import express from 'express';
import fetch from 'node-fetch';
import { getConfig, getModelById, getEndpointByType } from './config.js';
import { logInfo, logDebug, logError, logRequest, logResponse } from './logger.js';
import { transformToAnthropic, getAnthropicHeaders } from './transformers/request-anthropic.js';
import { transformToOpenAI, getOpenAIHeaders } from './transformers/request-openai.js';
import { AnthropicResponseTransformer } from './transformers/response-anthropic.js';
import { OpenAIResponseTransformer } from './transformers/response-openai.js';
import { getApiKey } from './auth.js';

const router = express.Router();

router.get('/v1/models', (req, res) => {
  logInfo('GET /v1/models');
  
  try {
    const config = getConfig();
    const models = config.models.map(model => ({
      id: model.id,
      object: 'model',
      created: Date.now(),
      owned_by: model.type,
      permission: [],
      root: model.id,
      parent: null
    }));

    const response = {
      object: 'list',
      data: models
    };

    logResponse(200, null, response);
    res.json(response);
  } catch (error) {
    logError('Error in GET /v1/models', error);
    res.status(500).json({ error: 'Internal server error' });
  }
});

// 标准 OpenAI 聊天补全处理函数（带格式转换）
async function handleChatCompletions(req, res) {
  logInfo('POST /v1/chat/completions');
  
  try {
    const openaiRequest = req.body;
    const modelId = openaiRequest.model;

    if (!modelId) {
      return res.status(400).json({ error: 'model is required' });
    }

    const model = getModelById(modelId);
    if (!model) {
      return res.status(404).json({ error: `Model ${modelId} not found` });
    }

    const endpoint = getEndpointByType(model.type);
    if (!endpoint) {
      return res.status(500).json({ error: `Endpoint type ${model.type} not found` });
    }

    logInfo(`Routing to ${model.type} endpoint: ${endpoint.base_url}`);

    // Get API key (will auto-refresh if needed)
    let authHeader;
    try {
      authHeader = await getApiKey();
    } catch (error) {
      logError('Failed to get API key', error);
      return res.status(500).json({ 
        error: 'API key not available',
        message: 'Failed to get or refresh API key. Please check server logs.'
      });
    }

    let transformedRequest;
    let headers;
    const clientHeaders = req.headers;

    // Log received client headers for debugging
    logDebug('Client headers received', {
      'x-factory-client': clientHeaders['x-factory-client'],
      'x-session-id': clientHeaders['x-session-id'],
      'x-assistant-message-id': clientHeaders['x-assistant-message-id'],
      'user-agent': clientHeaders['user-agent']
    });

    if (model.type === 'anthropic') {
      transformedRequest = transformToAnthropic(openaiRequest);
      const isStreaming = openaiRequest.stream !== false;
      headers = getAnthropicHeaders(authHeader, clientHeaders, isStreaming);
    } else if (model.type === 'openai') {
      transformedRequest = transformToOpenAI(openaiRequest);
      headers = getOpenAIHeaders(authHeader, clientHeaders);
    } else {
      return res.status(500).json({ error: `Unknown endpoint type: ${model.type}` });
    }

    logRequest('POST', endpoint.base_url, headers, transformedRequest);

    const response = await fetch(endpoint.base_url, {
      method: 'POST',
      headers,
      body: JSON.stringify(transformedRequest)
    });

    logInfo(`Response status: ${response.status}`);

    if (!response.ok) {
      const errorText = await response.text();
      logError(`Endpoint error: ${response.status}`, new Error(errorText));
      return res.status(response.status).json({ 
        error: `Endpoint returned ${response.status}`,
        details: errorText 
      });
    }

    const isStreaming = transformedRequest.stream !== false;

    if (isStreaming) {
      res.setHeader('Content-Type', 'text/event-stream');
      res.setHeader('Cache-Control', 'no-cache');
      res.setHeader('Connection', 'keep-alive');

      let transformer;
      if (model.type === 'anthropic') {
        transformer = new AnthropicResponseTransformer(modelId, `chatcmpl-${Date.now()}`);
      } else if (model.type === 'openai') {
        transformer = new OpenAIResponseTransformer(modelId, `chatcmpl-${Date.now()}`);
      }

      try {
        for await (const chunk of transformer.transformStream(response.body)) {
          res.write(chunk);
        }
        res.end();
        logInfo('Stream completed');
      } catch (streamError) {
        logError('Stream error', streamError);
        res.end();
      }
    } else {
      const data = await response.json();
      logResponse(200, null, data);
      res.json(data);
    }

  } catch (error) {
    logError('Error in /v1/chat/completions', error);
    res.status(500).json({ 
      error: 'Internal server error',
      message: error.message 
    });
  }
}

// 直接转发 OpenAI 请求（不做格式转换）
async function handleDirectResponses(req, res) {
  logInfo('POST /v1/responses');
  
  try {
    const openaiRequest = req.body;
    const modelId = openaiRequest.model;

    if (!modelId) {
      return res.status(400).json({ error: 'model is required' });
    }

    const model = getModelById(modelId);
    if (!model) {
      return res.status(404).json({ error: `Model ${modelId} not found` });
    }

    // 只允许 openai 类型端点
    if (model.type !== 'openai') {
      return res.status(400).json({ 
        error: 'Invalid endpoint type',
        message: `/v1/responses 接口只支持 openai 类型端点，当前模型 ${modelId} 是 ${model.type} 类型`
      });
    }

    const endpoint = getEndpointByType(model.type);
    if (!endpoint) {
      return res.status(500).json({ error: `Endpoint type ${model.type} not found` });
    }

    logInfo(`Direct forwarding to ${model.type} endpoint: ${endpoint.base_url}`);

    // Get API key
    let authHeader;
    try {
      authHeader = await getApiKey();
    } catch (error) {
      logError('Failed to get API key', error);
      return res.status(500).json({ 
        error: 'API key not available',
        message: 'Failed to get or refresh API key. Please check server logs.'
      });
    }

    const clientHeaders = req.headers;
    
    // 获取 headers，但请求体不做任何转换
    const headers = getOpenAIHeaders(authHeader, clientHeaders);

    logRequest('POST', endpoint.base_url, headers, openaiRequest);

    // 直接转发原始请求
    const response = await fetch(endpoint.base_url, {
      method: 'POST',
      headers,
      body: JSON.stringify(openaiRequest)  // 不做任何转换，直接转发
    });

    logInfo(`Response status: ${response.status}`);

    if (!response.ok) {
      const errorText = await response.text();
      logError(`Endpoint error: ${response.status}`, new Error(errorText));
      return res.status(response.status).json({ 
        error: `Endpoint returned ${response.status}`,
        details: errorText 
      });
    }

    const isStreaming = openaiRequest.stream !== false;

    if (isStreaming) {
      // 直接转发流式响应，不做任何转换
      res.setHeader('Content-Type', 'text/event-stream');
      res.setHeader('Cache-Control', 'no-cache');
      res.setHeader('Connection', 'keep-alive');

      try {
        // 直接将原始响应流转发给客户端
        for await (const chunk of response.body) {
          res.write(chunk);
        }
        res.end();
        logInfo('Stream forwarded successfully');
      } catch (streamError) {
        logError('Stream error', streamError);
        res.end();
      }
    } else {
      // 直接转发非流式响应，不做任何转换
      const data = await response.json();
      logResponse(200, null, data);
      res.json(data);
    }

  } catch (error) {
    logError('Error in /v1/responses', error);
    res.status(500).json({ 
      error: 'Internal server error',
      message: error.message 
    });
  }
}

// 直接转发 Anthropic 请求（不做格式转换）
async function handleDirectMessages(req, res) {
  logInfo('POST /v1/messages');
  
  try {
    const anthropicRequest = req.body;
    const modelId = anthropicRequest.model;

    if (!modelId) {
      return res.status(400).json({ error: 'model is required' });
    }

    const model = getModelById(modelId);
    if (!model) {
      return res.status(404).json({ error: `Model ${modelId} not found` });
    }

    // 只允许 anthropic 类型端点
    if (model.type !== 'anthropic') {
      return res.status(400).json({ 
        error: 'Invalid endpoint type',
        message: `/v1/messages 接口只支持 anthropic 类型端点，当前模型 ${modelId} 是 ${model.type} 类型`
      });
    }

    const endpoint = getEndpointByType(model.type);
    if (!endpoint) {
      return res.status(500).json({ error: `Endpoint type ${model.type} not found` });
    }

    logInfo(`Direct forwarding to ${model.type} endpoint: ${endpoint.base_url}`);

    // Get API key
    let authHeader;
    try {
      authHeader = await getApiKey();
    } catch (error) {
      logError('Failed to get API key', error);
      return res.status(500).json({ 
        error: 'API key not available',
        message: 'Failed to get or refresh API key. Please check server logs.'
      });
    }

    const clientHeaders = req.headers;
    
    // 获取 headers，但请求体不做任何转换
    const isStreaming = anthropicRequest.stream !== false;
    const headers = getAnthropicHeaders(authHeader, clientHeaders, isStreaming);

    logRequest('POST', endpoint.base_url, headers, anthropicRequest);

    // 直接转发原始请求
    const response = await fetch(endpoint.base_url, {
      method: 'POST',
      headers,
      body: JSON.stringify(anthropicRequest)  // 不做任何转换，直接转发
    });

    logInfo(`Response status: ${response.status}`);

    if (!response.ok) {
      const errorText = await response.text();
      logError(`Endpoint error: ${response.status}`, new Error(errorText));
      return res.status(response.status).json({ 
        error: `Endpoint returned ${response.status}`,
        details: errorText 
      });
    }

    if (isStreaming) {
      // 直接转发流式响应，不做任何转换
      res.setHeader('Content-Type', 'text/event-stream');
      res.setHeader('Cache-Control', 'no-cache');
      res.setHeader('Connection', 'keep-alive');

      try {
        // 直接将原始响应流转发给客户端
        for await (const chunk of response.body) {
          res.write(chunk);
        }
        res.end();
        logInfo('Stream forwarded successfully');
      } catch (streamError) {
        logError('Stream error', streamError);
        res.end();
      }
    } else {
      // 直接转发非流式响应，不做任何转换
      const data = await response.json();
      logResponse(200, null, data);
      res.json(data);
    }

  } catch (error) {
    logError('Error in /v1/messages', error);
    res.status(500).json({ 
      error: 'Internal server error',
      message: error.message 
    });
  }
}

// 注册路由
router.post('/v1/chat/completions', handleChatCompletions);
router.post('/v1/responses', handleDirectResponses);
router.post('/v1/messages', handleDirectMessages);

export default router;