<#
.SYNOPSIS
    GUI tool to export all members of an AD group (including nested groups) to a CSV file.
.PARAMETER LogPath
    Optional path for the log file. Defaults to script directory with a timestamp.
#>

param (
    [string]$LogPath = (Join-Path $PSScriptRoot ("export_log_" + (Get-Date -Format 'yyyyMMdd_HHmmss') + ".txt"))
)

Add-Type -AssemblyName System.Windows.Forms
Add-Type -AssemblyName System.Drawing
[System.Windows.Forms.Application]::EnableVisualStyles()

# ---------------------------------------------------------------------------
# Ensure AD module is loaded — called lazily before first AD operation
# ---------------------------------------------------------------------------
function Initialize-ADModule {
    if (Get-Module -Name ActiveDirectory) { return $true }

    if (-not (Get-Module -Name ActiveDirectory -ListAvailable)) {
        $isAdmin = ([Security.Principal.WindowsPrincipal][Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole(
            [Security.Principal.WindowsBuiltInRole]::Administrator)
        if (-not $isAdmin) {
            [System.Windows.Forms.MessageBox]::Show(
                "Das ActiveDirectory-Modul wurde nicht gefunden.`nBitte das Skript als Administrator starten.",
                "Modul fehlt", "OK", "Error") | Out-Null
            return $false
        }
        try {
            $os = (Get-CimInstance Win32_OperatingSystem).Caption
            if ($os -match "Server") {
                Import-Module ServerManager -ErrorAction Stop
                Add-WindowsFeature RSAT-AD-PowerShell -ErrorAction Stop | Out-Null
            } else {
                $feature = Get-WindowsCapability -Name "Rsat.ActiveDirectory*" -Online -ErrorAction Stop |
                           Where-Object State -ne Installed | Select-Object -First 1
                if ($feature) {
                    Add-WindowsCapability -Name $feature.Name -Online -ErrorAction Stop | Out-Null
                }
            }
        } catch {
            [System.Windows.Forms.MessageBox]::Show(
                "RSAT konnte nicht installiert werden:`n$_", "Fehler", "OK", "Error") | Out-Null
            return $false
        }
    }

    try {
        Import-Module ActiveDirectory -ErrorAction Stop -WarningAction SilentlyContinue
        return $true
    } catch {
        [System.Windows.Forms.MessageBox]::Show(
            "ActiveDirectory-Modul konnte nicht geladen werden:`n$_", "Fehler", "OK", "Error") | Out-Null
        return $false
    }
}

# ---------------------------------------------------------------------------
# Script-scope state for the recursive export
# ---------------------------------------------------------------------------
$script:visitedGroups  = $null
$script:exportResults  = $null
$script:exportAdParams = $null

# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------
function Write-Log {
    param([string]$Message, [string]$Level = 'INFO')
    $entry = "[{0}] [{1}] {2}" -f (Get-Date -Format 'yyyy-MM-dd HH:mm:ss'), $Level, $Message
    $entry | Out-File -FilePath $LogPath -Append -Encoding UTF8

    $color = switch ($Level) {
        'ERROR' { [System.Drawing.Color]::Salmon }
        'WARN'  { [System.Drawing.Color]::Goldenrod }
        default { [System.Drawing.Color]::White }
    }
    Write-OutputLine $entry $color
}

function Write-OutputLine {
    param([string]$Text, [System.Drawing.Color]$Color = [System.Drawing.Color]::White)
    $script:rtbOutput.SelectionStart  = $script:rtbOutput.TextLength
    $script:rtbOutput.SelectionLength = 0
    $script:rtbOutput.SelectionColor  = $Color
    $script:rtbOutput.AppendText("$Text`n")
    $script:rtbOutput.ScrollToCaret()
    [System.Windows.Forms.Application]::DoEvents()
}

function Get-NestedMembers {
    param([string]$Group, [string]$SourceGroup)

    if (-not $script:visitedGroups.Add($Group)) { return }

    try {
        $members = Get-ADGroupMember -Identity $Group -ErrorAction Stop @script:exportAdParams
    } catch {
        Write-Log "Gruppe '$Group' konnte nicht abgerufen werden: $_" -Level WARN
        return
    }

    foreach ($member in $members) {
        switch ($member.objectClass) {
            'user' {
                try {
                    $user = Get-ADUser -Identity $member.distinguishedName -Properties `
                        DisplayName, EmailAddress, Title, Department, Company,
                        Enabled, LastLogonDate, PasswordLastSet, PasswordNeverExpires,
                        Manager, telephoneNumber, DistinguishedName `
                        -ErrorAction Stop @script:exportAdParams

                    $managerName = ''
                    if ($user.Manager) {
                        try {
                            $mgr = Get-ADUser -Identity $user.Manager -Properties DisplayName `
                                -ErrorAction Stop @script:exportAdParams
                            $managerName = $mgr.DisplayName
                        } catch {}
                    }

                    $script:exportResults.Add([PSCustomObject]@{
                        SourceGroup          = $SourceGroup
                        MemberOfGroup        = $Group
                        SamAccountName       = $user.SamAccountName
                        DisplayName          = $user.DisplayName
                        GivenName            = $user.GivenName
                        Surname              = $user.Surname
                        EmailAddress         = $user.EmailAddress
                        Title                = $user.Title
                        Department           = $user.Department
                        Company              = $user.Company
                        TelephoneNumber      = $user.telephoneNumber
                        Enabled              = $user.Enabled
                        LastLogonDate        = $user.LastLogonDate
                        PasswordLastSet      = $user.PasswordLastSet
                        PasswordNeverExpires = $user.PasswordNeverExpires
                        Manager              = $managerName
                        DistinguishedName    = $user.DistinguishedName
                    })
                    Write-Log "  Benutzer: $($user.SamAccountName) ($($user.DisplayName))"
                } catch {
                    Write-Log "Benutzer '$($member.SamAccountName)' konnte nicht abgerufen werden: $_" -Level WARN
                }
            }
            'group' {
                Write-Log "Verschachtelte Gruppe: $($member.Name)"
                Get-NestedMembers -Group $member.distinguishedName -SourceGroup $SourceGroup
            }
        }
    }
}

function Start-Export {
    param([string]$GroupName, [string]$OutputPath, [string]$Server)

    $script:btnExport.Enabled = $false
    $script:rtbOutput.Clear()

    if (-not (Initialize-ADModule)) {
        $script:btnExport.Enabled = $true
        return
    }

    $script:exportAdParams = @{}
    if ($Server) { $script:exportAdParams['Server'] = $Server }

    try {
        $null = Get-ADGroup -Identity $GroupName -ErrorAction Stop @script:exportAdParams
        Write-Log "Gruppe gefunden: $GroupName"
    } catch {
        Write-Log "Gruppe '$GroupName' nicht gefunden: $_" -Level ERROR
        $script:btnExport.Enabled = $true
        return
    }

    $script:visitedGroups = [System.Collections.Generic.HashSet[string]]::new(
        [System.StringComparer]::OrdinalIgnoreCase)
    $script:exportResults = [System.Collections.Generic.List[PSCustomObject]]::new()

    Write-Log "Starte Export für '$GroupName' (inkl. verschachtelter Gruppen)..."
    Get-NestedMembers -Group $GroupName -SourceGroup $GroupName

    if ($script:exportResults.Count -eq 0) {
        Write-Log "Keine Benutzer in Gruppe '$GroupName' gefunden." -Level WARN
        $script:btnExport.Enabled = $true
        return
    }

    $unique = $script:exportResults | Sort-Object SamAccountName -Unique

    try {
        $unique | Export-Csv -Path $OutputPath -NoTypeInformation -Encoding UTF8 -Delimiter ';' -ErrorAction Stop
        $msg = "Export abgeschlossen.  Benutzer: {0}  |  Gruppen: {1}  |  Datei: {2}" -f `
               $unique.Count, $script:visitedGroups.Count, $OutputPath
        Write-Log $msg
        Write-OutputLine $msg ([System.Drawing.Color]::LightGreen)
    } catch {
        Write-Log "Fehler beim Schreiben der CSV: $_" -Level ERROR
    }

    $script:btnExport.Enabled = $true
}

# ---------------------------------------------------------------------------
# Form
# ---------------------------------------------------------------------------
$form                 = New-Object System.Windows.Forms.Form
$form.Text            = "AD Group Export"
$form.Size            = New-Object System.Drawing.Size(680, 600)
$form.StartPosition   = "CenterScreen"
$form.FormBorderStyle = "FixedDialog"
$form.MaximizeBox     = $false
$form.BackColor       = [System.Drawing.Color]::FromArgb(30, 30, 30)
$form.ForeColor       = [System.Drawing.Color]::White
$form.Font            = New-Object System.Drawing.Font('Segoe UI', 9)

$pad = 16

# --- Group row ---
$lblGroup          = New-Object System.Windows.Forms.Label
$lblGroup.Text     = "AD Gruppe:"
$lblGroup.Location = New-Object System.Drawing.Point($pad, 20)
$lblGroup.Size     = New-Object System.Drawing.Size(84, 22)
$form.Controls.Add($lblGroup)

$cmbGroup                    = New-Object System.Windows.Forms.ComboBox
$cmbGroup.Location           = New-Object System.Drawing.Point(104, 18)
$cmbGroup.Size               = New-Object System.Drawing.Size(436, 22)
$cmbGroup.BackColor          = [System.Drawing.Color]::FromArgb(45, 45, 45)
$cmbGroup.ForeColor          = [System.Drawing.Color]::White
$cmbGroup.FlatStyle          = "Flat"
$cmbGroup.AutoCompleteMode   = "SuggestAppend"
$cmbGroup.AutoCompleteSource = "ListItems"
$form.Controls.Add($cmbGroup)

$btnLoadGroups            = New-Object System.Windows.Forms.Button
$btnLoadGroups.Text       = "Gruppen laden"
$btnLoadGroups.Location   = New-Object System.Drawing.Point(550, 16)
$btnLoadGroups.Size       = New-Object System.Drawing.Size(96, 26)
$btnLoadGroups.BackColor  = [System.Drawing.Color]::FromArgb(0, 122, 204)
$btnLoadGroups.ForeColor  = [System.Drawing.Color]::White
$btnLoadGroups.FlatStyle  = "Flat"
$btnLoadGroups.FlatAppearance.BorderSize = 0
$form.Controls.Add($btnLoadGroups)

$btnLoadGroups.Add_Click({
    if (-not (Initialize-ADModule)) { return }
    $btnLoadGroups.Text    = "Lädt..."
    $btnLoadGroups.Enabled = $false
    [System.Windows.Forms.Application]::DoEvents()
    try {
        $adP = @{}
        if ($txtServer.Tag) { $adP['Server'] = $txtServer.Tag }
        $groups = Get-ADGroup -Filter * @adP | Select-Object -ExpandProperty Name | Sort-Object
        $cmbGroup.Items.Clear()
        $cmbGroup.Items.AddRange($groups)
        Write-OutputLine "$($groups.Count) Gruppen geladen." ([System.Drawing.Color]::LightGreen)
    } catch {
        Write-OutputLine "Fehler beim Laden der Gruppen: $_" ([System.Drawing.Color]::Salmon)
    }
    $btnLoadGroups.Text    = "Gruppen laden"
    $btnLoadGroups.Enabled = $true
})

# --- CSV output row ---
$lblOut          = New-Object System.Windows.Forms.Label
$lblOut.Text     = "CSV Datei:"
$lblOut.Location = New-Object System.Drawing.Point($pad, 58)
$lblOut.Size     = New-Object System.Drawing.Size(84, 22)
$form.Controls.Add($lblOut)

$txtOut             = New-Object System.Windows.Forms.TextBox
$txtOut.Location    = New-Object System.Drawing.Point(104, 56)
$txtOut.Size        = New-Object System.Drawing.Size(436, 22)
$txtOut.BackColor   = [System.Drawing.Color]::FromArgb(45, 45, 45)
$txtOut.ForeColor   = [System.Drawing.Color]::White
$txtOut.BorderStyle = "FixedSingle"
$txtOut.Text        = if ($PSScriptRoot) { Join-Path $PSScriptRoot "export.csv" } else { "export.csv" }
$form.Controls.Add($txtOut)

$btnBrowse            = New-Object System.Windows.Forms.Button
$btnBrowse.Text       = "Speichern..."
$btnBrowse.Location   = New-Object System.Drawing.Point(550, 54)
$btnBrowse.Size       = New-Object System.Drawing.Size(96, 26)
$btnBrowse.BackColor  = [System.Drawing.Color]::FromArgb(0, 122, 204)
$btnBrowse.ForeColor  = [System.Drawing.Color]::White
$btnBrowse.FlatStyle  = "Flat"
$btnBrowse.FlatAppearance.BorderSize = 0
$form.Controls.Add($btnBrowse)

$btnBrowse.Add_Click({
    $sfd          = New-Object System.Windows.Forms.SaveFileDialog
    $sfd.Filter   = "CSV files (*.csv)|*.csv|All files (*.*)|*.*"
    $sfd.Title    = "CSV-Datei speichern"
    $sfd.FileName = "export.csv"
    if ($sfd.ShowDialog() -eq "OK") { $txtOut.Text = $sfd.FileName }
})

# --- Server row ---
$lblServer          = New-Object System.Windows.Forms.Label
$lblServer.Text     = "DC (optional):"
$lblServer.Location = New-Object System.Drawing.Point($pad, 96)
$lblServer.Size     = New-Object System.Drawing.Size(84, 22)
$form.Controls.Add($lblServer)

$txtServer             = New-Object System.Windows.Forms.TextBox
$txtServer.Location    = New-Object System.Drawing.Point(104, 94)
$txtServer.Size        = New-Object System.Drawing.Size(436, 22)
$txtServer.BackColor   = [System.Drawing.Color]::FromArgb(45, 45, 45)
$txtServer.BorderStyle = "FixedSingle"
$txtServer.Tag         = ''
$txtServer.Text        = 'Domänencontroller (leer = Standard)'
$txtServer.ForeColor   = [System.Drawing.Color]::Gray
$form.Controls.Add($txtServer)

$txtServer.Add_GotFocus({
    if ($txtServer.Tag -eq '') {
        $txtServer.Text      = ''
        $txtServer.ForeColor = [System.Drawing.Color]::White
    }
})
$txtServer.Add_LostFocus({
    $txtServer.Tag = $txtServer.Text.Trim()
    if ($txtServer.Tag -eq '') {
        $txtServer.Text      = 'Domänencontroller (leer = Standard)'
        $txtServer.ForeColor = [System.Drawing.Color]::Gray
    }
})

# --- Separator ---
$sep           = New-Object System.Windows.Forms.Panel
$sep.Location  = New-Object System.Drawing.Point($pad, 130)
$sep.Size      = New-Object System.Drawing.Size(632, 1)
$sep.BackColor = [System.Drawing.Color]::FromArgb(70, 70, 70)
$form.Controls.Add($sep)

# --- Export button ---
$script:btnExport            = New-Object System.Windows.Forms.Button
$script:btnExport.Text       = "Export starten"
$script:btnExport.Location   = New-Object System.Drawing.Point($pad, 140)
$script:btnExport.Size       = New-Object System.Drawing.Size(632, 34)
$script:btnExport.BackColor  = [System.Drawing.Color]::FromArgb(16, 124, 16)
$script:btnExport.ForeColor  = [System.Drawing.Color]::White
$script:btnExport.FlatStyle  = "Flat"
$script:btnExport.FlatAppearance.BorderSize = 0
$script:btnExport.Font       = New-Object System.Drawing.Font('Segoe UI', 10, [System.Drawing.FontStyle]::Bold)
$form.Controls.Add($script:btnExport)

$script:btnExport.Add_Click({
    $groupName  = $cmbGroup.Text.Trim()
    $outputPath = $txtOut.Text.Trim()
    $server     = $txtServer.Tag

    if (-not $groupName) {
        [System.Windows.Forms.MessageBox]::Show(
            "Bitte eine AD-Gruppe eingeben oder auswählen.", "Validierung", "OK", "Warning") | Out-Null
        return
    }
    if (-not $outputPath) {
        [System.Windows.Forms.MessageBox]::Show(
            "Bitte einen Speicherpfad für die CSV angeben.", "Validierung", "OK", "Warning") | Out-Null
        return
    }

    Start-Export -GroupName $groupName -OutputPath $outputPath -Server $server
})

# --- Output panel ---
$lblOutput          = New-Object System.Windows.Forms.Label
$lblOutput.Text     = "Output:"
$lblOutput.Location = New-Object System.Drawing.Point($pad, 186)
$lblOutput.Size     = New-Object System.Drawing.Size(80, 18)
$form.Controls.Add($lblOutput)

$script:rtbOutput            = New-Object System.Windows.Forms.RichTextBox
$script:rtbOutput.Location   = New-Object System.Drawing.Point($pad, 206)
$script:rtbOutput.Size       = New-Object System.Drawing.Size(632, 320)
$script:rtbOutput.BackColor  = [System.Drawing.Color]::FromArgb(12, 12, 12)
$script:rtbOutput.ForeColor  = [System.Drawing.Color]::White
$script:rtbOutput.Font       = New-Object System.Drawing.Font('Consolas', 9)
$script:rtbOutput.ReadOnly   = $true
$script:rtbOutput.BorderStyle = "None"
$script:rtbOutput.ScrollBars = "Vertical"
$form.Controls.Add($script:rtbOutput)

# --- Status bar ---
$lblStatus           = New-Object System.Windows.Forms.Label
$lblStatus.Text      = "Log: $LogPath"
$lblStatus.Location  = New-Object System.Drawing.Point($pad, 536)
$lblStatus.Size      = New-Object System.Drawing.Size(632, 18)
$lblStatus.ForeColor = [System.Drawing.Color]::Gray
$lblStatus.Font      = New-Object System.Drawing.Font('Segoe UI', 8)
$form.Controls.Add($lblStatus)

# ---------------------------------------------------------------------------
$form.ShowDialog() | Out-Null
$form.Dispose()