#include "input.h"

#include <fstream>
#include <iostream>
#include <sstream>
#include <string>
#include <optional>

std::string ReadFile(const std::string &filepath) {
  std::ifstream file(filepath, std::ios::binary | std::ios::ate);
  std::streamsize size = file.tellg();
  file.seekg(0, std::ios::beg);
  std::string buffer(size, '\0');
  file.read(buffer.data(), size);
  return buffer;
}

std::optional<std::string_view> Lines::Next() {
  if (text_.empty()) {
    return std::nullopt;
  }

  for (size_t i = 0; i < text_.size(); ++i) {
    if (text_[i] == '\n') {
      std::string_view result(text_.data(), i);
      if (text_.size() > i + 1) {
        text_ = std::string_view(text_.data() + i + 1, text_.size() - i - 1);
      } else {
        text_ = std::string_view();
      }
      return result;
    }
  }

  std::string_view last_result = text_;
  text_ = std::string_view();

  return last_result;
}