/*
 *
 * Copyright 2017 gRPC 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.
 *
 */

extern "C" {
#include "src/core/lib/debug/stats.h"
}

#include <grpc/grpc.h>
#include <grpc/support/log.h>
#include <gtest/gtest.h>

namespace grpc {
namespace testing {

class Snapshot {
 public:
  Snapshot() { grpc_stats_collect(&begin_); }

  grpc_stats_data delta() {
    grpc_stats_data now;
    grpc_stats_collect(&now);
    grpc_stats_data delta;
    grpc_stats_diff(&now, &begin_, &delta);
    return delta;
  }

 private:
  grpc_stats_data begin_;
};

TEST(StatsTest, IncCounters) {
  for (int i = 0; i < GRPC_STATS_COUNTER_COUNT; i++) {
    Snapshot snapshot;

    grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
    GRPC_STATS_INC_COUNTER(&exec_ctx, (grpc_stats_counters)i);
    grpc_exec_ctx_finish(&exec_ctx);

    EXPECT_EQ(snapshot.delta().counters[i], 1);
  }
}

TEST(StatsTest, IncSpecificCounter) {
  Snapshot snapshot;

  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
  GRPC_STATS_INC_SYSCALL_POLL(&exec_ctx);
  grpc_exec_ctx_finish(&exec_ctx);

  EXPECT_EQ(snapshot.delta().counters[GRPC_STATS_COUNTER_SYSCALL_POLL], 1);
}

static int FindExpectedBucket(int i, int j) {
  if (j < 0) {
    return 0;
  }
  if (j >=
      grpc_stats_histo_bucket_boundaries[i][grpc_stats_histo_buckets[i] - 1]) {
    return grpc_stats_histo_buckets[i] - 1;
  }
  int r = 0;
  while (grpc_stats_histo_bucket_boundaries[i][r + 1] <= j) r++;
  return r;
}

static int FindNonZeroBucket(const grpc_stats_data& data, int i) {
  for (int j = 0; j < grpc_stats_histo_buckets[i]; j++) {
    if (data.histograms[grpc_stats_histo_start[i] + j] != 0) {
      return j;
    }
  }
  return -1;
}

TEST(StatsTest, IncHistogram) {
  for (int i = 0; i < GRPC_STATS_HISTOGRAM_COUNT; i++) {
    for (int j = -1000;
         j <
         grpc_stats_histo_bucket_boundaries[i]
                                           [grpc_stats_histo_buckets[i] - 1] +
             1000;
         j++) {
      gpr_log(GPR_DEBUG, "histo:%d value:%d", i, j);

      Snapshot snapshot;

      int expected_bucket = FindExpectedBucket(i, j);

      grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
      grpc_stats_inc_histogram[i](&exec_ctx, j);
      grpc_exec_ctx_finish(&exec_ctx);

      auto delta = snapshot.delta();
      int got_bucket = FindNonZeroBucket(delta, i);

      EXPECT_EQ(expected_bucket, got_bucket);
      EXPECT_EQ(delta.histograms[grpc_stats_histo_start[i] + expected_bucket],
                1);
    }
  }
}

}  // namespace testing
}  // namespace grpc

int main(int argc, char** argv) {
  ::testing::InitGoogleTest(&argc, argv);
  grpc_init();
  int ret = RUN_ALL_TESTS();
  grpc_shutdown();
  return ret;
}