9router/open-sse/translator/to-openai/claude.js

import { register } from "../index.js";
import { FORMATS } from "../formats.js";
import { adjustMaxTokens } from "../helpers/maxTokensHelper.js";

// Convert Claude request to OpenAI format
function claudeToOpenAI(model, body, stream) {
  const result = {
    model: model,
    messages: [],
    stream: stream
  };

  // Max tokens
  if (body.max_tokens) {
    result.max_tokens = adjustMaxTokens(body);
  }

  // Temperature
  if (body.temperature !== undefined) {
    result.temperature = body.temperature;
  }

  // System message
  if (body.system) {
    const systemContent = Array.isArray(body.system)
      ? body.system.map(s => s.text || "").join("\n")
      : body.system;
    
    if (systemContent) {
      result.messages.push({
        role: "system",
        content: systemContent
      });
    }
  }

  // Convert messages
  if (body.messages && Array.isArray(body.messages)) {
    for (let i = 0; i < body.messages.length; i++) {
      const msg = body.messages[i];
      const converted = convertClaudeMessage(msg);
      if (converted) {
        // Handle array of messages (multiple tool results)
        if (Array.isArray(converted)) {
          result.messages.push(...converted);
        } else {
          result.messages.push(converted);
        }
      }
    }
  }

  // Fix missing tool responses - OpenAI requires every tool_call to have a response
  fixMissingToolResponses(result.messages);

  // Tools
  if (body.tools && Array.isArray(body.tools)) {
    result.tools = body.tools.map(tool => ({
      type: "function",
      function: {
        name: tool.name,
        description: tool.description,
        parameters: tool.input_schema || { type: "object", properties: {} }
      }
    }));
  }

  // Tool choice
  if (body.tool_choice) {
    result.tool_choice = convertToolChoice(body.tool_choice);
  }

  return result;
}

// Fix missing tool responses - add empty responses for tool_calls without responses
function fixMissingToolResponses(messages) {
  for (let i = 0; i < messages.length; i++) {
    const msg = messages[i];
    if (msg.role === "assistant" && msg.tool_calls && msg.tool_calls.length > 0) {
      const toolCallIds = msg.tool_calls.map(tc => tc.id);
      
      // Collect all tool response IDs that IMMEDIATELY follow this assistant message
      // Stop at any non-tool message (user or assistant)
      const respondedIds = new Set();
      let insertPosition = i + 1;
      for (let j = i + 1; j < messages.length; j++) {
        const nextMsg = messages[j];
        if (nextMsg.role === "tool" && nextMsg.tool_call_id) {
          respondedIds.add(nextMsg.tool_call_id);
          insertPosition = j + 1;
        } else {
          // Stop at any non-tool message (user or assistant)
          break;
        }
      }
      
      // Find missing responses and insert them
      const missingIds = toolCallIds.filter(id => !respondedIds.has(id));
      
      if (missingIds.length > 0) {
        const missingResponses = missingIds.map(id => ({
          role: "tool",
          tool_call_id: id,
          content: "[No response received]"
        }));
        // Insert missing responses at the correct position
        messages.splice(insertPosition, 0, ...missingResponses);
        // Adjust index to skip inserted messages
        i = insertPosition + missingResponses.length - 1;
      }
    }
  }
}

// Convert single Claude message - returns single message or array of messages
function convertClaudeMessage(msg) {
  const role = msg.role === "user" || msg.role === "tool" ? "user" : "assistant";
  
  // Simple string content
  if (typeof msg.content === "string") {
    return { role, content: msg.content };
  }

  // Array content
  if (Array.isArray(msg.content)) {
    const parts = [];
    const toolCalls = [];
    const toolResults = [];

    for (const block of msg.content) {
      switch (block.type) {
        case "text":
          parts.push({ type: "text", text: block.text });
          break;

        case "image":
          if (block.source?.type === "base64") {
            parts.push({
              type: "image_url",
              image_url: {
                url: `data:${block.source.media_type};base64,${block.source.data}`
              }
            });
          }
          break;

        case "tool_use":
          toolCalls.push({
            id: block.id,
            type: "function",
            function: {
              name: block.name,
              arguments: JSON.stringify(block.input || {})
            }
          });
          break;

        case "tool_result":
          // Extract actual content from tool_result
          let resultContent = "";
          if (typeof block.content === "string") {
            resultContent = block.content;
          } else if (Array.isArray(block.content)) {
            // Claude tool_result content can be array of text blocks
            resultContent = block.content
              .filter(c => c.type === "text")
              .map(c => c.text)
              .join("\n") || JSON.stringify(block.content);
          } else if (block.content) {
            resultContent = JSON.stringify(block.content);
          }
          
          toolResults.push({
            role: "tool",
            tool_call_id: block.tool_use_id,
            content: resultContent
          });
          break;
      }
    }

    // If has tool results, return array of tool messages
    if (toolResults.length > 0) {
      // Also include text parts as user message if any
      if (parts.length > 0) {
        const textContent = parts.length === 1 && parts[0].type === "text" 
          ? parts[0].text 
          : parts;
        return [...toolResults, { role: "user", content: textContent }];
      }
      return toolResults;
    }

    // If has tool calls, return assistant message with tool_calls
    if (toolCalls.length > 0) {
      const result = { role: "assistant" };
      if (parts.length > 0) {
        result.content = parts.length === 1 && parts[0].type === "text" 
          ? parts[0].text 
          : parts;
      }
      result.tool_calls = toolCalls;
      return result;
    }

    // Return content
    if (parts.length > 0) {
      return {
        role,
        content: parts.length === 1 && parts[0].type === "text" ? parts[0].text : parts
      };
    }
    
    // Empty content array - return empty string content to keep message in conversation
    if (msg.content.length === 0) {
      return { role, content: "" };
    }
  }

  return null;
}

// Convert tool choice
function convertToolChoice(choice) {
  if (!choice) return "auto";
  if (typeof choice === "string") return choice;
  
  switch (choice.type) {
    case "auto": return "auto";
    case "any": return "required";
    case "tool": return { type: "function", function: { name: choice.name } };
    default: return "auto";
  }
}

// Register
register(FORMATS.CLAUDE, FORMATS.OPENAI, claudeToOpenAI, null);