//-----------------------------------------------------------------------
// -----------------------------------------------------------------------
// file="AutoTexture"
// Project: StgSharp
// AuthorGroup: Nitload
// Copyright (c) Nitload. All rights reserved.
//     
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//     
// -----------------------------------------------------------------------
// -----------------------------------------------------------------------
using StgSharp.Collections;
using StgSharp.Graphics;
using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;

using System.Threading.Tasks;

namespace StgSharp.Graphics.OpenGL
{
    /// <summary>
    ///   A collection of a sets of OpenGL textures. The collection can automatically select one of
    ///   the  texture with minimum costs to upgrade pixels to BufferHandle. Usually <see
    ///   cref="AutoTextureGL" /> is used for <see cref="IImageProvider" /> loading, but not for
    ///   target of  <see cref="OpenGLFunction.FrameBufferTexture2d(FrameBufferTarget, uint,
    ///   Texture2DTarget, GlHandle, int)" />.
    /// </summary>
    public sealed class AutoTextureGL
    {

        private TextureProperty[] propertyCache;
        private BidirectionalDictionary<Image, int> imageIndexMap = new BidirectionalDictionary<Image, int>(
            );
        private Dictionary<Image, int> imageUpdateIndex = new Dictionary<Image, int>();

        private int _size, _currentIndex;
        private LinkedList<int> usedTextureIndex;
        private Queue<int> unusedTextureUnitIndex;
        private TextureGL texturePackage;

        private TextureProperty _textureProperty;

        private AutoTextureGL(TextureGL texture)
        {
            texturePackage = texture;
            _size = texture.Count;
            imageIndexMap = new BidirectionalDictionary<Image, int>();
            unusedTextureUnitIndex = new Queue<int>(Enumerable.Range(0, _size));
            usedTextureIndex = new LinkedList<int>();
            propertyCache = new TextureProperty[_size];
        }

        public AutoTextureGL(int textureObjectSize, [NotNull]glRender binding)
        {
            this._size = textureObjectSize;
            imageIndexMap = new BidirectionalDictionary<Image, int>();
            texturePackage = new TextureGL(textureObjectSize, binding);
            unusedTextureUnitIndex = new Queue<int>(Enumerable.Range(0, _size));
            usedTextureIndex = new LinkedList<int>();
            propertyCache = new TextureProperty[_size];
        }

        public TextureProperty DefaultTextureProperty
        {
            get => _textureProperty;
            set => _textureProperty = value;
        }

        private OpenGLFunction GL
        {
            get => texturePackage.GL;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public void SelectTextureAndBind(Image i)
        {
            TextureProperty property = _textureProperty;

            SelectTextureAndBind(i, property);
        }

        public void SelectTextureAndBind([NotNull]Image i, TextureProperty property)
        {
            // usable texture with image match
            if (imageIndexMap.TryGetValue(i, out int index))
            {
                // prop setting match
                if (propertyCache[index] == property)
                {
                    _currentIndex = index;                          //GL.Assert(true);
                    texturePackage.Bind2D(index);                   //GL.Assert(true);
                    if (i.PixelUpdateCount != imageUpdateIndex[i])
                    {
                        texturePackage.LoadTexture(index, i);       //GL.Assert(true);
                    }
                } else
                {
                    _currentIndex = index;                          //GL.Assert(true);
                    texturePackage.Bind2D(index);                   //GL.Assert(true);
                    texturePackage.Set2dProperty(index, property);  //GL.Assert(true);
                    if (i.PixelUpdateCount != imageUpdateIndex[i])
                    {
                        texturePackage.LoadTexture(index, i);       //GL.Assert(true);
                    }
                }
            } else
            {
                if (unusedTextureUnitIndex.TryDequeue(out int newIndex))
                {
                    // has extra unused texture object
                    imageIndexMap.Add(i, index);
                    texturePackage.Bind2D(index);
                    texturePackage.Set2dProperty(index, property);
                    texturePackage.LoadTexture(index, i);
                    usedTextureIndex.AddLast(newIndex);
                    propertyCache[newIndex] = property;
                    imageUpdateIndex[i] = i.PixelUpdateCount;
                } else
                {
                    // recycle from current
                    int reusedIndex = usedTextureIndex.First!.Value;
                    usedTextureIndex.RemoveFirst();
                    usedTextureIndex.AddLast(reusedIndex);
                    imageIndexMap[i] = reusedIndex;
                    propertyCache[newIndex] = property;
                    imageUpdateIndex[i] = i.PixelUpdateCount;
                }
            }
        }

        public static AutoTextureGL ToAuto([NotNull]TextureGL texture)
        {
            if (texture.IndexOfCurrentTexture != -1) {
                throw new InvalidOperationException("Texture to be converted has been editted.");
            }
            return new AutoTextureGL(texture);
        }

    }
}