# ==========================================================
# System-Wide Outlook OST Repair Script
# ==========================================================
# Use Case:
# Repairs Outlook OST-related sync problems for ALL users by:
# 1. Closing Outlook
# 2. Searching all user profiles
# 3. Finding OST files
# 4. Backing up OST files
# 5. Deleting OST files
# 6. Allowing Outlook to recreate fresh OST files
#
# Backup Retention:
# - Maintains only latest 3 backups per OST file
# - Oldest backup will be removed automatically
# ==========================================================
Write-Host "========================================="
Write-Host " System-Wide Outlook OST Repair Started"
Write-Host "========================================="
# ----------------------------------------------------------
# Step 1 - Close Outlook
# ----------------------------------------------------------
Write-Host "`n[INFO] Closing Outlook..."
Get-Process OUTLOOK -ErrorAction SilentlyContinue | ForEach-Object {
    $_.CloseMainWindow() | Out-Null
    # Wait up to 10 seconds
    if (!$_.WaitForExit(10000)) {
        Write-Host "[INFO] Force closing Outlook..."
        $_ | Stop-Process -Force
    }
}
# ----------------------------------------------------------
# Step 2 - Get All User Profiles
# ----------------------------------------------------------
Write-Host "`n[INFO] Searching all user profiles..."
$ExcludedUsers = @(
    "Public",
    "Default",
    "Default User",
    "All Users"
)
# Add users passed through script arguments
for ($i = 0; $i -lt $args.Count; $i++) {
    if (![string]::IsNullOrWhiteSpace($args[$i])) {
        $ExcludedUsers += $args[$i]
    }
}
# Get profiles excluding specified users
$UserProfiles = Get-ChildItem "C:\Users" -Directory |
Where-Object {
    $_.Name -notin $ExcludedUsers
}
if ($UserProfiles.Count -eq 0) {
    Write-Host "[ERROR] No user profiles found."
    exit
}
# ----------------------------------------------------------
# Step 3 - Search, Backup and Delete OST Files
# ----------------------------------------------------------
foreach ($Profile in $UserProfiles) {
    $OutlookPath = Join-Path $Profile.FullName "AppData\Local\Microsoft\Outlook"
    Write-Host "`n-----------------------------------------"
    Write-Host "[INFO] Checking profile: $($Profile.Name)"
    Write-Host "[INFO] Path: $OutlookPath"
    if (!(Test-Path $OutlookPath)) {
        Write-Host "[WARNING] Outlook folder not found."
        continue
    }
    $OSTFiles = Get-ChildItem -Path $OutlookPath -Filter *.ost -ErrorAction SilentlyContinue
    if ($OSTFiles.Count -eq 0) {
        Write-Host "[WARNING] No OST files found."
        continue
    }
    Write-Host "`n[INFO] Processing OST files..."
    foreach ($File in $OSTFiles) {
        try {
            # --------------------------------------------------
            # Backup Folder
            # --------------------------------------------------
            $BackupRoot = Join-Path $OutlookPath "OST_Backups"
            if (!(Test-Path $BackupRoot)) {
                New-Item -Path $BackupRoot -ItemType Directory | Out-Null
            }
            # Create timestamp backup file
            $Timestamp = Get-Date -Format "yyyyMMdd_HHmmss"
            $BackupFileName = "$($File.BaseName)_$Timestamp.ost"
            $BackupPath = Join-Path $BackupRoot $BackupFileName
            # --------------------------------------------------
            # Backup OST File
            # --------------------------------------------------
            Write-Host "[INFO] Creating backup:"
            Write-Host "       $BackupFileName"
            Copy-Item -Path $File.FullName -Destination $BackupPath -Force
            # --------------------------------------------------
            # Maintain Only Latest 3 Backups
            # --------------------------------------------------
            $ExistingBackups = Get-ChildItem -Path $BackupRoot -Filter "$($File.BaseName)_*.ost" |
                               Sort-Object LastWriteTime -Descending
            if ($ExistingBackups.Count -gt 3) {
                $BackupsToDelete = $ExistingBackups | Select-Object -Skip 3
                foreach ($OldBackup in $BackupsToDelete) {
                    Write-Host "[INFO] Removing old backup:"
                    Write-Host "       $($OldBackup.Name)"
                    Remove-Item -Path $OldBackup.FullName -Force
                }
            }
            # --------------------------------------------------
            # Delete Original OST File
            # --------------------------------------------------
            Write-Host "[INFO] Deleting OST file:"
            Write-Host "       $($File.Name)"
            Remove-Item -Path $File.FullName -Force
            Write-Host "[SUCCESS] OST repaired successfully."
        }
        catch {
            Write-Host "[ERROR] Failed processing file:"
            Write-Host "        $($File.Name)"
            Write-Host $_.Exception.Message
        }
    }
}
# ----------------------------------------------------------
# Step 4 - Restart Outlook
# ----------------------------------------------------------
Write-Host "`n[INFO] Restarting Outlook..."
try {
    Start-Process "outlook.exe"
    Write-Host "[SUCCESS] Outlook restarted."
}
catch {
    Write-Host "[WARNING] Could not automatically start Outlook."
    Write-Host $_.Exception.Message
}
# ----------------------------------------------------------
# Step 5 - Completion Message
# ----------------------------------------------------------
Write-Host "`n========================================="
Write-Host " System-Wide OST Repair Completed"
Write-Host "========================================="

Write-Host "`nNext Steps:"
Write-Host "1. Open Outlook."
Write-Host "2. Outlook will create fresh OST files."
Write-Host "3. Mailbox data will sync automatically."