#region Copyright & License Information
/*
 * Copyright 2007-2011 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.Drawing;
using System.Linq;
using OpenRA.Graphics;
using OpenRA.Mods.RA.Activities;
using OpenRA.Traits;

namespace OpenRA.Mods.RA
{
	class MinelayerInfo : TraitInfo<Minelayer>
	{
		[ActorReference]
		public readonly string Mine = "minv";
		public readonly float MinefieldDepth = 1.5f;
		[ActorReference]
		public readonly string[] RearmBuildings = { "fix" };
	}

	class Minelayer : IIssueOrder, IResolveOrder, IPostRenderSelection, ISync
	{
		/* [Sync] when sync can cope with arrays! */ 
		public int2[] minefield = null;
		[Sync] int2 minefieldStart;

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

		public Order IssueOrder( Actor self, IOrderTargeter order, Target target, bool queued )
		{
			if( order is BeginMinefieldOrderTargeter )
			{
				var start = Traits.Util.CellContaining( target.CenterLocation );
				self.World.OrderGenerator = new MinefieldOrderGenerator( self, start );
				return new Order("BeginMinefield", self, false) { TargetLocation = start };
			}
			return null;
		}

		public void ResolveOrder(Actor self, Order order)
		{
			if( order.OrderString == "BeginMinefield" )
				minefieldStart = order.TargetLocation;

			if (order.OrderString == "PlaceMinefield")
			{
				var movement = self.Trait<IMove>();

				minefield = GetMinefieldCells(minefieldStart, order.TargetLocation,
					self.Info.Traits.Get<MinelayerInfo>().MinefieldDepth)
					.Where(p => movement.CanEnterCell(p)).ToArray();

				self.CancelActivity();
				self.QueueActivity(new LayMines());
			}
		}

		static IEnumerable<int2> GetMinefieldCells(int2 start, int2 end, float depth)
		{
			var mins = int2.Min(start, end);
			var maxs = int2.Max(start, end);

			/* todo: proper endcaps, if anyone cares (which won't happen unless depth is large) */

			var p = end - start;
			var q = new float2(p.Y, -p.X);
			q = (start != end) ? (1 / q.Length) * q : new float2(1, 0);
			var c = -float2.Dot(q, start);

			/* return all points such that |ax + by + c| < depth */

			for (var i = mins.X; i <= maxs.X; i++)
				for (var j = mins.Y; j <= maxs.Y; j++)
					if (Math.Abs(q.X * i + q.Y * j + c) < depth)
						yield return new int2(i, j);
		}

		class MinefieldOrderGenerator : IOrderGenerator
		{
			readonly Actor minelayer;
			readonly int2 minefieldStart;

			public MinefieldOrderGenerator(Actor self, int2 xy ) { minelayer = self; minefieldStart = xy; }

			public IEnumerable<Order> Order(World world, int2 xy, MouseInput mi)
			{
				if (mi.Button == MouseButton.Left)
				{
					world.CancelInputMode();
					yield break;
				}

				var underCursor = world.FindUnitsAtMouse(mi.Location)
					.OrderByDescending(a => a.Info.Traits.Contains<SelectableInfo>() 
						? a.Info.Traits.Get<SelectableInfo>().Priority : int.MinValue)
					.FirstOrDefault();

				if( mi.Button == MouseButton.Right && underCursor == null )
				{
					minelayer.World.CancelInputMode();
					yield return new Order("PlaceMinefield", minelayer, false) { TargetLocation = xy };
				}
			}

			public void Tick(World world)
			{
				if (!minelayer.IsInWorld || minelayer.IsDead())
					world.CancelInputMode();
			}

			int2 lastMousePos;
			public void RenderAfterWorld(WorldRenderer wr, World world)
			{
				if (!minelayer.IsInWorld)
					return;

				var movement = minelayer.Trait<IMove>();
				var minefield = GetMinefieldCells(minefieldStart, lastMousePos, 
					minelayer.Info.Traits.Get<MinelayerInfo>().MinefieldDepth)
					.Where(p => movement.CanEnterCell(p)).ToArray();

				wr.DrawLocus(Color.Cyan, minefield);
			}

			public void RenderBeforeWorld(WorldRenderer wr, World world) { }

			public string GetCursor(World world, int2 xy, MouseInput mi) { lastMousePos = xy; return "ability"; }	/* todo */
		}

		public void RenderAfterWorld(WorldRenderer wr, Actor self)
		{
			if (self.Owner != self.World.LocalPlayer)
				return;
			
			if (minefield != null)
				wr.DrawLocus(Color.Cyan, minefield);
		}

		class BeginMinefieldOrderTargeter : IOrderTargeter
		{
			public string OrderID { get { return "BeginMinefield"; } }
			public int OrderPriority { get { return 5; } }

			public bool CanTargetActor(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)
			{
				if (!self.World.Map.IsInMap(location))
					return false;
				
				cursor = "ability";
				IsQueued = forceQueued;

				return ( actorsAtLocation.Count == 0 && forceAttack );
			}
			public bool IsQueued { get; protected set; }
		}
	}
}