// Copyright 2021 The Tint Authors.
//
// 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 "src/tint/block_allocator.h"

#include "gtest/gtest.h"

namespace tint {
namespace {

struct LifetimeCounter {
  explicit LifetimeCounter(size_t* count) : count_(count) { (*count)++; }
  ~LifetimeCounter() { (*count_)--; }

  size_t* const count_;
};

using BlockAllocatorTest = testing::Test;

TEST_F(BlockAllocatorTest, Empty) {
  using Allocator = BlockAllocator<int>;

  Allocator allocator;

  for (int* i : allocator.Objects()) {
    (void)i;
    if ((true)) {  // Workaround for "error: loop will run at most once"
      FAIL() << "BlockAllocator should be empty";
    }
  }
  for (const int* i : static_cast<const Allocator&>(allocator).Objects()) {
    (void)i;
    if ((true)) {  // Workaround for "error: loop will run at most once"
      FAIL() << "BlockAllocator should be empty";
    }
  }
}

TEST_F(BlockAllocatorTest, ObjectLifetime) {
  using Allocator = BlockAllocator<LifetimeCounter>;

  size_t count = 0;
  {
    Allocator allocator;
    EXPECT_EQ(count, 0u);
    allocator.Create(&count);
    EXPECT_EQ(count, 1u);
    allocator.Create(&count);
    EXPECT_EQ(count, 2u);
    allocator.Create(&count);
    EXPECT_EQ(count, 3u);
  }
  EXPECT_EQ(count, 0u);
}

TEST_F(BlockAllocatorTest, MoveConstruct) {
  using Allocator = BlockAllocator<LifetimeCounter>;

  for (size_t n :
       {0, 1, 10, 16, 20, 32, 50, 64, 100, 256, 300, 512, 500, 512}) {
    size_t count = 0;
    {
      Allocator allocator_a;
      for (size_t i = 0; i < n; i++) {
        allocator_a.Create(&count);
      }
      EXPECT_EQ(count, n);

      Allocator allocator_b{std::move(allocator_a)};
      EXPECT_EQ(count, n);
    }

    EXPECT_EQ(count, 0u);
  }
}

TEST_F(BlockAllocatorTest, MoveAssign) {
  using Allocator = BlockAllocator<LifetimeCounter>;

  for (size_t n :
       {0, 1, 10, 16, 20, 32, 50, 64, 100, 256, 300, 512, 500, 512}) {
    size_t count_a = 0;
    size_t count_b = 0;

    {
      Allocator allocator_a;
      for (size_t i = 0; i < n; i++) {
        allocator_a.Create(&count_a);
      }
      EXPECT_EQ(count_a, n);

      Allocator allocator_b;
      for (size_t i = 0; i < n; i++) {
        allocator_b.Create(&count_b);
      }
      EXPECT_EQ(count_b, n);

      allocator_b = std::move(allocator_a);
      EXPECT_EQ(count_a, n);
      EXPECT_EQ(count_b, 0u);
    }

    EXPECT_EQ(count_a, 0u);
    EXPECT_EQ(count_b, 0u);
  }
}

TEST_F(BlockAllocatorTest, ObjectOrder) {
  using Allocator = BlockAllocator<int>;

  Allocator allocator;
  constexpr int N = 10000;
  for (int i = 0; i < N; i++) {
    allocator.Create(i);
  }

  {
    int i = 0;
    for (int* p : allocator.Objects()) {
      EXPECT_EQ(*p, i);
      i++;
    }
    EXPECT_EQ(i, N);
  }
  {
    int i = 0;
    for (const int* p : static_cast<const Allocator&>(allocator).Objects()) {
      EXPECT_EQ(*p, i);
      i++;
    }
    EXPECT_EQ(i, N);
  }
}

}  // namespace
}  // namespace tint