#include "StreamingTsvParser.h"
#include <algorithm>
#include <cstring>

namespace
{
	/// 从 buf 中取出一行（到 \n 或 \r\n），写入 line，返回消费的字节数
	size_t TakeLine(const std::string& buf, std::string& line)
	{
		size_t i = 0;
		while (i < buf.size() && buf[i] != '\n' && buf[i] != '\r')
		{
			++i;
		}
		line = buf.substr(0, i);
		if (i < buf.size())
		{
			++i;
			if (i < buf.size() && buf[i - 1] == '\r' && buf[i] == '\n')
			{
				++i;
			}
		}
		return i;
	}

	void SplitByTab(const std::string& line, std::vector<std::string>& out)
	{
		out.clear();
		size_t start = 0;
		for (size_t i = 0; i <= line.size(); ++i)
		{
			if (i == line.size() || line[i] == '\t')
			{
				out.push_back(line.substr(start, i - start));
				start = i + 1;
			}
		}
	}
}

void StreamingTsvParser::Feed(const void* data, size_t size)
{
	if (data == nullptr || size == 0)
	{
		return;
	}
	const char* p = static_cast<const char*>(data);
	m_buffer.append(p, size);
	ProcessBuffer();
}

void StreamingTsvParser::End()
{
	// 将剩余内容当作最后一行（可能无换行符）
	if (!m_buffer.empty())
	{
		std::vector<std::string> fields;
		SplitByTab(m_buffer, fields);
		if (!fields.empty() && m_callback)
		{
			m_callback(m_lineIndex, fields);
		}
		m_buffer.clear();
	}
}

void StreamingTsvParser::ProcessBuffer()
{
	if (!m_callback)
	{
		return;
	}
	std::string line;
	size_t consumed = TakeLine(m_buffer, line);
	while (consumed > 0)
	{
		std::vector<std::string> fields;
		SplitByTab(line, fields);
		if (!fields.empty())
		{
			m_callback(m_lineIndex++, fields);
		}
		m_buffer.erase(0, consumed);
		consumed = TakeLine(m_buffer, line);
	}
}