main.py

# File: main.py
# Purpose: install missing packages using the pip command line
# and sets up the jupyter notebook server for visualization.

from __future__ import annotations
from signal import SIGINT
from signal import signal
from subprocess import CalledProcessError
from subprocess import check_call
from subprocess import run
from sys import executable

PACKAGES = []

def set_packages() -> None:
    '''Set the const variable PACKAGES based on requirements.txt'''
    global PACKAGES
    with open('./requirements.txt', 'r') as file:
        contents = file.read()
        packages = contents.split('\n')
        while '' in packages:
            packages.remove('')
        PACKAGES = packages


def install(package: str) -> None:
    '''Attempt to install package by creating a subprocess
    to execute a command with the pip command line tool.'''
    try:
        check_call([executable, '-m', 'pip', 'install', package])
    except CalledProcessError:
        print(f'Could not install {package}.')
    except:
        print('Something went wrong.')


def installed(package: str, environment: List[str]) -> bool:
    '''Return True if the package is installed on the machine.'''
    return package in environment


def get_environment() -> List[str]:
    '''Return the list of packages that are currently installed by the
    host machine (also known as the machine environment).'''
    environment = []
    result = run(['pip', 'list'], capture_output = True, text = True)
    packages = result.stdout.split('\n')
    packages.pop() # Remove the entry that only contains a newline
    for package in reversed(packages):
        if package[0] == '-': # Stop when at the divider line
            break
        environment.append(package.split(' ')[0])
    return environment


def check_packages() -> None:
    '''Check that all required packages are properly installed 
    and install packages if they are missing.'''
    environment = get_environment()
    for package in PACKAGES:
        if not installed(package, environment):
            install(package)


def handler(number, frame) -> None:
    '''Handle the SIGINT signal when closing the jupyter notebook.'''
    print('[MediaCAT Visualization] Closed jupyter notebook successfully.')


def start() -> None:
    '''Start the Jupyter Notebook Server.'''
    run(['jupyter', 'notebook', 'notebooks'])


if __name__ == '__main__':
    signal(SIGINT, handler)
    set_packages()
    check_packages()
    start()