// Copyright (c), ETH Zurich and UNC Chapel Hill.
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//       notice, this list of conditions and the following disclaimer in the
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#include "colmap/util/types.h"

#include <limits>
#include <unordered_set>

#include <gmock/gmock.h>
#include <gtest/gtest.h>

namespace colmap {
namespace {

TEST(ShouldSwapImagePair, Nominal) {
  EXPECT_FALSE(ShouldSwapImagePair(0, 0));
  EXPECT_FALSE(ShouldSwapImagePair(0, 1));
  EXPECT_TRUE(ShouldSwapImagePair(1, 0));
  EXPECT_FALSE(ShouldSwapImagePair(1, 1));
}

TEST(ImagePairToPairId, Nominal) {
  EXPECT_EQ(ImagePairToPairId(0, 0), 0);
  EXPECT_EQ(ImagePairToPairId(0, 1), 1);
  EXPECT_EQ(ImagePairToPairId(0, 2), 2);
  EXPECT_EQ(ImagePairToPairId(0, 3), 3);
  EXPECT_EQ(ImagePairToPairId(1, 2), kMaxNumImages + 2);
  for (image_t i = 0; i < 20; ++i) {
    for (image_t j = 0; j < 20; ++j) {
      const image_pair_t pair_id = ImagePairToPairId(i, j);
      const auto [image_id1, image_id2] = PairIdToImagePair(pair_id);
      if (i < j) {
        EXPECT_EQ(i, image_id1);
        EXPECT_EQ(j, image_id2);
      } else {
        EXPECT_EQ(i, image_id2);
        EXPECT_EQ(j, image_id1);
      }
    }
  }
}

TEST(Span, SizeAndEmpty) {
  std::vector<int> container = {1, 2, 3};
  const span<int> non_empty(container.data(), container.size());
  EXPECT_EQ(non_empty.size(), 3);
  EXPECT_FALSE(non_empty.empty());

  const span<int> empty(container.data(), 0);
  EXPECT_EQ(empty.size(), 0);
  EXPECT_TRUE(empty.empty());
}

TEST(FilterView, Empty) {
  const std::vector<int> container;
  filter_view filtered_container(
      [](const int&) { return true; }, container.begin(), container.end());
  EXPECT_THAT(
      std::vector<int>(filtered_container.begin(), filtered_container.end()),
      testing::IsEmpty());
}

TEST(FilterView, All) {
  const std::vector<int> container = {1, 2, 3, 4, 5, 6};
  filter_view filtered_container(
      [](const int&) { return true; }, container.begin(), container.end());
  EXPECT_THAT(
      std::vector<int>(filtered_container.begin(), filtered_container.end()),
      container);
}

TEST(FilterView, None) {
  const std::vector<int> container = {1, 2, 3, 4, 5, 6};
  filter_view filtered_container(
      [](const int&) { return false; }, container.begin(), container.end());
  EXPECT_THAT(
      std::vector<int>(filtered_container.begin(), filtered_container.end()),
      testing::IsEmpty());
}

TEST(FilterView, Nominal) {
  const std::vector<int> container = {1, 2, 3, 4, 5, 6};
  filter_view filtered_container([](const int& d) { return d % 2 == 0; },
                                 container.begin(),
                                 container.end());
  EXPECT_THAT(
      std::vector<int>(filtered_container.begin(), filtered_container.end()),
      testing::ElementsAre(2, 4, 6));
}

TEST(FilterView, RangeExpression) {
  const std::vector<int> container = {1, 2, 3, 4, 5, 6};
  filter_view filtered_container([](const int& d) { return d % 2 == 0; },
                                 container.begin(),
                                 container.end());
  for (const int d : filtered_container) {
    EXPECT_EQ(d % 2, 0);
  }
}

TEST(FeatureMatchHashing, Nominal) {
  std::unordered_set<std::pair<point2D_t, point2D_t>> set;
  set.emplace(1, 2);
  EXPECT_EQ(set.size(), 1);
  set.emplace(1, 2);
  EXPECT_EQ(set.size(), 1);
  EXPECT_EQ(set.count(std::make_pair(0, 0)), 0);
  EXPECT_EQ(set.count(std::make_pair(1, 2)), 1);
  EXPECT_EQ(set.count(std::make_pair(2, 1)), 0);
  set.emplace(2, 1);
  EXPECT_EQ(set.size(), 2);
  EXPECT_EQ(set.count(std::make_pair(0, 0)), 0);
  EXPECT_EQ(set.count(std::make_pair(1, 2)), 1);
  EXPECT_EQ(set.count(std::make_pair(2, 1)), 1);
}

TEST(FeatureMatchHashing, LargeValues) {
  const point2D_t hi = std::numeric_limits<point2D_t>::max();
  const point2D_t lo = 1;
  std::unordered_set<std::pair<point2D_t, point2D_t>> set;
  set.emplace(hi, lo);
  set.emplace(lo, hi);
  set.emplace(hi, hi);
  set.emplace(lo, lo);
  EXPECT_EQ(set.size(), 4);
  EXPECT_EQ(set.count(std::make_pair(hi, lo)), 1);
  EXPECT_EQ(set.count(std::make_pair(lo, hi)), 1);
  EXPECT_EQ(set.count(std::make_pair(hi, hi)), 1);
  EXPECT_EQ(set.count(std::make_pair(lo, lo)), 1);
}

TEST(FeatureMatchHashing, Deterministic) {
  std::hash<std::pair<point2D_t, point2D_t>> h;
  EXPECT_EQ(h(std::make_pair<point2D_t, point2D_t>(42, 99)),
            h(std::make_pair<point2D_t, point2D_t>(42, 99)));
  EXPECT_NE(h(std::make_pair<point2D_t, point2D_t>(42, 99)),
            h(std::make_pair<point2D_t, point2D_t>(99, 42)));
}

TEST(Point3DPairHashing, Nominal) {
  std::unordered_set<std::pair<point3D_t, point3D_t>> set;
  set.emplace(1, 2);
  EXPECT_EQ(set.size(), 1);
  set.emplace(1, 2);
  EXPECT_EQ(set.size(), 1);
  EXPECT_EQ(set.count(std::make_pair<point3D_t, point3D_t>(0, 0)), 0);
  EXPECT_EQ(set.count(std::make_pair<point3D_t, point3D_t>(1, 2)), 1);
  EXPECT_EQ(set.count(std::make_pair<point3D_t, point3D_t>(2, 1)), 0);
  set.emplace(2, 1);
  EXPECT_EQ(set.size(), 2);
  EXPECT_EQ(set.count(std::make_pair<point3D_t, point3D_t>(0, 0)), 0);
  EXPECT_EQ(set.count(std::make_pair<point3D_t, point3D_t>(1, 2)), 1);
  EXPECT_EQ(set.count(std::make_pair<point3D_t, point3D_t>(2, 1)), 1);
}

TEST(Point3DPairHashing, LargeValues) {
  const point3D_t hi = std::numeric_limits<point3D_t>::max();
  const point3D_t lo = 1;
  std::unordered_set<std::pair<point3D_t, point3D_t>> set;
  set.emplace(hi, lo);
  set.emplace(lo, hi);
  set.emplace(hi, hi);
  set.emplace(lo, lo);
  EXPECT_EQ(set.size(), 4);
  EXPECT_EQ(set.count(std::make_pair(hi, lo)), 1);
  EXPECT_EQ(set.count(std::make_pair(lo, hi)), 1);
  EXPECT_EQ(set.count(std::make_pair(hi, hi)), 1);
  EXPECT_EQ(set.count(std::make_pair(lo, lo)), 1);
}

TEST(Point3DPairHashing, Deterministic) {
  std::hash<std::pair<point3D_t, point3D_t>> h;
  EXPECT_EQ(h(std::make_pair<point3D_t, point3D_t>(42, 99)),
            h(std::make_pair<point3D_t, point3D_t>(42, 99)));
  EXPECT_NE(h(std::make_pair<point3D_t, point3D_t>(42, 99)),
            h(std::make_pair<point3D_t, point3D_t>(99, 42)));
}

}  // namespace
}  // namespace colmap
