Function Find-Command {
<#
.SYNOPSIS
    Used to find a command somewhere on the system.
    Recursively looks in all paths and under special [Program Files] and [Program Files (x86)] folders if defined.
    Replacement of `which` command

.PARAMETER Filename
    The filename to look for.
#>
    param (
        [Parameter(Mandatory = $true, Position = 0)]
        $Filename
    )

    $result = (Get-Command $Filename)

    if ($null -ne $result) {
        if (![string]::IsNullOrWhiteSpace($result.Path)) {
            return $result.Path
        } else {
            return $result.Source
        }
    }

    if ($Filename.IndexOf('.') -eq -1) {
        # add a wildcard so it will look for all matching Filename extensions
        $Filename = "$Filename.*"
    }

    # TODO ~ Make this parallel and change the return type
    $paths = @($env:path -split ';')
    $paths += $env:ProgramFiles
    $paths += ${env:ProgramFiles(x86)}

    $paths = ($paths | Select-Object -Unique)

    foreach($path in $paths) {
        if (![string]::IsNullOrWhiteSpace($path)) {
            $foundItems = Get-ChildItem -Path (Join-Path -Path $path -ChildPath $Filename) -Recurse -ErrorAction Ignore
            if ($foundItems.Count -eq 1) {
                return $foundItems.FullName
            } elseif ($foundItems.Count -gt 1) {
                Write-Host "Found several results for $Filename"
                foreach ($foundItem in $foundItems) {
                    Write-Host $foundItem.FullName
                }
                Write-Host ""
                return $foundItems[0]
            }
        }
    }

    Write-Warning "Could not find a matching file"
}

Set-Alias -Name which -Value Find-Command