$ErrorActionPreference = 'STOP'
Add-Type -AssemblyName System.DirectoryServices.AccountManagement 

Write-Host "AD 密碼修改工具" -ForegroundColor Yellow
Write-Host "==============" -ForegroundColor Yellow
$domain = [Environment]::GetEnvironmentVariable("USERDOMAIN")
$userId = Read-Host "AD 帳號"
$p = $userId.Split('\')
if ($p.Length -eq 2) {
	$domain = $p[0]
	$userId = $p[1]
}
function decSecString($secString) {
	$BSTR = [System.Runtime.InteropServices.Marshal]::SecureStringToBSTR($secString)
	return [System.Runtime.InteropServices.Marshal]::PtrToStringAuto($BSTR)
}
$passwd = decSecString (Read-Host "請輸入原密碼" -AsSecureString)
$passwdNew = decSecString (Read-Host "請輸入新密碼" -AsSecureString)
$passwdConfirm = decSecString (Read-Host "請再輸一次新密碼" -AsSecureString)
if ($passwdNew -ne $passwdConfirm) {
	Write-Host "新舊密碼不符" -ForegroundColor Red
	return
}
try {
	$ctx = New-Object System.DirectoryServices.AccountManagement.PrincipalContext([System.DirectoryServices.AccountManagement.ContextType]::Domain, $domain, $userId, $passwd)
}
catch {
	Write-Host $error[0].Exception.Message -ForegroundColor Yellow
	return
}
try {
	$user = [System.DirectoryServices.AccountManagement.UserPrincipal]::FindByIdentity($ctx, [System.DirectoryServices.AccountManagement.IdentityType]::SamAccountName, $userId)
}
catch {
	Write-Host $error[0].Exception.Message -ForegroundColor Cyan
	$ctx.Dispose()
	return
}
try {
	$user.ChangePassword($passwd, $passwdNew)
	Write-Host "密碼更新完畢" -ForegroundColor Green
}
catch {
	Write-Host $error[0].Exception.Message -ForegroundColor Magenta
}
$user.Dispose()
$ctx.Dispose()