<#
.SYNOPSIS
  Report on inactive Active Directory user accounts based on true LastLogon

.DESCRIPTION
  Queries all domain controllers to find the most recent LastLogon time for users.
  The LastLogon attribute is not replicated, so each DC must be queried individually
  to get accurate results. Identifies accounts inactive for specified days.

.PARAMETER InactiveDays
  Number of days without logon to consider account inactive (default: 90)

.PARAMETER OutputFolder
  Destination folder for reports. Default: .\InactiveADUsers-<date>

.PARAMETER SearchBase
  Optional OU to limit search scope (default: entire domain)

.PARAMETER IncludeDisabled
  Include disabled accounts in the report (default: $false)

.NOTES
  ⚠️  AI-GENERATED SCRIPT - UNTESTED
  This script was generated by Claude AI and has not been tested in production.
  Review and test thoroughly in a non-production environment before use.

  - Requires Active Directory PowerShell module
  - Run with appropriate AD permissions
  - Can be slow in large environments (queries each DC)
  - LastLogon attribute is not replicated between DCs

.EXAMPLE
  .\Get-ADUserLastLogon.ps1

.EXAMPLE
  .\Get-ADUserLastLogon.ps1 -InactiveDays 180 -SearchBase "OU=Users,DC=domain,DC=com"
#>

[CmdletBinding()]
param(
    [int]$InactiveDays = 90,
    [string]$OutputFolder = (Join-Path -Path (Get-Location) -ChildPath ("InactiveADUsers-" + (Get-Date -Format "yyyyMMdd-HHmm"))),
    [string]$SearchBase = "",
    [bool]$IncludeDisabled = $false
)

function NowTag { (Get-Date).ToString("yyyy-MM-dd HH:mm:ss") }

Write-Host "[$(NowTag)] ⚠️  AI-GENERATED SCRIPT - UNTESTED" -ForegroundColor Yellow
Write-Host "[$(NowTag)] Starting AD user lastlogon analysis..." -ForegroundColor Green

# Import AD module
try {
    Import-Module ActiveDirectory -ErrorAction Stop
} catch {
    Write-Host "[$(NowTag)] ERROR: Active Directory module not available" -ForegroundColor Red
    exit 1
}

# Create output folder
New-Item -ItemType Directory -Path $OutputFolder -Force | Out-Null

$cutoffDate = (Get-Date).AddDays(-$InactiveDays)
Write-Host "[$(NowTag)] Cutoff date: $($cutoffDate.ToString('yyyy-MM-dd'))"

# Get all domain controllers
Write-Host "[$(NowTag)] Discovering domain controllers..."
$domainControllers = Get-ADDomainController -Filter * | Select-Object -ExpandProperty HostName
Write-Host "[$(NowTag)] Found $($domainControllers.Count) domain controller(s)"

# Get all users
Write-Host "[$(NowTag)] Retrieving AD users..."
$getUserParams = @{
    Filter     = "ObjectClass -eq 'user' -and Enabled -eq 'True'"
    Properties = @('LastLogon', 'LastLogonDate', 'WhenCreated', 'Department', 'Title', 'Description', 'PasswordLastSet', 'PasswordNeverExpires', 'Enabled')
}

if ($SearchBase) {
    $getUserParams['SearchBase'] = $SearchBase
}

if ($IncludeDisabled) {
    $getUserParams['Filter'] = "ObjectClass -eq 'user'"
}

$users = Get-ADUser @getUserParams
$userCount = ($users | Measure-Object).Count
Write-Host "[$(NowTag)] Found $userCount user(s) to analyze"

# Query each DC for LastLogon and find the most recent
$userLogonData = @()
$current = 0

foreach ($user in $users) {
    $current++
    $pct = [int](($current / $userCount) * 100)
    Write-Progress -Activity "Querying LastLogon from Domain Controllers" -Status "Processing $($user.SamAccountName) ($current/$userCount)" -PercentComplete $pct

    $mostRecentLogon = $null

    foreach ($dc in $domainControllers) {
        try {
            $userFromDC = Get-ADUser -Identity $user.SamAccountName -Server $dc -Properties LastLogon -ErrorAction SilentlyContinue

            if ($userFromDC.LastLogon) {
                $logonDate = [DateTime]::FromFileTime($userFromDC.LastLogon)

                if ($null -eq $mostRecentLogon -or $logonDate -gt $mostRecentLogon) {
                    $mostRecentLogon = $logonDate
                }
            }
        } catch {
            Write-Verbose "Could not query $dc for $($user.SamAccountName)"
        }
    }

    # Determine if inactive
    $isInactive = $false
    $reason = ""
    $daysSinceLogon = "N/A"

    if ($null -eq $mostRecentLogon) {
        $isInactive = $true
        $reason = "Never logged on"
    } elseif ($mostRecentLogon -lt $cutoffDate) {
        $isInactive = $true
        $daysSinceLogon = [int]((Get-Date) - $mostRecentLogon).TotalDays
        $reason = "Last logon: $($mostRecentLogon.ToString('yyyy-MM-dd'))"
    } else {
        $daysSinceLogon = [int]((Get-Date) - $mostRecentLogon).TotalDays
    }

    if ($isInactive) {
        $userLogonData += [PSCustomObject]@{
            SamAccountName       = $user.SamAccountName
            DisplayName          = $user.Name
            UserPrincipalName    = $user.UserPrincipalName
            Enabled              = $user.Enabled
            LastLogon            = $mostRecentLogon
            DaysSinceLogon       = $daysSinceLogon
            LastLogonDate        = $user.LastLogonDate  # Replicated attribute for comparison
            WhenCreated          = $user.WhenCreated
            PasswordLastSet      = $user.PasswordLastSet
            PasswordNeverExpires = $user.PasswordNeverExpires
            Department           = $user.Department
            Title                = $user.Title
            Description          = $user.Description
            DistinguishedName    = $user.DistinguishedName
            Reason               = $reason
        }
    }
}

Write-Progress -Activity "Querying LastLogon from Domain Controllers" -Completed

# Export results
Write-Host "[$(NowTag)] Found $($userLogonData.Count) inactive user(s)"

if ($userLogonData.Count -gt 0) {
    $csvFile = Join-Path $OutputFolder "Inactive-ADUsers.csv"
    $userLogonData | Sort-Object DaysSinceLogon -Descending |
        Export-Csv -NoTypeInformation -Encoding UTF8 -Path $csvFile
    Write-Host "[$(NowTag)] Report exported: $csvFile" -ForegroundColor Green

    # Summary statistics
    Write-Host "`nINACTIVE USER SUMMARY:" -ForegroundColor Cyan
    Write-Host "  Total Inactive Users: $($userLogonData.Count)"
    Write-Host "  Never Logged On: $(($userLogonData | Where-Object { $_.DaysSinceLogon -eq 'N/A' }).Count)"
    Write-Host "  Enabled Accounts: $(($userLogonData | Where-Object Enabled).Count)"
    Write-Host "  Disabled Accounts: $(($userLogonData | Where-Object { -not $_.Enabled }).Count)"
    Write-Host "  Password Never Expires: $(($userLogonData | Where-Object PasswordNeverExpires).Count)"

    # By department
    $byDept = $userLogonData | Where-Object Department | Group-Object Department | Sort-Object Count -Descending | Select-Object -First 5
    if ($byDept) {
        Write-Host "`nTop 5 Departments with Inactive Users:" -ForegroundColor Cyan
        $byDept | ForEach-Object {
            Write-Host "  $($_.Name): $($_.Count)"
        }
    }
} else {
    Write-Host "[$(NowTag)] No inactive users found!" -ForegroundColor Green
}

Write-Host "`n[$(NowTag)] Analysis complete! Output folder: $OutputFolder"