server.js

'use strict';
const express = require('express');
const axios = require('axios');
const cors = require('cors');
const path = require('path');

const app = express();
const PORT = process.env.PORT || 3000;

// Middlewares
app.use(cors());
app.use(express.json({ limit: '50mb' }));
app.use(express.urlencoded({ extended: true }));

// Serve static
app.use(express.static(path.join(__dirname, 'public')));

// Health
app.get('/health', (req, res) => {
  res.json({ status: 'ok' });
});

// Helper: extract API key
function extractApiKey(req) {
  const h = req.headers || {};
  let key = h['x-api-key'] || h['X-API-KEY'];
  if (!key && h.authorization) {
    const m = String(h.authorization).match(/Bearer\s+(.+)/i);
    if (m) key = m[1];
  }
  if (!key && req.body && req.body.apiKey) key = req.body.apiKey;
  return key;
}

// Helpers: sanitize/prune
function emptyToUndef(value) {
  if (value === '') return undefined;
  if (value === 'null') return undefined;
  if (Array.isArray(value)) return value.map(emptyToUndef);
  if (value && typeof value === 'object') {
    const out = {};
    for (const [k, v] of Object.entries(value)) out[k] = emptyToUndef(v);
    return out;
  }
  return value;
}
function pruneNullUndef(obj) {
  if (Array.isArray(obj)) {
    return obj.map(pruneNullUndef).filter((v) => v !== undefined && v !== null);
  }
  if (obj && typeof obj === 'object') {
    const out = {};
    for (const [k, v] of Object.entries(obj)) {
      const pv = pruneNullUndef(v);
      if (pv !== undefined && pv !== null && pv !== '') out[k] = pv;
    }
    return out;
  }
  return obj;
}
function prepareArgs(body) {
  const x = emptyToUndef({ ...body });
  delete x.apiKey;
  return pruneNullUndef(x);
}

// Detect image string type for logging/debug
function detectImageType(s) {
  if (!s) return 'empty';
  if (typeof s !== 'string') return typeof s;
  if (/^https?:\/\//i.test(s)) return 'url';
  if (/^data:image\//i.test(s)) return 'dataurl';
  // 粗略判断 base64
  if (/^[A-Za-z0-9+/=\s]+$/.test(s) && s.length > 512) return 'base64';
  return 'string';
}
function headSample(s, n = 48) {
  if (typeof s !== 'string') return '';
  return s.slice(0, n).replace(/\s+/g, ' ');
}
function stripDataUrl(dataUrl) {
  const i = String(dataUrl).indexOf(',');
  return i >= 0 ? dataUrl.slice(i + 1) : dataUrl;
}
// 将 dataURL 或含空白的 base64 规范化为纯标准 base64（无头、无换行）
function normalizeBase64(s) {
  if (typeof s !== 'string') return s;
  const cleaned = s
    .replace(/^data:image\/[a-zA-Z0-9.+-]+;base64,/, '')
    .replace(/\s+/g, '');
  try {
    const buf = Buffer.from(cleaned, 'base64');
    if (!buf || buf.length === 0) return cleaned;
    return buf.toString('base64'); // 标准化
  } catch {
    return cleaned;
  }
}
// 根据 base64 头部猜测 MIME（用于 dataURL 回退尝试）
function guessMimeFromBase64(b64) {
  if (typeof b64 !== 'string') return 'image/jpeg';
  const head = b64.slice(0, 10);
  if (head.startsWith('/9j/')) return 'image/jpeg';      // JPEG
  if (head.startsWith('iVBOR')) return 'image/png';      // PNG
  if (head.startsWith('R0lGOD')) return 'image/gif';     // GIF
  if (head.startsWith('UklGR')) return 'image/webp';     // WEBP
  return 'image/jpeg';
}

// Uniform upstream sender (handles JSON/ArrayBuffer)
function sendUpstreamResponse(res, upstream) {
  const status = upstream.status || 200;
  const ct = upstream.headers?.['content-type'] || upstream.headers?.['Content-Type'] || 'application/octet-stream';
  const data = upstream.data;

  if (ct.includes('application/json')) {
    try {
      const str = Buffer.isBuffer(data) ? data.toString('utf8')
        : (data instanceof ArrayBuffer ? Buffer.from(data).toString('utf8')
        : (typeof data === 'string' ? data : JSON.stringify(data)));
      const json = JSON.parse(str);
      return res.status(status).json(json);
    } catch {
      const text = Buffer.isBuffer(data) ? data.toString('utf8')
        : (data instanceof ArrayBuffer ? Buffer.from(data).toString('utf8')
        : String(data));
      res.status(status).set('Content-Type', 'application/json').send(text);
      return;
    }
  }

  const buf = Buffer.isBuffer(data) ? data
    : (data instanceof ArrayBuffer ? Buffer.from(data)
    : Buffer.from(String(data)));
  res.status(status).set('Content-Type', ct).send(buf);
}

function parseErrorResponse(errResp) {
  try {
    const ct = errResp.headers?.['content-type'] || '';
    if (!ct.includes('application/json')) return {};
    const str = Buffer.isBuffer(errResp.data)
      ? errResp.data.toString('utf8')
      : (errResp.data instanceof ArrayBuffer
          ? Buffer.from(errResp.data).toString('utf8')
          : String(errResp.data));
    return JSON.parse(str);
  } catch {
    return {};
  }
}

function upstreamError(err, res) {
  if (err.response) {
    const json = parseErrorResponse(err.response);
    const { status } = err.response;
    return res.status(status || 502).json({
      error: true,
      message: json?.message || json?.detail || 'Upstream error',
      upstream: json,
      status
    });
  } else if (err.request) {
    res.status(504).json({ error: true, message: 'No response from upstream' });
  } else {
    res.status(500).json({ error: true, message: err.message || 'Server error' });
  }
}

// Axios factory
function axPost(url, apiKey, body) {
  return axios.post(url, body, {
    headers: {
      Authorization: `Bearer ${apiKey}`,
      'Content-Type': 'application/json',
      Accept: '*/*'
    },
    timeout: 300000,
    responseType: 'arraybuffer',
    validateStatus: () => true,
    // 允许较大的 base64 图像负载
    maxContentLength: Infinity,
    maxBodyLength: Infinity
  });
}

// 在 public API 与内部 schema 差异不明确时，按顺序尝试两种载荷：plain 与 {args:...}
async function postVariants(url, apiKey, args) {
  const variants = [
    { label: 'plain', body: args },
    { label: 'args', body: { args } }
  ];
  let last = null;
  for (const v of variants) {
    console.log(`[postVariants] ${url} variant=${v.label}`);
    const resp = await axPost(url, apiKey, v.body);
    if (resp.status >= 200 && resp.status < 300) {
      return { ok: true, resp, variant: v.label };
    }
    const j = parseErrorResponse(resp);
    console.warn(`[postVariants] variant=${v.label} status=${resp.status} detail="${j?.detail || j?.message || ''}"`);
    last = resp;
  }
  return { ok: false, last };
}

// ========== WAN 2.2 ==========
// Strategy: 自动尝试两维度变体
// 1) 载荷包装形态：plain（直接传参）与 args（{ args: {...} }）
// 2) 图像编码：dataURL（data:image/...;base64,xxx）优先，失败回退为纯 base64（仅当 image 非 http(s) 时）
app.post('/api/wan22/generate', async (req, res) => {
  const apiKey = extractApiKey(req);
  if (!apiKey) return res.status(400).json({ error: true, message: 'Missing API key. Use header x-api-key or Authorization: Bearer <token>.' });

  // 严格按照 schema 组装 { I2VArgs }，并仅保留允许字段
  const raw = prepareArgs(req.body) || {};
  const allow = new Set([
    'fps', 'fast', 'seed', 'image', 'frames', 'prompt',
    'resolution', 'guidance_scale', 'negative_prompt', 'guidance_scale_2'
  ]);
  const args = {};
  for (const k of Object.keys(raw)) {
    if (allow.has(k)) args[k] = raw[k];
  }

  // 校验 prompt 与 image（必填）
  const prompt = typeof args.prompt === 'string' ? args.prompt.trim() : '';
  let image = typeof args.image === 'string' ? args.image.trim() : '';
  if (!prompt || prompt.length < 3) {
    return res.status(400).json({ error: true, message: 'Invalid prompt: must be string length >= 3' });
  }
  if (!image) {
    return res.status(400).json({ error: true, message: 'Invalid image: must be https URL or base64 string' });
  }

  // 若为 dataURL，剥离头得到纯 base64；若非 URL 则清空白
  if (/^data:image\/[a-zA-Z0-9.+-]+;base64,/.test(image)) {
    image = image.split(',')[1] || '';
  }
  if (!/^https?:\/\//i.test(image)) {
    image = image.replace(/\s+/g, '');
  }

  // 规范化其他字段（按 schema 取值范围裁剪）
  function clampInt(v, min, max) {
    if (v === undefined || v === null || v === '') return undefined;
    const n = parseInt(v, 10);
    if (!Number.isFinite(n)) return undefined;
    return Math.max(min, Math.min(max, n));
  }
  function clampNum(v, min, max) {
    if (v === undefined || v === null || v === '') return undefined;
    const n = Number(v);
    if (!Number.isFinite(n)) return undefined;
    return Math.max(min, Math.min(max, n));
  }
  function toBool(v) {
    if (typeof v === 'boolean') return v;
    if (v === 'true' || v === '1' || v === 1) return true;
    if (v === 'false' || v === '0' || v === 0) return false;
    return undefined;
  }

  const fps = clampInt(args.fps, 16, 24) ?? 16;
  const frames = clampInt(args.frames, 21, 140) ?? 81;
  const seed = args.seed === null ? null : clampInt(args.seed, -2147483648, 2147483647);
  const fast = toBool(args.fast);
  const guidance_scale = clampNum(args.guidance_scale, 0, 10) ?? 1;
  const guidance_scale_2 = clampNum(args.guidance_scale_2, 0, 10) ?? 1;
  const negative_prompt = typeof args.negative_prompt === 'string' ? args.negative_prompt : undefined;
  let resolution = (typeof args.resolution === 'string' ? args.resolution : '480p');
  if (resolution !== '480p' && resolution !== '720p') resolution = '480p';

  // 仅保留 schema 字段
  const finalArgs = {
    prompt,
    image,
    fps,
    frames,
    resolution,
    guidance_scale,
    guidance_scale_2
  };
  if (fast !== undefined) finalArgs.fast = fast;
  if (seed !== undefined) finalArgs.seed = seed;
  if (negative_prompt !== undefined) finalArgs.negative_prompt = negative_prompt;

  console.log('[WAN2.2] final args ->', {
    keys: Object.keys(finalArgs),
    promptLen: prompt.length,
    imageType: /^https?:\/\//i.test(image) ? 'url' : 'base64',
    imageHead: headSample(image)
  });

  try {
    const url = 'https://chutes-wan-2-2-i2v-14b-fast.chutes.ai/generate';
    const isHttpUrl = /^https?:\/\//i.test(image);

    async function tryWithWrapperVariants(a) {
      const pv = await postVariants(url, apiKey, a);
      console.log('[WAN2.2] tryWithWrapperVariants status=', pv.ok ? pv.resp.status : pv.last?.status, 'variant=', pv.ok ? pv.variant : 'last');
      return pv.ok ? pv.resp : pv.last;
    }

    let upstream;
    if (isHttpUrl) {
      // URL 直接两种包装形态
      upstream = await tryWithWrapperVariants(finalArgs);
    } else {
      // 非 URL：先 dataURL，再纯 base64；每一步都尝试两种包装形态
      const mime = guessMimeFromBase64(image);
      const asDataUrl = { ...finalArgs, image: `data:${mime};base64,${image}` };
      console.log('[WAN2.2] primary: image as dataURL + wrapper variants');
      upstream = await tryWithWrapperVariants(asDataUrl);

      if (!(upstream.status >= 200 && upstream.status < 300)) {
        console.warn('[WAN2.2] fallback: image as pure base64 + wrapper variants');
        upstream = await tryWithWrapperVariants(finalArgs);
      }
    }
    return sendUpstreamResponse(res, upstream);
  } catch (err) {
    return upstreamError(err, res);
  }
});

// ========== WAN 2.1 ==========
// text2video
app.post('/api/wan21/text2video', async (req, res) => {
  const apiKey = extractApiKey(req);
  if (!apiKey) return res.status(400).json({ error: true, message: 'Missing API key. Use header x-api-key or Authorization: Bearer <token>.' });

  // 按 schema 归一化/裁剪为 { args: VideoGenInput }
  const raw = prepareArgs(req.body) || {};
  const allow = new Set(['fps','seed','steps','frames','prompt','resolution','sample_shift','single_frame','guidance_scale','negative_prompt']);
  const clean = {};
  for (const k of Object.keys(raw)) if (allow.has(k)) clean[k] = raw[k];

  const prompt = typeof clean.prompt === 'string' ? clean.prompt.trim() : '';
  if (!prompt) return res.status(400).json({ error: true, message: 'Invalid prompt' });

  function clampInt(v, min, max) { if (v===undefined||v===null||v==='') return undefined; const n=parseInt(v,10); if(!Number.isFinite(n)) return undefined; return Math.max(min, Math.min(max, n)); }
  function clampNum(v, min, max) { if (v===undefined||v===null||v==='') return undefined; const n=Number(v); if(!Number.isFinite(n)) return undefined; return Math.max(min, Math.min(max, n)); }
  function toBool(v){ if(typeof v==='boolean') return v; if(v==='true'||v==='1'||v===1) return true; if(v==='false'||v==='0'||v===0) return false; return undefined; }

  const fps            = clampInt(clean.fps, 16, 60) ?? 16;
  const steps          = clampInt(clean.steps, 10, 30) ?? 25;
  let frames           = clean.frames === null ? null : (clampInt(clean.frames, 81, 241) ?? 81);
  // 确保frames符合4n+1格式（single_frame时为1）
  if (frames !== null && frames !== 1) {
    frames = frames - (frames % 4) + 1;
  }
  const seed           = clean.seed === null ? null : clampInt(clean.seed, -2147483648, 2147483647);
  const sample_shift   = clean.sample_shift === null ? null : clampNum(clean.sample_shift, 1, 7);
  const single_frame   = toBool(clean.single_frame);
  const guidance_scale = clean.guidance_scale === null ? null : clampNum(clean.guidance_scale, 1, 7.5) ?? 5;
  const negative_prompt= typeof clean.negative_prompt === 'string' ? clean.negative_prompt : undefined;

  let resolution = typeof clean.resolution === 'string' ? clean.resolution : undefined;
  const RES_ENUM = new Set(['1280*720','720*1280','832*480','480*832','1024*1024']);
  if (resolution && !RES_ENUM.has(resolution)) resolution = undefined; // 让上游走默认

  const finalArgs = { prompt, fps, steps };
  if (frames !== undefined) finalArgs.frames = frames;
  if (seed !== undefined) finalArgs.seed = seed;
  if (resolution !== undefined) finalArgs.resolution = resolution;
  if (sample_shift !== undefined) finalArgs.sample_shift = sample_shift;
  if (single_frame !== undefined) finalArgs.single_frame = single_frame;
  if (guidance_scale !== undefined) finalArgs.guidance_scale = guidance_scale;
  if (negative_prompt !== undefined) finalArgs.negative_prompt = negative_prompt;

  console.log('[WAN2.1 text2video] final args ->', { keys:Object.keys(finalArgs), promptLen:prompt.length, frames, resolution: finalArgs.resolution || '(default)' });

  try {
    const url = 'https://chutes-wan2-1-14b.chutes.ai/text2video';
    // WAN2.1：同时尝试 plain 与 {args:...} 载荷，提升兼容性
    const pv = await postVariants(url, apiKey, finalArgs);
    const upstream = pv.ok ? pv.resp : pv.last;
    return sendUpstreamResponse(res, upstream);
  } catch (err) {
    return upstreamError(err, res);
  }
});
// 强制尝试接口：允许通过 query 指定 img 编码与载荷变体，便于定位上游参数期望
// 用法示例：POST /api/wan22/generate_force?img=normalized&amp;variant=args
// img ∈ { normalized | dataurl | raw }，variant ∈ { plain | args | (省略=自动两种都试) }
app.post('/api/wan22/generate_force', async (req, res) => {
  const apiKey = extractApiKey(req);
  if (!apiKey) return res.status(400).json({ error: true, message: 'Missing API key. Use header x-api-key or Authorization: Bearer &lt;token&gt;.' });

  const argsRaw = prepareArgs(req.body);
  const imageRaw = argsRaw.image;
  const imgType = detectImageType(imageRaw);
  const isUrl = imgType === 'url';
  let imageNorm = imageRaw;
  if (!isUrl && typeof imageRaw === 'string') {
    imageNorm = normalizeBase64(imageRaw);
  }
  const mime = guessMimeFromBase64(typeof imageNorm === 'string' ? imageNorm : '');
  const dataUrl = typeof imageNorm === 'string' ? `data:${mime};base64,${imageNorm}` : imageNorm;

  const imgSel = (req.query.img || 'normalized').toString();
  let argsSel;
  if (imgSel === 'raw') {
    argsSel = { ...argsRaw, image: imageRaw };
  } else if (imgSel === 'dataurl') {
    argsSel = { ...argsRaw, image: dataUrl };
  } else {
    // normalized
    argsSel = { ...argsRaw, image: isUrl ? imageRaw : imageNorm };
  }

  const variant = req.query.variant ? req.query.variant.toString() : '';
  const url = 'https://chutes-wan-2-2-i2v-14b-fast.chutes.ai/generate';

  try {
    console.log(`[WAN2.2 force] img=${imgSel} variant=${variant || 'auto'} imageHead="${headSample(argsSel.image)}"`);

    if (variant === 'plain') {
      const r = await axPost(url, apiKey, argsSel);
      return sendUpstreamResponse(res, r);
    }
    if (variant === 'args') {
      const r = await axPost(url, apiKey, { args: argsSel });
      return sendUpstreamResponse(res, r);
    }

    // 自动尝试两种载荷
    const pv = await postVariants(url, apiKey, argsSel);
    if (pv.ok) return sendUpstreamResponse(res, pv.resp);
    return sendUpstreamResponse(res, pv.last);
  } catch (err) {
    return upstreamError(err, res);
  }
});
 
// image2video
app.post('/api/wan21/image2video', async (req, res) => {
  const apiKey = extractApiKey(req);
  if (!apiKey) return res.status(400).json({ error: true, message: 'Missing API key. Use header x-api-key or Authorization: Bearer <token>.' });

  // 按 schema 归一化/裁剪为 { args: I2VInput }
  const raw = prepareArgs(req.body) || {};
  const allow = new Set(['fps','seed','steps','frames','prompt','image_b64','image_url','sample_shift','single_frame','guidance_scale','negative_prompt']);
  const clean = {};
  for (const k of Object.keys(raw)) if (allow.has(k)) clean[k] = raw[k];

  const prompt = typeof clean.prompt === 'string' ? clean.prompt.trim() : '';
  if (!prompt) return res.status(400).json({ error: true, message: 'Invalid prompt' });

  // image_b64 必填；允许从 image_url 下载转换为 base64 兜底
  let image_b64 = typeof clean.image_b64 === 'string' ? clean.image_b64.trim() : '';
  if (!image_b64 && typeof clean.image_url === 'string' && clean.image_url.trim()) {
    try {
      const imgResp = await axios.get(clean.image_url.trim(), { responseType: 'arraybuffer', timeout: 60000, validateStatus: () => true });
      if (imgResp.status >= 200 && imgResp.status < 300 && imgResp.data) {
        const buf = Buffer.isBuffer(imgResp.data)
          ? imgResp.data
          : (imgResp.data instanceof ArrayBuffer ? Buffer.from(imgResp.data) : Buffer.from(String(imgResp.data)));
        image_b64 = buf.toString('base64');
      } else {
        console.warn('[WAN2.1 image2video] fetch image_url failed status=', imgResp.status);
      }
    } catch (e) {
      console.warn('[WAN2.1 image2video] fetch image_url error:', e?.message || e);
    }
  }
  if (!image_b64) return res.status(400).json({ error: true, message: 'image_b64 is required (upload image or provide image_url)' });
  if (/^data:image\/[a-zA-Z0-9.+-]+;base64,/.test(image_b64)) image_b64 = image_b64.split(',')[1] || '';
  image_b64 = image_b64.replace(/\s+/g, '');

  function clampInt(v, min, max) { if (v===undefined||v===null||v==='') return undefined; const n=parseInt(v,10); if(!Number.isFinite(n)) return undefined; return Math.max(min, Math.min(max, n)); }
  function clampNum(v, min, max) { if (v===undefined||v===null||v==='') return undefined; const n=Number(v); if(!Number.isFinite(n)) return undefined; return Math.max(min, Math.min(max, n)); }
  function toBool(v){ if(typeof v==='boolean') return v; if(v==='true'||v==='1'||v===1) return true; if(v==='false'||v==='0'||v===0) return false; return undefined; }

  const fps            = clampInt(clean.fps, 16, 60) ?? 24;
  const steps          = clampInt(clean.steps, 20, 50) ?? 25;
  // API硬编码frames为81，忽略用户输入
  const frames         = 81;
  const seed           = clean.seed === null ? null : clampInt(clean.seed, -2147483648, 2147483647);
  const sample_shift   = clean.sample_shift === null ? null : clampNum(clean.sample_shift, 1, 7);
  const single_frame   = toBool(clean.single_frame);
  const guidance_scale = clean.guidance_scale === null ? null : clampNum(clean.guidance_scale, 1, 7.5) ?? 5;
  const negative_prompt= typeof clean.negative_prompt === 'string' ? clean.negative_prompt : undefined;

  const finalArgs = { prompt, image_b64, fps, steps };
  if (frames !== undefined) finalArgs.frames = frames;
  if (seed !== undefined) finalArgs.seed = seed;
  if (sample_shift !== undefined) finalArgs.sample_shift = sample_shift;
  if (single_frame !== undefined) finalArgs.single_frame = single_frame;
  if (guidance_scale !== undefined) finalArgs.guidance_scale = guidance_scale;
  if (negative_prompt !== undefined) finalArgs.negative_prompt = negative_prompt;

  console.log('[WAN2.1 image2video] final args ->', { keys:Object.keys(finalArgs), promptLen:prompt.length, b64Len:image_b64.length, b64Head: headSample(image_b64) });

  try {
    const url = 'https://chutes-wan2-1-14b.chutes.ai/image2video';
    // WAN2.1：同时尝试 plain 与 {args:...} 载荷，提升兼容性
    const pv = await postVariants(url, apiKey, finalArgs);
    const upstream = pv.ok ? pv.resp : pv.last;
    return sendUpstreamResponse(res, upstream);
  } catch (err) {
    return upstreamError(err, res);
  }
});

// text2image
app.post('/api/wan21/text2image', async (req, res) => {
  const apiKey = extractApiKey(req);
  if (!apiKey) return res.status(400).json({ error: true, message: 'Missing API key. Use header x-api-key or Authorization: Bearer <token>.' });

  // 按 schema 归一化/裁剪为 { args: ImageGenInput }
  const raw = prepareArgs(req.body) || {};
  const allow = new Set(['seed','prompt','resolution','sample_shift','guidance_scale','negative_prompt']);
  const clean = {};
  for (const k of Object.keys(raw)) if (allow.has(k)) clean[k] = raw[k];

  const prompt = typeof clean.prompt === 'string' ? clean.prompt.trim() : '';
  if (!prompt) return res.status(400).json({ error: true, message: 'Invalid prompt' });

  function clampInt(v, min, max) { if (v===undefined||v===null||v==='') return undefined; const n=parseInt(v,10); if(!Number.isFinite(n)) return undefined; return Math.max(min, Math.min(max, n)); }
  function clampNum(v, min, max) { if (v===undefined||v===null||v==='') return undefined; const n=Number(v); if(!Number.isFinite(n)) return undefined; return Math.max(min, Math.min(max, n)); }

  let resolution = typeof clean.resolution === 'string' ? clean.resolution : undefined;
  const RES_ENUM = new Set(['1280*720','720*1280','832*480','480*832','1024*1024']);
  if (resolution && !RES_ENUM.has(resolution)) resolution = undefined; // 让上游默认

  const seed           = clean.seed === null ? null : clampInt(clean.seed, -2147483648, 2147483647);
  const sample_shift   = clean.sample_shift === null ? null : clampNum(clean.sample_shift, 1, 7);
  const guidance_scale = clean.guidance_scale === null ? null : clampNum(clean.guidance_scale, 1, 7.5) ?? 5;
  const negative_prompt= typeof clean.negative_prompt === 'string' ? clean.negative_prompt : undefined;

  const finalArgs = { prompt };
  if (seed !== undefined) finalArgs.seed = seed;
  if (resolution !== undefined) finalArgs.resolution = resolution;
  if (sample_shift !== undefined) finalArgs.sample_shift = sample_shift;
  if (guidance_scale !== undefined) finalArgs.guidance_scale = guidance_scale;
  if (negative_prompt !== undefined) finalArgs.negative_prompt = negative_prompt;

  console.log('[WAN2.1 text2image] final args ->', { keys:Object.keys(finalArgs), promptLen:prompt.length, resolution: finalArgs.resolution || '(default)' });

  try {
    const url = 'https://chutes-wan2-1-14b.chutes.ai/text2image';
    // WAN2.1：同时尝试 plain 与 {args:...} 载荷，提升兼容性
    const pv = await postVariants(url, apiKey, finalArgs);
    const upstream = pv.ok ? pv.resp : pv.last;
    return sendUpstreamResponse(res, upstream);
  } catch (err) {
    return upstreamError(err, res);
  }
});

// Fallback to index.html
app.get('*', (req, res) => {
  res.sendFile(path.join(__dirname, 'public', 'index.html'));
});

app.listen(PORT, () => {
  console.log(`Server running on http://localhost:${PORT}`);
});