#pragma once

#include <boost/test/data/size.hpp>

#include <string>
#include <string_view>
#include <tuple>
#include <vector>

namespace utf_data = boost::unit_test::data;

/// [Custom command line
/// arguments](https://www.boost.org/doc/libs/1_73_0/libs/test/doc/html/boost_test/runtime_config/custom_command_line_arguments.html)
class dataset_loader {
public:
  explicit dataset_loader(std::string_view testcase_group) {}
  virtual ~dataset_loader() = default;

public:
  enum { arity = 2 };

  struct iterator {
    using iterator_type = std::vector<std::string>::const_iterator;
    iterator(iterator_type input_iter_, iterator_type expected_iter_)
        : input_iter{input_iter_}, expected_iter{expected_iter_} {}

    std::tuple<std::string, std::string> operator*() const {
      return {*input_iter, *expected_iter};
    }

    void operator++() {
      ++input_iter;
      ++expected_iter;
    }

  private:
    iterator_type input_iter;
    iterator_type expected_iter;
  };

  utf_data::size_t size() const { return dataset.input.size(); }

  iterator begin() const {
    // in real, read data from filesystem into datasets depend on testcase_group
    // and argc/argv
    return iterator(dataset.input.begin(), dataset.expected.begin());
  }

private:
  struct test_dataset {
    std::vector<std::string> input;
    std::vector<std::string> expected;
  };
  test_dataset mutable dataset;
};