using System;
using System.Collections.Generic;
using System.Text;
using log4net;

namespace TBF.BenchControl
{
    public class State
    {
		/// <summary>
		/// DEBUG: all state changes and all operations
		/// INFO:  all state changes and operations that returned evnt != Event.None
		/// WARN:  only state changes
		/// </summary>
		private static readonly ILog log = LogManager.GetLogger(typeof(State));
		public override string ToString() { return Name + (Label==null ? "" : ", label=" + Label); }


		/// <summary>Current state (static)</summary>
		public static State CurrentState
		{
			get { return currentState; }
		}
		static State currentState;


		/// <summary>
		/// Events returned by the last RunOperations()
		/// </summary>
		public static IList<Event> LastEvents;


		/// <summary>State with an empty list of operations</summary>
		/// <remarks>Useful when entering the first state and leaving the last one</remarks>
		public static State Empty
		{
			get { return new State("empty"); }
		}

		/// <summary>
		/// Static constructor that initializes CurrentState
		/// </summary>
		static State()
		{
            PermanentOperations = new List<IOperation>();
            currentState = State.Empty;
		}

		///
		/// Instance fields set or initialized by the constructor
		///
		public static IList<IOperation> PermanentOperations;
		public readonly IList<IOperation> Operations;
		public readonly IList<Transition> Transitions;
		public readonly string Name;
		public readonly string Label;


		/// <summary>
		/// Constructor with a label
		/// </summary>
		public State(string name, string label)
		{
			this.Name = name;
			this.Label = label;
			Operations = new List<IOperation>();
			foreach (var op in PermanentOperations) Operations.Add(op);
			Transitions = new List<Transition>();
			log.Debug(this.ToString());
		}

		/// <summary>
		/// Default constructor
		/// </summary>
		public State(string name)
			: this(name, null)
		{
		}


		/// <summary>
		/// Create a new state without a label
		/// </summary>
		public static State Create(string name)
		{
			return new State(name);
		}

		/// <summary>
		/// Create a new state with a label
		/// </summary>
		public static State Create(string name, string label)
		{
			return new State(name, label);
		}

		/// <summary>
		/// Add an operation to the list of permanent opertion (and to this state)
		/// </summary>
		/// <param name="obj">operation</param>
		public State AddPermanentOperation(IOperation operation)
		{
			if (operation != null)
			{
				Operations.Add(operation);
				PermanentOperations.Add(operation);
			}
			return this;
		}

		/// <summary>
		/// Remove an operation from the list of permanent opertion (and from this state)
		/// </summary>
		/// <param name="obj">operation</param>
		public State RemovePermanentOperation(IOperation operation)
		{
			if (operation != null)
			{
				Operations.Remove(operation);
				PermanentOperations.Remove(operation);
			}
			return this;
		}

		/// <summary>
		/// Remove all permanent operations from this state and from the list
		/// (= clear the list of permanent operations)
		/// </summary>
		/// <param name="obj">operation</param>
		public State RemoveAllPermanentOperations()
		{
			if (PermanentOperations != null)
			{
				foreach (var op in PermanentOperations) Operations.Remove(op);
				PermanentOperations.Clear();
			}
			return this;
		}

		/// <summary>
		/// Add an operation to this state
		/// </summary>
		/// <param name="obj">operation</param>
		public State AddOperation(IOperation operation)
		{
			if (operation != null) Operations.Add(operation);
			return this;
		}

		/// <summary>
		/// Add a list of operations to this state
		/// </summary>
		/// <param name="obj">operation</param>
		public State AddOperations(IList<IOperation> operations)
		{
			if (operations != null)
			{
				foreach (var op in operations) { if (op != null) Operations.Add(op); }
			}
			return this;
		}

        /// <summary>
        /// Add a state transition to the state
        /// </summary>
        /// <param name="obj">transition</param>
		public State AddTransition(Transition transition)
        {
			if (transition != null) Transitions.Add(transition);
            return this;
        }

		/// <summary>
		/// Enter a new state
		/// </summary>
		public State EnterState()
		{
			ChangeState(State.currentState, this);
			State.currentState = this;
            UiBridge.Bridge.OnStateChanged(this, State.currentState.ToString());
			return this;
		}

		// ----------------------------------- Run time -----------------------------------------

		/// <summary>
		/// Execute Run() methods of all operations of the current state.
		/// </summary>
		/// <returns>List of Event-s returned from the state operations</returns>
		public static IList<Event> RunOperations()
		{
		    IList<Event> events = new List<Event>();

	        foreach (IOperation operation in currentState.Operations)
			{
				Event evnt = operation.Run();
				if (evnt != Event.None)
				{
					log.InfoFormat("Operation {0} returned {1}", operation, evnt);
					events.Add(evnt);
				}
				else
				{
					log.DebugFormat("Operation {0} returned {1}", operation, evnt);
				}
			}

			LastEvents = events;
			return events;
		}

        /// <summary>
        /// Execute Stop() methods of all operations of the current state.
        /// </summary>
        public static void StopOperations()
        {
            foreach (IOperation operation in currentState.Operations)
            {
                log.DebugFormat("stopping {0}", operation);
                operation.Stop();
            }
        }

        /// <summary>
		/// Run Stop() and Start() methods of operations when changing the state.
		/// </summary>
		/// <param name="previousState">Stopping state</param>
		/// <param name="newState">Starting state</param>
		static void ChangeState(State previousState, State newState)
		{
			/// Stop() the previous state operations, which are not in the next state
			foreach (IOperation operation in previousState.Operations)
			{
				if (!newState.Operations.Contains(operation))
				{
					log.DebugFormat("stopping {0}", operation);
					operation.Stop();
				}
			}

			log.WarnFormat("ChangeState( {0} -> {1} )", previousState.ToString(), newState.ToString());

			/// Start() the operations that are in the current (new) state, but aren't in the previous state.
			foreach (IOperation operation in newState.Operations)
			{
				if (!previousState.Operations.Contains(operation))
				{
					log.DebugFormat("starting {0}", operation);
					operation.Start();
				}
			}
		}
    }
}