/**
 * Utils - 通用工具函数
 */

/** 生成唯一 ID */
export function generateId() {
    return `${Date.now()}-${Math.random().toString(36).substr(2, 9)}`;
}

/** 格式化时间戳 */
export function formatTime(ts) {
    const d = new Date(ts);
    const pad = n => String(n).padStart(2, '0');
    return `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())} ${pad(d.getHours())}:${pad(d.getMinutes())}`;
}

/** 截断文本 */
export function truncate(str, len = 50) {
    if (!str) return '';
    return str.length > len ? str.substring(0, len) + '...' : str;
}

/** 防抖 */
export function debounce(fn, ms = 300) {
    let timer;
    return (...args) => {
        clearTimeout(timer);
        timer = setTimeout(() => fn(...args), ms);
    };
}

/** 格式化字节大小 */
export function formatSize(bytes) {
    if (!bytes) return '';
    const units = ['B', 'KB', 'MB', 'GB', 'TB'];
    let i = 0;
    let size = bytes;
    while (size >= 1024 && i < units.length - 1) {
        size /= 1024;
        i++;
    }
    return `${size.toFixed(1)} ${units[i]}`;
}

/** HTML 转义 */
export function escapeHtml(str) {
    const map = { '&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;', "'": '&#39;' };
    return String(str).replace(/[&<>"']/g, (c) => map[c]);
}

/** 下载文件 */
export function downloadFile(filename, content, type) {
    const blob = new Blob([content], { type: type + ';charset=utf-8' });
    const url = URL.createObjectURL(blob);
    const a = document.createElement('a');
    a.href = url;
    a.download = filename;
    a.click();
    URL.revokeObjectURL(url);
}

/** File → Base64（去前缀） */
export function fileToBase64(file) {
    return new Promise((resolve, reject) => {
        const reader = new FileReader();
        reader.onload = () => {
            const base64 = reader.result.split(',')[1];
            resolve(base64);
        };
        reader.onerror = reject;
        reader.readAsDataURL(file);
    });
}