const express = require('express');
const fetch = require('node-fetch');
const crypto = require('crypto');

const app = express();
const port = 8000;

const NOTDIAMOND_URL = 'https://chat.notdiamond.ai/mini-chat';
const NOTDIAMOND_HEADERS = {
  'Content-Type': 'application/json',
  'next-action': '8189eb37107121e024940f588629a394a594e6a4'
};
const AUTH_KEY = process.env.AUTH_KEY;

const DEFAULT_MODEL = 'gpt-4-turbo-2024-04-09';

function createOpenAIChunk(content, model, finishReason = null) {
  return {
    id: `chatcmpl-${crypto.randomUUID()}`,
    object: "chat.completion.chunk",
    created: Math.floor(Date.now() / 1000),
    model: model,
    system_fingerprint: "fp_4e2b2da518",
    choices: [
      {
        index: 0,
        delta: content ? { content: content } : {},
        logprobs: null,
        finish_reason: finishReason
      }
    ],
    usage: null
  };
}

async function* streamNotdiamondResponse(response, model) {
  const reader = response.body.getReader();
  const decoder = new TextDecoder();
  let buffer = "";
  let lastContent = "";

  function processDollars(str) {
    return str.replace(/\${2,}/, match => match.slice(1));
  }

  while (true) {
    const { done, value } = await reader.read();
    if (done) break;

    buffer += decoder.decode(value, { stream: true });
    let lines = buffer.split('\n');
    buffer = lines.pop() || "";

    for (const line of lines) {
      if (line.trim() === '') continue;
      
      try {
        const jsonMatch = line.match(/\{.*\}/);
        if (jsonMatch) {
          const data = JSON.parse(jsonMatch[0]);
          let content = '';
          
          if (data.output?.curr !== undefined) {
            content = processDollars(data.output.curr);
            lastContent = content;
          } else if (data.curr !== undefined) {
            content = processDollars(data.curr);
            lastContent = content;
          } else if (data.diff !== undefined && Array.isArray(data.diff) && data.diff.length > 1) {
            const newContent = processDollars(data.diff[1]);
            content = lastContent + newContent;
            lastContent = content;
          } else if (data.diff !== undefined && Array.isArray(data.diff) && data.diff.length === 1) {
            content = lastContent;  // If diff is empty, use the last content
          }
          
          if (content) {
            yield createOpenAIChunk(content, model);
          }
        }
      } catch (error) {
        console.error('Error processing line:', error, 'Raw line:', line);
      }
    }
  }

  if (buffer.trim()) {
    try {
      const jsonMatch = buffer.match(/\{.*\}/);
      if (jsonMatch) {
        const data = JSON.parse(jsonMatch[0]);
        let content = '';
        if (data.output?.curr !== undefined) {
          content = processDollars(data.output.curr);
        } else if (data.curr !== undefined) {
          content = processDollars(data.curr);
        } else if (data.diff !== undefined && Array.isArray(data.diff) && data.diff.length > 1) {
          const newContent = processDollars(data.diff[1]);
          content = lastContent + newContent;
        } else if (data.diff !== undefined && Array.isArray(data.diff) && data.diff.length === 1) {
          content = lastContent;
        }
        if (content) {
          yield createOpenAIChunk(content, model);
        }
      }
    } catch (error) {
      console.error('Error processing final buffer:', error);
    }
  }

  yield createOpenAIChunk('', model, 'stop');
}

app.use(express.json());

app.post('/ai/v1/chat/completions', async (req, res) => {
  const authHeader = req.headers['authorization'];
  if (!authHeader || !authHeader.startsWith('Bearer ') || authHeader.slice(7) !== AUTH_KEY) {
    return res.status(401).json({ error: 'Unauthorized' });
  }

  try {
    let requestData = req.body;

    let messages = requestData.messages;
    let model = requestData.model || DEFAULT_MODEL;
    const stream = requestData.stream || false;

    if (!messages || !Array.isArray(messages)) {
      return res.status(400).json({ 
        error: 'Invalid request body', 
        details: 'messages should be an array of message objects',
        receivedBody: req.body
      });
    }

    const payload = {
      messages: messages,
      model: model,
      stream: stream,
      frequency_penalty: requestData.frequency_penalty || 0,
      presence_penalty: requestData.presence_penalty || 0,
      temperature: requestData.temperature || 0.6,
      top_p: requestData.top_p || 1
    };

    const headers = {
      'Content-Type': 'application/json',
      'next-action': '4e63dabc37fef18cae74cbfd41d1bace49acf47e'
    };

    const response = await fetch(NOTDIAMOND_URL, {
      method: 'POST',
      headers: headers,
      body: JSON.stringify([payload])
    });

    const generator = streamNotdiamondResponse(response, model);
    
    if (stream) {
      res.writeHead(200, { 
        'Content-Type': 'text/event-stream',
        'Cache-Control': 'no-cache',
        'Connection': 'keep-alive'
      });

      for await (const chunk of generator) {
        res.write(`data: ${JSON.stringify(chunk)}\n\n`);
      }
      res.write("data: [DONE]\n\n");
      res.end();
    } else {
      let fullContent = "";
      for await (const chunk of generator) {
        if (chunk.choices[0].delta.content) {
          fullContent += chunk.choices[0].delta.content;
        }
      }

      res.json({
        id: `chatcmpl-${crypto.randomUUID()}`,
        object: "chat.completion",
        created: Math.floor(Date.now() / 1000),
        model: model,
        system_fingerprint: "fp_4e2b2da518",
        choices: [
          {
            index: 0,
            message: {
              role: "assistant",
              content: fullContent
            },
            finish_reason: "stop"
          }
        ],
        usage: {
          prompt_tokens: Math.floor(fullContent.length / 4),
          completion_tokens: Math.floor(fullContent.length / 4),
          total_tokens: Math.floor(fullContent.length / 2)
        }
      });
    } 
  } catch (error) {
    res.status(500).json({ 
      error: 'Internal Server Error', 
      details: error.message
    });
  }
});

app.listen(port, () => {
  console.log(`Server running on port ${port}`);
});