#region Copyright & License Information
/*
 * Copyright (c) The OpenRA Developers and Contributors
 * 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, either version 3 of
 * the License, or (at your option) any later version. For more
 * information, see COPYING.
 */
#endregion

using System.Linq;
using OpenRA.Graphics;
using OpenRA.Primitives;
using OpenRA.Traits;

namespace OpenRA.Mods.Common.Traits
{
	[Desc("Used to enable mouse interaction on actors that are not Selectable.")]
	public class InteractableInfo : TraitInfo, IMouseBoundsInfo
	{
		[Desc("Defines a custom rectangle for mouse interaction with the actor.",
			"If null, the engine will guess an appropriate size based on the With*Body trait.",
			"The first two numbers define the width and height of the rectangle as a world distance.",
			"The (optional) second two numbers define an x and y offset from the actor center.")]
		public readonly WDist[] Bounds = null;

		[Desc("Defines a custom rectangle for Decorations (e.g. the selection box).",
			"If null, Bounds will be used instead")]
		public readonly WDist[] DecorationBounds = null;

		[Desc("Defines a custom 2D polygon for mouse interaction with the actor.",
			"If null, Bounds will be used instead",
			"Each vertex has two components (so two numbers), which define an x and y offset from the actor center.")]
		public readonly int2[] Polygon = null;

		public override object Create(ActorInitializer init) { return new Interactable(this); }
	}

	public class Interactable : INotifyCreated, IMouseBounds
	{
		readonly InteractableInfo info;
		readonly int2 polygonCenterOffset;
		IAutoMouseBounds[] autoBounds;

		public Interactable(InteractableInfo info)
		{
			this.info = info;

			if (info.Polygon != null)
			{
				var rect = new Polygon(info.Polygon).BoundingRect;

				// Precalculate offset for centering the polygon over the actor
				polygonCenterOffset = new int2(-rect.Width / 2, -rect.Height / 2);
			}
		}

		void INotifyCreated.Created(Actor self)
		{
			autoBounds = self.TraitsImplementing<IAutoMouseBounds>().ToArray();
		}

		Rectangle AutoBounds(Actor self, WorldRenderer wr)
		{
			return autoBounds.Select(s => s.AutoMouseoverBounds(self, wr)).FirstOrDefault(r => !r.IsEmpty);
		}

		int2[] PolygonBounds(Actor self, WorldRenderer wr)
		{
			var screenVertices = new int2[info.Polygon.Length];

			for (var i = 0; i < info.Polygon.Length; i++)
			{
				var vec = info.Polygon[i] + polygonCenterOffset;
				var offset = new int2(vec.X * wr.TileSize.Width / wr.TileScale, vec.Y * wr.TileSize.Height / wr.TileScale);

				screenVertices[i] = wr.ScreenPxPosition(self.CenterPosition) + offset;
			}

			return screenVertices;
		}

		Polygon Bounds(Actor self, WorldRenderer wr, WDist[] bounds)
		{
			if (bounds == null)
				return new Polygon(AutoBounds(self, wr));

			// Convert from WDist to pixels
			var size = new int2(bounds[0].Length * wr.TileSize.Width / wr.TileScale, bounds[1].Length * wr.TileSize.Height / wr.TileScale);

			var offset = -size / 2;
			if (bounds.Length > 2)
				offset += new int2(bounds[2].Length * wr.TileSize.Width / wr.TileScale, bounds[3].Length * wr.TileSize.Height / wr.TileScale);

			var xy = wr.ScreenPxPosition(self.CenterPosition) + offset;
			return new Polygon(new Rectangle(xy.X, xy.Y, size.X, size.Y));
		}

		Polygon IMouseBounds.MouseoverBounds(Actor self, WorldRenderer wr)
		{
			if (info.Polygon != null)
				return new Polygon(PolygonBounds(self, wr));

			return Bounds(self, wr, info.Bounds);
		}

		public Rectangle DecorationBounds(Actor self, WorldRenderer wr)
		{
			return Bounds(self, wr, info.DecorationBounds ?? info.Bounds).BoundingRect;
		}
	}
}