<#
.SYNOPSIS
    Reverts the power-saving/hibernate changes made by Test-BatteryDrain.ps1.

.DESCRIPTION
    1. Re-launches itself elevated if not running as Administrator (powercfg changes require admin).
    2. Resets all built-in power schemes (Balanced, Power saver, High performance) to their Windows
       factory defaults, which undoes the timeout/USB/PCIe/battery-action tweaks applied by the test
       script.
    3. Removes the "Ultimate Performance" scheme duplicate if the test script created one.
    4. Restores hibernation to its original on/off state, and re-activates whichever power scheme was
       active before the test ran (both read from the state file saved by Test-BatteryDrain.ps1).

.PARAMETER StateFilePath
    Path to the JSON state file written by Test-BatteryDrain.ps1. Defaults to
    .\PowerSettingsBackup.json next to this script.

.EXAMPLE
    .\Restore-PowerSettings.ps1
#>

[CmdletBinding()]
param(
    [string]$StateFilePath = $(Join-Path -Path $PSScriptRoot -ChildPath 'PowerSettingsBackup.json')
)

$ErrorActionPreference = 'Stop'

#region Elevation check
function Test-IsAdmin {
    $identity = [Security.Principal.WindowsIdentity]::GetCurrent()
    $principal = New-Object Security.Principal.WindowsPrincipal($identity)
    return $principal.IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator)
}

if (-not (Test-IsAdmin)) {
    Write-Host "Not running elevated - relaunching as Administrator..." -ForegroundColor Yellow
    Start-Process -FilePath 'powershell.exe' -ArgumentList @(
        '-NoProfile', '-ExecutionPolicy', 'Bypass', '-File', "`"$PSCommandPath`"",
        '-StateFilePath', "`"$StateFilePath`""
    ) -Verb RunAs
    exit
}
#endregion

Write-Host "Restoring default power schemes (undoes timeout/USB/PCIe/battery-action changes)..." -ForegroundColor Cyan
powercfg -restoredefaultschemes | Out-Null

# Remove the Ultimate Performance duplicate scheme created by Test-BatteryDrain.ps1, if present.
$ultimateGuid = (powercfg /list | Select-String -Pattern 'Ultimate Performance' | ForEach-Object {
    if ($_ -match '([0-9a-fA-F-]{36})') { $Matches[1] }
}) | Select-Object -First 1

$state = $null
if (Test-Path $StateFilePath) {
    $state = Get-Content -Path $StateFilePath -Raw | ConvertFrom-Json
} else {
    Write-Host "No state file found at $StateFilePath - will restore hibernate to 'on' and leave the active scheme as Balanced." -ForegroundColor Yellow
}

# Re-activate whichever scheme was active before the test, so we don't strand the machine on the
# duplicated Ultimate Performance scheme right before deleting it.
if ($state -and $state.OriginalSchemeGuid) {
    try {
        powercfg /setactive $state.OriginalSchemeGuid | Out-Null
        Write-Host "Restored original active power scheme ($($state.OriginalSchemeGuid))." -ForegroundColor Green
    } catch {
        Write-Host "Could not restore original scheme GUID; falling back to Balanced." -ForegroundColor Yellow
        powercfg /setactive SCHEME_BALANCED | Out-Null
    }
} else {
    powercfg /setactive SCHEME_BALANCED | Out-Null
    Write-Host "Active plan set to Balanced (default)." -ForegroundColor Green
}

if ($ultimateGuid) {
    try {
        powercfg /delete $ultimateGuid | Out-Null
        Write-Host "Removed the Ultimate Performance scheme created for the test." -ForegroundColor Green
    } catch {
        Write-Host "Could not remove Ultimate Performance scheme (it may still be active); skipping." -ForegroundColor Yellow
    }
}

# Restore hibernate to its original state (defaults to "on" if no state file is available).
$hibernateEnabled = if ($state) { [bool]$state.HibernateEnabled } else { $true }
if ($hibernateEnabled) {
    powercfg /hibernate on | Out-Null
    Write-Host "Hibernate re-enabled." -ForegroundColor Green
} else {
    powercfg /hibernate off | Out-Null
    Write-Host "Hibernate left disabled (it was already off before the test)." -ForegroundColor Green
}

if (Test-Path $StateFilePath) {
    Remove-Item -Path $StateFilePath -Force
}

Write-Host "Power settings restored to their pre-test state." -ForegroundColor Yellow