Get-DiskUsage.ps1

[OutputType([System.IO.FileSystemInfo])] # +Property(Bytes, HumanBytes)
[CmdletBinding(
    DefaultParameterSetName = "Path"
)]
param (
    [Parameter(
        Position = 0,
        ValueFromPipeline,
        ParameterSetName = "FileSystemInfo")]
    [ValidateNotNullOrEmpty()]
    [System.IO.FileSystemInfo[]] $FileSystemInfo,

    [Parameter(
        Position = 0,
        ValueFromPipeline,
        ParameterSetName = "Path",
        ValueFromPipelineByPropertyName)]
    [ValidateNotNullOrEmpty()]
    [string[]] $Path = (Get-Location).Path,

    [Parameter(
        Position = 0,
        ParameterSetName = "LiteralPath",
        ValueFromPipelineByPropertyName)]
    [ValidateNotNullOrEmpty()]
    [string[]] $LiteralPath,

    [Parameter()]
    [Alias("d")]
    [ValidateNotNullOrEmpty()]
    [int] $Depth = 0,

    [Parameter()]
    [switch] $Force
)

function Format-Bytes {
    [OutputType([string])]
    [CmdletBinding()]
    param (
        [Parameter(Position = 0, Mandatory, ValueFromPipeline)]
        [long] $Value,
        [Parameter(Position = 1)]
        [int] $DecimalPlaces = 1
    )
    if ($DecimalPlaces -lt 0) {
        $DecimalPlaces = 0
    }

    if ($Value -lt 0) {
        return $('-' + (Format-Bytes [System.Math]::Abs($Value) $DecimalPlaces))
    }

    return $(switch ($Value) {
            { $_ -lt 1KB } { "{0:n$DecimalPlaces} B" -f $Value; break }
            { $_ -lt 1MB } { "{0:n$DecimalPlaces} KB" -f ($Value / 1KB); break }
            { $_ -lt 1GB } { "{0:n$DecimalPlaces} MB" -f ($Value / 1MB); break }
            { $_ -lt 1TB } { "{0:n$DecimalPlaces} GB" -f ($Value / 1GB); break }
            { $_ -lt 1PB } { "{0:n$DecimalPlaces} TB" -f ($Value / 1TB); break }
            default { "{0:n$DecimalPlaces} PB" -f ($Value / 1PB) }
        })
}

function Set-DefaultDisplayPropertySet(
    [Parameter(Mandatory, ValueFromPipeline)]
    [Object] $InputObject,
    [parameter(Mandatory, Position = 0)]
    [string[]] $DefaultProperties
) {
    $defaultDisplayPropertySet = New-Object Management.Automation.PSPropertySet(
        'DefaultDisplayPropertySet', [string[]] $DefaultProperties
    )
    $PSStandardMembers = [Management.Automation.PSMemberInfo[]] @($defaultDisplayPropertySet)
    $InputObject | Add-Member MemberSet PSStandardMembers $PSStandardMembers -Force -PassThru
}

$items = if ($FileSystemInfo) {
    $FileSystemInfo
}
elseif ($Depth) {
    if ($LiteralPath) {
        Get-ChildItem -LiteralPath $LiteralPath -Depth ($Depth - 1) -Force:$Force
    }
    else {
        Get-ChildItem -Path $Path -Depth ($Depth - 1) -Force:$Force
    }
}
else {
    if ($LiteralPath) {
        Get-Item -LiteralPath $LiteralPath -Force:$Force
    }
    else {
        Get-Item -Path $Path -Force:$Force
    }
}

$items | ForEach-Object {
    $_ | Add-Member Bytes ([long] (Get-ChildItem -LiteralPath $_.FullName -File -Recurse -Force:$Force | Measure-Object Length -Sum).Sum)
    $_ | Add-Member HumanBytes (Format-Bytes $_.Bytes)
    $_ | Select-Object * | Set-DefaultDisplayPropertySet Bytes, HumanBytes, Mode, FullName
}