#pragma once

#include <vector>
#include <math.h>

template<class It>
class IteratorRange {
 public:
  IteratorRange(It b, It e) : begin_(b), end_(e), size_(std::distance(b, e)) {}

  It begin() const {
	return begin_;
  }

  It end() const {
	return end_;
  }

  size_t size() const {
	return size_;
  }
 private:
  It begin_, end_;
  size_t size_;
};

template<typename It>
class Slicer {
 public:
  Slicer(It b, It e, int page_size) : size_(ceil(std::distance(b, e) / static_cast<double>(page_size))) {
	auto beg = b;
	for (; b != e; ++b) {
	  if (std::distance(beg, b)+1 == page_size) {
		pages_.push_back(IteratorRange<It>(beg, ++b));
		beg = b;
	  }
	  if (std::distance(beg, e) < page_size) {
		if (std::distance(beg, e) > 0) {
		  pages_.push_back(IteratorRange<It>(beg, e));
		}
		break;
	  }
	}
  }

  auto begin() const {
	return pages_.begin();
  }

  auto end() const {
	return pages_.end();
  }

  size_t size() const {
	return size_;
  }

 private:
  std::vector<IteratorRange<It>> pages_;
  size_t size_;
};

template<typename C>
auto Slice(C &c, size_t page_size) {
  return Slicer<typename C::iterator>(c.begin(), c.end(), page_size);
}

template<typename C>
auto Slice(const C &c, size_t page_size) {
  return Slicer<typename C::const_iterator>(c.begin(), c.end(), page_size);
}

template<>
auto Slice(const IteratorRange<std::vector<int>::iterator> &c, size_t page_size) {
  return Slicer<std::vector<int>::iterator>(c.begin(), c.end(), page_size);
}