# GOTT Remote Agent - Windows PowerShell Client
# Verbindet sich per WebSocket zum GOTT-Server und fuehrt Befehle aus.
#
# Verwendung:
#   irm https://gott.example.com/remote.ps1 | iex
#   oder:
#   .\remote.ps1 -Url "wss://gott.example.com/api/remote"

param(
    [string]$Url = "{{WS_URL}}"
)

$ErrorActionPreference = "Stop"

Write-Host ""
Write-Host "  ============================" -ForegroundColor Cyan
Write-Host "   GOTT Remote Agent" -ForegroundColor Cyan
Write-Host "  ============================" -ForegroundColor Cyan
Write-Host ""
Write-Host "  Verbinde zu: $Url" -ForegroundColor Gray
Write-Host ""

function Send-WsMessage {
    param([System.Net.WebSockets.ClientWebSocket]$ws, [string]$msg, [System.Threading.CancellationToken]$ct)
    $bytes = [System.Text.Encoding]::UTF8.GetBytes($msg)
    $ws.SendAsync((New-Object System.ArraySegment[byte] -ArgumentList @(,$bytes)),
        [System.Net.WebSockets.WebSocketMessageType]::Text, $true, $ct).GetAwaiter().GetResult() | Out-Null
}

function Receive-WsMessage {
    param([System.Net.WebSockets.ClientWebSocket]$ws, [System.Threading.CancellationToken]$ct)
    $buf = New-Object byte[] 65536
    $ms = New-Object System.IO.MemoryStream
    try {
        do {
            $seg = New-Object System.ArraySegment[byte] -ArgumentList @(,$buf)
            $result = $ws.ReceiveAsync($seg, $ct).GetAwaiter().GetResult()
            if ($result.MessageType -eq [System.Net.WebSockets.WebSocketMessageType]::Close) {
                return $null
            }
            $ms.Write($buf, 0, $result.Count)
        } while (-not $result.EndOfMessage)
        return [System.Text.Encoding]::UTF8.GetString($ms.ToArray())
    } finally {
        $ms.Dispose()
    }
}

try {
    $ws = New-Object System.Net.WebSockets.ClientWebSocket
    $cts = New-Object System.Threading.CancellationTokenSource
    $ct = $cts.Token

    # Ctrl+C abfangen → CancellationToken ausloesen
    [Console]::TreatControlCAsInput = $false
    $cancelHandler = [System.ConsoleCancelEventHandler]{
        param($s, $e)
        $e.Cancel = $true
        $cts.Cancel()
    }
    [Console]::add_CancelKeyPress($cancelHandler)

    # TLS 1.2 erzwingen (fuer aeltere Windows-Versionen)
    [System.Net.ServicePointManager]::SecurityProtocol = [System.Net.SecurityProtocolType]::Tls12

    # Verbindung aufbauen
    try {
        $ws.ConnectAsync([Uri]$Url, $ct).GetAwaiter().GetResult() | Out-Null
    } catch {
        Write-Host "  [FEHLER] Verbindung fehlgeschlagen: $_" -ForegroundColor Red
        Write-Host "  URL: $Url" -ForegroundColor Gray
        return
    }
    Write-Host "  [OK] Verbunden!" -ForegroundColor Green

    # Hello-Message senden
    $hostname = $env:COMPUTERNAME
    $username = $env:USERNAME
    $osVersion = [System.Environment]::OSVersion.VersionString
    $hello = @{
        type = "hello"
        hostname = $hostname
        username = $username
        os = $osVersion
    } | ConvertTo-Json -Compress
    Send-WsMessage $ws $hello $ct

    Write-Host "  Host: $username@$hostname ($osVersion)" -ForegroundColor Gray
    Write-Host ""
    Write-Host "  Warte auf Befehle... (Strg+C zum Beenden)" -ForegroundColor Yellow
    Write-Host ""

    # Synchroner Empfangs-Loop
    while ($ws.State -eq [System.Net.WebSockets.WebSocketState]::Open) {
        # Blockierend auf naechste Nachricht warten
        $json = Receive-WsMessage $ws $ct
        if ($null -eq $json) {
            Write-Host "  Server hat Verbindung geschlossen." -ForegroundColor Yellow
            break
        }

        try {
            $msg = $json | ConvertFrom-Json
        } catch {
            continue
        }

        switch ($msg.type) {
            "execute" {
                $command = $msg.command
                $timestamp = Get-Date -Format "HH:mm:ss"
                Write-Host "  [$timestamp] Ausfuehren: " -NoNewline -ForegroundColor Cyan
                Write-Host $command -ForegroundColor White

                $exitCode = 0
                $stdout = ""
                $stderr = ""

                try {
                    # EncodedCommand umgeht alle Quoting-Probleme (Anführungszeichen, Sonderzeichen)
                    $encodedCmd = [Convert]::ToBase64String([System.Text.Encoding]::Unicode.GetBytes($command))
                    $output = & powershell.exe -NoProfile -NonInteractive -EncodedCommand $encodedCmd 2>&1
                    $stdoutLines = @($output | Where-Object { $_ -isnot [System.Management.Automation.ErrorRecord] })
                    $stderrLines = @($output | Where-Object { $_ -is [System.Management.Automation.ErrorRecord] }) |
                        ForEach-Object { $_.ToString() }
                    $stdout = ($stdoutLines | Out-String).TrimEnd()
                    $stderr = ($stderrLines | Out-String).TrimEnd()
                    $exitCode = $LASTEXITCODE
                    if ($null -eq $exitCode) { $exitCode = 0 }
                } catch {
                    $stderr = $_.Exception.Message
                    $exitCode = 1
                }

                # Ergebnis senden
                $response = @{
                    type = "result"
                    exitCode = $exitCode
                    output = if ($stdout) { $stdout } else { "" }
                    error = if ($stderr) { $stderr } else { "" }
                } | ConvertTo-Json -Compress -Depth 3

                Send-WsMessage $ws $response $ct

                # Kurzausgabe lokal
                if ($stdout) {
                    $preview = if ($stdout.Length -gt 200) { $stdout.Substring(0, 200) + "..." } else { $stdout }
                    Write-Host "  -> $preview" -ForegroundColor Gray
                }
                if ($stderr) {
                    Write-Host "  [stderr] $stderr" -ForegroundColor Red
                }
                Write-Host "  [Exit: $exitCode]" -ForegroundColor $(if ($exitCode -eq 0) { "Green" } else { "Red" })
                Write-Host ""
            }
            "ping" {
                # Server-Heartbeat → mit pong antworten
                Send-WsMessage $ws '{"type":"pong"}' $ct
            }
            "pong" {
                # Heartbeat-Antwort - ignorieren
            }
            default {
                Write-Host "  Unbekannte Nachricht: $($msg.type)" -ForegroundColor Yellow
            }
        }
    }
} catch [System.OperationCanceledException] {
    # Ctrl+C
} catch [System.AggregateException] {
    # Kann durch CancellationToken in .GetAwaiter().GetResult() kommen
} catch [System.Net.WebSockets.WebSocketException] {
    Write-Host "  Verbindung verloren." -ForegroundColor Red
} catch {
    Write-Host "  Fehler: $_" -ForegroundColor Red
} finally {
    # Event-Handler entfernen
    try { [Console]::remove_CancelKeyPress($cancelHandler) } catch { }

    if ($ws -and $ws.State -eq [System.Net.WebSockets.WebSocketState]::Open) {
        try {
            $closeCt = (New-Object System.Threading.CancellationTokenSource(3000)).Token
            $ws.CloseAsync([System.Net.WebSockets.WebSocketCloseStatus]::NormalClosure, "bye", $closeCt).GetAwaiter().GetResult() | Out-Null
        } catch { }
    }
    if ($cts) { $cts.Dispose() }
    if ($ws) { $ws.Dispose() }
    Write-Host ""
    Write-Host "  Verbindung beendet." -ForegroundColor Yellow
}