# Use the base Python image
FROM python:3.9

# Set up a new user named "user" with user ID 1000
# This creates a new user within the Docker container with user ID 1000.
RUN useradd -m -u 1000 user

# Overrides permissions for Hugging Face Docker.
# Switches to the newly created user to run subsequent commands, enhancing security.
USER user

# Set environment variables for the user's home directory and executable path
ENV HOME=/home/user \
    PATH=/home/user/.local/bin:$PATH

# Set the working directory to /home/user/app
WORKDIR $HOME/app

# Install Python dependencies first to avoid reinstalling on code changes
# Copy the requirements.txt file into the container and install dependencies.
COPY ./requirements.txt $HOME/app/requirements.txt
RUN pip install --no-cache-dir --upgrade -r requirements.txt \
    && pip install --no-cache-dir --upgrade pymongo


# Switch back to root to install system dependencies
USER root

# Install system dependencies
RUN apt-get update \
    && apt-get install -y ffmpeg python3-pyaudio portaudio19-dev \
    && apt-get clean

# Switch back to the user
USER user

# Expose the secret OPENAI_API_KEY at buildtime and use its value as an environment variable
RUN --mount=type=secret,id=OPENAI_API_KEY,mode=0444,required=true \
    echo "export OPENAI_API_KEY=$(cat /run/secrets/OPENAI_API_KEY)" >> /home/user/app/.env

RUN --mount=type=secret,id=PINECONE_API_KEY,mode=0444,required=true \
    echo "export PINECONE_API_KEY=$(cat /run/secrets/PINECONE_API_KEY)" >> /home/user/app/.env

RUN --mount=type=secret,id=MONGO_URI,mode=0444,required=true \
    echo "export MONGO_URI=$(cat /run/secrets/MONGO_URI)" >> /home/user/app/.env

# Source the .env file to set environment variables
RUN echo "source $HOME/app/.env" >> $HOME/.bashrc

# Copy the rest of the application into the container
# This includes your Python scripts, models, and any other necessary files.
COPY --chown=user . $HOME/app


# Specify the command to run when the container starts
# Here, it runs the "app.py" script using the Python interpreter.
CMD ["python", "app.py"]

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

# Overview 

# This Dockerfile is used to build a Docker image for a Python application. 
# It starts with the official Python 3.9 image as a base. 
# It then sets up a new user, switches to that user for security reasons, and defines environment variables. 
# The working directory is set to "/home/user/app," where Python dependencies are installed from the "requirements.txt" file. 
# The entire application is copied into the container. 
# Finally, the CMD directive specifies that the "app.py" script should run when the container starts.

# Architecture:

# In the context of Hugging Face Docker Spaces, this Docker image encapsulates your Python application, 
# ensuring that it runs consistently across different environments (linus, macOS, windows, etc). 
# Docker containers provide a lightweight and isolated environment for applications, enhancing portability and reproducibility. 
# The use of a non-root user and defined environment variables contributes to security best practices. 
# The "CMD" instruction specifies the default behavior of the container.