/******************************************************************************
 * Spine Runtimes Software License v2.5
 *
 * Copyright (c) 2013-2016, Esoteric Software
 * All rights reserved.
 *
 * You are granted a perpetual, non-exclusive, non-sublicensable, and
 * non-transferable license to use, install, execute, and perform the Spine
 * Runtimes software and derivative works solely for personal or internal
 * use. Without the written permission of Esoteric Software (see Section 2 of
 * the Spine Software License Agreement), you may not (a) modify, translate,
 * adapt, or develop new applications using the Spine Runtimes or otherwise
 * create derivative works or improvements of the Spine Runtimes or (b) remove,
 * delete, alter, or obscure any trademarks or any copyright, trademark, patent,
 * or other intellectual property or proprietary rights notices on or in the
 * Software, including any copy thereof. Redistributions in binary or source
 * form must include this license and terms.
 *
 * THIS SOFTWARE IS PROVIDED BY ESOTERIC SOFTWARE "AS IS" AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 * EVENT SHALL ESOTERIC SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, BUSINESS INTERRUPTION, OR LOSS OF
 * USE, DATA, OR PROFITS) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
 * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *****************************************************************************/

using System;
using System.Collections.Generic;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework;

namespace Spine {
	/// <summary>Draws region and mesh attachments.</summary>
	public class SkeletonMeshRenderer {
		private const int TL = 0;
		private const int TR = 1;
		private const int BL = 2;
		private const int BR = 3;

		GraphicsDevice device;
		MeshBatcher batcher;
		RasterizerState rasterizerState;
		float[] vertices = new float[8];
		int[] quadTriangles = { 0, 1, 2, 1, 3, 2 };
		BlendState defaultBlendState;

		BasicEffect effect;
		public BasicEffect Effect { get { return effect; } set { effect = value; } }

		private bool premultipliedAlpha;
		public bool PremultipliedAlpha { get { return premultipliedAlpha; } set { premultipliedAlpha = value; } }

		public SkeletonMeshRenderer (GraphicsDevice device) {
			this.device = device;

			batcher = new MeshBatcher();

			effect = new BasicEffect(device);
			effect.World = Matrix.Identity;
			effect.View = Matrix.CreateLookAt(new Vector3(0.0f, 0.0f, 1.0f), Vector3.Zero, Vector3.Up);
			effect.TextureEnabled = true;
			effect.VertexColorEnabled = true;

			rasterizerState = new RasterizerState();
			rasterizerState.CullMode = CullMode.None;

			Bone.yDown = true;
		}

		public void Begin () {
			defaultBlendState = premultipliedAlpha ? BlendState.AlphaBlend : BlendState.NonPremultiplied;

			device.RasterizerState = rasterizerState;
			device.BlendState = defaultBlendState;

			effect.Projection = Matrix.CreateOrthographicOffCenter(0, device.Viewport.Width, device.Viewport.Height, 0, 1, 0);
		}

		public void End () {
			foreach (EffectPass pass in effect.CurrentTechnique.Passes) {
				pass.Apply();
				batcher.Draw(device);
			}
		}

		public void Draw (Skeleton skeleton) {
			float[] vertices = this.vertices;
			var drawOrder = skeleton.DrawOrder;
			var drawOrderItems = skeleton.DrawOrder.Items;
			float skeletonR = skeleton.R, skeletonG = skeleton.G, skeletonB = skeleton.B, skeletonA = skeleton.A;
			for (int i = 0, n = drawOrder.Count; i < n; i++) {
				Slot slot = drawOrderItems[i];
				Attachment attachment = slot.Attachment;
				if (attachment is RegionAttachment) {
					RegionAttachment regionAttachment = (RegionAttachment)attachment;
					BlendState blend = slot.Data.BlendMode == BlendMode.additive ? BlendState.Additive : defaultBlendState;
					if (device.BlendState != blend) {
						End();
						device.BlendState = blend;
					}

					MeshItem item = batcher.NextItem(4, 6);
					item.triangles = quadTriangles;
					VertexPositionColorTexture[] itemVertices = item.vertices;

					AtlasRegion region = (AtlasRegion)regionAttachment.RendererObject;
					item.texture = (Texture2D)region.page.rendererObject;

					Color color;
					float a = skeletonA * slot.A * regionAttachment.A;
					if (premultipliedAlpha) {
						color = new Color(
								skeletonR * slot.R * regionAttachment.R * a,
								skeletonG * slot.G * regionAttachment.G * a,
								skeletonB * slot.B * regionAttachment.B * a, a);
					} else {
						color = new Color(
								skeletonR * slot.R * regionAttachment.R,
								skeletonG * slot.G * regionAttachment.G,
								skeletonB * slot.B * regionAttachment.B, a);
					}
					itemVertices[TL].Color = color;
					itemVertices[BL].Color = color;
					itemVertices[BR].Color = color;
					itemVertices[TR].Color = color;

					regionAttachment.ComputeWorldVertices(slot.Bone, vertices);
					itemVertices[TL].Position.X = vertices[RegionAttachment.X1];
					itemVertices[TL].Position.Y = vertices[RegionAttachment.Y1];
					itemVertices[TL].Position.Z = 0;
					itemVertices[BL].Position.X = vertices[RegionAttachment.X2];
					itemVertices[BL].Position.Y = vertices[RegionAttachment.Y2];
					itemVertices[BL].Position.Z = 0;
					itemVertices[BR].Position.X = vertices[RegionAttachment.X3];
					itemVertices[BR].Position.Y = vertices[RegionAttachment.Y3];
					itemVertices[BR].Position.Z = 0;
					itemVertices[TR].Position.X = vertices[RegionAttachment.X4];
					itemVertices[TR].Position.Y = vertices[RegionAttachment.Y4];
					itemVertices[TR].Position.Z = 0;

					float[] uvs = regionAttachment.UVs;
					itemVertices[TL].TextureCoordinate.X = uvs[RegionAttachment.X1];
					itemVertices[TL].TextureCoordinate.Y = uvs[RegionAttachment.Y1];
					itemVertices[BL].TextureCoordinate.X = uvs[RegionAttachment.X2];
					itemVertices[BL].TextureCoordinate.Y = uvs[RegionAttachment.Y2];
					itemVertices[BR].TextureCoordinate.X = uvs[RegionAttachment.X3];
					itemVertices[BR].TextureCoordinate.Y = uvs[RegionAttachment.Y3];
					itemVertices[TR].TextureCoordinate.X = uvs[RegionAttachment.X4];
					itemVertices[TR].TextureCoordinate.Y = uvs[RegionAttachment.Y4];
				} else if (attachment is MeshAttachment) {
					MeshAttachment mesh = (MeshAttachment)attachment;
					int vertexCount = mesh.WorldVerticesLength;
					if (vertices.Length < vertexCount) vertices = new float[vertexCount];
					mesh.ComputeWorldVertices(slot, vertices);

					int[] triangles = mesh.Triangles;
					MeshItem item = batcher.NextItem(vertexCount, triangles.Length);
					item.triangles = triangles;

					AtlasRegion region = (AtlasRegion)mesh.RendererObject;
					item.texture = (Texture2D)region.page.rendererObject;

					Color color;
					float a = skeletonA * slot.A * mesh.A;
					if (premultipliedAlpha) {
						color = new Color(
								skeletonR * slot.R * mesh.R * a,
								skeletonG * slot.G * mesh.G * a,
								skeletonB * slot.B * mesh.B * a, a);
					} else {
						color = new Color(
								skeletonR * slot.R * mesh.R,
								skeletonG * slot.G * mesh.G,
								skeletonB * slot.B * mesh.B, a);
					}

					float[] uvs = mesh.UVs;
					VertexPositionColorTexture[] itemVertices = item.vertices;
					for (int ii = 0, v = 0; v < vertexCount; ii++, v += 2) {
						itemVertices[ii].Color = color;
						itemVertices[ii].Position.X = vertices[v];
						itemVertices[ii].Position.Y = vertices[v + 1];
						itemVertices[ii].Position.Z = 0;
						itemVertices[ii].TextureCoordinate.X = uvs[v];
						itemVertices[ii].TextureCoordinate.Y = uvs[v + 1];
					}
				}
			}
		}
	}
}