Get-AzurePowerShellMSI.ps1

Function Test-Url {
    [CmdletBinding()]
    param (
        [Parameter(Mandatory=$true)]
        [String] $Url
    )

    Process {
        if ([system.uri]::IsWellFormedUriString($Url,[System.UriKind]::Absolute)) {
            $true
        } else {
            $false
        }
    }
}

Function Get-AzurePowerShellMSI {
    [CmdletBinding()]
    param (
        [String]$Url = 'https://github.com/Azure/azure-powershell/releases',
        [Switch]$DownloadLatest,
        [String]$DownloadPath = "$env:USERPROFILE\Downloads",
        [Switch]$Passthru
    )

    Process {
        $Msi = @()
        $doc = Invoke-WebRequest -Uri $Url

        foreach ($href in ($doc.links.href -ne '')) {
            if ((Test-Url -Url $href) -and $href.EndsWith('.msi')) {
                $Msi += New-Object -TypeName PSObject -Property @{
                    "Url" = $href
                    "Version" = ([Regex]::Match($href,'\bv?[0-9]+\.[0-9]+\.[0-9]+(?:\.[0-9]+)?\b')).Value
                }
            }
        }

        if ($DownloadLatest) {
            if (-not (Test-Path $DownloadPath -PathType Container)) {
                Write-Warning "${DownloadPath} does not exist. Creating it ..."
                New-Item -Path $DownloadPath -ItemType Directory -ErrorAction Stop | Out-Null
            }

            $MsiFullPath = "${DownloadPath}\$(Split-Path -Path $Msi[0].Url -Leaf)"

            if (-not (Test-Path -Path $MsiFullPath)) {
                Write-Verbose "Starting MSI download from $($Msi[0].Url)"
                Start-BitsTransfer -Source $Msi[0].Url -Destination $MsiFullPath -ErrorAction Stop
            } else {
                Write-Warning ("{0} already exists at {1}. No action needed." -f $MsiFullPath, $DownloadPath)
            }

            if ($Passthru) {
                return $MsiFullPath
            }

        } else {
            $Msi
        }
    }
}