#region Copyright & License Information
/*
 * Copyright 2007-2014 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 System.Linq;
using OpenRA.Graphics;

namespace OpenRA.Mods.Common.Graphics
{
	public struct VoxelRenderable : IRenderable
	{
		readonly IEnumerable<VoxelAnimation> voxels;
		readonly WPos pos;
		readonly int zOffset;
		readonly WRot camera;
		readonly WRot lightSource;
		readonly float[] lightAmbientColor;
		readonly float[] lightDiffuseColor;
		readonly PaletteReference palette;
		readonly PaletteReference normalsPalette;
		readonly PaletteReference shadowPalette;
		readonly float scale;

		// Generated at render-time
		VoxelRenderProxy renderProxy;

		public VoxelRenderable(IEnumerable<VoxelAnimation> voxels, WPos pos, int zOffset, WRot camera, float scale,
		                       WRot lightSource, float[] lightAmbientColor, float[] lightDiffuseColor,
		                       PaletteReference color, PaletteReference normals, PaletteReference shadow)
		{
			this.voxels = voxels;
			this.pos = pos;
			this.zOffset = zOffset;
			this.scale = scale;
			this.camera = camera;
			this.lightSource = lightSource;
			this.lightAmbientColor = lightAmbientColor;
			this.lightDiffuseColor = lightDiffuseColor;
			this.palette = color;
			this.normalsPalette = normals;
			this.shadowPalette = shadow;
			this.renderProxy = null;
		}

		public WPos Pos { get { return pos; } }
		public float Scale { get { return scale; } }
		public PaletteReference Palette { get { return palette; } }
		public int ZOffset { get { return zOffset; } }
		public bool IsDecoration { get { return false; } }

		public IRenderable WithScale(float newScale)
		{
			return new VoxelRenderable(voxels, pos, zOffset, camera, newScale,
			                           lightSource, lightAmbientColor, lightDiffuseColor,
			                           palette, normalsPalette, shadowPalette);
		}

		public IRenderable WithPalette(PaletteReference newPalette)
		{
			return new VoxelRenderable(voxels, pos, zOffset, camera, scale,
			                           lightSource, lightAmbientColor, lightDiffuseColor,
			                           newPalette, normalsPalette, shadowPalette);
		}

		public IRenderable WithZOffset(int newOffset)
		{
			return new VoxelRenderable(voxels, pos, newOffset, camera, scale,
			                           lightSource, lightAmbientColor, lightDiffuseColor,
			                           palette, normalsPalette, shadowPalette);
		}

		public IRenderable OffsetBy(WVec vec)
		{
			return new VoxelRenderable(voxels, pos + vec, zOffset, camera, scale,
			                           lightSource, lightAmbientColor, lightDiffuseColor,
			                           palette, normalsPalette, shadowPalette);
		}

		public IRenderable AsDecoration() { return this; }

		// This will need generalizing once we support TS/RA2 terrain
		static readonly float[] GroundNormal = new float[] { 0, 0, 1, 1 };
		public void BeforeRender(WorldRenderer wr)
		{
			var draw = voxels.Where(v => v.DisableFunc == null || !v.DisableFunc());

			renderProxy = Game.Renderer.WorldVoxelRenderer.RenderAsync(
				wr, draw, camera, scale, GroundNormal, lightSource,
				lightAmbientColor, lightDiffuseColor,
				palette, normalsPalette, shadowPalette);
		}

		public void Render(WorldRenderer wr)
		{
			// TODO: This is a temporary workaround until we have a proper ramp-aware height calculation
			var groundPos = wr.world.Map.CenterOfCell(wr.world.Map.CellContaining(pos));

			var ts = Game.modData.Manifest.TileSize;
			var groundZ = ts.Height * (groundPos.Z - pos.Z) / 1024f;

			var pxOrigin = wr.ScreenPosition(pos);
			var shadowOrigin = pxOrigin - groundZ * (new float2(renderProxy.ShadowDirection, 1));

			var psb = renderProxy.ProjectedShadowBounds;
			var sa = shadowOrigin + psb[0];
			var sb = shadowOrigin + psb[2];
			var sc = shadowOrigin + psb[1];
			var sd = shadowOrigin + psb[3];
			Game.Renderer.WorldRgbaSpriteRenderer.DrawSprite(renderProxy.ShadowSprite, sa, sb, sc, sd);
			Game.Renderer.WorldRgbaSpriteRenderer.DrawSprite(renderProxy.Sprite, pxOrigin - 0.5f * renderProxy.Sprite.size);
		}

		public void RenderDebugGeometry(WorldRenderer wr)
		{
			var pxOrigin = wr.ScreenPosition(pos);
			var groundZ = 0.5f * (pxOrigin.Y - wr.ScreenZPosition(pos, 0));
			var shadowOrigin = pxOrigin - groundZ * (new float2(renderProxy.ShadowDirection, 1));

			// Draw sprite rect
			var offset = pxOrigin + renderProxy.Sprite.offset - 0.5f * renderProxy.Sprite.size;
			Game.Renderer.WorldLineRenderer.DrawRect(offset, offset + renderProxy.Sprite.size, Color.Red);

			// Draw transformed shadow sprite rect
			var c = Color.Purple;
			var psb = renderProxy.ProjectedShadowBounds;
			Game.Renderer.WorldLineRenderer.DrawLine(shadowOrigin + psb[1], shadowOrigin + psb[3], c, c);
			Game.Renderer.WorldLineRenderer.DrawLine(shadowOrigin + psb[3], shadowOrigin + psb[0], c, c);
			Game.Renderer.WorldLineRenderer.DrawLine(shadowOrigin + psb[0], shadowOrigin + psb[2], c, c);
			Game.Renderer.WorldLineRenderer.DrawLine(shadowOrigin + psb[2], shadowOrigin + psb[1], c, c);

			// Draw voxel bounding box
			var draw = voxels.Where(v => v.DisableFunc == null || !v.DisableFunc());
			var scaleTransform = Util.ScaleMatrix(scale, scale, scale);
			var cameraTransform = Util.MakeFloatMatrix(camera.AsMatrix());

			foreach (var v in draw)
			{
				var bounds = v.Voxel.Bounds(v.FrameFunc());
				var worldTransform = v.RotationFunc().Reverse().Aggregate(scaleTransform,
					(x, y) => Util.MatrixMultiply(x, Util.MakeFloatMatrix(y.AsMatrix())));

				var pxOffset = wr.ScreenVector(v.OffsetFunc());
				var pxPos = pxOrigin + new float2(pxOffset[0], pxOffset[1]);
				var screenTransform = Util.MatrixMultiply(cameraTransform, worldTransform);
				DrawBoundsBox(pxPos, screenTransform, bounds, Color.Yellow);
			}
		}

		static readonly uint[] CornerXIndex = new uint[] { 0, 0, 0, 0, 3, 3, 3, 3 };
		static readonly uint[] CornerYIndex = new uint[] { 1, 1, 4, 4, 1, 1, 4, 4 };
		static readonly uint[] CornerZIndex = new uint[] { 2, 5, 2, 5, 2, 5, 2, 5 };
		static void DrawBoundsBox(float2 pxPos, float[] transform, float[] bounds, Color c)
		{
			var corners = new float2[8];
			for (var i = 0; i < 8; i++)
			{
				var vec = new float[] { bounds[CornerXIndex[i]], bounds[CornerYIndex[i]], bounds[CornerZIndex[i]], 1 };
				var screen = Util.MatrixVectorMultiply(transform, vec);
				corners[i] = pxPos + new float2(screen[0], screen[1]);
			}

			Game.Renderer.WorldLineRenderer.DrawLine(corners[0], corners[1], c, c);
			Game.Renderer.WorldLineRenderer.DrawLine(corners[1], corners[3], c, c);
			Game.Renderer.WorldLineRenderer.DrawLine(corners[3], corners[2], c, c);
			Game.Renderer.WorldLineRenderer.DrawLine(corners[2], corners[0], c, c);

			Game.Renderer.WorldLineRenderer.DrawLine(corners[4], corners[5], c, c);
			Game.Renderer.WorldLineRenderer.DrawLine(corners[5], corners[7], c, c);
			Game.Renderer.WorldLineRenderer.DrawLine(corners[7], corners[6], c, c);
			Game.Renderer.WorldLineRenderer.DrawLine(corners[6], corners[4], c, c);

			Game.Renderer.WorldLineRenderer.DrawLine(corners[0], corners[4], c, c);
			Game.Renderer.WorldLineRenderer.DrawLine(corners[1], corners[5], c, c);
			Game.Renderer.WorldLineRenderer.DrawLine(corners[2], corners[6], c, c);
			Game.Renderer.WorldLineRenderer.DrawLine(corners[3], corners[7], c, c);
		}
	}
}