//
// Copyright 2016 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 "pxr/imaging/glf/glew.h"
#include "pxr/imaging/glf/contextCaps.h"

#include "pxr/imaging/hdSt/dispatchBuffer.h"
#include "pxr/imaging/hd/perfLog.h"

#include "pxr/imaging/hf/perfLog.h"

#include "pxr/imaging/hgi/hgi.h"
#include "pxr/imaging/hgi/buffer.h"

PXR_NAMESPACE_OPEN_SCOPE


class Hd_DispatchBufferArrayRange : public HdStBufferArrayRangeGL {
public:
    /// Constructor.
    Hd_DispatchBufferArrayRange(HdStDispatchBuffer *buffer) :
        _buffer(buffer) {
    }

    /// Returns true if this range is valid
    virtual bool IsValid() const {
        return true;
    }

    /// Returns true is the range has been assigned to a buffer
    virtual bool IsAssigned() const {
        return (_buffer != nullptr);
    }

    /// Dispatch buffer array range is always mutable
    virtual bool IsImmutable() const {
        return false;
    }

    /// Resize memory area for this range. Returns true if it causes container
    /// buffer reallocation.
    virtual bool Resize(int numElements) {
        TF_CODING_ERROR("Hd_DispatchBufferArrayRange doesn't support this operation");
        return false;
    }

    /// Copy source data into buffer
    virtual void CopyData(HdBufferSourceSharedPtr const &bufferSource) {
        TF_CODING_ERROR("Hd_DispatchBufferArrayRange doesn't support this operation");
    }

    /// Read back the buffer content
    virtual VtValue ReadData(TfToken const &name) const {
        TF_CODING_ERROR("Hd_DispatchBufferArrayRange doesn't support this operation");
        return VtValue();
    }

    /// Returns the offset at which this range begins in the underlying buffer 
    /// array in terms of elements.
    virtual int GetElementOffset() const {
        TF_CODING_ERROR("Hd_DispatchBufferArrayRange doesn't support this operation");
        return 0;
    }

    /// Returns the byte offset at which this range begins in the underlying
    /// buffer array for the given resource.
    virtual int GetByteOffset(TfToken const& resourceName) const {
        TF_CODING_ERROR("Hd_DispatchBufferArrayRange doesn't support this operation");
        return 0;
    }

    /// Returns the number of elements allocated
    virtual size_t GetNumElements() const {
        TF_CODING_ERROR("Hd_DispatchBufferArrayRange doesn't support this operation");
        return 0;
    }

    /// Returns the capacity of allocated area for this range
    virtual int GetCapacity() const {
        TF_CODING_ERROR("Hd_DispatchBufferArrayRange doesn't support this operation");
        return 0;
    }

    /// Returns the version of the buffer array.
    virtual size_t GetVersion() const {
        TF_CODING_ERROR("Hd_DispatchBufferArrayRange doesn't support this operation");
        return 0;
    }

    /// Increment the version of the buffer array.
    virtual void IncrementVersion() {
        TF_CODING_ERROR("Hd_DispatchBufferArrayRange doesn't support this operation");
    }

    /// Returns the max number of elements
    virtual size_t GetMaxNumElements() const {
        TF_CODING_ERROR("Hd_DispatchBufferArrayRange doesn't support this operation");
        return 1;
    }

    /// Returns the usage hint from the underlying buffer array
    virtual HdBufferArrayUsageHint GetUsageHint() const override {
        return _buffer->GetUsageHint();
    }

    /// Returns the GPU resource. If the buffer array contains more than one
    /// resource, this method raises a coding error.
    virtual HdStBufferResourceGLSharedPtr GetResource() const {
        return _buffer->GetResource();
    }

    /// Returns the named GPU resource.
    virtual HdStBufferResourceGLSharedPtr GetResource(TfToken const& name) {
        return _buffer->GetResource(name);
    }

    /// Returns the list of all named GPU resources for this bufferArrayRange.
    virtual HdStBufferResourceGLNamedList const& GetResources() const {
        return _buffer->GetResources();
    }

    /// Sets the buffer array associated with this buffer;
    virtual void SetBufferArray(HdBufferArray *bufferArray) {
        TF_CODING_ERROR("Hd_DispatchBufferArrayRange doesn't support this operation");
    }

    /// Debug dump
    virtual void DebugDump(std::ostream &out) const {
    }

    /// Make this range invalid
    void Invalidate() {
        TF_CODING_ERROR("Hd_DispatchBufferArrayRange doesn't support this operation");
    }

protected:
    /// Returns the aggregation container
    virtual const void *_GetAggregation() const {
        return this;
    }

private:
    HdStDispatchBuffer *_buffer;
};


HdStDispatchBuffer::HdStDispatchBuffer(Hgi* hgi, TfToken const &role, int count,
                                   unsigned int commandNumUints)
 : HdBufferArray(role, TfToken(), HdBufferArrayUsageHint())
 , _hgi(hgi)
 , _count(count)
 , _commandNumUints(commandNumUints)
{
    HD_TRACE_FUNCTION();
    HF_MALLOC_TAG_FUNCTION();

    size_t stride = commandNumUints * sizeof(GLuint);
    size_t dataSize = count * stride;
    
    // just allocate uninitialized
    HgiBufferDesc bufDesc;
    bufDesc.usage = HgiBufferUsageUniform;
    bufDesc.byteSize = dataSize;
    HgiBufferHandle newId = _hgi->CreateBuffer(bufDesc);

    // monolithic resource
    _entireResource = HdStBufferResourceGLSharedPtr(
        new HdStBufferResourceGL(
            role, {HdTypeInt32, 1},
            /*offset=*/0, stride));
    _entireResource->SetAllocation(newId, dataSize);

    // create a buffer array range, which aggregates all views
    // (will be added by AddBufferResourceView)
    _bar = HdStBufferArrayRangeGLSharedPtr(new Hd_DispatchBufferArrayRange(this));
}

HdStDispatchBuffer::~HdStDispatchBuffer()
{
    HgiBufferHandle& id = _entireResource->GetId();
    _hgi->DestroyBuffer(&id);
    _entireResource->SetAllocation(HgiBufferHandle(), 0);
}

void
HdStDispatchBuffer::CopyData(std::vector<GLuint> const &data)
{
    if (!TF_VERIFY(data.size()*sizeof(GLuint) == static_cast<size_t>(_entireResource->GetSize())))
        return;

    GlfContextCaps const &caps = GlfContextCaps::GetInstance();

    if (caps.directStateAccessEnabled) {
        glNamedBufferSubData(_entireResource->GetId()->GetRawResource(),
                             0,
                             _entireResource->GetSize(),
                             &data[0]);
    } else {
        glBindBuffer(GL_ARRAY_BUFFER,
                     _entireResource->GetId()->GetRawResource());
        glBufferSubData(GL_ARRAY_BUFFER, 0,
                        _entireResource->GetSize(),
                        &data[0]);
        glBindBuffer(GL_ARRAY_BUFFER, 0);
    }
}

void
HdStDispatchBuffer::AddBufferResourceView(
    TfToken const &name, HdTupleType tupleType, int offset)
{
    size_t stride = _commandNumUints * sizeof(GLuint);

    // add a binding view (resource binder iterates and automatically binds)
    HdStBufferResourceGLSharedPtr view =
        _AddResource(name, tupleType, offset, stride);

    // this is just a view, not consuming memory
    view->SetAllocation(_entireResource->GetId(), /*size=*/0);
}


bool
HdStDispatchBuffer::GarbageCollect()
{
    TF_CODING_ERROR("HdStDispatchBuffer doesn't support this operation");
    return false;
}

void
HdStDispatchBuffer::Reallocate(
    std::vector<HdBufferArrayRangeSharedPtr> const &,
    HdBufferArraySharedPtr const &)
{
    TF_CODING_ERROR("HdStDispatchBuffer doesn't support this operation");
}

void
HdStDispatchBuffer::DebugDump(std::ostream &out) const
{
    /*nothing*/
}

HdStBufferResourceGLSharedPtr
HdStDispatchBuffer::GetResource() const
{
    HD_TRACE_FUNCTION();

    if (_resourceList.empty()) return HdStBufferResourceGLSharedPtr();

    if (TfDebug::IsEnabled(HD_SAFE_MODE)) {
        // make sure this buffer array has only one resource.
        HgiBufferHandle const& id = _resourceList.begin()->second->GetId();
        TF_FOR_ALL (it, _resourceList) {
            if (it->second->GetId() != id) {
                TF_CODING_ERROR("GetResource(void) called on"
                                "HdBufferArray having multiple GL resources");
            }
        }
    }

    // returns the first item
    return _resourceList.begin()->second;
}

HdStBufferResourceGLSharedPtr
HdStDispatchBuffer::GetResource(TfToken const& name)
{
    HD_TRACE_FUNCTION();

    // linear search.
    // The number of buffer resources should be small (<10 or so).
    for (HdStBufferResourceGLNamedList::iterator it = _resourceList.begin();
         it != _resourceList.end(); ++it) {
        if (it->first == name) return it->second;
    }
    return HdStBufferResourceGLSharedPtr();
}

HdStBufferResourceGLSharedPtr
HdStDispatchBuffer::_AddResource(TfToken const& name,
                                 HdTupleType tupleType,
                                 int offset,
                                 int stride)
{
    HD_TRACE_FUNCTION();

    if (TfDebug::IsEnabled(HD_SAFE_MODE)) {
        // duplication check
        HdStBufferResourceGLSharedPtr bufferRes = GetResource(name);
        if (!TF_VERIFY(!bufferRes)) {
            return bufferRes;
        }
    }

    HdStBufferResourceGLSharedPtr bufferRes = HdStBufferResourceGLSharedPtr(
        new HdStBufferResourceGL(GetRole(), tupleType,
                                 offset, stride));

    _resourceList.emplace_back(name, bufferRes);
    return bufferRes;
}


PXR_NAMESPACE_CLOSE_SCOPE