using System;
using System.Collections.Generic;

namespace Cryville.Crtr.Event {
	public class EventBus : StateBase<EventBatch>, IDisposable {
		EventBus prototype = null;
		public ContainerState RootState {
			get;
			private set;
		}

		Dictionary<EventContainer, ContainerState> states
			= new Dictionary<EventContainer, ContainerState>();
		List<EventContainer> activeContainers
			= new List<EventContainer>();
		HashSet<ContainerState> workingStates
			= new HashSet<ContainerState>();
		HashSet<ContainerState> invalidatedStates
			= new HashSet<ContainerState>();

		public EventBus(ContainerState root, List<EventBatch> b) : base(b) {
			RootState = root;
			Expand();
			AttachBus();
			RootState.Working = true;
		}

		public EventBus Clone(byte ct, float offsetTime = 0) {
			var r = (EventBus)MemberwiseClone();
			r.prototype = this;
			r.states = new Dictionary<EventContainer, ContainerState>();
			r.activeContainers = new List<EventContainer>();
			r.workingStates = new HashSet<ContainerState>();
			r.invalidatedStates = new HashSet<ContainerState>();
			r.tempEvents = new List<StampedEvent>();
			r.Time += offsetTime;
			r.RootState = RootState.Clone(ct);
			r.RootState.StartUpdate();
			r.Expand();
			r.AttachBus();
			foreach (var s in r.states) r.invalidatedStates.Add(s.Value);
			r.ValidateStates();
			return r;
		}

		public void CopyTo(byte ct, EventBus dest) {
			base.CopyTo(dest);
			dest.workingStates.Clear();
			dest.invalidatedStates.Clear();
			RootState.CopyTo(ct, dest.RootState);
			if (ct >= 2) {
				dest.activeContainers.Clear();
				foreach (var c in activeContainers) {
					if (states[c].Working) {
						states[c].CopyTo(ct, dest.states[c]);
						dest.activeContainers.Add(c);
					}
				}
			}
			dest.ValidateStates();
		}

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

		public void NotifyWorkingChanged(ContainerState state) {
			if (!invalidatedStates.Contains(state)) invalidatedStates.Add(state);
		}

		void Expand(ContainerState s = null) {
			if (s == null) {
				states.Clear();
				s = RootState;
			}
			AddState(s);
			foreach (var c in s.Children.Values)
				Expand(c);
		}

		public void AddState(ContainerState s) {
			states[s.Container] = s;
			s.Bus = this;
		}

		void EnsureActivity(EventContainer c) {
			if (activeContainers.Contains(c)) return;
			var state = states[c];
			if (state.Parent != null) EnsureActivity(state.Parent.Container);
			if (RootState.CloneType >= 2) prototype.states[c].CopyTo(RootState.CloneType, state);
			state.Active = true;
			activeContainers.Add(c);

			if (state.StampedContainer.Coevents == null) return;
			foreach (var cev in state.StampedContainer.Coevents) {
				if (cev.Container == null) continue;
				EnsureActivity(cev.Container);
				states[cev.Container].Handle(cev);
			}
		}

		void AttachBus() {
			foreach (var s in states.Values)
				s.Bus = this;
		}
		
		public void AttachSystems(PdtSkin skin, Judge judge) {
			foreach (var s in states.Values)
				s.AttachSystems(skin, judge);
		}

		List<StampedEvent> tempEvents = new List<StampedEvent>();
		public void PushTempEvent(StampedEvent ev) {
			var index = tempEvents.BinarySearch(ev);
			if (index < 0) index = ~index;
			tempEvents.Insert(index, ev);
		}

		readonly StampedEvent _dummyEvent = new StampedEvent();
		public void StripTempEvents() {
			_dummyEvent.Time = Time;
			var index = tempEvents.BinarySearch(_dummyEvent);
			if (index < 0) index = ~index;
			tempEvents.RemoveRange(0, index);
		}

		public override void ForwardOnceToTime(double toTime) {
			double time1 = EventId < Events.Count ? Events[EventId].Time : double.PositiveInfinity;
			double time2 = tempEvents.Count > 0 ? tempEvents[0].Time : double.PositiveInfinity;
			double time0 = Math.Min(time1, time2);
			if (time0 <= toTime && time0 != double.PositiveInfinity) {
				Time = time0;
				foreach (var s in workingStates) s.Handle(null);
				ValidateStates();
				if (time1 == time0) {
					var batch = Events[EventId];
					for (var i = 0; i < batch.Count; i++) {
						var ev = batch[i];
						if (ev.Container != null) {
							if (ev.Unstamped is EventContainer) EnsureActivity((EventContainer)ev.Unstamped);
							else EnsureActivity(ev.Container);
							states[ev.Container].Handle(ev);
						}
						else if (ev.Coevents != null) EnsureActivity((EventContainer)ev.Unstamped);
					}
					EventId++;
				}
				if (time2 == time0) {
					while (tempEvents.Count > 0) {
						var ev = tempEvents[0];
						if (ev.Time != time0) break;
						if (ev.Container != null) {
							EnsureActivity(ev.Container);
							states[ev.Container].Handle(ev);
						}
						tempEvents.RemoveAt(0);
					}
				}
				ValidateStates();
			}
			else {
				Time = toTime;
				foreach (var s in workingStates) s.Handle(null);
				ValidateStates();
			}
		}

		private void ValidateStates() {
			foreach (var s in invalidatedStates)
				if (s.Working && !workingStates.Contains(s)) workingStates.Add(s);
				else if (!s.Working && workingStates.Contains(s)) workingStates.Remove(s);
			invalidatedStates.Clear();
		}
		
		public void BroadcastPreInit() {
			RootState.BroadcastPreInit();
		}
		public void BroadcastPostInit() {
			RootState.BroadcastPostInit();
		}

		public void BroadcastEndUpdate() {
			RootState.BroadcastEndUpdate();
			tempEvents.Clear();
		}

		public void Anchor() {
			RootState.Anchor();
		}
	}
}