# Backup_QVW.ps1 — rolling ring of pre-reload QVW snapshots.
# Usage: powershell -File Backup_QVW.ps1 -QvwPath "..\4.Apps.QVW\MyApp.qvw" [-Keep 20]
# Default retention 20 slots (a day of reloads won't evict good edits).
# NOTE: this is a FALLBACK. Primary safety net is git commits in Reload_*.bat.
param(
  [Parameter(Mandatory=$true)][string]$QvwPath,
  [int]$Keep = 20
)

$ErrorActionPreference = "Stop"
if (-not (Test-Path $QvwPath)) { Write-Host "No QVW to back up: $QvwPath"; exit 0 }

$dir = Split-Path $QvwPath -Parent
$name = [System.IO.Path]::GetFileNameWithoutExtension($QvwPath)
$ext  = [System.IO.Path]::GetExtension($QvwPath)
$backupDir = Join-Path $dir "backups"
if (-not (Test-Path $backupDir)) { New-Item -ItemType Directory -Path $backupDir -Force | Out-Null }

$stamp = Get-Date -Format "yyyyMMdd_HHmmss"
$dest  = Join-Path $backupDir ($name + "_" + $stamp + $ext)
Copy-Item $QvwPath $dest -Force
Write-Host "Backed up: $dest"

# Prune: keep only $Keep most-recent backups matching "$name_*.qvw"
Get-ChildItem $backupDir -Filter ($name + "_*" + $ext) -File |
  Sort-Object LastWriteTime -Descending |
  Select-Object -Skip $Keep |
  ForEach-Object { Remove-Item $_.FullName -Force; Write-Host "Pruned: $($_.Name)" }