# Define the local path to your default profile picture
$PicturePath = "C:\Temp\Profile_Picture.png"

if (-not (Test-Path $PicturePath)) {
    Write-Error "The specified picture file was not found at $PicturePath"
    exit
}

# Connect to Microsoft Graph. You must have the Microsoft.Graph.Users module installed.
# Scopes needed for modifying user photos.
Connect-MgGraph -Scopes "User.ReadWrite.All"

# Retrieve standard member accounts, ignoring service accounts or guests
$Users = Get-MgUser -Filter "userType eq 'Member' and accountEnabled eq true" -All

foreach ($User in $Users) {
    $HasPhoto = $true
    
    try {
        # Attempt to retrieve the user's photo. 
        # If none exists, Graph throws an ImageNotFound exception.
        $null = Get-MgUserPhoto -UserId $User.Id -ErrorAction Stop
    }
    catch {
        $HasPhoto = $false
    }

    if (-not $HasPhoto) {
        Write-Host "No profile picture found for $($User.UserPrincipalName). Applying default..." -ForegroundColor Cyan
        
        try {
            # Set the photo using the local file
            Set-MgUserPhotoContent -UserId $User.Id -InFile $PicturePath -ErrorAction Stop
            Write-Host "Successfully applied picture to $($User.UserPrincipalName)." -ForegroundColor Green
        }
        catch {
            Write-Host "Failed to apply picture to $($User.UserPrincipalName). Error: $($_.Exception.Message)" -ForegroundColor Red
        }
    }
    else {
        Write-Host "Profile picture already exists for $($User.UserPrincipalName). Skipping." -ForegroundColor DarkGray
    }
}

# Always sever the session.
Disconnect-MgGraph