# Ensure ImportExcel module is installed
if (-not (Get-Module -ListAvailable -Name ImportExcel)) {
    Write-Host "📦 ImportExcel module not found. Installing..."
    Install-Module -Name ImportExcel -Scope CurrentUser -Force
} else {
    Write-Host "✅ ImportExcel module is already installed."
}

# Ensure ExchangeOnlineManagement module is installed
if (-not (Get-Module -ListAvailable -Name ExchangeOnlineManagement)) {
    Write-Host "📦 ExchangeOnlineManagement module not found. Installing..."
    Install-Module -Name ExchangeOnlineManagement -Scope CurrentUser -Force
} else {
    Write-Host "✅ ExchangeOnlineManagement module is already installed."
}

# Output Excel file path
$excelPath = "C:\Temp\DeviceAccessReport.xlsx"

# Ensure C:\Temp exists
if (!(Test-Path -Path "C:\Temp")) {
    New-Item -Path "C:\" -Name "Temp" -ItemType Directory | Out-Null
}

# Connect to Exchange Online
Connect-ExchangeOnline

# Get all user mailboxes
$mailboxes = Get-Mailbox -ResultSize Unlimited -RecipientTypeDetails UserMailbox

# Store device stats
$deviceStats = @()

foreach ($mbx in $mailboxes) {
    try {
        $stats = Get-MobileDeviceStatistics -Mailbox $mbx.Identity -ErrorAction Stop
        foreach ($stat in $stats) {
            $deviceStats += [PSCustomObject]@{
                User             = $mbx.DisplayName
                DeviceID         = $stat.DeviceID
                DeviceType       = $stat.DeviceType
                DeviceModel      = $stat.DeviceModel
                OS               = $stat.DeviceOS
                ClientType       = $stat.ClientType
                AccessState      = $stat.DeviceAccessState
                AccessReason     = $stat.DeviceAccessStateReason
                LastSuccessSync  = $stat.LastSuccessSync
                FirstSyncTime    = $stat.FirstSyncTime
            }
        }
    } catch {
        Write-Warning "⚠️ Failed to get device stats for $($mbx.DisplayName): $_"
    }
}

# Export to Excel
$deviceStats | Export-Excel -Path $excelPath -AutoSize -WorksheetName "Device Access"

Write-Host "`n✅ Report exported to $excelPath"

# Disconnect from Exchange Online
Disconnect-ExchangeOnline -Confirm:$false

# Clear cached credentials to force reauthentication next time
Remove-Item "$env:USERPROFILE\.ExchangeOnline\TokenCache" -Force -ErrorAction SilentlyContinue
Write-Host "`n🧹 Cached credentials cleared. Reauthentication will be required on next run."