/Engine/Game/ProcessManager.cs

using System.Collections.Generic;

using Delta.Engine.Dynamic;

using Delta.InputSystem;



namespace Delta.Engine.Game

{

	/// <summary>

	/// The process manager has a list of all processes and runs them.

	/// This simplifies the logic and optimizes performance a lot for each

	/// of the process classes, which are only run if active.

	/// </summary>

	internal class ProcessManager : DynamicModule

	{

		#region Internal



		#region Instance (Internal)

		/// <summary>

		/// Helper to make sure to only create the ProcessManager once and via

		/// the Factory to be registered as a DynamicModule.

		/// </summary>

		internal static ProcessManager Instance

		{

			get

			{

				if (instance == null)

				{

					instance = Factory.Create<ProcessManager>();

				}

				return instance;

			}

		}

		#endregion



		#region processes (Internal)

		/// <summary>

		/// List of processes we want to run each tick. Some of them might not be

		/// active and will be skipped. This list can change at any time.

		/// </summary>

		internal List<BaseProcess> processes = new List<BaseProcess>();

		#endregion



		#endregion



		#region Private



		#region instance (Private)

		/// <summary>

		/// Remember the created ProcessManager instance

		/// </summary>

		private static ProcessManager instance;

		#endregion



		#endregion



		#region Constructors

		/// <summary>

		/// Create process manager, only allowed internally via the Instance

		/// property. Done automatically when creating processes.

		/// </summary>

		private ProcessManager()

			: base("ProcessManager", typeof(Input))

		{

		}

		#endregion



		#region Run (Public)

		/// <summary>

		/// Run goes through all processes and runs them if they are active.

		/// </summary>

		public override void Run()

		{

			// No need to go any further if there are no more processes alive

			if (processes.Count == 0)

			{

				return;

			}



			List<BaseProcess> removeProcesses = null;

			foreach (BaseProcess process in processes)

			{

				// Only run active processes.

				if (process.IsActive &&

				    process.Run())

				{

					if (removeProcesses == null)

					{

						removeProcesses = new List<BaseProcess>();

					}

					removeProcesses.Add(process);

					// If we have a next process after this, activate it.

					if (process.Next != null)

					{

						process.Next.IsActive = true;

					}

				}

			}



			// Remove all processes that are done

			if (removeProcesses != null)

			{

				foreach (BaseProcess processToRemove in removeProcesses)

				{

					processes.Remove(processToRemove);

				}

			}

		}

		#endregion

	}

}