/*     Copyright 2015-2018 Egor Yusov
 *  
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 *  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 OF ANY PROPRIETARY RIGHTS.
 *
 *  In no event and under no legal theory, whether in tort (including negligence), 
 *  contract, or otherwise, unless required by applicable law (such as deliberate 
 *  and grossly negligent acts) or agreed to in writing, shall any Contributor be
 *  liable for any damages, including any direct, indirect, special, incidental, 
 *  or consequential damages of any character arising as a result of this License or 
 *  out of the use or inability to use the software (including but not limited to damages 
 *  for loss of goodwill, work stoppage, computer failure or malfunction, or any and 
 *  all other commercial damages or losses), even if such Contributor has been advised 
 *  of the possibility of such damages.
 */

#pragma once

/// \file
/// Defines Diligent::StringPool class

#include <cstring>
#include "../../Primitives/interface/BasicTypes.h"
#include "../../Primitives/interface/MemoryAllocator.h"
#include "../../Platforms/Basic/interface/DebugUtilities.h"

namespace Diligent
{

/// Implementation of a simple fixed-size string pool
class StringPool
{
public:
    StringPool(){}
    
    StringPool             (const StringPool&) = delete;
    StringPool& operator = (const StringPool&) = delete;

    ~StringPool()
    {
        if(m_pBuffer != nullptr && m_pAllocator != nullptr)
        {
            m_pAllocator->Free(m_pBuffer);
        }
    }

    void Reserve(size_t Size, IMemoryAllocator &Allocator)
    {
        VERIFY(m_ReservedSize == 0, "Pool is already initialized");
        m_pAllocator = &Allocator;
        m_ReservedSize = Size;
        if (m_ReservedSize != 0)
        {
            m_pBuffer = reinterpret_cast<Char*>(m_pAllocator->Allocate(m_ReservedSize, "Memory for string pool", __FILE__, __LINE__));
        }
        m_pCurrPtr = m_pBuffer;
    }

    void AssignMemory(Char* pBuffer, size_t Size)
    {
        VERIFY(m_ReservedSize == 0, "Pool is already initialized");
        m_ReservedSize = Size;
        m_pBuffer = pBuffer;
        m_pCurrPtr = m_pBuffer;
    }

    Char* Allocate(size_t Length)
    {
        VERIFY(m_pCurrPtr + Length <= m_pBuffer + m_ReservedSize, "Not enough space in the buffer");
        auto *Ptr = m_pCurrPtr;
        m_pCurrPtr += Length;
        return Ptr;
    }

    Char* CopyString(const String& Str)
    {
        auto len = Str.length();
        auto *str = Allocate(len + 1);
        if(len != 0)
        {
            memcpy(str, Str.data(), len * sizeof(str[0]));
        }
        str[len] = 0;
        return str;
    }

    Char* CopyString(const char* Str)
    {
        auto* Ptr = m_pCurrPtr;
        while(*Str != 0 && m_pCurrPtr < m_pBuffer + m_ReservedSize)
        {
            *(m_pCurrPtr++) = *(Str++);
        }
        if(m_pCurrPtr < m_pBuffer + m_ReservedSize)
            *(m_pCurrPtr++) = 0;
        else
            UNEXPECTED("Not enough space reserved in the string pool");
        return Ptr;
    }


    size_t GetRemainingSize()const
    {
        VERIFY(m_pCurrPtr <= m_pBuffer + m_ReservedSize, "Buffer overflow");
        return m_ReservedSize - (m_pCurrPtr - m_pBuffer);
    }
    size_t GetUsedSize()const
    {
        VERIFY(m_pCurrPtr <= m_pBuffer + m_ReservedSize, "Buffer overflow");
        return m_pCurrPtr - m_pBuffer;
    }

private:
    Char*               m_pBuffer       = nullptr;
    Char*               m_pCurrPtr      = nullptr;
    size_t              m_ReservedSize  = 0;
    IMemoryAllocator*   m_pAllocator    = nullptr;
};

}
