const express = require('express');
const cors = require('cors');
const multer = require('multer');
const path = require('path');
const fs = require('fs');
const https = require('https');
const http = require('http');
require('dotenv').config();

const app = express();
const PORT = process.env.PORT || 7860;

// 中间件配置
app.use(cors());
app.use(express.json({ limit: '50mb' }));
app.use(express.urlencoded({ extended: true, limit: '50mb' }));
app.use(express.static(path.join(__dirname, 'public')));

// API key 存储文件路径
const API_KEY_FILE = path.join(__dirname, 'stored_api_key.json');

// 视频存储目录
const VIDEO_DIR = path.join(__dirname, 'video');

// 文件上传配置
const storage = multer.diskStorage({
  destination: (req, file, cb) => {
    const uploadDir = path.join(__dirname, 'uploads');
    if (!fs.existsSync(uploadDir)) {
      fs.mkdirSync(uploadDir, { recursive: true });
    }
    cb(null, uploadDir);
  },
  filename: (req, file, cb) => {
    cb(null, Date.now() + '-' + file.originalname);
  }
});

const upload = multer({ 
  storage: storage,
  limits: { fileSize: 50 * 1024 * 1024 }
});

// 读取存储的 API key
function getStoredApiKey() {
  try {
    if (fs.existsSync(API_KEY_FILE)) {
      const data = fs.readFileSync(API_KEY_FILE, 'utf8');
      const parsed = JSON.parse(data);
      return parsed.apiKey || null;
    }
  } catch (error) {
    console.log('读取存储的 API key 失败:', error.message);
  }
  return null;
}

// 保存 API key
function saveApiKey(apiKey) {
  try {
    const data = { apiKey, savedAt: new Date().toISOString() };
    fs.writeFileSync(API_KEY_FILE, JSON.stringify(data, null, 2));
    return true;
  } catch (error) {
    console.error('保存 API key 失败:', error);
    return false;
  }
}

// 获取有效的 API key
function getValidApiKey(userApiKey = null) {
  // 优先级：用户提供的 > 环境变量 > 存储的
  return userApiKey || process.env.FAL_KEY || getStoredApiKey();
}

// 下载并保存视频文件
function downloadVideo(videoUrl, filename) {
  return new Promise((resolve, reject) => {
    // 确保视频目录存在
    if (!fs.existsSync(VIDEO_DIR)) {
      fs.mkdirSync(VIDEO_DIR, { recursive: true });
    }
    
    const filepath = path.join(VIDEO_DIR, filename);
    const file = fs.createWriteStream(filepath);
    
    const protocol = videoUrl.startsWith('https:') ? https : http;
    
    protocol.get(videoUrl, (response) => {
      if (response.statusCode !== 200) {
        reject(new Error(`下载失败，状态码: ${response.statusCode}`));
        return;
      }
      
      response.pipe(file);
      
      file.on('finish', () => {
        file.close();
        console.log(`视频已保存到: ${filepath}`);
        resolve(filepath);
      });
      
      file.on('error', (err) => {
        fs.unlink(filepath, () => {}); // 删除不完整的文件
        reject(err);
      });
    }).on('error', (err) => {
      reject(err);
    });
  });
}

// 生成唯一的文件名
function generateVideoFilename(type = 'video') {
  const timestamp = new Date().toISOString().replace(/[:.]/g, '-');
  return `${type}-${timestamp}.mp4`;
}

// FAL AI 客户端初始化
let fal;
try {
  fal = require('@fal-ai/client');
  // 如果是对象形式的导入，尝试获取 fal 属性
  if (fal && typeof fal === 'object' && fal.fal) {
    fal = fal.fal;
  }
} catch (error) {
  console.error('FAL AI 客户端初始化失败:', error);
}

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

// API key 管理接口
app.post('/api/save-key', (req, res) => {
  const { apiKey } = req.body;
  
  if (!apiKey || !apiKey.trim()) {
    return res.status(400).json({ error: 'API key 不能为空' });
  }
  
  if (saveApiKey(apiKey.trim())) {
    res.json({ success: true, message: 'API key 保存成功' });
  } else {
    res.status(500).json({ error: 'API key 保存失败' });
  }
});

app.get('/api/check-key', (req, res) => {
  const storedKey = getStoredApiKey();
  const hasEnvKey = !!process.env.FAL_KEY;
  
  res.json({
    hasStoredKey: !!storedKey,
    hasEnvKey: hasEnvKey,
    keySource: hasEnvKey ? 'environment' : (storedKey ? 'stored' : 'none')
  });
});

// 图片到视频生成 API（支持模型切换：WAN v2.2-a14b 与 Bytedance Seedance 1.0 Pro Fast）
app.post('/api/image-to-video', upload.single('image'), async (req, res) => {
  try {
    const userApiKey = req.body.userApiKey;
    const apiKey = getValidApiKey(userApiKey);
    
    if (!apiKey) {
      return res.status(400).json({ error: '请提供 FAL AI API 密钥' });
    }

    const prompt = req.body.prompt;
    if (!prompt) {
      return res.status(400).json({ error: '请提供文本提示' });
    }

    // 解析图片输入（文件或 URL）
    let image_url;
    if (req.file) {
      const file = fs.readFileSync(req.file.path);
      const blob = new Blob([file], { type: req.file.mimetype });
      image_url = await fal.storage.upload(blob);
    } else if (req.body.image_url) {
      image_url = req.body.image_url;
    } else {
      return res.status(400).json({ error: '请提供图片文件或图片URL' });
    }

    // 模型选择：默认 WAN，支持 seedance-pro-fast
    const model = req.body.model || 'wan-v2.2-a14b';

    // 设置临时环境变量
    const originalFalKey = process.env.FAL_KEY;
    process.env.FAL_KEY = apiKey;

    let result;
    
    if (model === 'seedance-pro-fast') {
      // Bytedance Seedance 1.0 Pro Fast 入参映射
      const {
        aspect_ratio = 'auto',
        resolution = '1080p',
        duration = '5',
        camera_fixed = false,
        seed = -1,
        enable_safety_checker = true,
      } = req.body;

      result = await fal.subscribe("fal-ai/bytedance/seedance/v1/pro/fast/image-to-video", {
        input: {
          prompt,
          image_url,
          aspect_ratio,
          resolution,
          duration,
          camera_fixed: typeof camera_fixed === 'string' ? camera_fixed === 'true' : !!camera_fixed,
          seed: parseInt(seed, 10),
          enable_safety_checker: typeof enable_safety_checker === 'string' ? enable_safety_checker === 'true' : !!enable_safety_checker,
        },
        logs: true,
        onQueueUpdate: (update) => {
          if (update.status === "IN_PROGRESS") {
            console.log('生成进度(Seedance I2V):', update.logs?.map(log => log.message).join('\n'));
          }
        },
      });
    } else {
      // WAN v2.2-a14b 入参映射（保持原逻辑）
      const {
        negative_prompt = "",
        num_frames = 81,
        frames_per_second = 16,
        resolution = "720p",
        aspect_ratio = "auto",
        video_quality = "high",
        enable_safety_checker = "true"
      } = req.body;

      result = await fal.subscribe("fal-ai/wan/v2.2-a14b/image-to-video", {
        input: {
          image_url,
          prompt,
          negative_prompt,
          num_frames: parseInt(num_frames),
          frames_per_second: parseInt(frames_per_second),
          resolution,
          aspect_ratio,
          video_quality,
          num_inference_steps: 27,
          enable_safety_checker: enable_safety_checker === "true",
          acceleration: "regular",
          guidance_scale: 3.5,
          shift: 5
        },
        logs: true,
        onQueueUpdate: (update) => {
          if (update.status === "IN_PROGRESS") {
            console.log('生成进度(WAN I2V):', update.logs?.map(log => log.message).join('\n'));
          }
        },
      });
    }
    
    // 恢复原始环境变量
    if (originalFalKey) {
      process.env.FAL_KEY = originalFalKey;
    }

    // 下载并保存视频到本地
    let localVideoPath = null;
    if (result.data && result.data.video && result.data.video.url) {
      try {
        const filename = generateVideoFilename('image-to-video');
        localVideoPath = await downloadVideo(result.data.video.url, filename);
        console.log(`图片转视频完成，已保存到: ${localVideoPath}`);
      } catch (downloadError) {
        console.error('视频下载失败:', downloadError);
        // 不影响主要功能，继续返回结果
      }
    }

    if (req.file && fs.existsSync(req.file.path)) {
      fs.unlinkSync(req.file.path);
    }

    res.json({
      success: true,
      data: {
        ...result.data,
        localPath: localVideoPath ? path.relative(__dirname, localVideoPath) : null
      },
      requestId: result.requestId
    });

  } catch (error) {
    console.error('视频生成错误:', error);
    
    if (req.file && fs.existsSync(req.file.path)) {
      fs.unlinkSync(req.file.path);
    }
    
    res.status(500).json({
      success: false,
      error: error.message || '视频生成失败'
    });
  }
});

// 文本到视频生成 API（支持模型切换：WAN v2.2-a14b 与 Bytedance Seedance 1.0 Pro Fast）
app.post('/api/text-to-video', async (req, res) => {
  try {
    const userApiKey = req.body.userApiKey;
    const apiKey = getValidApiKey(userApiKey);
    
    if (!apiKey) {
      return res.status(400).json({ error: '请提供 FAL AI API 密钥' });
    }

    const prompt = req.body.prompt;
    if (!prompt) {
      return res.status(400).json({ error: '请提供文本提示' });
    }

    // 模型选择：默认 WAN，支持 seedance-pro-fast
    const model = req.body.model || 'wan-v2.2-a14b';

    // 设置临时环境变量
    const originalFalKey = process.env.FAL_KEY;
    process.env.FAL_KEY = apiKey;

    let result;
    
    if (model === 'seedance-pro-fast') {
      // Bytedance Seedance 1.0 Pro Fast 入参映射
      const {
        aspect_ratio = '16:9',
        resolution = '1080p',
        duration = '5',
        camera_fixed = false,
        seed = -1,
        enable_safety_checker = true,
      } = req.body;

      result = await fal.subscribe("fal-ai/bytedance/seedance/v1/pro/fast/text-to-video", {
        input: {
          prompt,
          aspect_ratio,
          resolution,
          duration,
          camera_fixed: !!camera_fixed,
          seed: parseInt(seed, 10),
          enable_safety_checker: !!enable_safety_checker,
        },
        logs: true,
        onQueueUpdate: (update) => {
          if (update.status === "IN_PROGRESS") {
            console.log('生成进度(Seedance):', update.logs?.map(log => log.message).join('\n'));
          }
        },
      });
    } else {
      // WAN v2.2-a14b 入参映射（保持原逻辑）
      const {
        negative_prompt = "",
        num_frames = 81,
        frames_per_second = 16,
        resolution = "720p",
        aspect_ratio = "16:9",
        video_quality = "high",
        enable_safety_checker = true
      } = req.body;

      result = await fal.subscribe("fal-ai/wan/v2.2-a14b/text-to-video", {
        input: {
          prompt,
          negative_prompt,
          num_frames: parseInt(num_frames),
          frames_per_second: parseInt(frames_per_second),
          resolution,
          aspect_ratio,
          video_quality,
          num_inference_steps: 27,
          enable_safety_checker: enable_safety_checker,
          acceleration: "regular",
          guidance_scale: 3.5,
          shift: 5
        },
        logs: true,
        onQueueUpdate: (update) => {
          if (update.status === "IN_PROGRESS") {
            console.log('生成进度(WAN):', update.logs?.map(log => log.message).join('\n'));
          }
        },
      });
    }
    
    // 恢复原始环境变量
    if (originalFalKey) {
      process.env.FAL_KEY = originalFalKey;
    }

    // 下载并保存视频到本地
    let localVideoPath = null;
    if (result.data && result.data.video && result.data.video.url) {
      try {
        const filename = generateVideoFilename('text-to-video');
        localVideoPath = await downloadVideo(result.data.video.url, filename);
        console.log(`文本转视频完成，已保存到: ${localVideoPath}`);
      } catch (downloadError) {
        console.error('视频下载失败:', downloadError);
        // 不影响主要功能，继续返回结果
      }
    }

    res.json({
      success: true,
      data: {
        ...result.data,
        localPath: localVideoPath ? path.relative(__dirname, localVideoPath) : null
      },
      requestId: result.requestId
    });

  } catch (error) {
    console.error('视频生成错误:', error);
    res.status(500).json({
      success: false,
      error: error.message || '视频生成失败'
    });
  }
});

// 获取本地视频列表
app.get('/api/videos', (req, res) => {
  try {
    if (!fs.existsSync(VIDEO_DIR)) {
      return res.json({ videos: [] });
    }
    
    const files = fs.readdirSync(VIDEO_DIR)
      .filter(file => file.endsWith('.mp4'))
      .map(file => {
        const filepath = path.join(VIDEO_DIR, file);
        const stats = fs.statSync(filepath);
        return {
          filename: file,
          path: path.join('video', file),
          size: stats.size,
          created: stats.birthtime,
          modified: stats.mtime
        };
      })
      .sort((a, b) => new Date(b.created) - new Date(a.created)); // 按创建时间倒序
    
    res.json({ videos: files });
  } catch (error) {
    console.error('获取视频列表失败:', error);
    res.status(500).json({ error: '获取视频列表失败' });
  }
});

// 提供视频文件访问
app.use('/video', express.static(path.join(__dirname, 'video')));

// 测试 API 密钥连接（使用免费的健康检查端点）
app.post('/api/test-key', async (req, res) => {
  try {
    const { apiKey } = req.body;
    const testKey = apiKey || getValidApiKey();
    
    if (!testKey) {
      return res.status(400).json({ 
        error: 'API 密钥未提供',
        success: false
      });
    }
    
    // 使用 FAL AI 的免费健康检查端点测试连接
    const https = require('https');
    
    const testPromise = new Promise((resolve, reject) => {
      // 使用 FAL AI 的状态检查端点（不消耗配额）
      const options = {
        hostname: 'fal.run',
        port: 443,
        path: '/status',
        method: 'GET',
        headers: {
          'Authorization': `Key ${testKey}`,
          'User-Agent': 'FAL-Video-Generator/1.0'
        },
        timeout: 5000
      };
      
      const req = https.request(options, (res) => {
        let data = '';
        res.on('data', (chunk) => data += chunk);
        res.on('end', () => {
          if (res.statusCode === 401) {
            reject(new Error('Unauthorized - API 密钥无效'));
          } else if (res.statusCode === 403) {
            reject(new Error('Forbidden - API 密钥被禁用'));
          } else if (res.statusCode === 429) {
            reject(new Error('Rate Limited - 请求过于频繁'));
          } else if (res.statusCode >= 200 && res.statusCode < 300) {
            resolve({ statusCode: res.statusCode, data });
          } else {
            // 其他状态码，但至少证明密钥被识别了
            resolve({ statusCode: res.statusCode, data });
          }
        });
      });
      
      req.on('error', (err) => {
        if (err.code === 'ENOTFOUND') {
          reject(new Error('Network - 无法连接到 FAL AI 服务器'));
        } else if (err.code === 'ECONNREFUSED') {
          reject(new Error('Connection - 连接被拒绝'));
        } else {
          reject(new Error(`Network - ${err.message}`));
        }
      });
      
      req.on('timeout', () => {
        req.destroy();
        reject(new Error('Timeout - 连接超时'));
      });
      
      req.end();
    });
    
    try {
      const result = await testPromise;
      
      res.json({ 
        success: true, 
        message: '✅ 连接成功！API 密钥有效',
        keyFormat: testKey.substring(0, 8) + '...' + testKey.substring(testKey.length - 4),
        statusCode: result.statusCode,
        note: '🆓 使用免费健康检查端点，不消耗配额'
      });
      
    } catch (testError) {
      let errorMessage = '❌ 连接测试失败';
      let errorType = 'error';
      
      if (testError.message.includes('Unauthorized')) {
        errorMessage = '❌ API 密钥无效或已过期';
        errorType = 'auth';
      } else if (testError.message.includes('Forbidden')) {
        errorMessage = '❌ API 密钥被禁用';
        errorType = 'auth';
      } else if (testError.message.includes('Rate Limited')) {
        errorMessage = '⚠️ 请求过于频繁，请稍后重试';
        errorType = 'rate';
      } else if (testError.message.includes('Network')) {
        errorMessage = '🌐 网络连接问题';
        errorType = 'network';
      } else if (testError.message.includes('Timeout')) {
        errorMessage = '⏱️ 连接超时，请重试';
        errorType = 'timeout';
      }
      
      res.status(errorType === 'auth' ? 401 : 500).json({ 
        success: false,
        error: errorMessage,
        errorType: errorType,
        details: testError.message
      });
    }
    
  } catch (error) {
    console.error('API 密钥连接测试失败:', error);
    res.status(500).json({ 
      success: false,
      error: '测试过程中发生错误',
      details: error.message
    });
  }
});

app.get('/api/health', (req, res) => {
  const apiKey = getValidApiKey();
  res.json({ 
    status: 'healthy', 
    timestamp: new Date().toISOString(),
    hasApiKey: !!apiKey,
    keyPreview: apiKey ? apiKey.substring(0, 8) + '...' : null
  });
});

app.listen(PORT, '0.0.0.0', () => {
  console.log(`服务器运行在端口 ${PORT}`);
  const apiKey = getValidApiKey();
  console.log(`API Key 状态: ${apiKey ? '已配置' : '未配置'}`);
});

module.exports = app;