Update All PowerShell Modules

function Update-Modules
{
    param (
        [switch]$AllowPrerelease,
        [string]$Name = '*',
        [switch]$WhatIf
    )

    # Test admin privileges without using -Requires RunAsAdministrator,
    # which causes a nasty error message, if trying to load the function within a PS profile but without admin privileges
    if (-not ([Security.Principal.WindowsPrincipal][Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole]'Administrator'))
    {
        Write-Warning ('Function {0} needs admin privileges. Break now.' -f $MyInvocation.MyCommand)
        return
    }

    # Get all installed modules
    Write-Host ('Retrieving all installed modules ...') -ForegroundColor Green
    $CurrentModules = Get-InstalledModule -Name $Name -ErrorAction SilentlyContinue | Select-Object Name, Version | Sort-Object Name

    if (-not $CurrentModules)
    {
        Write-Host ('No modules found.') -ForegroundColor Gray
        return
    }
    else
    {
        $ModulesCount = $CurrentModules.Name.Count
        $DigitsLength = $ModulesCount.ToString().Length
        Write-Host ('{0} modules found.' -f $ModulesCount) -ForegroundColor Gray
    }

    # Show status of AllowPrerelease Switch
    ''
    if ($AllowPrerelease)
    {
        Write-Host ('Updating installed modules to the latest PreRelease version ...') -ForegroundColor Green
    }
    else
    {
        Write-Host ('Updating installed modules to the latest Production version ...') -ForegroundColor Green
    }

    # Loop through the installed modules and update them if a newer version is available
    $i = 0
    foreach ($Module in $CurrentModules)
    {
        $i++
        $Counter = ("[{0,$DigitsLength}/{1,$DigitsLength}]" -f $i, $ModulesCount)
        $CounterLength = $Counter.Length
        Write-Host ('{0} Checking for updated version of module {1} ...' -f $Counter, $Module.Name) -ForegroundColor Green
        try
        {
            $latest = Find-Module $Module.Name -ErrorAction Stop
            if ([version]$Module.Version -lt [version]$latest.version)
            {
                Update-Module -Name $Module.Name -AllowPrerelease:$AllowPrerelease -AcceptLicense -Scope:AllUsers -Force:$True -ErrorAction Stop -WhatIf:$WhatIf.IsPresent
            }
        }
        catch
        {
            Write-Host ("{0$CounterLength} Error updating module {1}!" -f ' ', $Module.Name) -ForegroundColor Red
        }

        # Retrieve newest version number and remove old(er) version(s) if any
        $AllVersions = Get-InstalledModule -Name $Module.Name -AllVersions | Sort-Object PublishedDate -Descending
        $MostRecentVersion = $AllVersions[0].Version
        if ($AllVersions.Count -gt 1 )
        {
            Foreach ($Version in $AllVersions)
            {
                if ($Version.Version -ne $MostRecentVersion)
                {
                    try
                    {
                        Write-Host ("{0,$CounterLength} Uninstalling previous version {1} of module {2} ..." -f ' ', $Version.Version, $Module.Name) -ForegroundColor Gray
                        Uninstall-Module -Name $Module.Name -RequiredVersion $Version.Version -Force:$True -ErrorAction Stop -AllowPrerelease -WhatIf:$WhatIf.IsPresent
                    }
                    catch
                    {
                        Write-Warning ("{0,$CounterLength} Error uninstalling previous version {1} of module {2}!" -f ' ', $Version.Version, $Module.Name)
                    }
                }
            }
        }
    }

    # Get the new module versions for comparing them to to previous one if updated
    $NewModules = Get-InstalledModule -Name $Name | Select-Object Name, Version | Sort-Object Name
    if ($NewModules)
    {
        ''
        Write-Host ('List of updated modules:') -ForegroundColor Green
        $NoUpdatesFound = $true
        foreach ($Module in $NewModules)
        {
            $CurrentVersion = $CurrentModules | Where-Object Name -EQ $Module.Name
            if ($CurrentVersion.Version -notlike $Module.Version)
            {
                $NoUpdatesFound = $false
                Write-Host ('- Updated module {0} from version {1} to {2}' -f $Module.Name, $CurrentVersion.Version, $Module.Version) -ForegroundColor Green
            }
        }

        if ($NoUpdatesFound)
        {
            Write-Host ('No modules were updated.') -ForegroundColor Gray
        }
    }
}