Cake task autocomplete in powershell

build.ps1

[CmdletBinding()]
Param(
    [string]$Script = "build.cake",
    [ValidateSet("Quiet", "Minimal", "Normal", "Verbose", "Diagnostic")]
    [string]$Verbosity = "Normal",
    [Parameter(Position = 0, Mandatory = $false, ValueFromRemainingArguments = $true)]
    [string[]]$ScriptArgs
)

dynamicparam {
    # user defined files where to search for tasks
    $files = Get-ChildItem .\BuildScripts\*.cake -Recurse
    $files += (Get-ChildItem build.cake)

    # Regex to get the task names
    $values = $files | Select-String '^.*Task\("(.*)"\).*$' | % { $_.Matches[0].Groups[1].Value }

    # create validate set attribute
    $ValidateSet = new-object System.Management.Automation.ValidateSetAttribute($values)

    $attributes = new-object System.Management.Automation.ParameterAttribute
    $attributes.ParameterSetName = "__AllParameterSets"
    $attributes.Mandatory = $true

    $attributeCollection = new-object -Type System.Collections.ObjectModel.Collection[System.Attribute]

    $attributeCollection.Add($attributes)
    $attributeCollection.Add($ValidateSet)

    $dynParam1 = new-object -Type System.Management.Automation.RuntimeDefinedParameter("Target", [string], $attributeCollection)
    $paramDictionary = new-object -Type System.Management.Automation.RuntimeDefinedParameterDictionary
    $paramDictionary.Add("Target", $dynParam1)
    return $paramDictionary
}

process {
   # The actual bootstraping file here
}