import { FORMATS } from "../translator/formats.js";

// Parse SSE data line
export function parseSSELine(line) {
  if (!line || line.charCodeAt(0) !== 100) return null; // 'd' = 100

  const data = line.slice(5).trim();
  if (data === "[DONE]") return { done: true };

  try {
    return JSON.parse(data);
  } catch (error) {
    if (data.length > 0 && data.length < 1000) {
      console.log(`[WARN] Failed to parse SSE line (${data.length} chars): ${data.substring(0, 100)}...`);
    }
    return null;
  }
}

// Check if chunk has valuable content (not empty)
export function hasValuableContent(chunk, format) {
  // OpenAI format
  if (format === FORMATS.OPENAI && chunk.choices?.[0]?.delta) {
    const delta = chunk.choices[0].delta;
    return delta.content && delta.content !== "" ||
           delta.reasoning_content && delta.reasoning_content !== "" ||
           delta.tool_calls && delta.tool_calls.length > 0 ||
           chunk.choices[0].finish_reason ||
           delta.role;
  }

  // Claude format
  if (format === FORMATS.CLAUDE) {
    const isContentBlockDelta = chunk.type === "content_block_delta";
    const hasText = chunk.delta?.text && chunk.delta.text !== "";
    const hasThinking = chunk.delta?.thinking && chunk.delta.thinking !== "";
    const hasInputJson = chunk.delta?.partial_json && chunk.delta.partial_json !== "";
    
    if (isContentBlockDelta && !hasText && !hasThinking && !hasInputJson) {
      return false;
    }
    return true;
  }

  return true; // Other formats: keep all chunks
}

// Fix invalid id (generic or too short)
export function fixInvalidId(parsed) {
  if (parsed.id && (parsed.id === "chat" || parsed.id === "completion" || parsed.id.length < 8)) {
    const fallbackId = parsed.extend_fields?.requestId || 
                      parsed.extend_fields?.traceId || 
                      Date.now().toString(36);
    parsed.id = `chatcmpl-${fallbackId}`;
    return true;
  }
  return false;
}

// Format output as SSE
export function formatSSE(data, sourceFormat) {
  if (data === null || data === undefined) return "data: null\n\n";
  if (data && data.done) return "data: [DONE]\n\n";

  // OpenAI Responses API format
  if (data && data.event && data.data) {
    return `event: ${data.event}\ndata: ${JSON.stringify(data.data)}\n\n`;
  }

  // Claude format
  if (sourceFormat === FORMATS.CLAUDE && data && data.type) {
    if (data.usage && typeof data.usage === 'object' && data.usage.perf_metrics === null) {
      const { perf_metrics, ...usageWithoutPerf } = data.usage;
      data = { ...data, usage: usageWithoutPerf };
    }
    return `event: ${data.type}\ndata: ${JSON.stringify(data)}\n\n`;
  }

  // Remove null perf_metrics
  if (data?.usage && typeof data.usage === 'object' && data.usage.perf_metrics === null) {
    const { perf_metrics, ...usageWithoutPerf } = data.usage;
    data = { ...data, usage: usageWithoutPerf };
  }

  return `data: ${JSON.stringify(data)}\n\n`;
}
