/*
 * .============.
 * // M A K E / \
 * // C++ DEV / \
 * // E A S Y / \/ \
 * ++ ----------. \/\ .
 * \\ \ \ /\ /
 * \\ \ \ /
 * \\ \ \ /
 * -============'
 *
 * Copyright (c) 2018 Hevake and contributors, all rights reserved.
 *
 * This file is part of cpp-tbox (https://github.com/cpp-main/cpp-tbox)
 * Use of this source code is governed by MIT license that can be found
 * in the LICENSE file in the root of the source tree. All contributing
 * project authors may be found in the CONTRIBUTORS.md file in the root
 * of the source tree.
 */
#include <cstring>
#include <utility>

#include <tbox/base/assert.h>
#include <tbox/base/defines.h>

#include "buffer.h"

namespace tbox {
namespace util {

Buffer::Buffer(size_t reverse_size)
{
 //! 如果预留空间大小,那么要为缓冲分配空间
 if (reverse_size > 0) {
 uint8_t *p_buff = new uint8_t [reverse_size];
 TBOX_ASSERT(p_buff != nullptr);
 buffer_ptr_ = p_buff;
 buffer_size_ = reverse_size;
 }
}

Buffer::Buffer(const Buffer &other)
{
 cloneFrom(other);
}

Buffer::Buffer(Buffer &&other)
{
 swap(other);
}

Buffer::~Buffer()
{
 CHECK_DELETE_RESET_ARRAY(buffer_ptr_);
}

Buffer& Buffer::operator = (const Buffer &other)
{
 if (this != &other)
 cloneFrom(other);

 return *this;
}

Buffer& Buffer::operator = (Buffer &&other)
{
 if (this != &other) {
 reset();
 swap(other);
 }

 return *this;
}

void Buffer::swap(Buffer &other)
{
 if (&other == this)
 return;

 std::swap(other.buffer_ptr_, buffer_ptr_);
 std::swap(other.buffer_size_, buffer_size_);
 std::swap(other.read_index_, read_index_);
 std::swap(other.write_index_, write_index_);
}

void Buffer::reset()
{
 Buffer tmp(0);
 swap(tmp);
}

bool Buffer::ensureWritableSize(size_t write_size)
{
 if (write_size == 0)
 return true;

 //! 空间足够
 if (writableSize() >= write_size)
 return true;

 //! 检查是否可以通过将数据往前挪是否可以满足空间要求
 if ((writableSize() + read_index_) >= write_size) {
 //! 将 readable 区的数据往前移
 ::memmove(buffer_ptr_, (buffer_ptr_ + read_index_), (write_index_ - read_index_));
 write_index_ -= read_index_;
 read_index_ = 0;
 return true;

 } else { //! 只有重新分配更多的空间才可以
 size_t new_size = (write_index_ + write_size) << 1; //! 两倍扩展
 uint8_t *p_buff = new uint8_t[new_size];
 if (p_buff == nullptr)
 return false;

 if (buffer_ptr_ != nullptr) {
 //! 只需要复制 readable 部分数据
 ::memcpy((p_buff + read_index_), (buffer_ptr_ + read_index_), (write_index_ - read_index_));
 delete [] buffer_ptr_;
 }

 buffer_ptr_ = p_buff;
 buffer_size_ = new_size;

 return true;
 }
}

void Buffer::hasWritten(size_t write_size)
{
 if (write_index_ + write_size > buffer_size_) {
 write_index_ = buffer_size_;
 } else {
 write_index_ += write_size;
 }
}

size_t Buffer::append(const void *p_data, size_t data_size)
{
 if (ensureWritableSize(data_size)) {
 ::memcpy(writableBegin(), p_data, data_size);
 hasWritten(data_size);
 return data_size;
 }
 return 0;
}

void Buffer::hasRead(size_t read_size)
{
 if (read_index_ + read_size > write_index_) {
 read_index_ = write_index_ = 0;
 } else {
 read_index_ += read_size;
 if (read_index_ == write_index_)
 read_index_ = write_index_ = 0;
 }
}

void Buffer::hasReadAll()
{
 read_index_ = write_index_ = 0;
}

size_t Buffer::fetch(void *p_buff, size_t buff_size)
{
 size_t read_size = (buff_size > readableSize()) ? readableSize() : buff_size;
 ::memcpy(p_buff, readableBegin(), read_size);
 hasRead(read_size);
 return read_size;
}

//! 不是完全复制,只复制有效的数据
void Buffer::cloneFrom(const Buffer &other)
{
 CHECK_DELETE_RESET_ARRAY(buffer_ptr_);

 //! 如果 other 有可读数据,则要根据可读大小分配空间
 if (other.readableSize() > 0) {
 uint8_t *p_buff = new uint8_t[other.readableSize()];
 TBOX_ASSERT(p_buff != nullptr);
 ::memcpy(p_buff, other.readableBegin(), other.readableSize());
 buffer_ptr_ = p_buff;
 buffer_size_ = write_index_ = other.readableSize();

 } else {
 buffer_ptr_ = nullptr;
 buffer_size_ = write_index_ = 0;
 }

 read_index_ = 0;
}

void Buffer::shrink()
{
 Buffer tmp(*this); //! 将自己复制给 tmp,其间会缩减空间
 swap(tmp); //! 与 tmp 交换
}

}
}