// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0

#include <gtest/gtest.h>
#include <stddef.h>
#include <stdint.h>
#include <functional>
#include <memory>
#include <string>
#include <utility>

#include "opentelemetry/nostd/function_ref.h"
#include "opentelemetry/nostd/string_view.h"
#include "opentelemetry/sdk/common/attributemap_hash.h"
#include "opentelemetry/sdk/metrics/aggregation/aggregation.h"
#include "opentelemetry/sdk/metrics/aggregation/drop_aggregation.h"
#include "opentelemetry/sdk/metrics/state/attributes_hashmap.h"
#include "opentelemetry/sdk/metrics/view/attributes_processor.h"

using namespace opentelemetry::sdk::metrics;
namespace nostd = opentelemetry::nostd;

TEST(AttributesHashMap, BasicTests)
{
  // Empty map
  AttributesHashMap hash_map;
  EXPECT_EQ(hash_map.Size(), 0);
  MetricAttributes m1 = {{"k1", "v1"}};

  EXPECT_EQ(hash_map.Get(m1), nullptr);
  EXPECT_EQ(hash_map.Has(m1), false);

  // Set
  std::unique_ptr<Aggregation> aggregation1(
      new DropAggregation());  //  = std::unique_ptr<Aggregation>(new DropAggregation);
  hash_map.Set(m1, std::move(aggregation1));
  hash_map.Get(m1)->Aggregate(static_cast<int64_t>(1));
  EXPECT_EQ(hash_map.Size(), 1);
  EXPECT_EQ(hash_map.Has(m1), true);

  // Set same key again
  auto aggregation2 = std::unique_ptr<Aggregation>(new DropAggregation());
  hash_map.Set(m1, std::move(aggregation2));
  hash_map.Get(m1)->Aggregate(static_cast<int64_t>(1));
  EXPECT_EQ(hash_map.Size(), 1);
  EXPECT_EQ(hash_map.Has(m1), true);

  // Set more enteria
  auto aggregation3   = std::unique_ptr<Aggregation>(new DropAggregation());
  MetricAttributes m3 = {{"k1", "v1"}, {"k2", "v2"}};
  hash_map.Set(m3, std::move(aggregation3));
  EXPECT_EQ(hash_map.Has(m1), true);
  EXPECT_EQ(hash_map.Has(m3), true);
  hash_map.Get(m3)->Aggregate(static_cast<int64_t>(1));
  EXPECT_EQ(hash_map.Size(), 2);

  // GetOrSetDefault
  std::function<std::unique_ptr<Aggregation>()> create_default_aggregation =
      []() -> std::unique_ptr<Aggregation> {
    return std::unique_ptr<Aggregation>(new DropAggregation);
  };
  MetricAttributes m4 = {{"k1", "v1"}, {"k2", "v2"}, {"k3", "v3"}};
  hash_map.GetOrSetDefault(m4, create_default_aggregation)->Aggregate(static_cast<int64_t>(1));
  EXPECT_EQ(hash_map.Size(), 3);

  // Set attributes with different order - shouldn't create a new entry.
  MetricAttributes m5 = {{"k2", "v2"}, {"k1", "v1"}};
  EXPECT_EQ(hash_map.Has(m5), true);

  // Set attributes with different order - shouldn't create a new entry.
  MetricAttributes m6 = {{"k1", "v2"}, {"k2", "v1"}};
  EXPECT_EQ(hash_map.Has(m6), false);

  // GetAllEnteries
  size_t count = 0;
  hash_map.GetAllEnteries(
      [&count](const MetricAttributes & /* attributes */, Aggregation & /* aggregation */) {
        count++;
        return true;
      });
  EXPECT_EQ(count, hash_map.Size());
}

class MetricAttributeMapHashForCollision
{
public:
  size_t operator()(const MetricAttributes & /*attributes*/) const { return 42; }
};

TEST(AttributesHashMap, CollisionTest)
{
  // The hash on MetricsAttributes will be ignored by MetricAttributeMapHashForCollision
  MetricAttributes m1 = {{"k1", "v1"}};
  MetricAttributes m2 = {{"k2", "v2"}};
  MetricAttributes m3 = {{"k1", "v1"}, {"k2", "v2"}};
  MetricAttributes m4 = {};

  AttributesHashMapWithCustomHash<MetricAttributeMapHashForCollision> hash_map;

  hash_map.Set(m1, std::unique_ptr<Aggregation>(new DropAggregation()));
  hash_map.Set(m2, std::unique_ptr<Aggregation>(new DropAggregation()));
  hash_map.Set(m3, std::unique_ptr<Aggregation>(new DropAggregation()));
  hash_map.Set(m4, std::unique_ptr<Aggregation>(new DropAggregation()));

  EXPECT_EQ(hash_map.Size(), 4);
  EXPECT_EQ(hash_map.Has(m1), true);
  EXPECT_EQ(hash_map.Has(m2), true);
  EXPECT_EQ(hash_map.Has(m3), true);
  EXPECT_EQ(hash_map.Has(m4), true);

  MetricAttributes m5 = {{"k2", "v1"}};
  EXPECT_EQ(hash_map.Has(m5), false);

  //
  // Verify only one bucket used based on the custom hash
  //
  size_t total_active_buckets = 0;
  size_t total_elements       = 0;
  for (size_t i = 0; i < hash_map.BucketCount(); i++)
  {
    size_t bucket_size = hash_map.BucketSize(i);
    if (bucket_size > 0)
    {
      total_active_buckets++;
      total_elements += bucket_size;
    }
  }
  EXPECT_EQ(total_active_buckets, 1);
  EXPECT_EQ(total_elements, 4);
}

TEST(AttributesHashMap, HashConsistencyAcrossStringTypes)
{
  const char *c_str                 = "teststring";
  std::string std_str               = "teststring";
  nostd::string_view nostd_str_view = "teststring";
#if __cplusplus >= 201703L
  std::string_view std_str_view = "teststring";
#endif

  size_t hash_c_str          = 0;
  size_t hash_std_str        = 0;
  size_t hash_nostd_str_view = 0;
#if __cplusplus >= 201703L
  size_t hash_std_str_view = 0;
#endif

  opentelemetry::sdk::common::GetHash(hash_c_str, c_str);
  opentelemetry::sdk::common::GetHash(hash_std_str, std_str);
  opentelemetry::sdk::common::GetHash(hash_nostd_str_view, nostd_str_view);
#if __cplusplus >= 201703L
  opentelemetry::sdk::common::GetHash(hash_std_str_view, std_str_view);
#endif

  EXPECT_EQ(hash_c_str, hash_std_str);
  EXPECT_EQ(hash_c_str, hash_nostd_str_view);
#if __cplusplus >= 201703L
  EXPECT_EQ(hash_c_str, hash_std_str_view);
#endif
}

TEST(AttributesHashMap, OverflowCardinalityLimitBehavior)
{
  // Configure a very small limit to exercise overflow logic easily.
  const size_t limit = 4;  // real attributes limit
  AttributesHashMapWithCustomHash<> map(limit);

  // We expect to be able to insert exactly 'limit' distinct real attribute sets.
  // After that, further distinct attributes should route to the overflow bucket,
  // which should appear only once regardless of how many additional unique sets arrive.

  // Insert distinct attributes up to the limit.
  for (size_t i = 0; i < limit; ++i)
  {
    MetricAttributes attr = {{"k", std::to_string(i)}};
    map.GetOrSetDefault(attr, []() { return std::unique_ptr<Aggregation>(new DropAggregation()); })
        ->Aggregate(static_cast<int64_t>(1));
  }

  // Size should be exactly 'limit' (no overflow yet)
  EXPECT_EQ(map.Size(), limit);

  // Insert one more distinct attribute; this should not increase the real attributes count
  MetricAttributes overflow_trigger = {{"k", "overflow"}};
  map.GetOrSetDefault(overflow_trigger,
                      []() { return std::unique_ptr<Aggregation>(new DropAggregation()); })
      ->Aggregate(static_cast<int64_t>(1));

  EXPECT_EQ(map.Size(), limit);

  // Insert several more unique attributes - size must remain constant (limit)
  for (size_t i = 0; i < limit - 1; ++i)
  {
    MetricAttributes extra_attr = {{"k", std::string("extra") + std::to_string(i)}};
    map.GetOrSetDefault(extra_attr,
                        []() { return std::unique_ptr<Aggregation>(new DropAggregation()); })
        ->Aggregate(static_cast<int64_t>(1));
  }
  EXPECT_EQ(map.Size(), limit);

  // Ensure overflow key was actually created and accessible via Get
  EXPECT_NE(map.Get(kOverflowAttributes), nullptr);

  // Ensure original real attributes still present
  for (size_t i = 0; i < limit - 1; ++i)
  {
    MetricAttributes attr = {{"k", std::to_string(i)}};
    EXPECT_NE(map.Get(attr), nullptr);
  }

  // Copy the hash map to a new map in non-determistic order and verify all entries are present
  AttributesHashMapWithCustomHash<> map_copy(limit);
  map.GetAllEnteries([&map_copy](const MetricAttributes &attributes, Aggregation &) {
    map_copy.Set(attributes, std::unique_ptr<Aggregation>(new DropAggregation()));
    return true;
  });
  EXPECT_EQ(map_copy.Size(), map.Size());
  EXPECT_NE(map_copy.Get(kOverflowAttributes), nullptr);
  for (size_t i = 0; i < limit - 1; ++i)
  {
    MetricAttributes attr = {{"k", std::to_string(i)}};
    EXPECT_NE(map_copy.Get(attr), nullptr);
  }
}