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

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

// Create OpenAI chunk helper
function createChunk(state, delta, finishReason = null) {
  return {
    id: `chatcmpl-${state.messageId}`,
    object: "chat.completion.chunk",
    created: Math.floor(Date.now() / 1000),
    model: state.model,
    choices: [{
      index: 0,
      delta,
      finish_reason: finishReason
    }]
  };
}

// Convert Claude stream chunk to OpenAI format
function claudeToOpenAIResponse(chunk, state) {
  if (!chunk) return null;

  const results = [];
  const event = chunk.type;

  switch (event) {
    case "message_start": {
      state.messageId = chunk.message?.id || `msg_${Date.now()}`;
      state.model = chunk.message?.model;
      state.toolCallIndex = 0; // Reset tool call counter for OpenAI format
      console.log("🔍 ----------- toolCallIndex", state.toolCallIndex);
      results.push(createChunk(state, { role: "assistant" }));
      break;
    }

    case "content_block_start": {
      const block = chunk.content_block;
      if (block?.type === "text") {
        state.textBlockStarted = true;
      } else if (block?.type === "thinking") {
        // console.log("🧠 Thinking block started");
        state.inThinkingBlock = true;
        state.currentBlockIndex = chunk.index;
        results.push(createChunk(state, { content: "<think>" }));
      } else if (block?.type === "tool_use") {
        // OpenAI format: tool_calls index must be independent and start from 0
        const toolCallIndex = state.toolCallIndex++;
        const toolCall = {
          index: toolCallIndex,
          id: block.id,
          type: "function",
          function: {
            name: block.name,
            arguments: ""
          }
        };
        // Map Claude content_block index to OpenAI tool_call index
        state.toolCalls.set(chunk.index, toolCall);
        results.push(createChunk(state, { tool_calls: [toolCall] }));
      }
      break;
    }

    case "content_block_delta": {
      const delta = chunk.delta;
      if (delta?.type === "text_delta" && delta.text) {
        results.push(createChunk(state, { content: delta.text }));
      } else if (delta?.type === "thinking_delta" && delta.thinking) {
        // Stream thinking content
        results.push(createChunk(state, { content: delta.thinking }));
      } else if (delta?.type === "input_json_delta" && delta.partial_json) {
        const toolCall = state.toolCalls.get(chunk.index);
        if (toolCall) {
          toolCall.function.arguments += delta.partial_json;
          // Include both index and id for better client compatibility
          results.push(createChunk(state, {
            tool_calls: [{
              index: toolCall.index,
              id: toolCall.id,
              function: { arguments: delta.partial_json }
            }]
          }));
        }
      }
      break;
    }

    case "content_block_stop": {
      if (state.inThinkingBlock && chunk.index === state.currentBlockIndex) {
        // console.log("✅ Thinking block ended");
        results.push(createChunk(state, { content: "</think>" }));
        state.inThinkingBlock = false;
      }
      state.textBlockStarted = false;
      state.thinkingBlockStarted = false;
      break;
    }

    case "message_delta": {
      if (chunk.delta?.stop_reason) {
        state.finishReason = convertStopReason(chunk.delta.stop_reason);

        // Send the final chunk with finish_reason immediately
        results.push({
          id: `chatcmpl-${state.messageId}`,
          object: "chat.completion.chunk",
          created: Math.floor(Date.now() / 1000),
          model: state.model,
          choices: [{
            index: 0,
            delta: {},
            finish_reason: state.finishReason
          }]
        });
        state.finishReasonSent = true;
      }
      // Usage is now extracted in stream.js extractUsage()
      break;
    }

    case "message_stop": {
      // CLIProxyAPI and OpenAI standard: message_stop should send the final chunk with finish_reason
      // This ensures proper signaling to the client that the response is complete

      // Only send a chunk if we haven't already sent the finish_reason in message_delta
      // In some cases, finish_reason might not have been sent yet
      if (!state.finishReasonSent) {
        const finishReason = state.finishReason || (state.toolCalls?.size > 0 ? "tool_calls" : "stop");
        results.push({
          id: `chatcmpl-${state.messageId}`,
          object: "chat.completion.chunk",
          created: Math.floor(Date.now() / 1000),
          model: state.model,
          choices: [{
            index: 0,
            delta: {},
            finish_reason: finishReason
          }],
          ...(state.usage && {
            usage: {
              prompt_tokens: state.usage.input_tokens || 0,
              completion_tokens: state.usage.output_tokens || 0,
              total_tokens: (state.usage.input_tokens || 0) + (state.usage.output_tokens || 0)
            }
          })
        });
        state.finishReasonSent = true;
      }
      break;
    }
  }

  return results.length > 0 ? results : null;
}

// Helper: stop thinking block if started
function stopThinkingBlock(state, results) {
  if (!state.thinkingBlockStarted) return;
  results.push({
    type: "content_block_stop",
    index: state.thinkingBlockIndex
  });
  state.thinkingBlockStarted = false;
}

// Helper: stop text block if started
function stopTextBlock(state, results) {
  if (!state.textBlockStarted || state.textBlockClosed) return;
  state.textBlockClosed = true;
  results.push({
    type: "content_block_stop",
    index: state.textBlockIndex
  });
  state.textBlockStarted = false;
}

// Convert OpenAI stream chunk to Claude format
function openaiToClaudeResponse(chunk, state) {
  if (!chunk || !chunk.choices?.[0]) return null;

  const results = [];
  const choice = chunk.choices[0];
  const delta = choice.delta;

  // First chunk - ALWAYS send message_start first
  if (!state.messageStartSent) {
    state.messageStartSent = true;
    state.messageId = chunk.id?.replace("chatcmpl-", "") || `msg_${Date.now()}`;
    if (!state.messageId || state.messageId === "chat" || state.messageId.length < 8) {
      state.messageId = chunk.extend_fields?.requestId ||
        chunk.extend_fields?.traceId ||
        `msg_${Date.now()}`;
    }
    state.model = chunk.model || "unknown";
    state.nextBlockIndex = 0;
    results.push({
      type: "message_start",
      message: {
        id: state.messageId,
        type: "message",
        role: "assistant",
        model: state.model,
        content: [],
        stop_reason: null,
        stop_sequence: null,
        usage: { input_tokens: 0, output_tokens: 0 }
      }
    });
  }

  // Handle reasoning_content (thinking) - GLM, DeepSeek, etc.
  const reasoningContent = delta?.reasoning_content || delta?.reasoning;
  if (reasoningContent) {
    // Stop text block before thinking
    stopTextBlock(state, results);

    // Start thinking block if needed
    if (!state.thinkingBlockStarted) {
      state.thinkingBlockIndex = state.nextBlockIndex++;
      state.thinkingBlockStarted = true;
      results.push({
        type: "content_block_start",
        index: state.thinkingBlockIndex,
        content_block: { type: "thinking", thinking: "" }
      });
    }

    // Send thinking delta
    results.push({
      type: "content_block_delta",
      index: state.thinkingBlockIndex,
      delta: { type: "thinking_delta", thinking: reasoningContent }
    });
  }

  // Handle regular content
  if (delta?.content) {
    // Stop thinking block before text
    stopThinkingBlock(state, results);

    // Start text block if needed
    if (!state.textBlockStarted) {
      state.textBlockIndex = state.nextBlockIndex++;
      state.textBlockStarted = true;
      state.textBlockClosed = false;
      results.push({
        type: "content_block_start",
        index: state.textBlockIndex,
        content_block: { type: "text", text: "" }
      });
    }

    // Send text delta
    results.push({
      type: "content_block_delta",
      index: state.textBlockIndex,
      delta: { type: "text_delta", text: delta.content }
    });
  }

  // Tool calls
  if (delta?.tool_calls) {
    for (const tc of delta.tool_calls) {
      const idx = tc.index ?? 0;

      if (tc.id) {
        // Stop thinking and text blocks before tool use
        stopThinkingBlock(state, results);
        stopTextBlock(state, results);

        // New tool call
        const toolBlockIndex = state.nextBlockIndex++;
        state.toolCalls.set(idx, { id: tc.id, name: tc.function?.name || "", blockIndex: toolBlockIndex });
        results.push({
          type: "content_block_start",
          index: toolBlockIndex,
          content_block: {
            type: "tool_use",
            id: tc.id,
            name: tc.function?.name || "",
            input: {}
          }
        });
      }

      if (tc.function?.arguments) {
        const toolInfo = state.toolCalls.get(idx);
        if (toolInfo) {
          results.push({
            type: "content_block_delta",
            index: toolInfo.blockIndex,
            delta: { type: "input_json_delta", partial_json: tc.function.arguments }
          });
        }
      }
    }
  }

  // Finish
  if (choice.finish_reason) {
    // Stop all open blocks
    stopThinkingBlock(state, results);
    stopTextBlock(state, results);

    // Close tool call blocks
    for (const [, toolInfo] of state.toolCalls) {
      results.push({
        type: "content_block_stop",
        index: toolInfo.blockIndex
      });
    }

    results.push({
      type: "message_delta",
      delta: { stop_reason: convertFinishReason(choice.finish_reason) },
      usage: { output_tokens: 0 }
    });
    results.push({ type: "message_stop" });
  }

  return results.length > 0 ? results : null;
}

// Convert Claude stop_reason to OpenAI finish_reason
function convertStopReason(reason) {
  switch (reason) {
    case "end_turn": return "stop";
    case "max_tokens": return "length";
    case "tool_use": return "tool_calls";
    case "stop_sequence": return "stop";
    default: return "stop";
  }
}

// Convert OpenAI finish_reason to Claude stop_reason
function convertFinishReason(reason) {
  switch (reason) {
    case "stop": return "end_turn";
    case "length": return "max_tokens";
    case "tool_calls": return "tool_use";
    default: return "end_turn";
  }
}

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