# Read the username from DefaultUsername.txt
try {
    $defaultUsername = Get-Content -Path ".\DefaultUsername.txt" -ErrorAction Stop
    Write-Host "Using username from file: $defaultUsername"
} catch {
    Write-Host -ForegroundColor Red "Failed to read DefaultUsername.txt: $_"
    exit 1
}

# Prompt for credentials, prepopulating the username
$credential = Get-Credential -UserName $defaultUsername -Message "Enter your domain admin credentials"

try {
    # Import the Active Directory module
    Import-Module ActiveDirectory -ErrorAction Stop

    # Get the domain information
    $domain = (Get-ADDomain -ErrorAction Stop).DNSRoot
    Write-Host "Domain detected: $domain"

    # Construct the LDAP path for your domain
    $ldapPath = "LDAP://$domain"

    # Create a DirectoryEntry object for the LDAP connection
    $directoryEntry = New-Object System.DirectoryServices.DirectoryEntry($ldapPath, $credential.UserName, $credential.GetNetworkCredential().Password)

    # Perform a simple query to validate credentials
    $searcher = New-Object System.DirectoryServices.DirectorySearcher($directoryEntry)
    $searcher.Filter = "(objectClass=User)"
    $result = $searcher.FindOne()

    if ($result -ne $null) {
        Write-Host -ForegroundColor Green "Credentials are valid. Authentication succeeded."

        # Try to export credentials securely
        try {
            Export-Clixml -Path ".\AdminCredential.xml" -InputObject $credential
            Write-Host -ForegroundColor Green "Credentials stored securely for the session."
        } catch {
            Write-Host -ForegroundColor Red "Failed to export credentials: $_"
        }
    } else {
        Write-Host -ForegroundColor Red "Invalid credentials. Authentication failed."
    }
} catch {
    Write-Host -ForegroundColor Red "An error occurred during authentication: $_"
}