# ----------  Front‑end build stage ----------
    FROM node:18-alpine AS frontend-build

    WORKDIR /app/frontend
    COPY frontend/package*.json ./
    RUN npm ci --only=production
    COPY frontend/ ./
    RUN npm run build && npm run export
    
    
    # ----------  Back‑end stage ----------
    FROM python:3.11-slim AS backend
    
    WORKDIR /app/backend                       # <─ matches compose volumes
    
    # System build deps
    RUN apt-get update && apt-get install -y gcc curl && rm -rf /var/lib/apt/lists/*
    
    # Python deps
    COPY backend/requirements.txt ./
    RUN pip install --no-cache-dir -r requirements.txt
    
    # App source code
    COPY backend/ ./
    
    # Static export from previous stage
    COPY --from=frontend-build /app/frontend/out /app/frontend_out
    
    # Create folders & DB file and make them writable
    RUN mkdir -p /app/backend/uploads /app/backend/chroma_db \
        && touch /app/backend/pdf_chatbot.db \
        && chmod -R 777 /app/backend/uploads /app/backend/chroma_db /app/backend/pdf_chatbot.db
    
    # Expose API port
    EXPOSE 8000
    
    # Small health‑check
    HEALTHCHECK --interval=30s --timeout=30s --start-period=5s --retries=3 \
      CMD curl -f http://localhost:8000/health || exit 1
    
    # Start FastAPI
    CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8000"]