Add -DryRun switch for safe preview without making changes

Update-StaffAD.ps1

@@ -4,6 +4,14 @@
 # If duplicate entries exist, ACTV takes priority over INAC/LEFT.
 # Creates new AD accounts for ACTV users not found in AD.
 # Applies changes automatically and appends results to a log file.
+#
+# Usage:
+#   .\Update-StaffAD.ps1           - Run normally, apply all changes
+#   .\Update-StaffAD.ps1 -DryRun   - Preview only, no changes made
+
+param(
+    [switch]$DryRun
+)
 
 # --- Configuration ---
 $CsvPath         = "C:\Scripts\Staff_Extract.csv"
@@ -30,7 +38,9 @@ $Timestamp = Get-Date -Format "yyyy-MM-dd HH:mm:ss"
 function Write-Log {
     param([string]$Message, [string]$Color = "White")
     Write-Host $Message -ForegroundColor $Color
+    if (-not $DryRun) {
         Add-Content -Path $LogFile -Value $Message
+    }
 }
 
 # --- Deduplicate: ACTV wins over INAC/LEFT ---
@@ -40,16 +50,23 @@ foreach ($entry in $Staff) {
     if (-not $Deduped.ContainsKey($key)) {
         $Deduped[$key] = $entry
     } elseif ($entry.STAFF_STATUS.Trim() -eq "ACTV") {
-        # ACTV always overrides whatever was stored
         $Deduped[$key] = $entry
     }
 }
 
 # --- Run Header ---
-Write-Log ""
-Write-Log $RunHeader
-Write-Log "  RUN: $Timestamp"
-Write-Log $RunHeader
+if ($DryRun) {
+    Write-Host ""
+    Write-Host $RunHeader -ForegroundColor Magenta
+    Write-Host "  DRY RUN - NO CHANGES WILL BE MADE" -ForegroundColor Magenta
+    Write-Host "  $Timestamp" -ForegroundColor Magenta
+    Write-Host $RunHeader -ForegroundColor Magenta
+} else {
+    Write-Log ""
+    Write-Log $RunHeader
+    Write-Log "  RUN: $Timestamp"
+    Write-Log $RunHeader
+}
 
 $emailUpdates = 0
 $disables     = 0
@@ -85,6 +102,14 @@ foreach ($entry in $Deduped.Values) {
             continue
         }
 
+        Write-Log ""
+        Write-Log "  User    : $displayName ($samAccount)"
+        Write-Log "  Status  : $status"
+
+        if ($DryRun) {
+            Write-Log "  Account : WOULD BE CREATED in $NewUserOU" "Magenta"
+            Write-Log "  Email   : $email  [WOULD BE SET]" "Magenta"
+        } else {
             try {
                 New-ADUser `
                     -SamAccountName    $samAccount `
@@ -98,17 +123,14 @@ foreach ($entry in $Deduped.Values) {
                     -Enabled           $true `
                     -Path              $NewUserOU
 
-            Write-Log ""
-            Write-Log "  User    : $displayName ($samAccount)"
-            Write-Log "  Status  : $status"
                 Write-Log "  Account : CREATED in $NewUserOU  [CREATED]" "Green"
                 Write-Log "  Email   : $email  [SET]" "Green"
                 $created++
             } catch {
-            Write-Log ""
-            Write-Log "  User    : $displayName ($samAccount)"
                 Write-Log "  Account : FAILED to create - $_" "Red"
             }
+        }
+        $created++
         continue
     }
 
@@ -126,6 +148,9 @@ foreach ($entry in $Deduped.Values) {
 
     # Update email
     if ($willUpdateEmail) {
+        if ($DryRun) {
+            Write-Log "  Email   : $($adUser.EmailAddress) --> $email  [WOULD UPDATE]" "Magenta"
+        } else {
             try {
                 Set-ADUser -Identity $samAccount -EmailAddress $email
                 Write-Log "  Email   : $($adUser.EmailAddress) --> $email  [UPDATED]" "Green"
@@ -134,9 +159,14 @@ foreach ($entry in $Deduped.Values) {
                 Write-Log "  Email   : FAILED to update - $_" "Red"
             }
         }
+        $emailUpdates++
+    }
 
     # Disable account
     if ($willDisable) {
+        if ($DryRun) {
+            Write-Log "  Account : WOULD BE DISABLED (status: $status)" "Magenta"
+        } else {
             try {
                 Disable-ADAccount -Identity $samAccount
                 Write-Log "  Account : DISABLED (status: $status)  [UPDATED]" "Green"
@@ -145,17 +175,19 @@ foreach ($entry in $Deduped.Values) {
                 Write-Log "  Account : FAILED to disable - $_" "Red"
             }
         }
+        $disables++
+    }
 }
 
 # --- Summary ---
 Write-Log ""
-Write-Log "  --- Summary ---"
+Write-Log "  --- Summary $(if ($DryRun) { '(DRY RUN)' }) ---"
 
 if ($emailUpdates -eq 0 -and $disables -eq 0 -and $created -eq 0) {
-    Write-Log "  No changes were made on this run." "Cyan"
+    Write-Log "  No changes $(if ($DryRun) { 'would be' } else { 'were' }) made on this run." "Cyan"
 }
 
-Write-Log "  Accounts created    : $created"
+Write-Log "  Accounts $(if ($DryRun) { 'to create' } else { 'created' })    : $created"
 Write-Log "  Email updates       : $emailUpdates"
 Write-Log "  Accounts disabled   : $disables"
 Write-Log "  No changes needed   : $noChanges"