src/app/api/translate/route.ts

import { NextResponse } from 'next/server';

const MEDGEMMA_BACKEND_URL =
  process.env.MEDGEMMA_BACKEND_URL || 'http://localhost:8100';
const MEDGEMMA_API_KEY = process.env.MEDGEMMA_API_KEY || '';

function backendHeaders(): Record<string, string> {
  const h: Record<string, string> = { 'Content-Type': 'application/json' };
  if (MEDGEMMA_API_KEY) h['x-api-key'] = MEDGEMMA_API_KEY;
  return h;
}

interface TranslateRequest {
  text: string;
  source_lang?: string;
  target_lang?: string;
  provider?: string; // 'local' | 'vastai'
  model_id?: string;
  quantize?: string | null;
}

// POST /api/translate — Proxy to the MedGemma backend /api/v1/translate
export async function POST(request: Request) {
  try {
    const body: TranslateRequest = await request.json();

    if (!body.text || body.text.trim().length === 0) {
      return NextResponse.json(
        { success: false, error: 'Text to translate is required' },
        { status: 400 }
      );
    }

    const backendResponse = await fetch(
      `${MEDGEMMA_BACKEND_URL}/api/v1/translate`,
      {
        method: 'POST',
        headers: backendHeaders(),
        body: JSON.stringify({
          text: body.text,
          source_lang: body.source_lang ?? 'hr',
          target_lang: body.target_lang ?? 'en',
          provider: body.provider ?? 'local',
          model_id: body.model_id ?? 'google/translategemma-12b-it',
          quantize: body.quantize ?? null,
        }),
        // Translation can take a few minutes for long reports
        signal: AbortSignal.timeout(600_000), // 10 min
      }
    );

    if (!backendResponse.ok) {
      const errorData = await backendResponse.json().catch(() => null);
      const errorMessage =
        errorData?.detail || `Backend returned ${backendResponse.status}`;

      return NextResponse.json(
        { success: false, error: errorMessage },
        { status: backendResponse.status }
      );
    }

    const data = await backendResponse.json();

    return NextResponse.json({
      success: true,
      translated_text: data.translated_text,
      source_lang: data.source_lang,
      target_lang: data.target_lang,
      chunks_count: data.chunks_count,
      elapsed_ms: data.elapsed_ms,
      model_id: data.model_id,
      provider: data.provider,
    });
  } catch (error) {
    const message =
      error instanceof Error ? error.message : 'Translation failed';

    if (message.includes('timeout') || message.includes('Timeout')) {
      return NextResponse.json(
        {
          success: false,
          error:
            'Translation timed out. The model may still be loading or the text is very long.',
        },
        { status: 504 }
      );
    }

    if (
      message.includes('ECONNREFUSED') ||
      message.includes('fetch failed') ||
      message.includes('connect')
    ) {
      return NextResponse.json(
        {
          success: false,
          error:
            'Cannot connect to translation backend. Make sure the MedGemma backend is running on port 8100.',
        },
        { status: 503 }
      );
    }

    return NextResponse.json(
      { success: false, error: message },
      { status: 500 }
    );
  }
}