# Stage 1: Builder with full compilation environment
FROM python:3.8-bullseye as builder

# Install comprehensive build tools
RUN apt-get update && apt-get install -y --no-install-recommends \
    build-essential \
    cmake \
    git \
    curl \
    wget \
    libopenblas-dev \
    libssl-dev \
    zlib1g-dev \
    libbz2-dev \
    libncurses5-dev \
    libffi-dev \
    liblzma-dev \
    && rm -rf /var/lib/apt/lists/*

# Create and use virtual environment
RUN python -m venv /opt/venv
ENV PATH="/opt/venv/bin:$PATH"

# Install packages with precise order and fallbacks
COPY requirements.txt .
RUN pip install --upgrade pip setuptools wheel && \
    pip install torch==2.2.1 --index-url https://download.pytorch.org/whl/cpu && \
    pip install ninja==1.11.1 && \
    pip install transformers==4.38.2 && \
    pip install accelerate==0.27.2 && \
    pip install datasets==2.18.0 && \
    pip install huggingface_hub==0.20.3 && \
    { pip install deepspeed==0.13.1 || pip install deepspeed==0.13.1 --no-deps; } && \
    pip install unsloth==0.2.0 && \
    { pip install vllm==0.3.0 || pip install vllm==0.3.0 --no-deps; } && \
    pip install fastapi==0.109.1 uvicorn==0.27.0

# Stage 2: Slim runtime image
FROM python:3.8-slim

# Copy virtual env from builder
COPY --from=builder /opt/venv /opt/venv
ENV PATH="/opt/venv/bin:$PATH"

# Install runtime dependencies only
RUN apt-get update && apt-get install -y --no-install-recommends \
    libopenblas-base \
    && rm -rf /var/lib/apt/lists/*

WORKDIR /app
COPY . /app

# Verify installation
RUN python -c "import torch; print(f'PyTorch {torch.__version__} installed')" && \
    python -c "from transformers import __version__; print(f'Transformers {__version__} installed')"

CMD ["python", "train.py"]