using System.Collections.Generic;
using System.Security;

namespace System.Threading.Tasks;

internal sealed class SynchronizationContextScheduler : TaskScheduler
{
	private readonly SynchronizationContext ctx;

	private readonly SendOrPostCallback callback;

	public override int MaximumConcurrencyLevel => base.MaximumConcurrencyLevel;

	public SynchronizationContextScheduler(SynchronizationContext ctx)
	{
		this.ctx = ctx;
		callback = TaskLaunchWrapper;
	}

	[SecurityCritical]
	protected internal override void QueueTask(Task task)
	{
		ctx.Post(callback, task);
	}

	private void TaskLaunchWrapper(object obj)
	{
		TryExecuteTask((Task)obj);
	}

	[SecurityCritical]
	protected override IEnumerable<Task> GetScheduledTasks()
	{
		return null;
	}

	protected internal override bool TryDequeue(Task task)
	{
		return false;
	}

	[SecurityCritical]
	protected override bool TryExecuteTaskInline(Task task, bool taskWasPreviouslyQueued)
	{
		ctx.Send(callback, task);
		return true;
	}
}