/******************************************************************************
 * Spine Runtimes Software License
 * Version 2.3
 * 
 * Copyright (c) 2013-2015, 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 (the "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 otherwise create derivative works, improvements of the
 * Software or develop new applications using the Software 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; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) 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 {
	// #region License
	// /*
	// Microsoft Public License (Ms-PL)
	// MonoGame - Copyright © 2009 The MonoGame Team
	//
	// All rights reserved.
	//
	// This license governs use of the accompanying software. If you use the software, you accept this license. If you do not
	// accept the license, do not use the software.
	//
	// 1. Definitions
	// The terms "reproduce," "reproduction," "derivative works," and "distribution" have the same meaning here as under
	// U.S. copyright law.
	//
	// A "contribution" is the original software, or any additions or changes to the software.
	// A "contributor" is any person that distributes its contribution under this license.
	// "Licensed patents" are a contributor's patent claims that read directly on its contribution.
	//
	// 2. Grant of Rights
	// (A) Copyright Grant- Subject to the terms of this license, including the license conditions and limitations in section 3,
	// each contributor grants you a non-exclusive, worldwide, royalty-free copyright license to reproduce its contribution, prepare derivative works of its contribution, and distribute its contribution or any derivative works that you create.
	// (B) Patent Grant- Subject to the terms of this license, including the license conditions and limitations in section 3,
	// each contributor grants you a non-exclusive, worldwide, royalty-free license under its licensed patents to make, have made, use, sell, offer for sale, import, and/or otherwise dispose of its contribution in the software or derivative works of the contribution in the software.
	//
	// 3. Conditions and Limitations
	// (A) No Trademark License- This license does not grant you rights to use any contributors' name, logo, or trademarks.
	// (B) If you bring a patent claim against any contributor over patents that you claim are infringed by the software,
	// your patent license from such contributor to the software ends automatically.
	// (C) If you distribute any portion of the software, you must retain all copyright, patent, trademark, and attribution
	// notices that are present in the software.
	// (D) If you distribute any portion of the software in source code form, you may do so only under this license by including
	// a complete copy of this license with your distribution. If you distribute any portion of the software in compiled or object
	// code form, you may only do so under a license that complies with this license.
	// (E) The software is licensed "as-is." You bear the risk of using it. The contributors give no express warranties, guarantees
	// or conditions. You may have additional consumer rights under your local laws which this license cannot change. To the extent
	// permitted under your local laws, the contributors exclude the implied warranties of merchantability, fitness for a particular
	// purpose and non-infringement.
	// */
	// #endregion License
	//

	/// <summary>Draws batched meshes.</summary>
	public class MeshBatcher {
		private readonly List<MeshItem> items;
		private readonly Queue<MeshItem> freeItems;
		private VertexPositionColorTexture[] vertexArray = { };
		private short[] triangles = { };

		public MeshBatcher () {
			items = new List<MeshItem>(256);
			freeItems = new Queue<MeshItem>(256);
			EnsureCapacity(256, 512);
		}

		/// <summary>Returns a pooled MeshItem.</summary>
		public MeshItem NextItem (int vertexCount, int triangleCount) {
			MeshItem item = freeItems.Count > 0 ? freeItems.Dequeue() : new MeshItem();
			if (item.vertices.Length < vertexCount) item.vertices = new VertexPositionColorTexture[vertexCount];
			if (item.triangles.Length < triangleCount) item.triangles = new int[triangleCount];
			item.vertexCount = vertexCount;
			item.triangleCount = triangleCount;
			items.Add(item);
			return item;
		}

		private void EnsureCapacity (int vertexCount, int triangleCount) {
			if (vertexArray.Length < vertexCount) vertexArray = new VertexPositionColorTexture[vertexCount];
			if (triangles.Length < triangleCount) triangles = new short[triangleCount];
		}

		public void Draw (GraphicsDevice device) {
			if (items.Count == 0) return;

			int itemCount = items.Count;
			int vertexCount = 0, triangleCount = 0;
			for (int i = 0; i < itemCount; i++) {
				MeshItem item = items[i];
				vertexCount += item.vertexCount;
				triangleCount += item.triangleCount;
			}
			EnsureCapacity(vertexCount, triangleCount);

			vertexCount = 0;
			triangleCount = 0;
			Texture2D lastTexture = null;
			for (int i = 0; i < itemCount; i++) {
				MeshItem item = items[i];
				int itemVertexCount = item.vertexCount;

				if (item.texture != lastTexture || vertexCount + itemVertexCount > short.MaxValue) {
					FlushVertexArray(device, vertexCount, triangleCount);
					vertexCount = 0;
					triangleCount = 0;
					lastTexture = item.texture;
					device.Textures[0] = lastTexture;
				}

				int[] itemTriangles = item.triangles;
				int itemTriangleCount = item.triangleCount;
				for (int ii = 0, t = triangleCount; ii < itemTriangleCount; ii++, t++)
					triangles[t] = (short)(itemTriangles[ii] + vertexCount);
				triangleCount += itemTriangleCount;

				Array.Copy(item.vertices, 0, vertexArray, vertexCount, itemVertexCount);
				vertexCount += itemVertexCount;

				item.texture = null;
				freeItems.Enqueue(item);
			}
			FlushVertexArray(device, vertexCount, triangleCount);
			items.Clear();
		}

		private void FlushVertexArray (GraphicsDevice device, int vertexCount, int triangleCount) {
			if (vertexCount == 0) return;
			device.DrawUserIndexedPrimitives(
				PrimitiveType.TriangleList,
				vertexArray, 0, vertexCount,
				triangles, 0, triangleCount / 3,
				VertexPositionColorTexture.VertexDeclaration);
		}
	}

	public class MeshItem {
		public Texture2D texture;
		public int vertexCount, triangleCount;
		public VertexPositionColorTexture[] vertices = { };
		public int[] triangles = { };
	}
}