<#
.SYNOPSIS
    GUI tool to import users from a CSV and add them to an Active Directory group.

.DESCRIPTION
    Opens a Windows Forms GUI. The user selects a CSV file (Username or
    SamAccountName column) and picks a target AD group, then clicks Import.
    Results and a log are shown in the output panel.

.PARAMETER LogPath
    Optional path for the log file. Defaults to script directory with a timestamp.
#>

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

# ---------------------------------------------------------------------------
# Ensure ActiveDirectory module is available
# ---------------------------------------------------------------------------
if (-not (Get-Module -Name ActiveDirectory -ListAvailable)) {
    # Installing RSAT requires elevation - check before attempting
    $isAdmin = ([Security.Principal.WindowsPrincipal][Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator)
    if (-not $isAdmin) {
        Write-Error "ActiveDirectory module not found. Please run this script as Administrator to install it automatically, or install RSAT manually."
        exit 1
    }

    Write-Host "ActiveDirectory module not found. Attempting to install..." -ForegroundColor Yellow

    $os = (Get-CimInstance Win32_OperatingSystem).Caption

    if ($os -match "Server") {
        try {
            Import-Module ServerManager -ErrorAction Stop
            Add-WindowsFeature RSAT-AD-PowerShell -ErrorAction Stop | Out-Null
            Write-Host "ActiveDirectory module installed via Add-WindowsFeature." -ForegroundColor Green
        } catch {
            Write-Error "Failed to install ActiveDirectory module on Server: $_"
            exit 1
        }
    } else {
        try {
            $feature = Get-WindowsCapability -Name "Rsat.ActiveDirectory*" -Online -ErrorAction Stop |
                       Where-Object State -ne Installed |
                       Select-Object -First 1
            if ($feature) {
                Add-WindowsCapability -Name $feature.Name -Online -ErrorAction Stop | Out-Null
                Write-Host "ActiveDirectory module installed via Add-WindowsCapability." -ForegroundColor Green
            } else {
                Write-Host "RSAT ActiveDirectory feature already present." -ForegroundColor Green
            }
        } catch {
            Write-Error "Failed to install ActiveDirectory module on Windows client: $_"
            exit 1
        }
    }
}

try {
    Import-Module ActiveDirectory -ErrorAction Stop
} catch {
    Write-Error "ActiveDirectory module could not be loaded: $_"
    exit 1
}

Add-Type -AssemblyName System.Windows.Forms
Add-Type -AssemblyName System.Drawing

[System.Windows.Forms.Application]::EnableVisualStyles()

# ---------------------------------------------------------------------------
# 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 Start-Import {
    param([string]$CsvPath, [string]$GroupName)

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

    try {
        $group = Get-ADGroup -Identity $GroupName -ErrorAction Stop
        Write-Log "Target group: $($group.DistinguishedName)"
    } catch {
        Write-Log "Group '$GroupName' not found: $_" -Level ERROR
        $script:btnImport.Enabled = $true
        return
    }

    try {
        $csv = Import-Csv -Path $CsvPath -ErrorAction Stop
    } catch {
        Write-Log "Failed to read CSV: $_" -Level ERROR
        $script:btnImport.Enabled = $true
        return
    }

    if ($csv.Count -eq 0) {
        Write-Log "CSV is empty." -Level WARN
        $script:btnImport.Enabled = $true
        return
    }

    $header = $csv[0].PSObject.Properties.Name |
              Where-Object { $_ -in @('Username', 'SamAccountName') } |
              Select-Object -First 1

    if (-not $header) {
        $found = $csv[0].PSObject.Properties.Name -join ', '
        Write-Log "CSV must contain a 'Username' or 'SamAccountName' column. Found: $found" -Level ERROR
        $script:btnImport.Enabled = $true
        return
    }

    Write-Log "Processing $($csv.Count) row(s) using column '$header'."

    $stats = @{ Added = 0; Skipped = 0; NotFound = 0; Errors = 0 }

    foreach ($row in $csv) {
        $sam = $row.$header.Trim()
        if ([string]::IsNullOrWhiteSpace($sam)) {
            Write-Log "Empty username - skipping." -Level WARN
            $stats.Skipped++
            continue
        }

        try {
            $user = Get-ADUser -Identity $sam -ErrorAction Stop
        } catch {
            Write-Log "User '$sam' not found in AD - skipping." -Level WARN
            $stats.NotFound++
            continue
        }

        $isMember = Get-ADGroupMember -Identity $group -Recursive |
                    Where-Object { $_.SamAccountName -eq $sam }

        if ($isMember) {
            Write-Log "User '$sam' is already a member - skipping." -Level WARN
            $stats.Skipped++
            continue
        }

        try {
            Add-ADGroupMember -Identity $group -Members $user -ErrorAction Stop
            Write-Log "Added '$sam' to '$GroupName'."
            $stats.Added++
        } catch {
            Write-Log "Failed to add '$sam': $_" -Level ERROR
            $stats.Errors++
        }
    }

    $summary = "Done.  Added: {0}  |  Skipped: {1}  |  Not found: {2}  |  Errors: {3}" -f `
               $stats.Added, $stats.Skipped, $stats.NotFound, $stats.Errors
    Write-Log $summary
    Write-Log "Log saved to: $LogPath"
    $script:btnImport.Enabled = $true
}

# ---------------------------------------------------------------------------
# Form
# ---------------------------------------------------------------------------
$form = New-Object System.Windows.Forms.Form
$form.Text            = "AD Group Import"
$form.Size            = New-Object System.Drawing.Size(680, 560)
$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

# --- CSV row ---
$lblCsv          = New-Object System.Windows.Forms.Label
$lblCsv.Text     = "CSV File:"
$lblCsv.Location = New-Object System.Drawing.Point($pad, 20)
$lblCsv.Size     = New-Object System.Drawing.Size(80, 22)
$form.Controls.Add($lblCsv)

$txtCsv             = New-Object System.Windows.Forms.TextBox
$txtCsv.Location    = New-Object System.Drawing.Point(100, 18)
$txtCsv.Size        = New-Object System.Drawing.Size(440, 22)
$txtCsv.BackColor   = [System.Drawing.Color]::FromArgb(45, 45, 45)
$txtCsv.ForeColor   = [System.Drawing.Color]::White
$txtCsv.BorderStyle = "FixedSingle"
$form.Controls.Add($txtCsv)

$btnBrowse          = New-Object System.Windows.Forms.Button
$btnBrowse.Text     = "Browse..."
$btnBrowse.Location = New-Object System.Drawing.Point(550, 16)
$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({
    $ofd        = New-Object System.Windows.Forms.OpenFileDialog
    $ofd.Filter = "CSV files (*.csv)|*.csv|All files (*.*)|*.*"
    $ofd.Title  = "Select CSV file"
    if ($ofd.ShowDialog() -eq "OK") {
        $txtCsv.Text = $ofd.FileName
    }
})

# --- Group row ---
$lblGroup          = New-Object System.Windows.Forms.Label
$lblGroup.Text     = "AD Group:"
$lblGroup.Location = New-Object System.Drawing.Point($pad, 58)
$lblGroup.Size     = New-Object System.Drawing.Size(80, 22)
$form.Controls.Add($lblGroup)

$cmbGroup                    = New-Object System.Windows.Forms.ComboBox
$cmbGroup.Location           = New-Object System.Drawing.Point(100, 56)
$cmbGroup.Size               = New-Object System.Drawing.Size(440, 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     = "Load Groups"
$btnLoadGroups.Location = New-Object System.Drawing.Point(550, 54)
$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({
    $btnLoadGroups.Text    = "Loading..."
    $btnLoadGroups.Enabled = $false
    [System.Windows.Forms.Application]::DoEvents()
    try {
        $groups = Get-ADGroup -Filter * | Select-Object -ExpandProperty Name | Sort-Object
        $cmbGroup.Items.Clear()
        $cmbGroup.Items.AddRange($groups)
        Write-OutputLine "Loaded $($groups.Count) groups." ([System.Drawing.Color]::LightGreen)
    } catch {
        Write-OutputLine "Failed to load groups: $_" ([System.Drawing.Color]::Salmon)
    }
    $btnLoadGroups.Text    = "Load Groups"
    $btnLoadGroups.Enabled = $true
})

# --- Separator ---
$sep          = New-Object System.Windows.Forms.Panel
$sep.Location = New-Object System.Drawing.Point($pad, 94)
$sep.Size     = New-Object System.Drawing.Size(632, 1)
$sep.BackColor = [System.Drawing.Color]::FromArgb(70, 70, 70)
$form.Controls.Add($sep)

# --- Import button ---
$script:btnImport          = New-Object System.Windows.Forms.Button
$script:btnImport.Text     = "Import Users"
$script:btnImport.Location = New-Object System.Drawing.Point($pad, 104)
$script:btnImport.Size     = New-Object System.Drawing.Size(632, 34)
$script:btnImport.BackColor = [System.Drawing.Color]::FromArgb(16, 124, 16)
$script:btnImport.ForeColor = [System.Drawing.Color]::White
$script:btnImport.FlatStyle = "Flat"
$script:btnImport.FlatAppearance.BorderSize = 0
$script:btnImport.Font = New-Object System.Drawing.Font('Segoe UI', 10, [System.Drawing.FontStyle]::Bold)
$form.Controls.Add($script:btnImport)

$script:btnImport.Add_Click({
    $csvPath   = $txtCsv.Text.Trim()
    $groupName = $cmbGroup.Text.Trim()

    if (-not $csvPath) {
        [System.Windows.Forms.MessageBox]::Show("Please select a CSV file.", "Validation", "OK", "Warning") | Out-Null
        return
    }
    if (-not (Test-Path $csvPath -PathType Leaf)) {
        [System.Windows.Forms.MessageBox]::Show("CSV file not found:`n$csvPath", "Validation", "OK", "Warning") | Out-Null
        return
    }
    if (-not $groupName) {
        [System.Windows.Forms.MessageBox]::Show("Please enter or select an AD group.", "Validation", "OK", "Warning") | Out-Null
        return
    }

    Start-Import -CsvPath $csvPath -GroupName $groupName
})

# --- Output panel ---
$lblOutput          = New-Object System.Windows.Forms.Label
$lblOutput.Text     = "Output:"
$lblOutput.Location = New-Object System.Drawing.Point($pad, 150)
$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, 170)
$script:rtbOutput.Size        = New-Object System.Drawing.Size(632, 310)
$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, 490)
$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()