#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.Collections.Generic;
using System.Drawing;
using OpenRA.FileFormats;
using OpenRA.Graphics;
using OpenRA.Traits;

namespace OpenRA.Mods.RA
{
	class ContrailInfo : ITraitInfo
	{
		public readonly int[] ContrailOffset = {0, 0};

		public readonly int TrailLength = 20;
        public readonly Color Color = Color.White;
		public readonly bool UsePlayerColor = true;

		public object Create(ActorInitializer init) { return new Contrail(init.self, this); }
	}

	class Contrail : ITick, IPostRender
	{
		private ContrailInfo Info = null;

		private Turret ContrailTurret = null;

        ContrailHistory history;

		public Contrail(Actor self, ContrailInfo info)
		{
			Info = info;
			ContrailTurret = new Turret(Info.ContrailOffset);
            history = new ContrailHistory(Info.TrailLength, Info.UsePlayerColor ? ContrailHistory.ChooseColor(self) : Info.Color);
		}

		public void Tick(Actor self)
		{
			var facing = self.Trait<IFacing>();
			var altitude = new float2(0, self.Trait<IMove>().Altitude);

			var pos = self.CenterLocation - Combat.GetTurretPosition(self, facing, ContrailTurret) - altitude;
            history.Tick(pos);
		}

        public void RenderAfterWorld(WorldRenderer wr, Actor self) { history.Render(self); }
	}

    class ContrailHistory
    {
        List<float2> positions = new List<float2>();
        readonly int TrailLength;
        readonly Color Color;
        readonly int StartSkip;

        public static Color ChooseColor(Actor self)
        {
            var ownerColor = Color.FromArgb(255, self.Owner.ColorRamp.GetColor(0));
            return PlayerColorRemap.ColorLerp(0.5f, ownerColor, Color.White);
        }

        public ContrailHistory(int trailLength, Color color)
            : this(trailLength, color, 0) { }

        public ContrailHistory(int trailLength, Color color, int startSkip)
        {
            this.TrailLength = trailLength;
            this.Color = color;
            this.StartSkip = startSkip;
        }

        public void Tick(float2 currentPos)
        {
            positions.Add(currentPos);
            if (positions.Count >= TrailLength)
                positions.RemoveAt(0);
        }

        public void Render(Actor self)
        {
            Color trailStart = Color;
            Color trailEnd = Color.FromArgb(trailStart.A - 255 / TrailLength, trailStart.R,
                                            trailStart.G, trailStart.B);

            for (int i = positions.Count - 1 - StartSkip; i >= 1; --i)
            {
                var conPos = positions[i];
                var nextPos = positions[i - 1];

                if (self.World.LocalShroud.IsVisible(OpenRA.Traits.Util.CellContaining(conPos)) ||
                    self.World.LocalShroud.IsVisible(OpenRA.Traits.Util.CellContaining(nextPos)))
                {
                    Game.Renderer.LineRenderer.DrawLine(conPos, nextPos, trailStart, trailEnd);

                    trailStart = trailEnd;
                    trailEnd = Color.FromArgb(trailStart.A - 255 / positions.Count, trailStart.R,
                                                trailStart.G, trailStart.B);
                }
            }
        }
    }
}