// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you 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 <algorithm>
#include <cstring>
#include <memory>
#include <string>

#include <gtest/gtest.h>

#include "kudu/util/faststring.h"
#include "kudu/util/random.h"
#include "kudu/util/random_util.h"
#include "kudu/util/test_util.h"

using std::string;
using std::unique_ptr;

namespace kudu {
class FaststringTest : public KuduTest {};

TEST_F(FaststringTest, TestShrinkToFit_Empty) {
  faststring s;
  s.shrink_to_fit();
  ASSERT_EQ(faststring::kInitialCapacity, s.capacity());
}

// Test that, if the string contents is shorter than the initial capacity
// of the faststring, shrink_to_fit() leaves the string in the built-in
// array.
TEST_F(FaststringTest, TestShrinkToFit_SmallerThanInitialCapacity) {
  faststring s;
  s.append("hello");
  s.shrink_to_fit();
  ASSERT_EQ(faststring::kInitialCapacity, s.capacity());
}

TEST_F(FaststringTest, TestShrinkToFit_Random) {
  Random r(GetRandomSeed32());
  int kMaxSize = faststring::kInitialCapacity * 2;
  unique_ptr<char[]> random_bytes(new char[kMaxSize]);
  RandomString(random_bytes.get(), kMaxSize, &r);

  faststring s;
  for (int i = 0; i < 100; i++) {
    int new_size = r.Uniform(kMaxSize);
    s.resize(new_size);
    memcpy(s.data(), random_bytes.get(), new_size);
    s.shrink_to_fit();
    ASSERT_EQ(0, memcmp(s.data(), random_bytes.get(), new_size));
    ASSERT_EQ(std::max<int>(faststring::kInitialCapacity, new_size), s.capacity());
  }
}

TEST_F(FaststringTest, TestPushBack) {
  faststring s;
  for (int i = 0; i < faststring::kInitialCapacity * 2; ++i) {
    s.push_back('a');
    ASSERT_LE(s.size(), s.capacity());
    ASSERT_EQ(i + 1, s.size());
    if (i + 1 <= faststring::kInitialCapacity) {
      ASSERT_EQ(s.capacity(), faststring::kInitialCapacity);
    }
  }
}

TEST_F(FaststringTest, TestAppend_Simple) {
  faststring s;
  ASSERT_EQ(s.capacity(), faststring::kInitialCapacity);
  ASSERT_EQ(s.size(), 0);

  // append empty string
  s.append("");
  ASSERT_EQ(s.capacity(), faststring::kInitialCapacity);
  ASSERT_EQ(s.size(), 0);

  // len_ < kInitialCapacity
  s.append("hello");
  ASSERT_EQ(s.capacity(), faststring::kInitialCapacity);
  ASSERT_EQ(s.size(), 5);

  // len_ > kInitialCapacity
  string tmp(faststring::kInitialCapacity, 'a');
  s.append(tmp);
  ASSERT_GT(s.capacity(), faststring::kInitialCapacity);
  ASSERT_EQ(s.size(), 5 + faststring::kInitialCapacity);
}

TEST_F(FaststringTest, TestAppend_ExponentiallyExpand) {
  size_t initial_capacity = faststring::kInitialCapacity / 2;
  string tmp1(initial_capacity, 'a');

  {
    // Less than 150% after expansion
    faststring s;
    string tmp2(faststring::kInitialCapacity - 1, 'a');
    s.append(tmp1);
    s.append(tmp2);
    ASSERT_EQ(s.capacity(), faststring::kInitialCapacity * 3 / 2);
  }

  {
    // More than 150% after expansion
    faststring s;
    string tmp2(faststring::kInitialCapacity + 1, 'a');
    s.append(tmp1);
    s.append(tmp2);
    ASSERT_GT(s.capacity(), faststring::kInitialCapacity * 3 / 2);
  }
}

TEST_F(FaststringTest, TestMoveConstruct) {
  for (int string_size = 0;
       string_size < faststring::kInitialCapacity + 10;
       string_size++) {
    string test_str(string_size, 'a');
    faststring f1;
    f1.append(test_str);
    faststring f2 = std::move(f1);
    // NOTE: NOLINT here since we are purposefully checking the behavior
    // of 'f1' after it was moved.
    ASSERT_EQ(0, f1.size()); // NOLINT(*)
    ASSERT_EQ(test_str, f2.ToString()); // NOLINT(*)
    ASSERT_NE(f1.data(), f2.data()); // NOLINT(*)
    f1.CheckInvariants(); // NOLINT(*)
    f2.CheckInvariants();
  }
}

TEST_F(FaststringTest, TestMoveAssignment) {
  for (int string_size = 0;
       string_size < faststring::kInitialCapacity + 10;
       string_size++) {
    string test_str(string_size, 'a');

    faststring f1;
    f1.append(test_str);

    // Move to 'f2' by assignment operator.
    faststring f2;
    f2 = std::move(f1);
    ASSERT_EQ(test_str, f2.ToString());
    ASSERT_EQ(0, f1.size()); // NOLINT(*)
    f1.CheckInvariants(); // NOLINT(*)
    f2.CheckInvariants(); // NOLINT(*)

    // Move back to f1.
    f1 = std::move(f2);
    ASSERT_EQ(0, f2.size()); // NOLINT(*)
    ASSERT_EQ(test_str, f1.ToString());
    f1.CheckInvariants(); // NOLINT(*)
    f2.CheckInvariants(); // NOLINT(*)

    // Check self-move doesn't have any effect.
    f1 = std::move(f1); // NOLINT(*)
    ASSERT_EQ(0, f2.size()); // NOLINT(*)
    ASSERT_EQ(test_str, f1.ToString()); // NOLINT(*)
    f1.CheckInvariants(); // NOLINT(*)
    f2.CheckInvariants(); // NOLINT(*)
  }
}


} // namespace kudu