Minecraft-Phantom-Panel/Agent/Phantom.Agent.Services/Instances/States/InstanceStoppingState.cs

using System.Diagnostics;
using Phantom.Agent.Minecraft.Command;
using Phantom.Agent.Minecraft.Instance;
using Phantom.Common.Data.Instance;
using Phantom.Common.Data.Minecraft;
using Phantom.Common.Data.Replies;

namespace Phantom.Agent.Services.Instances.States; 

sealed class InstanceStoppingState : IInstanceState, IDisposable {
	private readonly InstanceContext context;
	private readonly InstanceProcess process;
	private readonly IDisposable sessionDisposer;

	public InstanceStoppingState(InstanceContext context, InstanceProcess process, IDisposable sessionDisposer) {
		this.context = context;
		this.process = process;
		this.sessionDisposer = sessionDisposer;
	}

	public void Initialize() {
		context.Logger.Information("Session stopping.");
		context.SetStatus(InstanceStatus.Stopping);
		context.Services.TaskManager.Run("Stop procedure for instance " + context.ShortName, DoStop);
	}

	private async Task DoStop() {
		try {
			// Do not release the semaphore after this point.
			if (!await process.BackupSemaphore.CancelAndWait(TimeSpan.FromSeconds(1))) {
				context.Logger.Information("Waiting for backup to finish...");
				await process.BackupSemaphore.CancelAndWait(Timeout.InfiniteTimeSpan);
			}
			
			context.Logger.Information("Sending stop command...");
			await DoSendStopCommand();

			context.Logger.Information("Waiting for session to end...");
			await DoWaitForSessionToEnd();
		} finally {
			context.Logger.Information("Session stopped.");
			context.ReportEvent(InstanceEvent.Stopped);
			context.TransitionState(new InstanceNotRunningState(), InstanceStatus.NotRunning);
		}
	}

	private async Task DoSendStopCommand() {
		using var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(5));
		try {
			await process.SendCommand(MinecraftCommand.Stop, timeout.Token);
		} catch (OperationCanceledException) {
			// ignore
		} catch (ObjectDisposedException e) when (e.ObjectName == typeof(Process).FullName && process.HasEnded) {
			// ignore
		} catch (Exception e) {
			context.Logger.Warning(e, "Caught exception while sending stop command.");
		}
	}

	private async Task DoWaitForSessionToEnd() {
		using var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(55));
		try {
			await process.WaitForExit(timeout.Token);
		} catch (OperationCanceledException) {
			try {
				context.Logger.Warning("Waiting timed out, killing session...");
				process.Kill();
			} catch (Exception e) {
				context.Logger.Error(e, "Caught exception while killing session.");
			}
		}
	}

	public (IInstanceState, LaunchInstanceResult) Launch(InstanceContext context) {
		return (this, LaunchInstanceResult.InstanceIsStopping);
	}

	public (IInstanceState, StopInstanceResult) Stop(MinecraftStopStrategy stopStrategy) {
		return (this, StopInstanceResult.InstanceAlreadyStopping); // TODO maybe provide a way to kill?
	}

	public Task<bool> SendCommand(string command, CancellationToken cancellationToken) {
		return Task.FromResult(false);
	}

	public void Dispose() {
		sessionDisposer.Dispose();
	}
}