#Script créé par Nicolas Lang - Sous licence CC-BY-SA
#https://nicolaslang.fr

function Get-LinuxGroups 
{
    [CmdletBinding(
        SupportsShouldProcess=$false,
        HelpUri="http://nicolaslang.blogspot.com"
    )]
    param(
    [Parameter (Position=0, ValueFromPipeline=$true, ValueFromPipelineByPropertyName=$true)]
    [ValidateNotNullOrEmpty()]
    [string]$Name,
    [Parameter (Mandatory=$false)]
    [ValidateNotNullOrEmpty()]
    [ValidatePattern('(?&ltpropertyname&gt(Name|ID_Group|Member))\s+(?&ltoperator&gt(-like|-eq|-ceq|-clike))\s+"(?&ltvalue&gt.*)"')]
    [string]$filter
    )
    begin
    {
        $groups = Get-Content /etc/group
        $grouparray = New-Object System.Collections.ArrayList

        $maxgroup = 0
        #Calcul de la valeur maxgroup
        foreach ($group in $groups)
        {
            $splitted = $group.split(":")
            $count = $splitted[-1].split(",")
            
            if ($count.count -gt $maxgroup)
            {
                $maxgroup = $count.count
                
            }
        }

        foreach ($group in $groups)
        {
            $splitted = $group.split(":")
            $count = $splitted[-1].split(",")
            $object = [PSCustomObject]@{
                "Name" = $splitted[0]
                "ID_Group" = $splitted[2]
            }
            $loop = 0
            
            foreach ($member in $count)
            {
                $object | Add-Member -Name "Member $($loop + 1)" -MemberType NoteProperty -Value $member 
                $loop++
            }
            while ($loop -lt $maxgroup)
            {
                $object | Add-Member -Name "Member $($loop + 1)" -MemberType NoteProperty -Value ""
                $loop++

            }
            

            $object | Add-Member -name "TotalList" -MemberType NoteProperty -Value $count
            $grouparray.Add($object) | Out-Null    
        }

            #Définition des paramètres affichés par défaut


            $defaultProperties = ($grouparray | Get-Member | Where-Object {$_.membertype -eq "NoteProperty" -and $_.name -like "Member*"}).Name
            $defaultDisplayPropertySet = New-Object System.Management.Automation.PSPropertySet(‘DefaultDisplayPropertySet’,[string[]]$defaultProperties)
            $defaultdisplaypropertyset.ReferencedPropertyNames.insert(0,"ID_Group")
            $defaultdisplaypropertyset.ReferencedPropertyNames.insert(0,"Name")
            $PSStandardMembers = [System.Management.Automation.PSMemberInfo[]]@($defaultDisplayPropertySet)

            $grouparray | Add-Member MemberSet PSStandardMembers $PSStandardMembers

    }

    Process
    {
        if ($filter)
        {
            $filter -match '(?&ltpropertyname&gt(Name|ID_Group|Member))\s+(?&ltoperator&gt(-like|-eq|-ceq|-clike))\s+"(?&ltvalue&gt.*)"' | Out-Null
            
            if ($matches.propertyname -eq "Member")
            {
             

                Switch ($matches.operator)
                {
                    "-like" {
                                $return = $grouparray | Where-object {$_.totallist.split(",") -like "$($matches.value)"}
                            }
                    "-clike"{
                                $return = $grouparray | Where-object {$_.totallist.split(",") -clike "$($matches.value)"}
                            }
                    "-eq"   {
                                $return = $grouparray | Where-object {$_.totallist.split(",") -eq "$($matches.value)"}
                            }   
                    "-ceq"  {
                                $return = $grouparray | Where-object {$_.totallist.split(",") -ceq "$($matches.value)"}
                            }
                }

                return $return
            }
            else 
            {
                Switch ($matches.operator)
                {
                    "-like" {$return = $grouparray | Where-Object {$_.$($matches.propertyname) -like "$($matches.value)"}}
                    "-clike"{$return = $grouparray | Where-Object {$_.$($matches.propertyname) -clike "$($matches.value)"}}
                    "-eq"   {$return = $grouparray | Where-Object {$_.$($matches.propertyname) -eq "$($matches.value)"}}
                    "-ceq"  {$return = $grouparray | Where-Object {$_.$($matches.propertyname) -ceq "$($matches.value)"}}
                }
                return $return
            }
        }
        elseif ($name)
        {
            return $($grouparray | Where-Object {$_.name -eq $name})
        }
        else 
        {
            return $grouparray    
        }
    }
}