@echo OFF
cls

REM ===============================================================
REM              Python Virtual Environment Manager
REM ===============================================================
REM This script helps you create and manage Python virtual environments
REM with multiple Python installations on your system. It lists all
REM available Python versions, allows you to select one, and creates
REM a new project directory with a virtual environment using the
REM selected Python version.
REM 
REM Features:
REM - Lists all installed Python versions and allows you to select one.
REM - Creates a new project folder and initializes a virtual environment.
REM - Automatically upgrades dependencies if supported.
REM - Opens a new Python script file with the appropriate shebang line.
REM - Activates the virtual environment and opens the script in Notepad++.
REM 
REM Requirements:
REM - Python installed with multiple versions (detected via 'py -0').
REM - Notepad++ for editing Python scripts.
REM
REM How to start:
REM - Simply double-click on the 'new_python_environment.bat' file.
REM
REM How to use:
REM - Type your Python code in the Notepad++ file, save, then run by
REM   typing 'python run.py' at the command line and hitting Enter.
REM - Install packages, or show them with 'pip list' as normal.
REM - When done, you can 'deactivate' or 'exit' to end.
REM - Open the same project simply by running the script again. Just
REM   enter the same name you used to create it.
REM ===============================================================

REM List installed Python versions and create a selection menu
echo Available Python versions:
py -0 > temp_versions.txt
setlocal enabledelayedexpansion
set "count=0"
set "choices="

REM Read the list of installed Python versions
for /f "tokens=*" %%i in (temp_versions.txt) do (
    if not "%%i"=="" (
        set /a count+=1
        echo !count!. %%i
        set "version!count!=%%i"
        set "choices=!choices!!count!"
    )
)
del temp_versions.txt

REM Prompt user to select a Python version
choice /C %choices% /M "Select the desired Python version by number: "
set "PYTHON_VERSION=!version%ERRORLEVEL%!"

REM Extract the version number from the selected line
for /f "tokens=2 delims=:- " %%i in ("!PYTHON_VERSION!") do set "PYTHON_VERSION=%%i"

REM Debugging: Display selected Python version
echo Selected Python version: %PYTHON_VERSION%

REM Set the paths for the Python project
set "PYTHON=%USERPROFILE%\Code\Python"
set /P "PROJECT=New project name: "
set "PRDIR=%PYTHON%\%PROJECT%"
set "ENV=%PRDIR%\venv"

REM Check if the virtual environment already exists
if exist "%ENV%" (
    echo That project already exists.
    REM Jump to the part where we activate the environment and open Notepad++
    goto :ACTIVATE_ENV
)

REM Initialize UPGRADE_DEPS to be empty
set "UPGRADE_DEPS="

REM Process version numbers
for /f "tokens=1,2 delims=." %%v in ("%PYTHON_VERSION%") do (
    set "MAJOR=%%v"
    set "MINOR=%%w"

    REM Check if the Python version should use --upgrade-deps
    if !MAJOR! GTR 3 set "UPGRADE_DEPS=--upgrade-deps" else if !MAJOR!==3 (
        if !MINOR! GEQ 9 set "UPGRADE_DEPS=--upgrade-deps"
    )
)

REM Define the command to create the virtual environment with the selected Python version.
set "CREATE_VENV_CMD=py -%PYTHON_VERSION% -m venv "%ENV%" %UPGRADE_DEPS%"

REM Create the virtual environment
title New Python virtual environment
echo Creating the virtual environment with Python %PYTHON_VERSION% . . .
call %CREATE_VENV_CMD%

REM Temporarily disable delayed expansion to write the correct line to run.py.
setlocal disabledelayedexpansion
echo #! python%PYTHON_VERSION%>"%PRDIR%\run.py"
endlocal

:ACTIVATE_ENV

REM Activate the virtual environment
title Python virtual environment
cd "%PRDIR%"
cls
echo Activating the virtual environment...
start "" /D "%PRDIR%" "C:\Program Files\Notepad++\notepad++.exe" "%PRDIR%\run.py"
cmd /K "%ENV%\Scripts\activate.bat"