# List of undo actions to execute after forward changes.
# Each entry is a PSCustomObject with FeatureId and UndoRegFile (filename, without folder prefix).
$script:UndoRegistryKeys = @()

# List of undo actions for features that do not use registry undo files.
# Each entry is a PSCustomObject with FeatureId.
$script:UndoFeatureActions = @()

# Resolves the path of an undo reg file relative to $script:RegfilesPath.
# Checks the Undo/ subfolder first, then falls back to the root Regfiles/ folder.
function Resolve-UndoRegFilePath {
    param ([string]$FileName)
    $undoSubPath = Join-Path 'Undo' $FileName
    if (Test-Path (Join-Path $script:RegfilesPath $undoSubPath)) {
        return $undoSubPath
    }
    return $FileName
}

function Invoke-UndoFeatureAction {
    param(
        [Parameter(Mandatory)]
        [string]$FeatureId
    )

    switch ($FeatureId) {
        'DisableStoreSearchSuggestions' {
            if ($script:Params.ContainsKey('Sysprep')) {
                Write-Host "> Re-enabling Microsoft Store search suggestions in the start menu for all users..."
                EnableStoreSearchSuggestionsForAllUsers
                Write-Host ""
                return
            }

            Write-Host "> Re-enabling Microsoft Store search suggestions for user $(GetUserName)..."
            EnableStoreSearchSuggestions
            Write-Host ""
            return
        }
        'EnableWindowsSandbox' {
            Write-Host "> Disabling Windows Sandbox..."
            DisableWindowsFeature 'Containers-DisposableClientVM'
            Write-Host ""
            return
        }
        'EnableWindowsSubsystemForLinux' {
            Write-Host "> Disabling Windows Subsystem for Linux..."
            DisableWindowsFeature 'Microsoft-Windows-Subsystem-Linux'
            DisableWindowsFeature 'VirtualMachinePlatform'
            Write-Host ""
            return
        }
    }
}

# Executes a single parameter/feature based on its key
# Parameters:
#   $paramKey - The parameter name to execute
function ExecuteParameter {
    param (
        [string]$paramKey
    )
    
    # Check if this feature has metadata in Features.json
    $feature = $null
    if ($script:Features.ContainsKey($paramKey)) {
        $feature = $script:Features[$paramKey]
    }
    
    # If feature has RegistryKey and ApplyText, use dynamic ImportRegistryFile
    if ($feature -and $feature.RegistryKey -and $feature.ApplyText) {
        ImportRegistryFile "> $($feature.ApplyText)" $feature.RegistryKey
        
        # Handle special cases that have additional logic after ImportRegistryFile
        switch ($paramKey) {
            'DisableBing' {
                # Also remove the app package for Bing search
                RemoveApps 'Microsoft.BingSearch'
            }
            'DisableCopilot' {
                # Also remove the app package for Copilot
                RemoveApps 'Microsoft.Copilot'
            }
        }
        return
    }
    
    # Handle features without RegistryKey or with special logic
    switch ($paramKey) {
        'RemoveApps' {
            Write-Host "> Removing selected apps for $(GetFriendlyTargetUserName)..."
            $appsList = GenerateAppsList

            if ($appsList.Count -eq 0) {
                Write-Host "No valid apps were selected for removal" -ForegroundColor Yellow
                Write-Host ""
                return
            }

            Write-Host "$($appsList.Count) apps selected for removal"
            RemoveApps $appsList
        }
        'RemoveAppsCustom' {
            Write-Host "> Removing selected apps..."
            $appsList = LoadAppsFromFile $script:CustomAppsListFilePath

            if ($appsList.Count -eq 0) {
                Write-Host "No valid apps were selected for removal" -ForegroundColor Yellow
                Write-Host ""
                return
            }

            Write-Host "$($appsList.Count) apps selected for removal"
            RemoveApps $appsList
        }
        'RemoveCommApps' {
            $appsList = 'Microsoft.windowscommunicationsapps', 'Microsoft.People'
            Write-Host "> Removing Mail, Calendar and People apps..."
            RemoveApps $appsList
            return
        }
        'RemoveW11Outlook' {
            $appsList = 'Microsoft.OutlookForWindows'
            Write-Host "> Removing new Outlook for Windows app..."
            RemoveApps $appsList
            return
        }
        'RemoveGamingApps' {
            $appsList = 'Microsoft.GamingApp', 'Microsoft.XboxGameOverlay', 'Microsoft.XboxGamingOverlay'
            Write-Host "> Removing gaming related apps..."
            RemoveApps $appsList
            return
        }
        'RemoveHPApps' {
            $appsList = 'AD2F1837.HPAIExperienceCenter', 'AD2F1837.HPJumpStarts', 'AD2F1837.HPPCHardwareDiagnosticsWindows', 'AD2F1837.HPPowerManager', 'AD2F1837.HPPrivacySettings', 'AD2F1837.HPSupportAssistant', 'AD2F1837.HPSureShieldAI', 'AD2F1837.HPSystemInformation', 'AD2F1837.HPQuickDrop', 'AD2F1837.HPWorkWell', 'AD2F1837.myHP', 'AD2F1837.HPDesktopSupportUtilities', 'AD2F1837.HPQuickTouch', 'AD2F1837.HPEasyClean', 'AD2F1837.HPConnectedMusic', 'AD2F1837.HPFileViewer', 'AD2F1837.HPRegistration', 'AD2F1837.HPWelcome', 'AD2F1837.HPConnectedPhotopoweredbySnapfish', 'AD2F1837.HPPrinterControl'
            Write-Host "> Removing HP apps..."
            RemoveApps $appsList
            return
        }
        'DisableWidgets' {
            Write-Host "> Disabling widgets on the taskbar & lock screen..."
            # Stop widgets related processes before removing the app packages to prevent potential issues
            Get-Process *Widget* | Stop-Process
            
            RemoveApps 'Microsoft.StartExperiencesApp','MicrosoftWindows.Client.WebExperience','Microsoft.WidgetsPlatformRuntime'
        }
        "EnableWindowsSandbox" {
            Write-Host "> Enabling Windows Sandbox..."
            EnableWindowsFeature "Containers-DisposableClientVM"
            Write-Host ""
            return
        }
        "EnableWindowsSubsystemForLinux" {
            Write-Host "> Enabling Windows Subsystem for Linux..."
            EnableWindowsFeature "VirtualMachinePlatform"
            EnableWindowsFeature "Microsoft-Windows-Subsystem-Linux"
            Write-Host ""
            return
        }
        'ClearStart' {
            Write-Host "> Removing all pinned apps from the start menu for user $(GetUserName)..."
            ReplaceStartMenu
            Write-Host ""
            return
        }
        'ReplaceStart' {
            Write-Host "> Replacing the start menu for user $(GetUserName)..."
            ReplaceStartMenu $script:Params.Item("ReplaceStart")
            Write-Host ""
            return
        }
        'ClearStartAllUsers' {
            ReplaceStartMenuForAllUsers
            return
        }
        'ReplaceStartAllUsers' {
            ReplaceStartMenuForAllUsers $script:Params.Item("ReplaceStartAllUsers")
            return
        }
        'DisableStoreSearchSuggestions' {
            if ($script:Params.ContainsKey("Sysprep")) {
                Write-Host "> Disabling Microsoft Store search suggestions in the start menu for all users..."
                DisableStoreSearchSuggestionsForAllUsers
                Write-Host ""
                return
            }

            Write-Host "> Disabling Microsoft Store search suggestions for user $(GetUserName)..."
            DisableStoreSearchSuggestions
            Write-Host ""
            return
        }
    }
}


# Executes all selected parameters/features
function ExecuteAllChanges {    
    $script:RegistryImportFailures = 0

    # Build list of actionable parameters (skip control params and data-only params)
    $actionableKeys = @()
    foreach ($paramKey in $script:Params.Keys) {
        if ($script:ControlParams -contains $paramKey) { continue }
        if ($paramKey -eq 'Apps') { continue }
        if ($paramKey -eq 'CreateRestorePoint') { continue }
        $actionableKeys += $paramKey
    }

    $hasRegistryBackedFeature = $false
    foreach ($paramKey in $actionableKeys) {
        if (-not $script:Features.ContainsKey($paramKey)) { continue }

        $feature = $script:Features[$paramKey]
        if ($feature -and -not [string]::IsNullOrWhiteSpace([string]$feature.RegistryKey)) {
            $hasRegistryBackedFeature = $true
            break
        }
    }
    # Undo operations that write registry values also require a backup
    if (-not $hasRegistryBackedFeature -and $script:UndoRegistryKeys.Count -gt 0) {
        $hasRegistryBackedFeature = $true
    }
    
    $totalSteps = $actionableKeys.Count + $script:UndoRegistryKeys.Count + $script:UndoFeatureActions.Count
    if ($hasRegistryBackedFeature) { $totalSteps++ }
    if ($script:Params.ContainsKey("CreateRestorePoint")) { $totalSteps++ }
    $currentStep = 0

    if ($hasRegistryBackedFeature) {
        $currentStep++
        if ($script:ApplyProgressCallback) {
            & $script:ApplyProgressCallback $currentStep $totalSteps "Creating registry backup..."
        }

        Write-Host "> Creating registry backup..."
        try {
            $undoSyntheticFeatures = @($script:UndoRegistryKeys | ForEach-Object {
                [PSCustomObject]@{ FeatureId = $_.FeatureId; RegistryKey = (Resolve-UndoRegFilePath $_.UndoRegFile) }
            })
            New-RegistrySettingsBackup -ActionableKeys $actionableKeys -ExtraFeatures $undoSyntheticFeatures | Out-Null
        }
        catch {
            throw "Registry backup failed before applying changes. $($_.Exception.Message)"
        }
    }
    
    # Create restore point if requested (CLI only - GUI handles this separately)
    if ($script:Params.ContainsKey("CreateRestorePoint")) {
        $currentStep++
        if ($script:ApplyProgressCallback) {
            & $script:ApplyProgressCallback $currentStep $totalSteps "Creating system restore point, this may take a moment..."
        }
        Write-Host "> Creating a system restore point..."
        CreateSystemRestorePoint
        Write-Host ""
    }
    
    # Execute all parameters
    foreach ($paramKey in $actionableKeys) {
        if ($script:CancelRequested) { 
            return
        }

        $currentStep++
        
        # Get friendly name for the step
        $stepName = $paramKey
        if ($script:Features.ContainsKey($paramKey)) {
            $feature = $script:Features[$paramKey]
            if ($feature.ApplyText) {
                # Prefer explicit ApplyText when provided
                $stepName = $feature.ApplyText
            } elseif ($feature.Label) {
                # Fallback: use label from Features.json
                $stepName = $feature.Label
            }
        }
        
        if ($script:ApplyProgressCallback) {
            & $script:ApplyProgressCallback $currentStep $totalSteps $stepName
        }
        
        ExecuteParameter -paramKey $paramKey
    }

    # Execute all undo operations
    foreach ($undoAction in $script:UndoRegistryKeys) {
        if ($script:CancelRequested) { return }

        $undoLabel = if ($script:FeatureLabelLookup) { $script:FeatureLabelLookup[$undoAction.FeatureId] } else { $null }
        if (-not $undoLabel) { $undoLabel = $undoAction.FeatureId }

        $currentStep++
        if ($script:ApplyProgressCallback) {
            & $script:ApplyProgressCallback $currentStep $totalSteps "Undoing: $undoLabel"
        }

        ImportRegistryFile "> Undoing: $undoLabel" (Resolve-UndoRegFilePath $undoAction.UndoRegFile)
    }

    foreach ($undoAction in $script:UndoFeatureActions) {
        if ($script:CancelRequested) { return }

        $undoLabel = if ($script:FeatureLabelLookup) { $script:FeatureLabelLookup[$undoAction.FeatureId] } else { $null }
        if (-not $undoLabel) { $undoLabel = $undoAction.FeatureId }

        $currentStep++
        if ($script:ApplyProgressCallback) {
            & $script:ApplyProgressCallback $currentStep $totalSteps "Undoing: $undoLabel"
        }

        Invoke-UndoFeatureAction -FeatureId $undoAction.FeatureId
    }

    $script:UndoRegistryKeys = @()
    $script:UndoFeatureActions = @()

    if ($script:RegistryImportFailures -gt 0) {
        Write-Host ""
        Write-Host "$($script:RegistryImportFailures) registry import change(s) failed. See output above for details." -ForegroundColor Yellow
    }
}