# STAGE 1: Build Stage
FROM python:3.11-slim AS builder
WORKDIR /app

# --- CACHE BUSTING MECHANISM ---
# Define a build argument that will be passed during the docker build command.
# Change the number (e.g., from 1 to 2) every time you build if the installation fails.
ARG BUILD_ID=1 

# Install build dependencies for the Python packages
RUN apt-get update && apt-get install -y --no-install-recommends \
    build-essential \
    git \
    && rm -rf /var/lib/apt/lists/*

# Create a virtual environment and set it in the PATH
RUN python -m venv /opt/venv
ENV PATH="/opt/venv/bin:$PATH"

# Copy the requirements file and install dependencies
COPY requirements.txt .

# Use the BUILD_ID as an ENV variable. When this ENV value changes, 
# Docker's cache for the following RUN instruction (pip install) is invalidated.
ENV FORCE_INSTALL=${BUILD_ID} 
RUN pip install --no-cache-dir -r requirements.txt

# --------------------------------------------------------------------------

# STAGE 2: Final Stage
FROM python:3.11-slim
WORKDIR /app

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

# Add a non-root user and group
RUN addgroup --system app && adduser --system --group app

# CRITICAL FIX: Ensure the working directory (/app) is owned by the app user
RUN chown app:app /app

# Copy the virtual environment, source code, and data file with correct ownership
COPY --from=builder --chown=app:app /opt/venv /opt/venv
COPY --chown=app:app ./src ./src
COPY --chown=app:app ./training_data.csv .

# Switch to the non-root user
USER app

# Set up environment variables and create the cache directory as the 'app' user
ENV PATH="/opt/venv/bin:$PATH"
ENV HF_HOME="/tmp/hf_cache" 
RUN mkdir -p /app/hf_cache

# --- Container configuration ---
EXPOSE 8501
HEALTHCHECK CMD curl --fail http://localhost:8501/_stcore/health

# --- Streamlit configuration and Entrypoint ---
ENV STREAMLIT_SERVER_HEADLESS=true
ENV STREAMLIT_BROWSER_GATHERUSAGETSTATS=false
ENTRYPOINT ["streamlit", "run", "src/app.py", "--server.port=8501", "--server.address=0.0.0.0"]