#region Copyright & License Information
/*
 * Copyright 2007-2010 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 LICENSE.
 */
#endregion

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using OpenRA.Effects;
using OpenRA.Mods.RA.Activities;
using OpenRA.Traits.Activities;
using OpenRA.FileFormats;
using System.Diagnostics;
using OpenRA.Orders;
using OpenRA.Traits;

namespace OpenRA.Mods.RA.Move
{
    public class MobileInfo : ITraitInfo
    {
        [FieldLoader.LoadUsing("LoadSpeeds")]
        public readonly Dictionary<string, TerrainInfo> TerrainSpeeds;
        [FieldLoader.Load]
        public readonly string[] Crushes;
        [FieldLoader.Load]
        public readonly int WaitAverage = 60;
        [FieldLoader.Load]
        public readonly int WaitSpread = 20;
        [FieldLoader.Load]
        public readonly int InitialFacing = 128;
        [FieldLoader.Load]
        public readonly int ROT = 255;
        [FieldLoader.Load]
        public readonly int Speed = 1;
        [FieldLoader.Load]
        public readonly bool OnRails = false;

        public virtual object Create(ActorInitializer init) { return new Mobile(init, this); }

        static object LoadSpeeds(MiniYaml y)
        {
            Dictionary<string, TerrainInfo> ret = new Dictionary<string, TerrainInfo>();
            foreach (var t in y.NodesDict["TerrainSpeeds"].Nodes)
            {
                var speed = (decimal)FieldLoader.GetValue("speed", typeof(decimal), t.Value.Value);
                var cost = t.Value.NodesDict.ContainsKey("PathingCost") ? (int)FieldLoader.GetValue("cost", typeof(int), t.Value.NodesDict["PathingCost"].Value) : (int)(10000 / speed);
                ret.Add(t.Key, new TerrainInfo { Speed = speed, Cost = cost });
            }

            return ret;
        }

        public class TerrainInfo
        {
            public int Cost = int.MaxValue;
            public decimal Speed = 0;
        }

        public int MovementCostForCell(World world, int2 cell)
        {
            if (!world.Map.IsInMap(cell.X, cell.Y))
                return int.MaxValue;

            var type = world.GetTerrainType(cell);
            if (!TerrainSpeeds.ContainsKey(type))
                return int.MaxValue;

            return TerrainSpeeds[type].Cost;
        }

        public bool CanEnterCell(World world, UnitInfluence uim, int2 cell, Actor ignoreActor, bool checkTransientActors)
        {
            if (MovementCostForCell(world, cell) == int.MaxValue)
                return false;

            var blockingActors = uim.GetUnitsAt(cell).Where(x => x != ignoreActor).ToList();
            if (checkTransientActors && blockingActors.Count > 0)
            {
                // We can enter a cell with nonshareable units only if we can crush all of them
                if (Crushes == null)
                    return false;

                if (blockingActors.Any(a => !(a.HasTrait<ICrushable>() &&
                                             a.TraitsImplementing<ICrushable>().Any(b => b.CrushClasses.Intersect(Crushes).Any()))))
                    return false;
            }

            return true;
        }

        public bool CanEnterCell(World world, int2 cell, Actor ignoreActor, bool checkTransientActors)
        {
            var uim = world.WorldActor.Trait<UnitInfluence>();
            return CanEnterCell(world, uim, cell, ignoreActor, checkTransientActors);
        }
    }

    public class Mobile : IIssueOrder, IResolveOrder, IOrderVoice, IOccupySpace, IMove, IFacing, INudge
    {
        public readonly Actor self;
        public readonly MobileInfo Info;
        public bool IsMoving { get; internal set; }

        int __facing;
        int2 __fromCell, __toCell;
        int __altitude;

        [Sync]
        public int Facing
        {
            get { return __facing; }
            set { __facing = value; }
        }

        [Sync]
        public int Altitude
        {
            get { return __altitude; }
            set { __altitude = value; }
        }

        public int ROT { get { return Info.ROT; } }
        public int InitialFacing { get { return Info.InitialFacing; } }

        [Sync]
        public int2 PxPosition { get; set; }
        [Sync]
        public int2 fromCell { get { return __fromCell; } }
        [Sync]
        public int2 toCell { get { return __toCell; } }

        [Sync]
        public int PathHash;	// written by Move.EvalPath, to temporarily debug this crap.

        public void SetLocation(int2 from, int2 to)
        {
            if (fromCell == from && toCell == to) return;
            RemoveInfluence();
            __fromCell = from;
            __toCell = to;
            AddInfluence();
        }

        UnitInfluence uim;

        const int avgTicksBeforePathing = 5;
        const int spreadTicksBeforePathing = 5;
        internal int ticksBeforePathing = 0;

        public Mobile(ActorInitializer init, MobileInfo info)
        {
            this.self = init.self;
            this.Info = info;

            uim = self.World.WorldActor.Trait<UnitInfluence>();

            if (init.Contains<LocationInit>())
            {
                this.__fromCell = this.__toCell = init.Get<LocationInit, int2>();
                this.PxPosition = Util.CenterOfCell(fromCell);
            }

            this.Facing = init.Contains<FacingInit>() ? init.Get<FacingInit, int>() : info.InitialFacing;
            this.Altitude = init.Contains<AltitudeInit>() ? init.Get<AltitudeInit, int>() : 0;
        }

        public void SetPosition(Actor self, int2 cell)
        {
            SetLocation(cell, cell);
            PxPosition = Util.CenterOfCell(fromCell);
            FinishedMoving(self);
        }

        public void SetPxPosition(Actor self, int2 px)
        {
            var cell = Util.CellContaining(px);
            SetLocation(cell, cell);
            PxPosition = px;
            FinishedMoving(self);
        }

        public IEnumerable<IOrderTargeter> Orders { get { yield return new MoveOrderTargeter(Info); } }

        // Note: Returns a valid order even if the unit can't move to the target
        public Order IssueOrder(Actor self, IOrderTargeter order, Target target, bool queued)
        {
            if (order is MoveOrderTargeter)
            {
                if (Info.OnRails) return null;
                return new Order("Move", self, queued) { TargetLocation = Util.CellContaining(target.CenterLocation) };
            }
            return null;
        }

        public int2 NearestMoveableCell(int2 target)
        {
            if (CanEnterCell(target))
                return target;

            var searched = new List<int2>() { };
            // Limit search to a radius of 10 tiles
            for (int r = 1; r < 10; r++)
                foreach (var tile in self.World.FindTilesInCircle(target, r).Except(searched))
                {
                    if (CanEnterCell(tile))
                        return tile;

                    searched.Add(tile);
                }

            // Couldn't find a cell
            return target;
        }

        protected void PerformMove(Actor self, int2 targetLocation, bool queued)
        {
            var ph = new QueuedActivity(
                (qa) =>
                {
                    int2 currentLocation = NearestMoveableCell(targetLocation);

                    if (!CanEnterCell(currentLocation))
                    {
                        if (queued) self.CancelActivity();
                        return;
                    }

                    if (!queued) self.CancelActivity();

                    ticksBeforePathing = avgTicksBeforePathing + self.World.SharedRandom.Next(-spreadTicksBeforePathing, spreadTicksBeforePathing);

                    qa.Insert(new Move(currentLocation, 8));

                    self.SetTargetLine(Target.FromCell(currentLocation), Color.Green);
                });

            self.QueueActivity(queued ? ph : ph.Run(self));
        }

        public void ResolveOrder(Actor self, Order order)
        {
            if (order.OrderString == "Move")
            {
                var target = order.TargetLocation.Clamp(self.World.Map.Bounds);
                PerformMove(self, target, order.Queued && !self.IsIdle);
            }

            if (order.OrderString == "Stop")
            {
                self.CancelActivity();
            }
        }

        public string VoicePhraseForOrder(Actor self, Order order)
        {
            if (order.OrderString == "Move")
                return "Move";
            return null;
        }

        public int2 TopLeft { get { return toCell; } }

        public IEnumerable<int2> OccupiedCells()
        {
            return (fromCell == toCell)
                ? new[] { fromCell }
                : CanEnterCell(toCell)
                    ? new[] { toCell }
                    : new[] { fromCell, toCell };
        }

        public bool CanEnterCell(int2 p)
        {
            return CanEnterCell(p, null, true);
        }

        public bool CanEnterCell(int2 cell, Actor ignoreActor, bool checkTransientActors)
        {
            var uim = self.World.WorldActor.Trait<UnitInfluence>();
            return Info.CanEnterCell(self.World, uim, cell, ignoreActor, checkTransientActors);
        }

        public void FinishedMoving(Actor self)
        {
            var crushable = uim.GetUnitsAt(toCell).Where(a => a != self && a.HasTrait<ICrushable>());
            foreach (var a in crushable)
            {
                var crushActions = a.TraitsImplementing<ICrushable>().Where(b => b.CrushClasses.Intersect(Info.Crushes).Any());
                foreach (var b in crushActions)
                    b.OnCrush(self);
            }
        }

        public int MovementSpeedForCell(Actor self, int2 cell)
        {
            var type = self.World.GetTerrainType(cell);

            if (!Info.TerrainSpeeds.ContainsKey(type))
                return 0;

            decimal speed = Info.Speed * Info.TerrainSpeeds[type].Speed;
            foreach (var t in self.TraitsImplementing<ISpeedModifier>())
                speed *= t.GetSpeedModifier();
            return (int)(speed / 100);
        }

        public void AddInfluence()
        {
            if (self.IsInWorld)
                uim.Add(self, this);
        }

        public void RemoveInfluence()
        {
            if (self.IsInWorld)
                uim.Remove(self, this);
        }

        public void OnNudge(Actor self, Actor nudger)
        {
            /* initial fairly braindead implementation. */

            if (self.Owner.Stances[nudger.Owner] != Stance.Ally)
                return;		/* don't allow ourselves to be pushed around
							 * by the enemy! */

            if (!self.IsIdle)
                return;		/* don't nudge if we're busy doing something! */

            // pick an adjacent available cell.
            var availCells = new List<int2>();
            var notStupidCells = new List<int2>();

            for (var i = -1; i < 2; i++)
                for (var j = -1; j < 2; j++)
                {
                    var p = toCell + new int2(i, j);
                    if (CanEnterCell(p))
                        availCells.Add(p);
                    else
                        if (p != nudger.Location && p != toCell)
                            notStupidCells.Add(p);
                }

            var moveTo = availCells.Any() ? availCells.Random(self.World.SharedRandom) :
                notStupidCells.Any() ? notStupidCells.Random(self.World.SharedRandom) : (int2?)null;

            if (moveTo.HasValue)
            {
                self.CancelActivity();
                self.SetTargetLine(Target.FromCell(moveTo.Value), Color.Green, false);
                self.QueueActivity(new Move(moveTo.Value, 0));

                Log.Write("debug", "OnNudge #{0} from {1} to {2}",
                    self.ActorID, self.Location, moveTo.Value);
            }
            else
                Log.Write("debug", "OnNudge #{0} refuses at {1}",
                    self.ActorID, self.Location);
        }

        class MoveOrderTargeter : IOrderTargeter
        {
            readonly MobileInfo unitType;

            public MoveOrderTargeter(MobileInfo unitType)
            {
                this.unitType = unitType;
            }

            public string OrderID { get { return "Move"; } }
            public int OrderPriority { get { return 4; } }
            public bool IsQueued { get; protected set; }
            public bool CanTargetUnit(Actor self, Actor target, bool forceAttack, bool forceMove, bool forceQueued, ref string cursor)
            {
                return false;
            }

            public bool CanTargetLocation(Actor self, int2 location, List<Actor> actorsAtLocation, bool forceAttack, bool forceMove, bool forceQueued, ref string cursor)
            {
                IsQueued = forceQueued;
                cursor = "move";
                if (!self.World.Map.IsInMap(location) || (self.World.LocalPlayer.Shroud.IsExplored(location) &&
                        self.Trait<Mobile>().Info.MovementCostForCell(self.World, location) == int.MaxValue))
                    cursor = "move-blocked";

                return true;
            }
        }

        public IActivity ScriptedMove(int2 cell) { return new Move(cell); }
        public IActivity MoveTo(int2 cell, int nearEnough) { return new Move(cell, nearEnough); }
        public IActivity MoveTo(int2 cell, Actor ignoredActor) { return new Move(cell, ignoredActor); }
        public IActivity MoveWithinRange(Actor target, int range) { return new Move(target, range); }
        public IActivity MoveWithinRange(Target target, int range) { return new Move(target, range); }
        public IActivity MoveTo(Func<List<int2>> pathFunc) { return new Move(pathFunc); }
    }
}