functions/utility/Resolve-PSFDefaultParameterValue.ps1

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function Resolve-PSFDefaultParameterValue
{
<#
    .SYNOPSIS
        Used to filter and process default parameter values.
     
    .DESCRIPTION
        This command picks all the default parameter values from a reference hashtable.
        It then filters all that match a specified command and binds them to that specific command, narrowing its focus.
        These get merged into either a new or a specified hashtable and returned.
     
    .PARAMETER Reference
        The hashtable to pick default parameter valeus from.
     
    .PARAMETER CommandName
        The commands to pick default parameter values for.
     
    .PARAMETER Target
        The target hashtable to merge results into.
        By default an empty hashtable is used.
     
    .PARAMETER ParameterName
        Only resolve for specific parameter names.
     
    .EXAMPLE
        PS C:\> Resolve-PSFDefaultParameterValue -Reference $global:PSDefaultParameterValues -CommandName 'Invoke-WebRequest'
     
        Returns a hashtable containing all default parameter values in the global scope affecting the command 'Invoke-WebRequest'.
#>

    [OutputType([System.Collections.Hashtable])]
    [CmdletBinding()]
    param (
        [Parameter(Mandatory = $true)]
        [System.Collections.Hashtable]
        $Reference,
        
        [Parameter(Mandatory = $true)]
        [string[]]
        $CommandName,
        
        [System.Collections.Hashtable]
        $Target = @{ },
        
        [string[]]
        $ParameterName = "*"
    )
    
    begin
    {
        $defaultItems = @()
        foreach ($key in $Reference.Keys)
        {
            $defaultItems += [PSCustomObject]@{
                Key        = $key
                Value   = $Reference[$key]
                Command = $key.Split(":")[0]
                Parameter = $key.Split(":")[1]
            }
        }
    }
    process
    {
        foreach ($command in $CommandName)
        {
            foreach ($item in $defaultItems)
            {
                if ($command -notlike $item.Command) { continue }
                
                foreach ($parameter in $ParameterName)
                {
                    if ($item.Parameter -like $parameter)
                    {
                        if ($parameter -ne "*") { $Target["$($command):$($parameter)"] = $item.Value }
                        else { $Target["$($command):$($item.Parameter)"] = $item.Value }
                    }
                }
            }
        }
    }
    end
    {
        $Target
    }
}