DeployConcept/src/ConceptDeploy/Initialize-Python.ps1

function Initialize-Python {
    [CmdletBinding()]
    Param(
        [string] $minimalVersion = '3.12.2',
        [string] $installPath = 'C:\Tools\Python312-venv',
        [string] $pythonInstall = 'C:\Tools\Python312',
        [string] $pythonDistr = ''
    )
    $python = SearchInstalledEnvironment -TargetPath $installPath -MinimalVersion $minimalVersion
    if ($python -ne '') {
        return $python
    }
    $python = SearchLocalInstallation -TargetPath $pythonInstall -MinimalVersion $minimalVersion
    if ($python -eq '') {
        Write-Host "Failed to locate local installation of python"
        $python = SearchUserPath -MinimalVersion $minimalVersion
    }
    if ($python -eq '') {
        Write-Host "Failed to locate python in PATH variable"
        $python = SearchUserRegistry -MinimalVersion $minimalVersion
    }
    if ($python -eq '') {
        Write-Host "Failed to locate python in Windows registry"
        $python = InstallLocalPython -Version $minimalVersion -TargetPath $pythonInstall -PythonDistr $pythonDistr
    }
    if ($python -eq '') {
        return ''
    }
    CreateVirtualEnvironment -Python $python -TargetPath $installPath
    return "$installPath\Scripts\python.exe"
}

function SearchInstalledEnvironment($targetPath, $minimalVersion) {
    $python = "$targetPath\Scripts\python.exe"
    if (-not (Test-Path -Path $python -PathType Leaf)) {
        Write-Host "Failed to locate Python venv at $targetPath"
        return ''
    }
    $installedVersion = GetPythonVersion $python
    if(!$installedVersion -or 
            $installedVersion -eq '' -or 
            [System.Version] $installedVersion -lt [System.Version] $minimalVersion) {
        Write-Host "Removing invalid python env: $targetPath" -ForegroundColor DarkRed
        Remove-Item $targetPath -Recurse
        return ''
    } else {
        Write-Host "Found Python environment $installedVersion : $python"
        return $python
    }
}

function SearchLocalInstallation($targetPath, $minimalVersion) {
    $python = "$targetPath\python.exe"
    if (-not (Test-Path -Path $python -PathType Leaf)) {
        return ''
    }
    $installedVersion = GetPythonVersion $python
    if(!$installedVersion -or 
        $installedVersion -eq '' -or 
        [System.Version] $installedVersion -ne [System.Version] $minimalVersion) {
        return ''
    }
    Write-Host "Found installed python $installedVersion : $python"
    return $python
}

function SearchUserPath($minimalVersion) {
    $globalVersion = GetPythonVersion 'python'
    if(!$globalVersion -or 
        $globalVersion -eq '' -or
        [System.Version] $globalVersion -ne [System.Version] $minimalVersion) {
        return ''
    }
    Write-Host "Found globally installed python: $globalVersion"    
    return 'python'
}

function SearchUserRegistry($minimalVersion) {
    if ([Environment]::Is64BitProcess) {
        $pythonRegistry = 'HKCU:\SOFTWARE\Python\PythonCore\3.12\InstallPath'
        if(!$pythonRegistry) {
            $pythonRegistry = 'HKLM:\SOFTWARE\Python\PythonCore\3.12\InstallPath'
        }
    } else {
        $pythonRegistry = 'HKCU:\SOFTWARE\WOW6432Node\Python\PythonCore\3.12-32\InstallPath'
        if(!$pythonRegistry) {
            $pythonRegistry = 'HKLM:\SOFTWARE\WOW6432Node\Python\PythonCore\3.12-32\InstallPath'
        }
    }
    $python = Get-ItemPropertyValue -Path $pythonRegistry -Name 'ExecutablePath' -ErrorAction 'SilentlyContinue' 
    if (-not $python) {
        return ''
    }
    $version = GetPythonVersion $python
    if(!$version -or 
        $version -eq '' -or
        [System.Version] $version -lt [System.Version] $minimalVersion) {
        return ''
    }
    Write-Host "Found installed local python: $python" -ForegroundColor DarkGreen
    return $python
}

function InstallLocalPython($version, $targetPath, $pythonDistr = '') {
    if ($pythonDistr -eq '') {
        $installer = DowloadPython $version
    } else {
        $installer = $pythonDistr
    }
    
    $arguments = "/quiet InstallAllUsers=0 Include_test=0 Include_doc=0 Include_launcher=0 TargetDir=$targetPath"
    $process = (Start-Process -FilePath $installer -ArgumentList $arguments -PassThru -NoNewWindow)
    $process.WaitForExit()
    
    if ($pythonDistr -eq '') {
        Remove-Item $installer -ErrorAction SilentlyContinue
    }

    $python = "$targetPath\python.exe"
    if (-not (Test-Path -Path $python -PathType Leaf)) {
        Write-Error "Failed to install local python: $installer"
        return ''
    } else {
        Write-Host "Installed local python: $targetPath" -ForegroundColor DarkGreen
        return $python
    }
}

function GetPythonVersion($pythonExe) {
    $eap = $ErrorActionPreference
    $ErrorActionPreference = 'SilentlyContinue'
    $version = & $pythonExe --version
    $ErrorActionPreference = $eap
    if (!$version -or $version -eq '' -or $LASTEXITCODE -ne 0) {
        return ''
    } else {
        return $version.Split(' ')[1]
    }
}

function DowloadPython($version) {
    $pythonUrl = GetPythonURL $version
    $pythonTemp = "$Env:TEMP\installer-python-$version.exe"
    Write-Host "Downloading python installer to $pythonTemp"
    try {
        (New-Object System.Net.WebClient).DownloadFile($pythonUrl, $pythonTemp)
    } catch [System.Net.WebException] { 
        Write-Error "An exception was caught when trying to download Python: $($_.Exception.Message)"
        Exit
    } 
    return $pythonTemp
}

function CreateVirtualEnvironment($python, $targetPath) {
    & $python -m venv $targetPath
    Write-Host "Created virtual environment $targetPath" -ForegroundColor DarkGreen
}

function GetPythonURL($version) {
    if ([Environment]::Is64BitProcess) {
        return "https://www.python.org/ftp/python/$version/python-$version-amd64.exe"
    } else {
        return = "https://www.python.org/ftp/python/$version/python-$version.exe"
    }
}