//
// Copyright 2015 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//

// VertexArrayGL.cpp: Implements the class methods for VertexArrayGL.

#include "libANGLE/renderer/gl/VertexArrayGL.h"

#include "common/debug.h"
#include "common/mathutil.h"
#include "common/utilities.h"
#include "libANGLE/Buffer.h"
#include "libANGLE/angletypes.h"
#include "libANGLE/formatutils.h"
#include "libANGLE/renderer/gl/BufferGL.h"
#include "libANGLE/renderer/gl/FunctionsGL.h"
#include "libANGLE/renderer/gl/StateManagerGL.h"

namespace rx
{

VertexArrayGL::VertexArrayGL(const FunctionsGL *functions, StateManagerGL *stateManager)
    : VertexArrayImpl(),
      mFunctions(functions),
      mStateManager(stateManager),
      mVertexArrayID(0),
      mElementArrayBuffer(),
      mAttributes(),
      mAppliedElementArrayBuffer(0),
      mAppliedAttributes(),
      mStreamingElementArrayBufferSize(0),
      mStreamingElementArrayBuffer(0),
      mStreamingArrayBufferSize(0),
      mStreamingArrayBuffer(0)
{
    ASSERT(mFunctions);
    ASSERT(mStateManager);
    mFunctions->genVertexArrays(1, &mVertexArrayID);

    // Set the cached vertex attribute array size
    GLint maxVertexAttribs;
    mFunctions->getIntegerv(GL_MAX_VERTEX_ATTRIBS, &maxVertexAttribs);
    mAttributes.resize(maxVertexAttribs);
    mAppliedAttributes.resize(maxVertexAttribs);
}

VertexArrayGL::~VertexArrayGL()
{
    mStateManager->deleteVertexArray(mVertexArrayID);
    mVertexArrayID = 0;

    mStateManager->deleteBuffer(mStreamingElementArrayBuffer);
    mStreamingElementArrayBufferSize = 0;
    mStreamingElementArrayBuffer = 0;

    mStateManager->deleteBuffer(mStreamingArrayBuffer);
    mStreamingArrayBufferSize = 0;
    mStreamingArrayBuffer = 0;

    mElementArrayBuffer.set(nullptr);
    for (size_t idx = 0; idx < mAttributes.size(); idx++)
    {
        mAttributes[idx].buffer.set(NULL);
    }

    for (size_t idx = 0; idx < mAppliedAttributes.size(); idx++)
    {
        mAppliedAttributes[idx].buffer.set(NULL);
    }
}

void VertexArrayGL::setElementArrayBuffer(const gl::Buffer *buffer)
{
    mElementArrayBuffer.set(buffer);

    // If the buffer is being unbound/deleted, reset the currently applied buffer ID
    // so that even if a new buffer is generated with the same ID, it will be re-bound.
    if (buffer == nullptr && mAppliedElementArrayBuffer != mStreamingElementArrayBuffer)
    {
        mAppliedElementArrayBuffer = 0;
    }
}

void VertexArrayGL::setAttribute(size_t idx, const gl::VertexAttribute &attr)
{
    mAttributes[idx] = attr;
}

void VertexArrayGL::setAttributeDivisor(size_t idx, GLuint divisor)
{
    mAttributes[idx].divisor = divisor;
}

void VertexArrayGL::enableAttribute(size_t idx, bool enabledState)
{
    mAttributes[idx].enabled = enabledState;
}

gl::Error VertexArrayGL::syncDrawArraysState(GLint first, GLsizei count) const
{
    return syncDrawState(first, count, GL_NONE, nullptr, nullptr);
}

gl::Error VertexArrayGL::syncDrawElementsState(GLsizei count, GLenum type, const GLvoid *indices, const GLvoid **outIndices) const
{
    return syncDrawState(0, count, type, indices, outIndices);
}

gl::Error VertexArrayGL::syncDrawState(GLint first, GLsizei count, GLenum type, const GLvoid *indices, const GLvoid **outIndices) const
{
    mStateManager->bindVertexArray(mVertexArrayID, mAppliedElementArrayBuffer);

    // Check if any attributes need to be streamed, determines if the index range needs to be computed
    bool attributesNeedStreaming = doAttributesNeedStreaming();

    // Determine if an index buffer needs to be streamed and the range of vertices that need to be copied
    gl::RangeUI indexRange(0, 0);
    if (type != GL_NONE)
    {
        gl::Error error = syncIndexData(count, type, indices, attributesNeedStreaming, &indexRange, outIndices);
        if (error.isError())
        {
            return error;
        }
    }
    else
    {
        // Not an indexed call, set the range to [first, first + count)
        indexRange.start = first;
        indexRange.end = first + count;
    }

    // Sync the vertex attribute state and track what data needs to be streamed
    size_t streamingDataSize = 0;
    size_t maxAttributeDataSize = 0;
    gl::Error error = syncAttributeState(attributesNeedStreaming, indexRange, &streamingDataSize, &maxAttributeDataSize);
    if (error.isError())
    {
        return error;
    }

    if (streamingDataSize > 0)
    {
        ASSERT(attributesNeedStreaming);

        gl::Error error = streamAttributes(streamingDataSize, maxAttributeDataSize, indexRange);
        if (error.isError())
        {
            return error;
        }
    }

    return gl::Error(GL_NO_ERROR);
}

bool VertexArrayGL::doAttributesNeedStreaming() const
{
    // TODO: if GLES, nothing needs to be streamed
    for (size_t idx = 0; idx < mAttributes.size(); idx++)
    {
        if (mAttributes[idx].enabled && mAttributes[idx].buffer.get() == nullptr)
        {
            return true;
        }
    }

    return false;
}

gl::Error VertexArrayGL::syncAttributeState(bool attributesNeedStreaming, const gl::RangeUI &indexRange,
                                            size_t *outStreamingDataSize, size_t *outMaxAttributeDataSize) const
{
    *outStreamingDataSize = 0;
    *outMaxAttributeDataSize = 0;

    for (size_t idx = 0; idx < mAttributes.size(); idx++)
    {
        // Always sync the enabled and divisor state, they are required for both streaming and buffered
        // attributes
        if (mAppliedAttributes[idx].enabled != mAttributes[idx].enabled)
        {
            if (mAttributes[idx].enabled)
            {
                mFunctions->enableVertexAttribArray(idx);
            }
            else
            {
                mFunctions->disableVertexAttribArray(idx);
            }
            mAppliedAttributes[idx].enabled = mAttributes[idx].enabled;
        }
        if (mAppliedAttributes[idx].divisor != mAttributes[idx].divisor)
        {
            mFunctions->vertexAttribDivisor(idx, mAttributes[idx].divisor);
            mAppliedAttributes[idx].divisor = mAttributes[idx].divisor;
        }

        if (mAttributes[idx].enabled && mAttributes[idx].buffer.get() == nullptr)
        {
            ASSERT(attributesNeedStreaming);

            const size_t streamedVertexCount = indexRange.end - indexRange.start + 1;

            // If streaming is going to be required, compute the size of the required buffer
            // and how much slack space at the beginning of the buffer will be required by determining
            // the attribute with the largest data size.
            size_t typeSize = ComputeVertexAttributeTypeSize(mAttributes[idx]);
            *outStreamingDataSize += typeSize * streamedVertexCount;
            *outMaxAttributeDataSize = std::max(*outMaxAttributeDataSize, typeSize);
        }
        else
        {
            // Sync the attribute with no translation
            if (mAppliedAttributes[idx] != mAttributes[idx])
            {
                const gl::Buffer *arrayBuffer = mAttributes[idx].buffer.get();
                if (arrayBuffer != nullptr)
                {
                    const BufferGL *arrayBufferGL = GetImplAs<BufferGL>(arrayBuffer);
                    mStateManager->bindBuffer(GL_ARRAY_BUFFER, arrayBufferGL->getBufferID());
                }
                else
                {
                    mStateManager->bindBuffer(GL_ARRAY_BUFFER, 0);
                }

                if (mAttributes[idx].pureInteger)
                {
                    mFunctions->vertexAttribIPointer(idx, mAttributes[idx].size, mAttributes[idx].type,
                                                     mAttributes[idx].stride, mAttributes[idx].pointer);
                }
                else
                {
                    mFunctions->vertexAttribPointer(idx, mAttributes[idx].size, mAttributes[idx].type,
                                                    mAttributes[idx].normalized, mAttributes[idx].stride,
                                                    mAttributes[idx].pointer);
                }

                mAppliedAttributes[idx] = mAttributes[idx];
            }
        }
    }

    return gl::Error(GL_NO_ERROR);
}

gl::Error VertexArrayGL::syncIndexData(GLsizei count, GLenum type, const GLvoid *indices, bool attributesNeedStreaming,
                                       gl::RangeUI *outIndexRange, const GLvoid **outIndices) const
{
    ASSERT(outIndices);

    // Need to check the range of indices if attributes need to be streamed
    if (mElementArrayBuffer.get() != nullptr)
    {
        const BufferGL *bufferGL = GetImplAs<BufferGL>(mElementArrayBuffer.get());
        GLuint elementArrayBufferID = bufferGL->getBufferID();
        if (elementArrayBufferID != mAppliedElementArrayBuffer)
        {
            mStateManager->bindBuffer(GL_ELEMENT_ARRAY_BUFFER, elementArrayBufferID);
            mAppliedElementArrayBuffer = elementArrayBufferID;
        }

        // Only compute the index range if the attributes also need to be streamed
        if (attributesNeedStreaming)
        {
            ptrdiff_t elementArrayBufferOffset = reinterpret_cast<ptrdiff_t>(indices);
            gl::Error error = mElementArrayBuffer->getIndexRange(type, static_cast<size_t>(elementArrayBufferOffset), count, outIndexRange);
            if (error.isError())
            {
                return error;
            }
        }

        // Indices serves as an offset into the index buffer in this case, use the same value for the draw call
        *outIndices = indices;
    }
    else
    {
        // Need to stream the index buffer
        // TODO: if GLES, nothing needs to be streamed

        // Only compute the index range if the attributes also need to be streamed
        if (attributesNeedStreaming)
        {
            *outIndexRange = gl::ComputeIndexRange(type, indices, count);
        }

        // Allocate the streaming element array buffer
        if (mStreamingElementArrayBuffer == 0)
        {
            mFunctions->genBuffers(1, &mStreamingElementArrayBuffer);
            mStreamingElementArrayBufferSize = 0;
        }

        mStateManager->bindBuffer(GL_ELEMENT_ARRAY_BUFFER, mStreamingElementArrayBuffer);
        mAppliedElementArrayBuffer = mStreamingElementArrayBuffer;

        // Make sure the element array buffer is large enough
        const gl::Type &indexTypeInfo = gl::GetTypeInfo(type);
        size_t requiredStreamingBufferSize = indexTypeInfo.bytes * count;
        if (requiredStreamingBufferSize > mStreamingElementArrayBufferSize)
        {
            // Copy the indices in while resizing the buffer
            mFunctions->bufferData(GL_ELEMENT_ARRAY_BUFFER, requiredStreamingBufferSize, indices, GL_DYNAMIC_DRAW);
            mStreamingElementArrayBufferSize = requiredStreamingBufferSize;
        }
        else
        {
            // Put the indices at the beginning of the buffer
            mFunctions->bufferSubData(GL_ELEMENT_ARRAY_BUFFER, 0, requiredStreamingBufferSize, indices);
        }

        // Set the index offset for the draw call to zero since the supplied index pointer is to client data
        *outIndices = nullptr;
    }

    return gl::Error(GL_NO_ERROR);
}

gl::Error VertexArrayGL::streamAttributes(size_t streamingDataSize, size_t maxAttributeDataSize, const gl::RangeUI &indexRange) const
{
    if (mStreamingArrayBuffer == 0)
    {
        mFunctions->genBuffers(1, &mStreamingArrayBuffer);
        mStreamingArrayBufferSize = 0;
    }

    // If first is greater than zero, a slack space needs to be left at the beginning of the buffer so that
    // the same 'first' argument can be passed into the draw call.
    const size_t bufferEmptySpace = maxAttributeDataSize * indexRange.start;
    const size_t requiredBufferSize = streamingDataSize + bufferEmptySpace;

    mStateManager->bindBuffer(GL_ARRAY_BUFFER, mStreamingArrayBuffer);
    if (requiredBufferSize > mStreamingArrayBufferSize)
    {
        mFunctions->bufferData(GL_ARRAY_BUFFER, requiredBufferSize, nullptr, GL_DYNAMIC_DRAW);
        mStreamingArrayBufferSize = requiredBufferSize;
    }

    // Unmapping a buffer can return GL_FALSE to indicate that the system has corrupted the data
    // somehow (such as by a screen change), retry writing the data a few times and return OUT_OF_MEMORY
    // if that fails.
    GLboolean unmapResult = GL_FALSE;
    size_t unmapRetryAttempts = 5;
    while (unmapResult != GL_TRUE && --unmapRetryAttempts > 0)
    {
        uint8_t *bufferPointer = reinterpret_cast<uint8_t*>(mFunctions->mapBuffer(GL_ARRAY_BUFFER, GL_WRITE_ONLY));
        size_t curBufferOffset = bufferEmptySpace;

        const size_t streamedVertexCount = indexRange.end - indexRange.start + 1;

        for (size_t idx = 0; idx < mAttributes.size(); idx++)
        {
            if (mAttributes[idx].enabled && mAttributes[idx].buffer.get() == nullptr)
            {
                const size_t sourceStride = ComputeVertexAttributeStride(mAttributes[idx]);
                const size_t destStride = ComputeVertexAttributeTypeSize(mAttributes[idx]);

                const uint8_t *inputPointer = reinterpret_cast<const uint8_t*>(mAttributes[idx].pointer);

                // Pack the data when copying it, user could have supplied a very large stride that would
                // cause the buffer to be much larger than needed.
                if (destStride == sourceStride)
                {
                    // Can copy in one go, the data is packed
                    memcpy(bufferPointer + curBufferOffset,
                           inputPointer + (sourceStride * indexRange.start),
                           destStride * streamedVertexCount);
                }
                else
                {
                    // Copy each vertex individually
                    for (size_t vertexIdx = indexRange.start; vertexIdx <= indexRange.end; vertexIdx++)
                    {
                        memcpy(bufferPointer + curBufferOffset + (destStride * vertexIdx),
                               inputPointer + (sourceStride * vertexIdx),
                               destStride);
                    }
                }

                // Compute where the 0-index vertex would be.
                const size_t vertexStartOffset = curBufferOffset - (indexRange.start * destStride);

                mFunctions->vertexAttribPointer(idx, mAttributes[idx].size, mAttributes[idx].type,
                                                mAttributes[idx].normalized, destStride,
                                                reinterpret_cast<const GLvoid*>(vertexStartOffset));

                curBufferOffset += destStride * streamedVertexCount;

                // Mark the applied attribute as dirty by setting an invalid size so that if it doesn't
                // need to be streamed later, there is no chance that the caching will skip it.
                mAppliedAttributes[idx].size = static_cast<GLuint>(-1);
            }
        }

        unmapResult = mFunctions->unmapBuffer(GL_ARRAY_BUFFER);
    }

    if (unmapResult != GL_TRUE)
    {
        return gl::Error(GL_OUT_OF_MEMORY, "Failed to unmap the client data streaming buffer.");
    }

    return gl::Error(GL_NO_ERROR);
}

GLuint VertexArrayGL::getVertexArrayID() const
{
    return mVertexArrayID;
}

GLuint VertexArrayGL::getAppliedElementArrayBufferID() const
{
    return mAppliedElementArrayBuffer;
}

}
