/*     Copyright 2015-2018 Egor Yusov
 *  
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 *  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 OF ANY PROPRIETARY RIGHTS.
 *
 *  In no event and under no legal theory, whether in tort (including negligence), 
 *  contract, or otherwise, unless required by applicable law (such as deliberate 
 *  and grossly negligent acts) or agreed to in writing, shall any Contributor be
 *  liable for any damages, including any direct, indirect, special, incidental, 
 *  or consequential damages of any character arising as a result of this License or 
 *  out of the use or inability to use the software (including but not limited to damages 
 *  for loss of goodwill, work stoppage, computer failure or malfunction, or any and 
 *  all other commercial damages or losses), even if such Contributor has been advised 
 *  of the possibility of such damages.
 */

#include "pch.h"

#include "TextureCube_OGL.h"
#include "RenderDeviceGLImpl.h"
#include "DeviceContextGLImpl.h"
#include "GLTypeConversions.h"
#include "GraphicsAccessories.h"
#include "BufferGLImpl.h"

namespace Diligent
{

TextureCube_OGL::TextureCube_OGL( IReferenceCounters *pRefCounters, 
                                  FixedBlockMemoryAllocator& TexViewObjAllocator,
                                  class RenderDeviceGLImpl *pDeviceGL, 
                                  class DeviceContextGLImpl *pDeviceContext, 
                                  const TextureDesc& TexDesc, 
                                  const TextureData &InitData /*= TextureData()*/,
							      bool bIsDeviceInternal /*= false*/) : 
    TextureBaseGL(pRefCounters, TexViewObjAllocator, pDeviceGL, TexDesc, GL_TEXTURE_CUBE_MAP, InitData, bIsDeviceInternal)
{
    VERIFY(m_Desc.SampleCount == 1, "Multisampled cubemap textures are not supported");
    
    auto &ContextState = pDeviceContext->GetContextState();
    ContextState.BindTexture(-1, m_BindTarget, m_GlTexture);

    VERIFY( m_Desc.ArraySize == 6, "Cubemap texture is expected to have 6 slices");
    //                             levels             format          width         height
    glTexStorage2D(m_BindTarget, m_Desc.MipLevels, m_GLTexFormat, m_Desc.Width, m_Desc.Height);
    CHECK_GL_ERROR_AND_THROW("Failed to allocate storage for the Cubemap texture");
    //When target is GL_TEXTURE_CUBE_MAP, glTexStorage2D is equivalent to:
    //
    //for (i = 0; i < levels; i++) {
    //    for (face in (+X, -X, +Y, -Y, +Z, -Z)) {
    //        glTexImage2D(face, i, internalformat, width, height, 0, format, type, NULL);
    //    }
    //    width = max(1, (width / 2));
    //    height = max(1, (height / 2));
    //}
    SetDefaultGLParameters();

    if( InitData.pSubResources )
    {
        auto ExpectedSubresources = m_Desc.MipLevels*6;
        if( m_Desc.MipLevels*6 == InitData.NumSubresources )
        {
            for(Uint32 Face = 0; Face < 6; ++Face)
            {
                for(Uint32 Mip = 0; Mip < m_Desc.MipLevels; ++Mip)
                {
                    Box DstBox{0, std::max(m_Desc.Width >>Mip, 1U),
                               0, std::max(m_Desc.Height>>Mip, 1U)};
                    // UpdateData() is a virtual function. If we try to call it through vtbl from here,
                    // we will get into TextureBaseGL::UpdateData(), because instance of TextureCube_OGL
                    // is not fully constructed yet.
                    // To call the required function, we need to explicitly specify the class: 
                    TextureCube_OGL::UpdateData( pDeviceContext, Mip, Face, DstBox, InitData.pSubResources[Face*m_Desc.MipLevels + Mip] );
                }
            }
        }
        else
        {
            UNEXPECTED("Incorrect number of subresources. ", InitData.NumSubresources, " while ", ExpectedSubresources," is expected" );
        }
    }

    ContextState.BindTexture( -1, m_BindTarget, GLObjectWrappers::GLTextureObj(false) );
}

TextureCube_OGL::TextureCube_OGL( IReferenceCounters *pRefCounters, 
                                  FixedBlockMemoryAllocator& TexViewObjAllocator,     
                                  RenderDeviceGLImpl *pDeviceGL, 
                                  DeviceContextGLImpl *pDeviceContext,
                                  const TextureDesc& TexDesc, 
                                  GLuint GLTextureHandle,
                                  bool bIsDeviceInternal)  : 
    TextureBaseGL(pRefCounters, TexViewObjAllocator, pDeviceGL, pDeviceContext, TexDesc, GLTextureHandle, GL_TEXTURE_CUBE_MAP, bIsDeviceInternal)
{
}

TextureCube_OGL::~TextureCube_OGL()
{
}

// Move static member initialization out of function to avoid
// potential issues in multithreaded code
static const GLenum CubeMapFaces[6] = 
{
    GL_TEXTURE_CUBE_MAP_POSITIVE_X, 
    GL_TEXTURE_CUBE_MAP_NEGATIVE_X, 
    GL_TEXTURE_CUBE_MAP_POSITIVE_Y, 
    GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, 
    GL_TEXTURE_CUBE_MAP_POSITIVE_Z, 
    GL_TEXTURE_CUBE_MAP_NEGATIVE_Z
};

void TextureCube_OGL::UpdateData( IDeviceContext *pContext, Uint32 MipLevel, Uint32 Slice, const Box &DstBox, const TextureSubResData &SubresData )
{
    auto &ContextState = ValidatedCast<DeviceContextGLImpl>(pContext)->GetContextState();
    TextureBaseGL::UpdateData(ContextState, pContext, MipLevel, Slice, DstBox, SubresData);

    // Texture must be bound as GL_TEXTURE_CUBE_MAP, but glTexSubImage2D() 
    // then takes one of GL_TEXTURE_CUBE_MAP_POSITIVE_X ... GL_TEXTURE_CUBE_MAP_NEGATIVE_Z
    ContextState.BindTexture(-1, m_BindTarget, m_GlTexture);

    auto CubeMapFaceBindTarget = CubeMapFaces[Slice];

    // Bind buffer if it is provided; copy from CPU memory otherwise
    GLuint UnpackBuffer = 0;
    if (SubresData.pSrcBuffer != nullptr)
    {
        auto *pBufferGL = ValidatedCast<BufferGLImpl>(SubresData.pSrcBuffer);
        UnpackBuffer = pBufferGL->GetGLHandle();
    }

    // Transfers to OpenGL memory are called unpack operations
    // If there is a buffer bound to GL_PIXEL_UNPACK_BUFFER target, then all the pixel transfer
    // operations will be performed from this buffer.
    glBindBuffer(GL_PIXEL_UNPACK_BUFFER, UnpackBuffer);

    const auto &TransferAttribs = GetNativePixelTransferAttribs(m_Desc.Format);
    
    glPixelStorei(GL_UNPACK_ALIGNMENT, 4);

    if( TransferAttribs.IsCompressed )
    {
        auto MipWidth  = std::max(m_Desc.Width  >> MipLevel, 1U);
        auto MipHeight = std::max(m_Desc.Height >> MipLevel, 1U);
        VERIFY( (DstBox.MinX % 4) == 0 && (DstBox.MinY % 4) == 0 &&
                ((DstBox.MaxX % 4) == 0 || DstBox.MaxX == MipWidth) && 
                ((DstBox.MaxY % 4) == 0 || DstBox.MaxY == MipHeight), 
                "Compressed texture update region must be 4 pixel-aligned" );
        const auto &FmtAttribs = GetTextureFormatAttribs(m_Desc.Format);
        auto BlockBytesInRow = ((DstBox.MaxX - DstBox.MinX + 3)/4) * Uint32{FmtAttribs.ComponentSize};
        VERIFY( SubresData.Stride == BlockBytesInRow, 
                "Compressed data stride (", SubresData.Stride, " must match the size of a row of compressed blocks (", BlockBytesInRow, ")" );
        
        //glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
        //glPixelStorei(GL_UNPACK_COMPRESSED_BLOCK_WIDTH, 0);
        
        // Texture must be bound as GL_TEXTURE_CUBE_MAP, but glCompressedTexSubImage2D() 
        // takes one of GL_TEXTURE_CUBE_MAP_POSITIVE_X ... GL_TEXTURE_CUBE_MAP_NEGATIVE_Z
        auto UpdateRegionWidth  = DstBox.MaxX - DstBox.MinX;
        auto UpdateRegionHeight = DstBox.MaxY - DstBox.MinY;
        UpdateRegionWidth  = std::min(UpdateRegionWidth,  MipWidth  - DstBox.MinX);
        UpdateRegionHeight = std::min(UpdateRegionHeight, MipHeight - DstBox.MinY);
        glCompressedTexSubImage2D(CubeMapFaceBindTarget, MipLevel, 
                        DstBox.MinX, 
                        DstBox.MinY, 
                        UpdateRegionWidth,
                        UpdateRegionHeight,
                        // The format must be the same compressed-texture format previously 
                        // specified by glTexStorage2D() (thank you OpenGL for another useless 
                        // parameter that is nothing but the source of confusion), otherwise
                        // INVALID_OPERATION error is generated.
                        m_GLTexFormat, 
                        // An INVALID_VALUE error is generated if imageSize is not consistent with
                        // the format, dimensions, and contents of the compressed image( too little or
                        // too much data ),
                        ((DstBox.MaxY - DstBox.MinY + 3)/4) * SubresData.Stride,
                        SubresData.pData);
    }
    else
    {
        const auto& TexFmtInfo = GetTextureFormatAttribs(m_Desc.Format);
        const auto PixelSize = Uint32{TexFmtInfo.NumComponents} * Uint32{TexFmtInfo.ComponentSize};
        VERIFY( (SubresData.Stride % PixelSize)==0, "Data stride is not multiple of pixel size" );
        glPixelStorei(GL_UNPACK_ROW_LENGTH, SubresData.Stride / PixelSize);
        glPixelStorei(GL_UNPACK_SKIP_PIXELS, 0);
        glPixelStorei(GL_UNPACK_SKIP_ROWS, 0);

        // Texture must be bound as GL_TEXTURE_CUBE_MAP, but glTexSubImage2D() 
        // takes one of GL_TEXTURE_CUBE_MAP_POSITIVE_X ... GL_TEXTURE_CUBE_MAP_NEGATIVE_Z
        glTexSubImage2D(CubeMapFaceBindTarget, MipLevel, 
                        DstBox.MinX, 
                        DstBox.MinY, 
                        DstBox.MaxX - DstBox.MinX, 
                        DstBox.MaxY - DstBox.MinY, 
                        TransferAttribs.PixelFormat, TransferAttribs.DataType, 
                        SubresData.pData);
    }
    CHECK_GL_ERROR("Failed to update subimage data");

    if(UnpackBuffer != 0)
        glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);

    ContextState.BindTexture( -1, m_BindTarget, GLObjectWrappers::GLTextureObj(false) );
}

void TextureCube_OGL::AttachToFramebuffer( const TextureViewDesc& ViewDesc, GLenum AttachmentPoint )
{
    if( ViewDesc.NumArraySlices == m_Desc.ArraySize )
    {
        glFramebufferTexture( GL_DRAW_FRAMEBUFFER, AttachmentPoint, m_GlTexture, ViewDesc.MostDetailedMip );
        CHECK_GL_ERROR( "Failed to attach texture cube to draw framebuffer" );
        glFramebufferTexture( GL_READ_FRAMEBUFFER, AttachmentPoint, m_GlTexture, ViewDesc.MostDetailedMip );
        CHECK_GL_ERROR( "Failed to attach texture cube to read framebuffer" );
    }
    else if( ViewDesc.NumArraySlices == 1 )
    {
        // Texture name must either be zero or the name of an existing 3D texture, 1D or 2D array texture, 
        // cube map array texture, or multisample array texture.

        auto CubeMapFaceBindTarget = CubeMapFaces[ViewDesc.FirstArraySlice];
        // For glFramebufferTexture2D, if texture is not zero, textarget must be one of GL_TEXTURE_2D, GL_TEXTURE_RECTANGLE, 
        // GL_TEXTURE_CUBE_MAP_POSITIVE_X, GL_TEXTURE_CUBE_MAP_POSITIVE_Y, GL_TEXTURE_CUBE_MAP_POSITIVE_Z, 
        // GL_TEXTURE_CUBE_MAP_NEGATIVE_X, GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, 
        // or GL_TEXTURE_2D_MULTISAMPLE.
        glFramebufferTexture2D( GL_DRAW_FRAMEBUFFER, AttachmentPoint, m_GlTexture, CubeMapFaceBindTarget, ViewDesc.MostDetailedMip );
        CHECK_GL_ERROR( "Failed to attach texture cube face to draw framebuffer" );
        glFramebufferTexture2D( GL_READ_FRAMEBUFFER, AttachmentPoint, m_GlTexture, CubeMapFaceBindTarget, ViewDesc.MostDetailedMip );
        CHECK_GL_ERROR( "Failed to attach texture cube face to read framebuffer" );
    }
    else
    {
        UNEXPECTED( "Only one slice or the entire cubemap can be attached to a framebuffer" );
    }
}

}
