//
// 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.
//
#include <GL/glew.h>
#include "pxr/base/tf/diagnostic.h"

#include "pxr/imaging/hgiGL/diagnostic.h"
#include "pxr/imaging/hgiGL/shaderProgram.h"
#include "pxr/imaging/hgiGL/shaderFunction.h"

PXR_NAMESPACE_OPEN_SCOPE


HgiGLShaderProgram::HgiGLShaderProgram(HgiShaderProgramDesc const& desc)
    : HgiShaderProgram(desc)
    , _programId(0)
    , _programByteSize(0)
    , _uniformBuffer(0)
    , _uboByteSize(0)
{
    _programId = glCreateProgram();

    if (!_descriptor.debugName.empty()) {
        glObjectLabel(GL_PROGRAM, _programId,-1, _descriptor.debugName.c_str());
    }

    for (HgiShaderFunctionHandle const& shd : desc.shaderFunctions) {
        HgiGLShaderFunction* glShader = 
            static_cast<HgiGLShaderFunction*>(shd.Get());
        uint32_t id = glShader->GetShaderId();
        TF_VERIFY(id>0, "Invalid shader provided to program");
        glAttachShader(_programId, id);
    }
    glLinkProgram(_programId);

    // Grab compile errors
    GLint status;
    glGetProgramiv(_programId, GL_LINK_STATUS, &status);
    if (status != GL_TRUE) {
        int logSize = 0;
        glGetProgramiv(_programId, GL_INFO_LOG_LENGTH, &logSize);
        _errors.resize(logSize+1);
        glGetProgramInfoLog(_programId, logSize, nullptr, &_errors[0]);
        glDeleteProgram(_programId);
        _programId = 0;
    } else {
        GLint size;
        glGetProgramiv(_programId, GL_PROGRAM_BINARY_LENGTH, &size);
        _programByteSize = (size_t)size;
    }

    glCreateBuffers(1, &_uniformBuffer);

    HGIGL_POST_PENDING_GL_ERRORS();
}

HgiGLShaderProgram::~HgiGLShaderProgram()
{
    glDeleteProgram(_programId);
    _programId = 0;
    glDeleteBuffers(1, &_uniformBuffer);
    _uniformBuffer = 0;
    HGIGL_POST_PENDING_GL_ERRORS();
}

HgiShaderFunctionHandleVector const&
HgiGLShaderProgram::GetShaderFunctions() const
{
    return _descriptor.shaderFunctions;
}

bool
HgiGLShaderProgram::IsValid() const
{
    return _programId>0 && _errors.empty();
}

std::string const&
HgiGLShaderProgram::GetCompileErrors()
{
    return _errors;
}

size_t
HgiGLShaderProgram::GetByteSizeOfResource() const
{
    return _programByteSize + _uboByteSize;
}

uint64_t
HgiGLShaderProgram::GetRawResource() const
{
    return (uint64_t) _programId;
}

uint32_t
HgiGLShaderProgram::GetProgramId() const
{
    return _programId;
}

uint32_t
HgiGLShaderProgram::GetUniformBuffer(size_t sizeHint)
{
    _uboByteSize = sizeHint;
    return _uniformBuffer;
}

PXR_NAMESPACE_CLOSE_SCOPE