EnvPaths.psm1

#  How to use
#
#  First, you need to import the script:
#  > Import-Module -Name "C:\Your\Path\to\EnvPaths.psm1"
#
#  Add C:\Foo as the first path in the current session (goes away when you log out / close the window):
#  > Add-EnvPathFirst -Path "C:\Foo"
#
#  Add C:\Foo as the first path in the machine path (all users):
#  > Add-EnvPathFirst -Path "C:\Foo" -Container Machine
#
#  Remove any path matching *Foo* from the system paths for all users:
#  > Remove-EnvPath -Path *Foo* -Container Machine
#
#  Look for the existance of a wildcard path:
#  > $present = Find-EnvPath -Path "*CMake\bin*" -Container Machine
#  > if ([bool]$present) { Write-Host "found cmake binary path" }

function Add-EnvPathLast {
    param(
        [Parameter(Mandatory=$true)]
        [string] $Path,

        [ValidateSet('Machine', 'User', 'Session')]
        [string] $Container = 'Session'
    )

    if ($Container -ne 'Session') {
        $containerMapping = @{
            Machine = [EnvironmentVariableTarget]::Machine
            User = [EnvironmentVariableTarget]::User
        }
        $containerType = $containerMapping[$Container]

        $persistedPaths = [Environment]::GetEnvironmentVariable('Path', $containerType) -split ';'
        if ($persistedPaths -notcontains $Path) {
            $persistedPaths = $persistedPaths + $Path | where { $_ }
            [Environment]::SetEnvironmentVariable('Path', $persistedPaths -join ';', $containerType)
        }
    }

    $envPaths = $env:Path -split ';'
    if ($envPaths -notcontains $Path) {
        $envPaths = $envPaths + $Path | where { $_ }
        $env:Path = $envPaths -join ';'
    }
}

function Add-EnvPathFirst {
    param(
        [Parameter(Mandatory=$true)]
        [string] $Path,

        [ValidateSet('Machine', 'User', 'Session')]
        [string] $Container = 'Session'
    )

    if ($Container -ne 'Session') {
        $containerMapping = @{
            Machine = [EnvironmentVariableTarget]::Machine
            User = [EnvironmentVariableTarget]::User
        }
        $containerType = $containerMapping[$Container]

        $persistedPaths = [Environment]::GetEnvironmentVariable('Path', $containerType) -split ';'
        if ($persistedPaths -notcontains $Path) {
            $persistedPaths = ,$Path + $persistedPaths | where { $_ }
            [Environment]::SetEnvironmentVariable('Path', $persistedPaths -join ';', $containerType)
        }
    }

    $envPaths = $env:Path -split ';'
    if ($envPaths -notcontains $Path) {
        $envPaths = ,$Path + $envPaths | where { $_ }
        $env:Path = $envPaths -join ';'
    }
}

function Remove-EnvPath {
    param(
        [Parameter(Mandatory=$true)]
        [string] $Path,

        [ValidateSet('Machine', 'User', 'Session')]
        [string] $Container = 'Session'
    )

    if ($Container -ne 'Session') {
        $containerMapping = @{
            Machine = [EnvironmentVariableTarget]::Machine
            User = [EnvironmentVariableTarget]::User
        }
        $containerType = $containerMapping[$Container]

        $persistedPaths = [Environment]::GetEnvironmentVariable('Path', $containerType) -split ';'
        $persistedPaths = $persistedPaths | where { $_ -and $_ -notlike $Path }
        [Environment]::SetEnvironmentVariable('Path', $persistedPaths -join ';', $containerType)
    }

    $envPaths = $env:Path -split ';'
    # filter out the possible wildcard path
    $envPaths = $envPaths | where { $_ -and $_ -notlike $Path }
    $env:Path = $envPaths -join ';'
}

function Get-EnvPath {
    param(
        [Parameter(Mandatory=$true)]
        [ValidateSet('Machine', 'User')]
        [string] $Container
    )

    $containerMapping = @{
        Machine = [EnvironmentVariableTarget]::Machine
        User = [EnvironmentVariableTarget]::User
    }
    $containerType = $containerMapping[$Container]

    [Environment]::GetEnvironmentVariable('Path', $containerType) -split ';' |
        where { $_ }
}

# returns True when the path is defined in the set of paths
function Find-EnvPath {
    param(
        [Parameter(Mandatory=$true)]
        [string] $Path,

        [ValidateSet('Machine', 'User', 'Session')]
        [string] $Container = 'Session'
    )

    if ($Container -ne 'Session') {
        $containerMapping = @{
            Machine = [EnvironmentVariableTarget]::Machine
            User = [EnvironmentVariableTarget]::User
        }
        $containerType = $containerMapping[$Container]

        $persistedPaths = [Environment]::GetEnvironmentVariable('Path', $containerType) -split ';'
        $persistedPaths = $persistedPaths | where { $_ -and $_ -like $Path }

        return $persistedPaths -ne $null
    }

    $envPaths = $env:Path -split ';'
    # filter out the possible wildcard path
    $envPaths = $envPaths | where { $_ -and $_ -like $Path }
    return $envPaths -ne $null
}

Export-ModuleMember -Function *