using System;
using System.Threading;
using System.Collections.Generic;

namespace org.budnhead.tools
{
	public delegate T JobDelegate<T>();

	public class JobThreader
	{
		Thread		workerThread;
		List<Job>	queuedJobs;


		public JobThreader()
		{
			workerThread = Thread.CurrentThread;
			queuedJobs = new List<Job>();
		}
		public JobThreader(Thread workerThread){
			this.workerThread = workerThread;
			queuedJobs = new List<Job>();
		}

		public void execute(){
			Monitor.Enter(queuedJobs);

			foreach (Job j in queuedJobs){
				j.execute();
			}

			queuedJobs.Clear();

			Monitor.PulseAll(queuedJobs);
			Monitor.Exit(queuedJobs);
		}

		public T execute<T>(JobDelegate<T> jobDelegate) where T : class{
			if (workerThread.Equals(Thread.CurrentThread)){
				return jobDelegate();
			} else {
				return Enqueue(jobDelegate);
			}
		}

		private T Enqueue<T>(JobDelegate<T> jobDelegate) where T : class {
			Job<T> job;
			Monitor.Enter(queuedJobs);

			job = new Job<T>(jobDelegate);

			queuedJobs.Add(job);

			Monitor.Wait(queuedJobs);
			Monitor.Exit(queuedJobs);

			return job.Result;
		}

		public abstract class Job{
			public virtual void execute(){
			}
		}

		public class Job<T> : Job{
			T result;
			JobDelegate<T> jobDelegate;

			public Job(JobDelegate<T> jobDelegate){
				this.jobDelegate = jobDelegate;
			}

			public override void execute()
			{
				this.result = this.jobDelegate();
			}

			public T Result {
				get { return this.result; }
			}

		}
	}
}