#pragma once

#include <iostream>
#include <ostream>
#include <sstream>
#include <string>

class log_stream
{
public:
  log_stream(): m_active(false), m_buffer(), m_log_lines() {}

  void log_lines(int n) {
    m_log_lines = n;
  }

  std::string get_log() {
    return m_buffer.str();
  }

  // log to buffer
  void activate()
  {
    m_active = true;
  }

  // log to plain console
  void deactivate()
  {
    m_active = false;
  }

  template<typename T>
  log_stream& operator<<(const T& arg) {
    if (m_active) {
      m_buffer << arg;
      trim_buffer();
    }
    else
    {
      std::cout << arg;
    }
    return *this;
  }

  log_stream& operator<<(
    std::basic_ostream<char>& (*func)
        (std::basic_ostream<char>&) ) {
    if (m_active) {
      m_buffer << *func;
      trim_buffer();
    }
    else
    {
      std::cout << *func;
    }
    return *this;
  }

private:
  void trim_buffer()
  {
    std::string s = m_buffer.str();
    size_t pos = s.npos;
    for (int i = 0; i <= m_log_lines; ++i) {
      pos = s.rfind("\n", pos);
      if (pos == s.npos) {
        // too few lines
        return;
      }
      if (pos > 0) {
        --pos;
      }
    }

    m_buffer.str(s.substr((pos <= (s.size() - 2)) ? pos + 2 : pos));
  }

  bool m_active;
  std::stringstream m_buffer;
  int m_log_lines;
};

extern log_stream log_cout;