//
// Urho3D Engine
// Copyright (c) 2008-2011 Lasse Öörni
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// 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. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//

#include "Precompiled.h"
#include "Context.h"
#include "Graphics.h"
#include "GraphicsImpl.h"
#include "IndexBuffer.h"
#include "Log.h"

#include <cstring>

#include "DebugNew.h"

OBJECTTYPESTATIC(IndexBuffer);

IndexBuffer::IndexBuffer(Context* context) :
    Object(context),
    GPUObject(GetSubsystem<Graphics>()),
    discardLockData_(0),
    indexCount_(0),
    indexSize_(0),
    dynamic_(false),
    locked_(false)
{
}

IndexBuffer::~IndexBuffer()
{
    Release();
}

void IndexBuffer::OnDeviceLost()
{
    if (object_)
    {
        void* hwData = Lock(0, indexCount_, LOCK_READONLY);
        if (hwData)
        {
            saveData_ = new unsigned char[indexCount_ * indexSize_];
            memcpy(saveData_.Get(), hwData, indexCount_ * indexSize_);
        }
        Unlock();
        Release();
    }
}

void IndexBuffer::OnDeviceReset()
{
    if (!object_)
    {
        Create();
        if (saveData_)
        {
            SetData(saveData_.Get());
            saveData_.Reset();
        }
    }
}

void IndexBuffer::Release()
{
    if (object_)
    {
        if (!graphics_)
            return;
        
        Unlock();
        
        if (graphics_->GetIndexBuffer() == this)
            graphics_->SetIndexBuffer(0);
        
        glDeleteBuffers(1, &object_);
        object_ = 0;
    }
    
    fallbackData_.Reset();
}

bool IndexBuffer::SetSize(unsigned indexCount, bool largeIndices, bool dynamic)
{
    dynamic_ = dynamic;
    indexCount_ = indexCount;
    indexSize_ = largeIndices ? sizeof(unsigned) : sizeof(unsigned short);
    
    return Create();
}

bool IndexBuffer::SetData(const void* data)
{
    if (!data)
    {
        LOGERROR("Null pointer for index buffer data");
        return false;
    }
    
    if (locked_)
        Unlock();
    
    if (object_)
    {
        graphics_->SetIndexBuffer(0);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, object_);
        glBufferData(GL_ELEMENT_ARRAY_BUFFER, indexCount_ * indexSize_, data, dynamic_ ? GL_DYNAMIC_DRAW : GL_STATIC_DRAW);
        return true;
    }
    else if (fallbackData_)
    {
        memcpy(fallbackData_.Get(), data, indexCount_ * indexSize_);
        return true;
    }
    
    return false;
}

bool IndexBuffer::SetDataRange(const void* data, unsigned start, unsigned count)
{
    if (!data)
    {
        LOGERROR("Null pointer for index buffer data");
        return false;
    }
    
    if (start + count > indexCount_)
    {
        LOGERROR("Illegal range for setting new index buffer data");
        return false;
    }
    
    if (locked_)
        Unlock();
    
    if (object_)
    {
        graphics_->SetIndexBuffer(0);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, object_);
        glBufferSubData(GL_ELEMENT_ARRAY_BUFFER, start * indexSize_, count * indexSize_, data);
        return true;
    }
    else if (fallbackData_)
    {
        memcpy(fallbackData_.Get() + start * indexSize_, data, count * indexSize_);
        return true;
    }
    
    return false;
}

void* IndexBuffer::Lock(unsigned start, unsigned count, LockMode mode)
{
    if (!object_ && !fallbackData_)
        return 0;
    
    if (locked_)
    {
        LOGERROR("Index buffer already locked");
        return 0;
    }

    if (!count || start + count > indexCount_)
    {
        LOGERROR("Illegal range for locking index buffer");
        return 0;
    }
    
    void* hwData = 0;
    
    if (object_)
    {
        GLenum glLockMode = GL_WRITE_ONLY;
        if (mode == LOCK_READONLY)
            glLockMode = GL_READ_ONLY;
        else if (mode == LOCK_NORMAL)
            glLockMode = GL_READ_WRITE;
        
        // In discard mode, use a CPU side buffer to avoid stalling
        if (mode == LOCK_DISCARD)
        {
            hwData = discardLockData_ = graphics_->ReserveDiscardLockBuffer(count * indexSize_);
            discardLockStart_ = start;
            discardLockCount_ = count;
        }
        else
        {
            graphics_->SetIndexBuffer(0);
            glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, object_);
            hwData = glMapBuffer(GL_ELEMENT_ARRAY_BUFFER, glLockMode);
            if (!hwData)
                return 0;
            hwData = (unsigned char*)hwData + start * indexSize_;
        }
    }
    else
        hwData = fallbackData_.Get() + start * indexSize_;
    
    locked_ = true;
    return hwData;
}

void IndexBuffer::Unlock()
{
    if (locked_)
    {
        locked_ = false;
        
        if (object_)
        {
            if (!discardLockData_)
            {
                graphics_->SetIndexBuffer(0);
                glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, object_);
                glUnmapBuffer(GL_ELEMENT_ARRAY_BUFFER);
            }
            else
            {
                if (discardLockCount_ < indexCount_)
                    SetDataRange(discardLockData_, discardLockStart_, discardLockCount_);
                else
                    SetData(discardLockData_);
                graphics_->FreeDiscardLockBuffer(discardLockData_);
                discardLockData_ = 0;
            }
        }
    }
}

void IndexBuffer::ClearDataLost()
{
}

bool IndexBuffer::GetUsedVertexRange(unsigned start, unsigned count, unsigned& minVertex, unsigned& vertexCount)
{
    void* data = Lock(start, count, LOCK_READONLY);
    if (!data)
        return false;
    
    minVertex = M_MAX_UNSIGNED;
    unsigned maxVertex = 0;
    
    if (indexSize_ == sizeof(unsigned))
    {
        unsigned* indices = (unsigned*)data;
        
        for (unsigned i = 0; i < count; ++i)
        {
            if (indices[i] < minVertex)
                minVertex = indices[i];
            if (indices[i] > maxVertex)
                maxVertex = indices[i];
        }
    }
    else
    {
        unsigned short* indices = (unsigned short*)data;
        
        for (unsigned i = 0; i < count; ++i)
        {
            if (indices[i] < minVertex)
                minVertex = indices[i];
            if (indices[i] > maxVertex)
                maxVertex = indices[i];
        }
    }
    
    vertexCount = maxVertex - minVertex + 1;
    
    Unlock();
    return true;
}

bool IndexBuffer::Create()
{
    if (!indexCount_)
    {
        Release();
        return true;
    }
    
    if (graphics_)
    {
        graphics_->SetIndexBuffer(0);
        
        if (!object_)
            glGenBuffers(1, &object_);
        
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, object_);
        glBufferData(GL_ELEMENT_ARRAY_BUFFER, indexCount_ * indexSize_, 0, dynamic_ ? GL_DYNAMIC_DRAW : GL_STATIC_DRAW);
    }
    else
        fallbackData_ = new unsigned char[indexCount_ * indexSize_];
    
    return true;
}