# --- Stage 1: Build Stage ---
# Use a specific Python version to ensure consistency.
FROM python:3.11-slim as builder

# Set the working directory
WORKDIR /usr/src/app

# Upgrade pip and install wheel to build dependencies efficiently
RUN pip install --upgrade pip wheel

# Copy only the requirements file to leverage Docker's layer caching.
# This step will only be re-run if requirements.txt changes.
COPY ./requirements.txt .

# Build wheel files for all dependencies. This is faster and more reliable
# for the final stage than a simple 'pip install'.
RUN pip wheel --no-cache-dir --wheel-dir /usr/src/app/wheels -r requirements.txt


# --- Stage 2: Runtime Stage ---
# Use the same slim Python base image for a smaller final image size.
FROM python:3.11-slim

# Set a non-root user for better security
RUN addgroup --system app && adduser --system --group app

# Set the working directory
WORKDIR /home/app

# Copy the pre-built wheel dependencies from the builder stage
COPY --from=builder /usr/src/app/wheels /wheels
COPY --from=builder /usr/src/app/requirements.txt .

# Install the dependencies from local wheel files without needing to rebuild them.
# --no-index and --find-links ensure pip only uses the local wheels.
RUN pip install --no-cache /wheels/*

# Copy the application code into the container
COPY --chown=app:app . .

# Switch to the non-root user
USER app

# Expose the port Gunicorn will listen on
EXPOSE 8000

# The command to start the Gunicorn server
CMD ["gunicorn", "-c", "gunicorn_config.py", "main:app"]