$null = New-Module {
    . "$PSScriptRoot/Constants.ps1";
    . "$PSScriptRoot/Registry.ps1";
    . "$PSScriptRoot/../Types/OneShotTask.ps1";
    . "$PSScriptRoot/../../Common/Scripts/Config.ps1";
    $oneShotTaskName = "PortValhalla OneShot";
    $logName = "Application";
    $oneShotTrigger = 1337;
    $taskOption = "OneShotTask";

    $getErrorPath = {
        Join-Path (Get-ArtifactRoot) "error.txt";
    };

    $getUserName = {
        "$(Get-SetupUser)OneShot";
    };

    $taskSetter = {
        param([Nullable[OneShotTask]] $Task)
        Set-SetupOption $taskOption ([string]$Task);
    };

    <#
        .SYNOPSIS
        Gets the current OneShot task.
    #>
    function Get-OneShotTask {
        $task = Get-SetupOption $taskOption;

        if ($task) {
            return [OneShotTask]$task;
        } else {
            return $null;
        }
    }

    <#
        .SYNOPSIS
        Registers a task for listening to OneShot invocations.
    #>
    function Enable-OneShotListener {
        $tempTask = "PortValhalla Temp";
        $user = & $getUserName;
        $password = [string]([guid]::NewGuid());

        $adminGroup = @{
            SID = [SecurityIdentifier]::new([WellKnownSidType]::BuiltinAdministratorsSid, $null);
        };

        $null = New-LocalUser -Name $user -Password (ConvertTo-SecureString -AsPlainText $password);
        Add-LocalGroupMember -Member $user @adminGroup;
        $logPath = Join-Path (Get-ArtifactRoot) "OneShotTask.log";
        $path = "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList";
        $null = New-Item -Force -ErrorAction SilentlyContinue $path;
        Set-ItemProperty $path -Name $user -Value 0;

        $action = New-ScheduledTaskAction -Execute "pwsh" -Argument "-Command & { $([string](Get-StartupCommand)) } 2>&1 | Tee-Object -FilePath $(ConvertTo-Injection $logPath)";
        schtasks /Create /SC ONEVENT /EC $logName /MO "*[System[Provider[@Name='$logName'] and EventID=$($oneShotTrigger)]]" /TR cmd.exe /TN $tempTask;
        $trigger = (Get-ScheduledTask $tempTask).Triggers;
        $null = Register-ScheduledTask -Force $oneShotTaskName -Action $action -Trigger $trigger -RunLevel Highest -User $user -Password $password;
        $null = Unregister-ScheduledTask -Confirm:$false $tempTask;
    }

    <#
        .SYNOPSIS
        Removes the OneShot task.
    #>
    function Disable-OneShotListener {
        Unregister-ScheduledTask -Confirm:$false $oneShotTaskName;
        $user = Get-LocalUser (& $getUserName);
        [string] $sid = $user.SID;
        Remove-LocalUser $user;
        Get-CimInstance Win32_UserProfile | Where-Object { $_.SID -eq $sid } | Remove-CimInstance;
    }

    <#
        .SYNOPSIS
        Invokes a one-shot task.

        .PARAMETER Task
        The task to run.
    #>
    function Invoke-OneShot {
        param(
            [OneShotTask] $Task
        )

        $errorPath = & $getErrorPath;
        & $taskSetter $Task;

        & {
            $identifier = "EventLog$oneShotTrigger";
            $log = [System.Diagnostics.EventLog]::new($logName);
            $log.EnableRaisingEvents = $true;

            $null = Register-ObjectEvent -InputObject $log -EventName EntryWritten -Action {
                    $entry = $Event.SourceEventArgs.Entry;
                    $trigger = $Event.MessageData.Trigger;
                    $identifier = $Event.MessageData.Identifier;

                    if ($entry.EventID -eq $trigger) {
                        $null = New-Event -SourceIdentifier $identifier;
                    }
                } `
                -MessageData @{
                    Trigger = $oneShotTrigger;
                    Identifier = $identifier;
                };

            Write-EventLog -LogName $logName -Source $logName -EventId $oneShotTrigger -Message "Starting OneShot task ``$(Get-OneShotTask)``…";

            for ($i = 0; $i -lt 2; $i++) {
                Remove-Event -EventIdentifier (Wait-Event -SourceIdentifier $identifier).EventIdentifier;
            }
        };

        if (Test-Path $errorPath) {
            $errorMessage = Get-Content $errorPath;
            Remove-Item $errorPath;

            if ($errorMessage) {
                Write-Error $errorMessage;
            }
        }
    }

    <#
        .SYNOPSIS
        Executes the specified action and notifies the OneShot task executor.
    #>
    function Start-OneShot {
        try {
            Write-Host "Running OneShot task ``$(Get-OneShotTask)``";

            switch (Get-OneShotTask) {
                ([OneShotTask]::InitializeMSAccount) {
                    Initialize-UserCreation;
                }
                ([OneShotTask]::DisableUAC) {
                    Disable-UAC;
                    Register-Setup;
                }
            }
        }
        catch {
            $errorPath = & $getErrorPath;
            Set-Content -Path $errorPath -Value $Error;
            Set-UserPermissions $errorPath;
        }
        finally {
            & $taskSetter $null;
            Write-EventLog -LogName $logName -Source $logName -EventId $oneShotTrigger -Message "The OneShot task ``$(Get-OneShotTask)`` finished.";
        }
    }
}