/*
 * Copyright 2018 Google
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "Firestore/core/src/firebase/firestore/immutable/sorted_map.h"

#include <numeric>
#include <random>
#include <unordered_set>
#include <utility>

#include "Firestore/core/src/firebase/firestore/immutable/array_sorted_map.h"
#include "Firestore/core/src/firebase/firestore/immutable/tree_sorted_map.h"
#include "Firestore/core/src/firebase/firestore/util/secure_random.h"

#include "Firestore/core/test/firebase/firestore/immutable/testing.h"
#include "gtest/gtest.h"

using firebase::firestore::immutable::impl::SortedMapBase;

namespace firebase {
namespace firestore {
namespace immutable {

using SizeType = SortedMapBase::size_type;

template <typename MapType>
struct TestPolicy {
  static const SizeType kLargeSize = 100;
};

template <>
struct TestPolicy<impl::ArraySortedMap<int, int>> {
  // ArraySortedMap cannot insert more than this number
  static const SizeType kLargeSize = SortedMapBase::kFixedSize;
};

template <typename IntMap>
class SortedMapTest : public ::testing::Test {
 public:
  SortedMapBase::size_type large_size() const {
    return TestPolicy<IntMap>::kLargeSize;
  }

  int large_number() const {
    return static_cast<int>(large_size());
  }
};

// NOLINTNEXTLINE: must be a typedef for the gtest macros
typedef ::testing::Types<SortedMap<int, int>,
                         impl::ArraySortedMap<int, int>,
                         impl::TreeSortedMap<int, int>>
    TestedTypes;
TYPED_TEST_CASE(SortedMapTest, TestedTypes);

TYPED_TEST(SortedMapTest, EmptySize) {
  TypeParam map;
  EXPECT_TRUE(map.empty());
  EXPECT_EQ(0u, map.size());
}

TYPED_TEST(SortedMapTest, Empty) {
  TypeParam map = TypeParam{}.insert(10, 10).erase(10);
  EXPECT_TRUE(map.empty());
  EXPECT_EQ(0u, map.size());

  // TODO(wilhuff): re-add find
  // EXPECT_TRUE(NotFound(map, 1));
  // EXPECT_TRUE(NotFound(map, 10));
}

TYPED_TEST(SortedMapTest, Size) {
  std::mt19937 rand;
  std::uniform_int_distribution<int> dist(0, 999);

  std::unordered_set<int> expected;

  TypeParam map;
  auto n = this->large_number();
  for (int i = 0; i < n; ++i) {
    int value = dist(rand);

    // The random number sequence can generate duplicates, so the expected size
    // won't necessarily depend upon `i`.
    expected.insert(value);

    map = map.insert(value, value);
    EXPECT_EQ(expected.size(), map.size());
  }
}

TYPED_TEST(SortedMapTest, Increasing) {
  std::vector<int> to_insert = Sequence(this->large_number());
  TypeParam map = ToMap<TypeParam>(to_insert);
  ASSERT_EQ(this->large_size(), map.size());

  for (int i : to_insert) {
    map = map.erase(i);
  }
  ASSERT_EQ(0u, map.size());

  std::vector<int> empty;
  ASSERT_EQ(Pairs(empty), Collect(map));
}

TYPED_TEST(SortedMapTest, IteratorsAreDefaultConstructible) {
  // If this compiles the test has succeeded
  typename TypeParam::const_iterator iter;
  (void)iter;
}

TYPED_TEST(SortedMapTest, BeginEndEmpty) {
  TypeParam map;
  ASSERT_EQ(map.begin(), map.end());
}

TYPED_TEST(SortedMapTest, BeginEndOne) {
  TypeParam map = ToMap<TypeParam>(Sequence(1));
  auto begin = map.begin();
  auto end = map.end();

  ASSERT_NE(begin, end);
  ASSERT_EQ(0, begin->first);

  ++begin;
  ASSERT_EQ(begin, end);
}

TYPED_TEST(SortedMapTest, Iterates) {
  std::vector<int> to_insert = Sequence(this->large_number());
  TypeParam map = ToMap<TypeParam>(to_insert);
  auto iter = map.begin();
  auto end = map.end();

  std::vector<int> actual;
  for (; iter != end; ++iter) {
    actual.push_back(iter->first);
  }
  ASSERT_EQ(to_insert, actual);
}

TYPED_TEST(SortedMapTest, IteratorsUsingRangeBasedForLoop) {
  std::vector<int> to_insert = Sequence(this->large_number());
  TypeParam map = ToMap<TypeParam>(to_insert);

  std::vector<int> actual = Keys(map);
  ASSERT_EQ(to_insert, actual);
}

TYPED_TEST(SortedMapTest, CompatibleWithStdDistance) {
  int n = this->large_number();
  TypeParam map = ToMap<TypeParam>(Sequence(n));

  auto iter = map.begin();
  ASSERT_EQ(map.size(), static_cast<size_t>(std::distance(iter, map.end())));

  std::advance(iter, 1);
  ASSERT_EQ(map.size() - 1,
            static_cast<size_t>(std::distance(iter, map.end())));

  std::advance(iter, map.size() - 1);
  ASSERT_EQ(0u, static_cast<size_t>(std::distance(iter, map.end())));
}

TYPED_TEST(SortedMapTest, CompatibleWithStdAccumulate) {
  // World's worst way to compute triangular numbers...
  auto add = [](int lhs, const typename TypeParam::value_type& rhs) {
    return lhs + rhs.first;
  };

  TypeParam map = ToMap<TypeParam>(Sequence(6));
  int result = std::accumulate(map.begin(), map.end(), 0, add);
  ASSERT_EQ(15, result);
}

TYPED_TEST(SortedMapTest, CompatibleWithStdMismatch) {
  TypeParam lhs = TypeParam{}.insert(1, 1).insert(3, 3).insert(4, 4);
  TypeParam rhs = TypeParam{}.insert(1, 1).insert(2, 2).insert(4, 4);

  using Iter = typename TypeParam::const_iterator;

  // C++11 does not define an overload of std::mismatch that takes the end of
  // rhs, so rhs must be a sequence at least as long as lhs.
  std::pair<Iter, Iter> miss =
      std::mismatch(lhs.begin(), lhs.end(), rhs.begin());

  auto lhs_miss = lhs.begin();
  std::advance(lhs_miss, 1);

  auto rhs_miss = rhs.begin();
  std::advance(rhs_miss, 1);

  ASSERT_EQ(std::make_pair(lhs_miss, rhs_miss), miss);
}

TYPED_TEST(SortedMapTest, IteratorInvalidation) {
  // Tests that iterators are not invalidated by changes
  int n = this->large_number();
  TypeParam map = ToMap<TypeParam>(Sequence(0, n - 1, 2));
  size_t size = static_cast<size_t>(n) / 2;
  ASSERT_EQ(size, map.size());

  // Insert elements ahead of the current iteration position
  TypeParam result = map;
  for (const auto& element : map) {
    result = result.insert(element.first + 1, element.second + 1);
  }
  size *= 2;

  ASSERT_EQ(size, result.size());
}

}  // namespace immutable
}  // namespace firestore
}  // namespace firebase