# Check PowerShell version for use in path
if ($PSVersionTable.PSVersion.Major -ge 3) {
    # Use new variable syntax in PowerShell 3 and above
    $currentDir = $PSScriptRoot
}
else {
    # Use old variable syntax in Windows PowerShell 3 and below
    $currentDir = (Get-Item .).FullName
}

# Import script-helper.ps1
. "$currentDir\..\..\scripts\script-helper.ps1"

# Get system information
$systemInfo = Get-SystemInfo
$windowsInfo = Get-WindowsVersionDetails

# Create a systemRestore point before making any changes to the system,
# this way we can be sure that the user can easily revert back to a working state if anything goes wrong.
Checkpoint-Computer -Description "Pre-UpdatePackages-oxmc Changes" -RestorePointType "MODIFY_SETTINGS"

# Create a backupfolder for the registry,
# this way we can be sure that we can easily revert back to a working state if anything goes wrong with the registry changes.
$backupFolder = "$windowsDrive\Windows\OEM\RegistryBackups"
$timestamp = Get-Date -Format "yyyyMMdd_HHmmss"

# Ensure backup folder exists
if (-not (Test-Path $backupFolder)) {
    New-Item -Path $backupFolder -ItemType Directory | Out-Null
}

# Save the registry backup with a timestamp, and the build number of windows as the filename,
# this way we can easily identify the backup and restore it if anything goes wrong.
$backupPath = "$backupFolder\RegistryBackup_Build-$($systemInfo.BuildNumber)_$($timestamp)"

# Define hives to backup
$hives = @("HKLM", "HKCU", "HKCR", "HKU", "HKCC")
foreach ($hive in $hives) {
    try {
        $backupFile = "$backupPath`_$hive.reg"
        reg export $hive $backupFile /y | Out-Null
        Write-Output "Backup succeeded for $hive -> $backupFile"
    }
    catch {
        Write-Warning "Failed to backup $hive. Error: $_"
    }
}

# =========================================
# Cleanup old registry backups (keep 20)
# =========================================
# This ensures we don't accumulate unlimited backups over time,
# while still retaining a reasonable rollback history.

$maxBackups = 20

$files = Get-ChildItem -Path $backupFolder -Filter "RegistryBackup_Build-*.reg" -File

$groups = $files | ForEach-Object {
    if ($_.BaseName -match "^(RegistryBackup_Build-\d+_\d{8}_\d{6})_") {
        [PSCustomObject]@{
            BaseName = $matches[1]
            File     = $_
        }
    }
} | Group-Object BaseName

$sortedGroups = $groups | Sort-Object {
    if ($_.Name -match "_(\d{8}_\d{6})$") {
        [datetime]::ParseExact($matches[1], "yyyyMMdd_HHmmss", $null)
    }
} -Descending

$groupsToDelete = $sortedGroups | Select-Object -Skip $maxBackups

foreach ($group in $groupsToDelete) {
    foreach ($item in $group.Group) {
        try {
            Remove-Item $item.File.FullName -Force -ErrorAction Stop
            Write-Output "Removed old backup file: $($item.File.Name)"
        }
        catch {
            Write-Warning "Failed to remove $($item.File.Name): $_"
        }
    }
}

# On certain windows versions we have to run specific commands and or apply registry updates,
# As this update script is made to fix/migrate settings for new windows updates and features,
# we will use the build number as a reference to run those commands,
# this way we can be sure that the script will work on older and newer windows versions without breaking anything.

# Windows 11 22H2 and above (All editions)
#Invoke-CommandsForBuildVersion -targetBuildNumber 22000 -commands {
#    # Add any commands or registry updates that are specific to Windows 11 22H2 and above here
#}