/**
 * 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);
    });
}

/** File → 文本内容 */
export function fileToText(file) {
    return new Promise((resolve, reject) => {
        const reader = new FileReader();
        reader.onload = () => resolve(reader.result);
        reader.onerror = reject;
        reader.readAsText(file);
    });
}

/** 根据文件名检测语言标识（用于 Markdown 代码块） */
export function detectLanguage(filename) {
    const ext = filename.split('.').pop().toLowerCase();
    const map = {
        py: 'python', pyw: 'python', pyi: 'python',
        js: 'javascript', mjs: 'javascript', cjs: 'javascript',
        ts: 'typescript', tsx: 'tsx', jsx: 'jsx',
        java: 'java', class: 'java',
        c: 'c', h: 'c',
        cpp: 'cpp', cc: 'cpp', cxx: 'cpp', hpp: 'cpp',
        go: 'go', rs: 'rust', rb: 'ruby', php: 'php',
        sh: 'bash', bash: 'bash', zsh: 'bash', fish: 'bash',
        sql: 'sql', html: 'html', htm: 'html', css: 'css',
        json: 'json', jsonl: 'json',
        xml: 'xml', svg: 'svg',
        yaml: 'yaml', yml: 'yaml', toml: 'toml',
        ini: 'ini', cfg: 'ini', conf: 'ini',
        md: 'markdown', markdown: 'markdown', rst: 'rst',
        txt: '', csv: 'csv', tsv: 'csv', log: '',
        swift: 'swift', kt: 'kotlin', kts: 'kotlin',
        scala: 'scala', lua: 'lua', pl: 'perl', r: 'r',
        m: 'matlab', mm: 'objectivec',
        cs: 'csharp', fs: 'fsharp', vb: 'vbnet',
        ex: 'elixir', exs: 'elixir', erl: 'erlang',
        hs: 'haskell', clj: 'clojure', lisp: 'lisp',
        dockerfile: 'dockerfile', makefile: 'makefile',
        diff: 'diff', patch: 'diff',
    };
    return map[ext] ?? ext;
}