// Rotate a square matrix in place.

#define CATCH_CONFIG_MAIN
#include <catch.hpp>

#include <fmt/format.h>
#include <experimental/string_view>
#include <string>

using string_view = std::experimental::string_view;

using image = std::array<std::array<uint32_t, 3>, 3>;

image parse(string_view in) {
  image out;

  size_t x = 0;
  size_t y = 0;

  for (auto ch : in) {
    if (ch == ';') {
      continue;
    }
    out[y][x] = ch;
    if (++x == out[0].size()) {
      y++;
      x = 0;
    }
  }
  return out;
}

std::string to_string(const image& img) {
  std::string out;

  for (const auto& row : img) {
    for (auto ch : row) {
      out.push_back(char(ch));
    }
    out.push_back(';');
  }
  return out;
}

image rotate(image in) {
  // TODO(michaelh): image is heavy but there's no temporary to pass
  // about.
  image out;

  // TODO(michaelh): the problem says in-place.  I think you can using
  // one temporary value so, for example, the flow is:
  //
  // c -> tmp
  // a -> c'
  // h -> a'
  // j -> h'
  // tmp -> j'
  //
  for (size_t y = 0; y < in.size(); y++) {
    for (size_t x = 0; x < in[0].size(); x++) {
      out[x][in.size() - y - 1] = in[y][x];
    }
  }

  return out;
}

TEST_CASE("cc17", "compress") {
  // abc     hda
  // def --> ieb
  // hij     jfc
  CHECK(to_string(rotate(parse("abcdefhij"))) == "hda;ieb;jfc;");
}