#region Copyright & License Information
/*
 * Copyright 2007-2015 The OpenRA Developers (see AUTHORS)
 * This file is part of OpenRA, which is free software. It is made
 * available to you under the terms of the GNU General Public License
 * as published by the Free Software Foundation. For more information,
 * see COPYING.
 */
#endregion

using System;
using System.Collections.Generic;
using System.Linq;
using OpenRA.Effects;
using OpenRA.FileFormats;
using OpenRA.Graphics;
using OpenRA.Network;
using OpenRA.Orders;
using OpenRA.Primitives;
using OpenRA.Support;
using OpenRA.Traits;

namespace OpenRA
{
	public enum WorldType { Regular, Shellmap }

	public interface IWorld
	{
		IActor WorldActor { get; }
		int WorldTick { get; }
		IMap Map { get; }
		TileSet TileSet { get; }
	}

	public class World : IWorld
	{
		class ActorIDComparer : IComparer<Actor>
		{
			public static readonly ActorIDComparer Instance = new ActorIDComparer();
			private ActorIDComparer() { }
			public int Compare(Actor x, Actor y) { return x.ActorID.CompareTo(y.ActorID); }
		}

		static readonly Func<MPos, bool> FalsePredicate = _ => false;
		internal readonly TraitDictionary TraitDict = new TraitDictionary();
		readonly SortedSet<Actor> actors = new SortedSet<Actor>(ActorIDComparer.Instance);
		readonly List<IEffect> effects = new List<IEffect>();
		readonly Queue<Action<World>> frameEndActions = new Queue<Action<World>>();

		public int Timestep;

		internal readonly OrderManager OrderManager;
		public Session LobbyInfo { get { return OrderManager.LobbyInfo; } }

		public readonly MersenneTwister SharedRandom;

		public readonly List<Player> Players = new List<Player>();

		public void AddPlayer(Player p) { Players.Add(p); }
		public Player LocalPlayer { get; private set; }

		public event Action GameOver = () => { };
		bool gameOver;
		public void EndGame()
		{
			if (!gameOver)
			{
				gameOver = true;
				GameOver();
			}
		}

		public bool ObserveAfterWinOrLose;
		Player renderPlayer;
		public Player RenderPlayer
		{
			get { return renderPlayer == null || (ObserveAfterWinOrLose && renderPlayer.WinState != WinState.Undefined) ? null : renderPlayer; }
			set { renderPlayer = value; }
		}

		public bool FogObscures(Actor a) { return RenderPlayer != null && !RenderPlayer.Shroud.IsVisible(a); }
		public bool FogObscures(CPos p) { return RenderPlayer != null && !RenderPlayer.Shroud.IsVisible(p); }
		public bool ShroudObscures(Actor a) { return RenderPlayer != null && !RenderPlayer.Shroud.IsExplored(a); }
		public bool ShroudObscures(CPos p) { return RenderPlayer != null && !RenderPlayer.Shroud.IsExplored(p); }
		public bool ShroudObscures(MPos uv) { return RenderPlayer != null && !RenderPlayer.Shroud.IsExplored(uv); }

		public Func<MPos, bool> FogObscuresTest(CellRegion region)
		{
			var rp = RenderPlayer;
			if (rp == null)
				return FalsePredicate;
			var predicate = rp.Shroud.IsVisibleTest(region);
			return uv => !predicate(uv);
		}

		public Func<MPos, bool> ShroudObscuresTest(CellRegion region)
		{
			var rp = RenderPlayer;
			if (rp == null)
				return FalsePredicate;
			var predicate = rp.Shroud.IsExploredTest(region);
			return uv => !predicate(uv);
		}

		public bool IsReplay
		{
			get { return OrderManager.Connection is ReplayConnection; }
		}

		public bool AllowDevCommands
		{
			get { return LobbyInfo.GlobalSettings.AllowCheats || LobbyInfo.IsSinglePlayer; }
		}

		public void SetLocalPlayer(string pr)
		{
			if (IsReplay)
				return;

			LocalPlayer = Players.FirstOrDefault(p => p.InternalName == pr);
			RenderPlayer = LocalPlayer;
		}

		public readonly Actor WorldActor;
		IActor IWorld.WorldActor { get { return WorldActor; } }

		public readonly Map Map;
		IMap IWorld.Map { get { return Map; } }

		public readonly TileSet TileSet;
		TileSet IWorld.TileSet { get { return TileSet; } }

		public readonly ActorMap ActorMap;
		public readonly ScreenMap ScreenMap;
		public readonly WorldType Type;

		readonly GameInformation gameInfo;

		public void IssueOrder(Order o) { OrderManager.IssueOrder(o); } /* avoid exposing the OM to mod code */

		IOrderGenerator orderGenerator;
		public IOrderGenerator OrderGenerator
		{
			get
			{
				return orderGenerator;
			}

			set
			{
				Sync.AssertUnsynced("The current order generator may not be changed from synced code");
				orderGenerator = value;
			}
		}

		public Selection Selection = new Selection();

		public void CancelInputMode() { OrderGenerator = new UnitOrderGenerator(); }

		public bool ToggleInputMode<T>() where T : IOrderGenerator, new()
		{
			if (OrderGenerator is T)
			{
				CancelInputMode();
				return false;
			}
			else
			{
				OrderGenerator = new T();
				return true;
			}
		}

		internal World(Map map, OrderManager orderManager, WorldType type)
		{
			Type = type;
			OrderManager = orderManager;
			orderGenerator = new UnitOrderGenerator();
			Map = map;

			TileSet = map.Rules.TileSets[Map.Tileset];
			SharedRandom = new MersenneTwister(orderManager.LobbyInfo.GlobalSettings.RandomSeed);

			WorldActor = CreateActor("World", new TypeDictionary());
			ActorMap = WorldActor.Trait<ActorMap>();
			ScreenMap = WorldActor.Trait<ScreenMap>();

			// Add players
			foreach (var cmp in WorldActor.TraitsImplementing<ICreatePlayers>())
				cmp.CreatePlayers(this);

			// Set defaults for any unset stances
			foreach (var p in Players)
				foreach (var q in Players)
					if (!p.Stances.ContainsKey(q))
						p.Stances[q] = Stance.Neutral;

			Sound.SoundVolumeModifier = 1.0f;

			gameInfo = new GameInformation
			{
				MapUid = Map.Uid,
				MapTitle = Map.Title
			};
		}

		public void LoadComplete(WorldRenderer wr)
		{
			foreach (var wlh in WorldActor.TraitsImplementing<IWorldLoaded>())
			{
				using (new Support.PerfTimer(wlh.GetType().Name + ".WorldLoaded"))
					wlh.WorldLoaded(this, wr);
			}

			gameInfo.StartTimeUtc = DateTime.UtcNow;
			foreach (var player in Players)
				gameInfo.AddPlayer(player, OrderManager.LobbyInfo);

			var rc = OrderManager.Connection as ReplayRecorderConnection;
			if (rc != null)
				rc.Metadata = new ReplayMetadata(gameInfo);
		}

		public Actor CreateActor(string name, TypeDictionary initDict)
		{
			return CreateActor(true, name, initDict);
		}

		public Actor CreateActor(bool addToWorld, string name, TypeDictionary initDict)
		{
			var a = new Actor(this, name, initDict);
			foreach (var t in a.TraitsImplementing<INotifyCreated>())
				t.Created(a);
			if (addToWorld)
				Add(a);
			return a;
		}

		public void Add(Actor a)
		{
			a.IsInWorld = true;
			actors.Add(a);
			ActorAdded(a);

			foreach (var t in a.TraitsImplementing<INotifyAddedToWorld>())
				t.AddedToWorld(a);
		}

		public void Remove(Actor a)
		{
			a.IsInWorld = false;
			actors.Remove(a);
			ActorRemoved(a);

			foreach (var t in a.TraitsImplementing<INotifyRemovedFromWorld>())
				t.RemovedFromWorld(a);
		}

		public void Add(IEffect b) { effects.Add(b); }
		public void Remove(IEffect b) { effects.Remove(b); }
		public void RemoveAll(Predicate<IEffect> predicate) { effects.RemoveAll(predicate); }

		public void AddFrameEndTask(Action<World> a) { frameEndActions.Enqueue(a); }

		public event Action<Actor> ActorAdded = _ => { };
		public event Action<Actor> ActorRemoved = _ => { };

		public bool Paused { get; internal set; }
		public bool PredictedPaused { get; internal set; }
		public bool PauseStateLocked { get; set; }

		public int WorldTick { get; private set; }

		public void SetPauseState(bool paused)
		{
			if (PauseStateLocked)
				return;

			IssueOrder(Order.PauseGame(paused));
			PredictedPaused = paused;
		}

		public void SetLocalPauseState(bool paused)
		{
			Paused = PredictedPaused = paused;
		}

		public void Tick()
		{
			if (!Paused && (Type != WorldType.Shellmap || Game.Settings.Game.ShowShellmap))
			{
				WorldTick++;

				using (new PerfSample("tick_idle"))
					foreach (var ni in ActorsWithTrait<INotifyIdle>())
						if (ni.Actor.IsIdle)
							ni.Trait.TickIdle(ni.Actor);

				using (new PerfSample("tick_activities"))
					foreach (var a in actors)
						a.Tick();

				ActorsWithTrait<ITick>().DoTimed(x => x.Trait.Tick(x.Actor), "Trait");

				effects.DoTimed(e => e.Tick(this), "Effect");
			}

			while (frameEndActions.Count != 0)
				frameEndActions.Dequeue()(this);
		}

		// For things that want to update their render state once per tick, ignoring pause state
		public void TickRender(WorldRenderer wr)
		{
			ActorsWithTrait<ITickRender>().DoTimed(x => x.Trait.TickRender(wr, x.Actor), "Render");
		}

		public IEnumerable<Actor> Actors { get { return actors; } }
		public IEnumerable<IEffect> Effects { get { return effects; } }

		uint nextAID = 0;
		internal uint NextAID()
		{
			return nextAID++;
		}

		public int SyncHash()
		{
			// using (new PerfSample("synchash"))
			{
				var n = 0;
				var ret = 0;

				// hash all the actors
				foreach (var a in Actors)
					ret += n++ * (int)(1 + a.ActorID) * Sync.CalculateSyncHash(a);

				// hash all the traits that tick
				foreach (var x in ActorsWithTrait<ISync>())
					ret += n++ * (int)(1 + x.Actor.ActorID) * Sync.CalculateSyncHash(x.Trait);

				// TODO: don't go over all effects
				foreach (var e in Effects)
				{
					var sync = e as ISync;
					if (sync != null)
						ret += n++ * Sync.CalculateSyncHash(sync);
				}

				// Hash the shared rng
				ret += SharedRandom.Last;

				return ret;
			}
		}

		public IEnumerable<TraitPair<T>> ActorsWithTrait<T>()
		{
			return TraitDict.ActorsWithTrait<T>();
		}

		public void OnPlayerWinStateChanged(Player player)
		{
			var pi = gameInfo.GetPlayer(player);
			if (pi != null)
			{
				pi.Outcome = player.WinState;
				pi.OutcomeTimestampUtc = DateTime.UtcNow;
			}
		}
	}

	public struct TraitPair<T>
	{
		public Actor Actor;
		public T Trait;

		public override string ToString()
		{
			return "{0}->{1}".F(Actor.Info.Name, Trait.GetType().Name);
		}
	}
}