = Math.ceil((expireTime - now) / (1000 * 60));
            fileExpire.textContent = `剩余时间: ${diffMinutes}分钟`;
            fileExpire.style.color = 'var(--warning-color)';
            downloadFileBtn.disabled = false;
            downloadFileBtn.textContent = '⬇️ 下载文件';
            downloadFileBtn.onclick = () => this.handleFileDownload(fileInfo.code);
        }
    }

    // 隐藏文件信息
    hideFileInfo() {
        const fileInfoDiv = document.getElementById('fileInfo');
        fileInfoDiv.style.display = 'none';
    }

    // 重置上传区域
    resetUploadSection() {
        const dropZone = document.getElementById('dropZone');
        const progressSection = document.getElementById('progressSection');
        const uploadResult = document.getElementById('uploadResult');
        const fileInput = document.getElementById('fileInput');
        
        dropZone.style.display = 'block';
        progressSection.style.display = 'none';
        uploadResult.style.display = 'none';
        
        if (fileInput) {
            fileInput.value = '';
        }
    }

    // 重置文本区域
    resetTextSection() {
        const textResult = document.getElementById('textResult');
        const textInputArea = document.querySelector('.text-input-area');
        const textContent = document.getElementById('textContent');
        const textFilename = document.getElementById('textFilename');
        
        textResult.style.display = 'none';
        textInputArea.style.display = 'block';
        
        textContent.value = '';
        textFilename.value = 'shared_text.txt';
    }

    // 复制到剪贴板
    async copyToClipboard(elementId) {
        const element = document.getElementById(elementId);
        if (!element) return;

        const text = element.textContent;
        await this.copyTextToClipboard(text);
    }

    // 复制文本到剪贴板
    async copyTextToClipboard(text) {
        try {
            await navigator.clipboard.writeText(text);
            this.showToast('已复制到剪贴板', 'success');
        } catch (err) {
            // 降级处理
            const textArea = document.createElement('textarea');
            textArea.value = text;
            textArea.style.position = 'fixed';
            textArea.style.opacity = '0';
            document.body.appendChild(textArea);
            textArea.select();
            
            try {
                document.execCommand('copy');
                this.showToast('已复制到剪贴板', 'success');
            } catch (err) {
                this.showToast('复制失败', 'error');
            }
            
            document.body.removeChild(textArea);
        }
    }

    // 格式化文件大小
    formatFileSize(bytes) {
        if (bytes === 0) return '0 B';
        
        const k = 1024;
        const sizes = ['B', 'KB', 'MB', 'GB'];
        const i = Math.floor(Math.log(bytes) / Math.log(k));
        
        return parseFloat((bytes / Math.pow(k, i)).toFixed(1)) + ' ' + sizes[i];
    }

    // 显示通知
    showToast(message, type = 'success') {
        const toast = document.getElementById('toast');
        const toastMessage = document.getElementById('toastMessage');
        
        if (!toast || !toastMessage) return;

        // 清除之前的类
        toast.className = 'toast';
        
        // 添加类型类
        if (type !== 'success') {
            toast.classList.add(type);
        }

        toastMessage.textContent = message;
        toast.style.display = 'block';

        // 3秒后自动隐藏
        setTimeout(() => {
            toast.style.display = 'none';
        }, 3000);
    }

    // 格式化时间
    formatTime(dateString) {
        const date = new Date(dateString);
        return date.toLocaleString('zh-CN');
    }

    // 计算剩余时间
    calculateRemainingTime(expireTime) {
        const now = new Date();
        const expire = new Date(expireTime);
        const diffMs = expire - now;
        
        if (diffMs <= 0) {
            return '已过期';
        }
        
        const diffMinutes = Math.ceil(diffMs / (1000 * 60));
        
        if (diffMinutes > 60) {
            const hours = Math.floor(diffMinutes / 60);
            const minutes = diffMinutes % 60;
            return `${hours}小时${minutes}分钟`;
        }
        
        return `${diffMinutes}分钟`;
    }
}

// 页面加载完成后初始化应用
document.addEventListener('DOMContentLoaded', () => {
    new FileShareApp();
});

// 工具函数：检测移动设备
function isMobile() {
    return /Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent);
}

// 工具函数：检测是否支持文件API
function supportsFileAPI() {
    return window.File && window.FileReader && window.FileList && window.Blob;
}

// 工具函数：检测是否支持拖拽
function supportsDragAndDrop() {
    const div = document.createElement('div');
    return (('draggable' in div) || ('ondragstart' in div && 'ondrop' in div)) && 
           'FormData' in window && 
           'FileReader' in window;
}

// 页面可见性变化时的处理
document.addEventListener('visibilitychange', () => {
    if (!document.hidden) {
        // 页面重新可见时，可以刷新一些数据
        console.log('页面重新可见');
    }
});

// 全局错误处理
window.addEventListener('error', (e) => {
    console.error('全局错误:', e.error);
});

// 未处理的Promise错误
window.addEventListener('unhandledrejection', (e) => {
    console.error('未处理的Promise错误:', e.reason);
});

// 导出工具函数供其他脚本使用
window.FileShareUtils = {
    isMobile,
    supportsFileAPI,
    supportsDragAndDrop
};