/* ═══════════════════════════════════════════════════════════
   巨子测肤 · 1'me — 后端服务(零依赖,Node ≥ 18)
   1) 静态托管 h5/ 目录
   2) POST /api/skin-analyze:三视图(正/左/右)中转 Face++ 专业版测肤
      密钥只存在服务端(SKIN_API_KEY / SKIN_API_SECRET),
      前端永远接触不到 api_secret。
   启动: node server.js   (默认 8080,可用 PORT 环境变量改)
   ═══════════════════════════════════════════════════════════ */
'use strict';

const http = require('http');
const fs = require('fs');
const path = require('path');

const PORT = Number(process.env.PORT) || 8080;
const ROOT = __dirname;
const FACEPP_URL = 'https://api-cn.faceplusplus.com/facepp/v1/skinanalyze_pro';
const DATA_DIR = path.join(ROOT, 'data', 'results'); // 每次检测的原始返回落盘(复核用,已在 .gitignore)

/* ─── 密钥加载:环境变量优先,其次 apikey.bash,最后 reference 下的 credentials.env ─── */
function loadCredentials() {
  if (process.env.SKIN_API_KEY && process.env.SKIN_API_SECRET) {
    return { key: process.env.SKIN_API_KEY, secret: process.env.SKIN_API_SECRET };
  }
  try {
    const txt = fs.readFileSync(path.join(ROOT, '..', 'apikey.bash'), 'utf8');
    const key = (txt.match(/SKIN_API_KEY\s*=\s*["']?([A-Za-z0-9_-]+)/) || [])[1];
    const secret = (txt.match(/SKIN_API_SECRET\s*=\s*["']?([A-Za-z0-9_-]+)/) || [])[1];
    if (key && secret) return { key, secret };
  } catch (e) { /* 文件不存在则继续下一级兜底 */ }
  try {
    const txt = fs.readFileSync(path.join(ROOT, '..', 'reference', 'facepp-skinanalyze', 'credentials.env'), 'utf8');
    const key = (txt.match(/FACEPP_API_KEY\s*=\s*["']?([A-Za-z0-9_-]+)/) || [])[1];
    const secret = (txt.match(/FACEPP_API_SECRET\s*=\s*["']?([A-Za-z0-9_-]+)/) || [])[1];
    if (key && secret) return { key, secret };
  } catch (e) { /* 文件不存在则走下面的报错 */ }
  console.error('[启动失败] 找不到密钥:请设置 SKIN_API_KEY / SKIN_API_SECRET 环境变量,');
  console.error('           或在项目根目录放置 apikey.bash(内容为 export SKIN_API_KEY=... 等),');
  console.error('           或在 reference/facepp-skinanalyze/credentials.env 放置 FACEPP_API_KEY=... 等');
  process.exit(1);
}
const CRED = loadCredentials();

/* ─── 静态文件 ─── */
const MIME = {
  '.html': 'text/html; charset=utf-8', '.css': 'text/css; charset=utf-8',
  '.js': 'application/javascript; charset=utf-8', '.json': 'application/json; charset=utf-8',
  '.png': 'image/png', '.jpg': 'image/jpeg', '.jpeg': 'image/jpeg', '.svg': 'image/svg+xml',
  '.ico': 'image/x-icon', '.webp': 'image/webp', '.woff2': 'font/woff2'
};
function serveStatic(req, res, pathname) {
  let p;
  try {
    p = decodeURIComponent(pathname);
  } catch (e) { // 畸形编码(如 /%、/%zz)会抛 URIError,返回 400 而不是打挂进程
    res.writeHead(400, { 'Content-Type': 'text/plain; charset=utf-8' });
    return res.end('Bad Request');
  }
  if (p === '/') p = '/index.html';
  const file = path.normalize(path.join(ROOT, p));
  if (file !== ROOT && !file.startsWith(ROOT + path.sep)) { res.writeHead(403); return res.end('Forbidden'); }
  fs.readFile(file, (err, data) => {
    if (err) { res.writeHead(404, { 'Content-Type': 'text/plain; charset=utf-8' }); return res.end('Not Found'); }
    res.writeHead(200, { 'Content-Type': MIME[path.extname(file)] || 'application/octet-stream' });
    res.end(data);
  });
}

/* ─── Face++ 错误 → 用户可读提示 ─── */
const ERR_MSG = {
  'NO_FACE_FOUND': '未检测到人脸,请正对镜头、露出完整五官后重试',
  'INVALID_IMAGE_FACE': '照片中人脸不完整或检测到多张人脸,请单人正脸出镜',
  'INVALID_FACE_SIZE': '距离太远啦,请靠近镜头一些',
  'INVALID_IMAGE_SIZE': '照片尺寸不符合要求,请重试',
  'IMAGE_FILE_TOO_LARGE': '照片过大,请重试',
  'IMAGE_ERROR_UNSUPPORTED_FORMAT': '照片格式不支持,请重试',
  'AUTHENTICATION_ERROR': '检测服务配置有误,请联系管理员',
  'AUTHORIZATION_ERROR': '检测服务额度或权限异常,请联系管理员',
  'CONCURRENCY_LIMIT_EXCEEDED': '当前检测人数较多,请稍候重试',
  'INTERNAL_ERROR': '检测服务开小差了,请稍候重试',
  'NETWORK_ERROR': '网络异常,请检查网络后重试'
};

function readBody(req, limitBytes) {
  return new Promise((resolve, reject) => {
    let size = 0, tooLarge = false; const chunks = [];
    req.on('data', c => {
      size += c.length;
      if (size > limitBytes) {
        // 不 destroy:否则 catch 里的 JSON 响应永远发不出去;只 reject 并丢弃后续 chunk(排空)
        if (!tooLarge) { tooLarge = true; reject(new Error('TOO_LARGE')); }
        return;
      }
      chunks.push(c);
    });
    req.on('end', () => { if (!tooLarge) resolve(Buffer.concat(chunks)); });
    req.on('error', reject);
  });
}

const sleep = ms => new Promise(r => setTimeout(r, ms));

/* ─── 报告页图层白名单:face_maps 只透传这几层,一行增删 ─── */
const REPORT_MAPS = ['red_area', 'brown_area', 'texture_enhanced_lines', 'texture_enhanced_pores', 'texture_enhanced_blackheads'];

/* 按 magic bytes 判断图片格式并补 data: URL 前缀(实测 red_area/brown_area 为 jpeg 头、其余 png,不硬编码) */
function toDataUrl(b64) {
  const head = Buffer.from(b64.slice(0, 16), 'base64');
  const mime = (head[0] === 0xFF && head[1] === 0xD8) ? 'image/jpeg' : 'image/png';
  return 'data:' + mime + ';base64,' + b64;
}

/* 剥离 data:image/xxx;base64, 前缀,空值返回 '' */
function stripDataPrefix(s) {
  return (s || '').replace(/^data:image\/[a-zA-Z0-9+.-]+;base64,/, '');
}

/* base64 可用性校验:字符集合法且解码后 >500B(过小人脸框必然不合格,提前拦截避免白烧次数包) */
function isUsableB64(b64) {
  if (!b64 || !/^[A-Za-z0-9+/=\s]+$/.test(b64)) return false;
  return Buffer.from(b64, 'base64').length > 500;
}

/* 调用 Face++ 专业版三视图测肤;
 * 接口超时/网络错误(fetch 抛错)、HTTP 5xx、CONCURRENCY_LIMIT_EXCEEDED → 等 4s 重试 1 次(V2.0 第七章) */
async function callFacepp(front, left, right) {
  const form = new FormData();
  form.append('api_key', CRED.key);
  form.append('api_secret', CRED.secret);
  // 专业版三视图必须走文件形式(image_file),不支持 image_base64
  form.append('image_file', new Blob([Buffer.from(front, 'base64')]), 'front.jpg');
  if (left) form.append('left_side_image_file', new Blob([Buffer.from(left, 'base64')]), 'left.jpg');
  if (right) form.append('right_side_image_file', new Blob([Buffer.from(right, 'base64')]), 'right.jpg');
  form.append('return_side_results', 'jawline_info');
  form.append('return_maps', 'water_area,red_area,brown_area,texture_enhanced_pores,texture_enhanced_blackheads,texture_enhanced_oily_area,texture_enhanced_lines,rough_area,roi_outline_map,texture_enhanced_bw');
  form.append('return_marks', 'wrinkle_mark,melanin_mark,dark_circle_outline');

  let fetchErr = null, fpRes = null, fpJson = null;
  for (let attempt = 0; attempt < 2; attempt++) {
    fetchErr = null; fpRes = null; fpJson = null;
    try {
      fpRes = await fetch(FACEPP_URL, { method: 'POST', body: form, signal: AbortSignal.timeout(60000) });
      fpJson = await fpRes.json().catch(() => ({}));
    } catch (e) { // 60s 超时(AbortError)/网络异常:无 fpJson,与 5xx/并发超限统一走「等 4s 重试 1 次」
      fetchErr = e;
    }
    const isConcurrency = !fetchErr && typeof fpJson.error_message === 'string' && fpJson.error_message.startsWith('CONCURRENCY_LIMIT_EXCEEDED');
    const is5xx = !fetchErr && fpRes && !fpRes.ok && fpRes.status >= 500;
    if (!fetchErr && !is5xx && !isConcurrency) return fpJson; // 正常响应(含 4xx 业务错误)直接返回
    if (attempt === 0) {
      const why = fetchErr ? '请求超时/网络异常' : (is5xx ? `HTTP ${fpRes.status}` : '并发超限');
      console.log(`[analyze] Face++ ${why},4s 后重试 1 次`);
      await sleep(4000);
    }
  }
  // 重试后仍失败:fetch 抛错无 fpJson,合成 NETWORK_ERROR 走现有错误响应;5xx 则返回最后一次响应
  return fetchErr ? { error_message: 'NETWORK_ERROR' } : fpJson;
}

async function handleAnalyze(req, res) {
  try {
    const body = JSON.parse((await readBody(req, 20 * 1024 * 1024)).toString('utf8'));
    // 三个 image 字段先做类型检查:非字符串视为缺失(左/右图缺失时仅发正脸,接口自动降级为单视图)
    const front = stripDataPrefix(typeof body.front_image === 'string' ? body.front_image : '');
    const leftB64 = stripDataPrefix(typeof body.left_image === 'string' ? body.left_image : '');
    const rightB64 = stripDataPrefix(typeof body.right_image === 'string' ? body.right_image : '');
    // 左/右图校验失败按未传处理(降级单视图),不报错
    const left = isUsableB64(leftB64) ? leftB64 : '';
    const right = isUsableB64(rightB64) ? rightB64 : '';
    if (!front) { res.writeHead(400, { 'Content-Type': 'application/json; charset=utf-8' }); return res.end(JSON.stringify({ ok: false, code: 'NO_IMAGE', message: '缺少图片' })); }
    if (!isUsableB64(front)) {
      res.writeHead(400, { 'Content-Type': 'application/json; charset=utf-8' });
      return res.end(JSON.stringify({ ok: false, code: 'INVALID_IMAGE_SIZE', message: '照片数据异常,请重试' }));
    }

    const fpJson = await callFacepp(front, left, right);

    if (fpJson.error_message) {
      const code = fpJson.error_message.split(':')[0];
      console.log(`[analyze] Face++ 错误: ${code}`);
      res.writeHead(200, { 'Content-Type': 'application/json; charset=utf-8' });
      return res.end(JSON.stringify({ ok: false, code, message: ERR_MSG[code] || '检测失败,请重试' }));
    }
    if (!fpJson.result) {
      res.writeHead(200, { 'Content-Type': 'application/json; charset=utf-8' });
      return res.end(JSON.stringify({ ok: false, code: 'INTERNAL_ERROR', message: ERR_MSG.INTERNAL_ERROR }));
    }
    const result = fpJson.result;
    // 原始返回完整落盘(含 face_maps base64),供复核/真值比对;写盘失败不影响检测响应
    try {
      fs.mkdirSync(DATA_DIR, { recursive: true });
      const reqId = String(fpJson.request_id || 'noreq').replace(/[^\w,-]/g, '').slice(0, 40);
      const stamp = new Date().toISOString().replace(/[:.]/g, '').slice(0, 15);
      const fname = `${stamp}-${reqId}.json`;
      fs.writeFile(path.join(DATA_DIR, fname), JSON.stringify(fpJson), () => {});
      console.log(`[analyze] 原始返回已落盘: data/results/${fname}`);
    } catch (e) { console.log(`[analyze] 落盘失败(忽略): ${e.message}`); }
    // face_maps 是整幅 base64 叠加图,体积很大:只透传报告页所需图层(REPORT_MAPS),
    // 值补 data: URL 前缀供前端 <img> 直接用;未选中的图层直接删除键;
    // marks 坐标字段(acne/brown_spot/mole/closed_comedones/wrinkle_mark 等)本就在 result 里,原样透传
    if (result.face_maps && typeof result.face_maps === 'object') {
      const maps = {};
      for (const k of REPORT_MAPS) {
        if (typeof result.face_maps[k] === 'string' && result.face_maps[k]) maps[k] = toDataUrl(result.face_maps[k]);
      }
      result.face_maps = maps;
    }
    // 下颌线结果在响应顶层 left_side_result/right_side_result(不在 result 内),
    // 个别批次可能嵌套在 side_result 下,两种层级都兼容
    const nested = fpJson.side_result || {};
    res.writeHead(200, { 'Content-Type': 'application/json; charset=utf-8' });
    res.end(JSON.stringify({
      ok: true,
      result,
      face_rectangle: fpJson.face_rectangle || null,
      side: {
        left: fpJson.left_side_result || nested.left_side_result || null,
        right: fpJson.right_side_result || nested.right_side_result || null
      }
    }));
  } catch (e) {
    const tooLarge = e.message === 'TOO_LARGE';
    const code = tooLarge ? 'IMAGE_FILE_TOO_LARGE' : 'NETWORK_ERROR';
    res.writeHead(200, { 'Content-Type': 'application/json; charset=utf-8' });
    // 响应发出后再销毁底层 socket:超大请求体客户端可能仍在推送,直接断开避免连接悬挂
    res.end(JSON.stringify({ ok: false, code, message: ERR_MSG[code] }), () => { if (tooLarge) req.destroy(); });
  }
}

http.createServer((req, res) => {
  if (req.method === 'POST' && req.url.split('?')[0] === '/api/skin-analyze') return handleAnalyze(req, res);
  if (req.method === 'GET' && req.url.split('?')[0] === '/api/health') {
    res.writeHead(200, { 'Content-Type': 'application/json' });
    return res.end(JSON.stringify({ ok: true }));
  }
  return serveStatic(req, res, req.url.split('?')[0]);
}).listen(PORT, '0.0.0.0', () => {
  console.log(`[server] 巨子测肤 H5 已启动: http://127.0.0.1:${PORT}  (静态 + /api/skin-analyze)`);
});