//
// Copyright 2020 Pixar
//
// Licensed under the Apache License, Version 2.0 (the "Apache License")
// with the following modification; you may not use this file except in
// compliance with the Apache License and the following modification to it:
// Section 6. Trademarks. is deleted and replaced with:
//
// 6. Trademarks. This License does not grant permission to use the trade
//    names, trademarks, service marks, or product names of the Licensor
//    and its affiliates, except as required to comply with Section 4(c) of
//    the License and to reproduce the content of the NOTICE file.
//
// You may obtain a copy of the Apache License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the Apache License with the above modification is
// distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the Apache License for the specific
// language governing permissions and limitations under the Apache License.
//
#ifndef PXR_IMAGING_HGIINTEROP_HGIINTEROPMETAL_H
#define PXR_IMAGING_HGIINTEROP_HGIINTEROPMETAL_H

#include <GL/glew.h>
#include <Metal/Metal.h>
#include <AppKit/AppKit.h>

#include "pxr/pxr.h"
#include "pxr/imaging/hgi/texture.h"
#include "pxr/imaging/hgiInterop/api.h"


PXR_NAMESPACE_OPEN_SCOPE

class Hgi;
class HgiMetal;

/// \class HgiInteropMetal
///
/// Provides Metal/GL interop
///
class HgiInteropMetal final {
public:

    HGIINTEROP_API
    HgiInteropMetal(Hgi* hgi);

    HGIINTEROP_API
    ~HgiInteropMetal();

    /// Copy/Present provided color (and optional depth) textures to app.
    HGIINTEROP_API
    void CompositeToInterop(
        HgiTextureHandle const &color,
        HgiTextureHandle const &depth);

private:
    HgiInteropMetal() = delete;

    enum {
        ShaderContextColor,
        ShaderContextColorDepth,

        ShaderContextCount
    };

    struct ShaderContext {
        uint32_t program;
        uint32_t vao;
        uint32_t vbo;
        int32_t posAttrib;
        int32_t texAttrib;
        int32_t samplerColorLoc;
        int32_t samplerDepthLoc;
        uint32_t blitTexSizeUniform;
    };

    struct VertexAttribState {
        int32_t enabled;
        int32_t size;
        int32_t type;
        int32_t normalized;
        int32_t stride;
        int32_t bufferBinding;
        void* pointer;
    };

    void _BlitToOpenGL(bool flipY, int shaderIndex);
    void _FreeTransientTextureCacheRefs();
    void _CaptureOpenGlState();
    void _RestoreOpenGlState();
    void _CreateShaderContext(
        int32_t vertexSource,
        int32_t fragmentSource,
        ShaderContext &shader);
    void _SetAttachmentSize(int width, int height);
    void _ValidateGLContext();

    HgiMetal* _hgiMetal;

    id<MTLDevice> _device;

    id<MTLTexture> _mtlAliasedColorTexture;
    id<MTLTexture> _mtlAliasedDepthRegularFloatTexture;

    id<MTLLibrary> _defaultLibrary;
    id<MTLFunction> _computeDepthCopyProgram;
    id<MTLFunction> _computeColorCopyProgram;
    id<MTLComputePipelineState> _computePipelineStateColor;
    id<MTLComputePipelineState> _computePipelineStateDepth;

    CVPixelBufferRef _pixelBuffer;
    CVPixelBufferRef _depthBuffer;
    CVMetalTextureCacheRef _cvmtlTextureCache;
    CVMetalTextureRef _cvmtlColorTexture;
    CVMetalTextureRef _cvmtlDepthTexture;

    CVOpenGLTextureCacheRef _cvglTextureCache;
    CVOpenGLTextureRef _cvglColorTexture;
    CVOpenGLTextureRef _cvglDepthTexture;

    uint32_t _glColorTexture;
    uint32_t _glDepthTexture;
    
    ShaderContext _shaderProgramContext[ShaderContextCount];
    
    NSOpenGLContext* _currentOpenGLContext;

    int32_t _restoreVao;
    int32_t _restoreVbo;
    bool _restoreDepthTest;
    bool _restoreDepthWriteMask;
    bool _restoreStencilWriteMask;
    bool _restoreCullFace;
    int32_t _restoreFrontFace;
    int32_t _restoreDepthFunc;
    int32_t _restoreViewport[4];
    bool _restoreblendEnabled;
    int32_t _restoreColorOp;
    int32_t _restoreAlphaOp;
    int32_t _restoreColorSrcFnOp;
    int32_t _restoreAlphaSrcFnOp;
    int32_t _restoreColorDstFnOp;
    int32_t _restoreAlphaDstFnOp;
    bool _restoreAlphaToCoverage;
    int32_t _restorePolygonMode;
    int32_t _restoreActiveTexture;
    int32_t _restoreTexture[2];
    VertexAttribState _restoreVertexAttribState[2];
    int32_t _restoreProgram;
};

PXR_NAMESPACE_CLOSE_SCOPE

#endif