#include <iostream>
#include <sstream>

#include "ebook.h"

using namespace std;

Ebook::Ebook(string const& text,
             int char_per_line,
             int line_per_page)
  : text{text},
    next_page_start{},
    char_per_line{char_per_line},
    line_per_page{line_per_page}
{
}

void Ebook::set_page_size(int char_per_l, int line_per_p)
{
  char_per_line = char_per_l;
  line_per_page = line_per_p;
}

std::string Ebook::next_page()
{
  ostringstream out_page_stream;

  int i{};
  
  while ( ! at_end() && i < line_per_page )
  {
    string line = text.substr(next_page_start, char_per_line);

    auto section_end = line.rfind('\n');
    auto line_end = line.rfind(' ');

    if ( section_end != string::npos )
    {
      line = line.substr(0, section_end + 1);
      next_page_start += section_end + 1;
      ++i;
    }
    else if ( line_end != string::npos )
    {
      line = line.substr(0, line_end);
      next_page_start += line_end + 1;
    }
    else // no space or newline
    {
      next_page_start += char_per_line;      
    }

    out_page_stream << line << endl;
    ++i;
  }
  
  return out_page_stream.str();
}

bool Ebook::at_end() const
{
  return text.size() <= next_page_start;
}