//-----------------------------------------------------------------------
//-----------------------------------------------------------------------
//     file="AutoTexture.cs"
//     Project: StgSharp
//     AuthorGroup: Nitload Space
//     Copyright (c) Nitload Space. 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 System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;

using StgSharp.Collections;

namespace StgSharp.Graphics.OpenGL
{
    public sealed class AutoTextureGL
    {
        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 TextureProperty[] propertyCache;
        private TextureGL texturePackage;

        private TextureProperty _textureProperty;

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

        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]glRenderStream 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;
        }

        [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);
        }

    }

}