#include "dl_stream_input.h"

#include <cassert>
#include <fstream>

#include "io/dl_log.h"
#include "memory/dl_buffer.h"
#include "io/dl_file.h"
#include "memory/dl_memory.h"

namespace dl
{

StreamInput::StreamInput() :
	_head{0}
{
}

StreamInput::~StreamInput()
{
}

const std::byte* StreamInput::GetBuffer()
{
	return _buf.data();
}

bool StreamInput::Read(void* data, size_t byte_count)
{
	size_t result_head = _head + byte_count;

	if (result_head > _buf.size())
	{
		log_warn0("Read超出了buffer大小！");
		_head = _buf.size();
		return false;
	}

	memcpy(data, _buf.data() + _head, byte_count);

	_head = result_head;
	return true;
}

bool StreamInput::LoadFromFile(std::string_view path_name, bool decompress, size_t length)
{
	std::ifstream ifs = File::Get(path_name);
	if (!ifs.is_open())
	{
		return false;
	}

	//有可能已经加载过了
	_buf.clear();
	_head = 0;

	if (decompress || length == 0)
	{
		ifs.seekg(0, std::ios::end);
		_buf.resize((size_t)ifs.tellg());
	}
	else
	{
		ifs.seekg(length, std::ios::beg);
		_buf.resize(length);
	}


	ifs.seekg(0);
	ifs.read((char*)_buf.data(), _buf.size());

	ifs.close();


	if (decompress)
	{
		BufferView zip { _buf };
		_buf = Memory::DecompressLz4(zip);
	}

	return true;
}

void StreamInput::LoadFromMemory(BufferView buf, bool decompress)
{
	//有可能已经加载过了
	_buf.clear();
	_head = 0;

	if (decompress)
	{
		_buf = Memory::DecompressLz4(buf);
	}
	else
	{
		_buf = CreateBuffer(buf);
	}
}


void StreamInput::SetPos(size_t pos)
{
	if (pos > _buf.size())
	{
		log_err("SetPos超出了buffer大小！", 10);
		return;
	}
	_head = pos;
}


bool StreamInput::IsEnd()
{
	assert(_head <= _buf.size());
	return _head == _buf.size();
}

}