//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
//  This source code is licensed under the BSD-style license found in the
//  LICENSE file in the root directory of this source tree. An additional grant
//  of patent rights can be found in the PATENTS file in the same directory.
//
#include "util/file_reader_writer.h"
#include <algorithm>
#include <vector>
#include "util/random.h"
#include "util/testharness.h"
#include "util/testutil.h"

namespace rocksdb {

class WritableFileWriterTest : public testing::Test {};

const uint32_t kMb = 1 << 20;

TEST_F(WritableFileWriterTest, RangeSync) {
  class FakeWF : public WritableFile {
   public:
    explicit FakeWF() : size_(0), last_synced_(0) {}
    ~FakeWF() {}

    Status Append(const Slice& data) override {
      size_ += data.size();
      return Status::OK();
    }
    virtual Status Truncate(uint64_t size) override {
      return Status::OK();
    }
    Status Close() override {
      EXPECT_GE(size_, last_synced_ + kMb);
      EXPECT_LT(size_, last_synced_ + 2 * kMb);
      // Make sure random writes generated enough writes.
      EXPECT_GT(size_, 10 * kMb);
      return Status::OK();
    }
    Status Flush() override { return Status::OK(); }
    Status Sync() override { return Status::OK(); }
    Status Fsync() override { return Status::OK(); }
    void SetIOPriority(Env::IOPriority pri) override {}
    uint64_t GetFileSize() override { return size_; }
    void GetPreallocationStatus(size_t* block_size,
                                size_t* last_allocated_block) override {}
    size_t GetUniqueId(char* id, size_t max_size) const override { return 0; }
    Status InvalidateCache(size_t offset, size_t length) override {
      return Status::OK();
    }

   protected:
    Status Allocate(uint64_t offset, uint64_t len) override { return Status::OK(); }
    Status RangeSync(uint64_t offset, uint64_t nbytes) override {
      EXPECT_EQ(offset % 4096, 0u);
      EXPECT_EQ(nbytes % 4096, 0u);

      EXPECT_EQ(offset, last_synced_);
      last_synced_ = offset + nbytes;
      EXPECT_GE(size_, last_synced_ + kMb);
      if (size_ > 2 * kMb) {
        EXPECT_LT(size_, last_synced_ + 2 * kMb);
      }
      return Status::OK();
    }

    uint64_t size_;
    uint64_t last_synced_;
  };

  EnvOptions env_options;
  env_options.bytes_per_sync = kMb;
  unique_ptr<FakeWF> wf(new FakeWF);
  unique_ptr<WritableFileWriter> writer(
      new WritableFileWriter(std::move(wf), env_options));
  Random r(301);
  std::unique_ptr<char[]> large_buf(new char[10 * kMb]);
  for (int i = 0; i < 1000; i++) {
    int skew_limit = (i < 700) ? 10 : 15;
    uint32_t num = r.Skewed(skew_limit) * 100 + r.Uniform(100);
    writer->Append(Slice(large_buf.get(), num));

    // Flush in a chance of 1/10.
    if (r.Uniform(10) == 0) {
      writer->Flush();
    }
  }
  writer->Close();
}

TEST_F(WritableFileWriterTest, AppendStatusReturn) {
  class FakeWF : public WritableFile {
   public:
    explicit FakeWF() : use_direct_io_(false), io_error_(false) {}

    virtual bool use_direct_io() const override { return use_direct_io_; }
    Status Append(const Slice& data) override {
      if (io_error_) {
        return Status::IOError("Fake IO error");
      }
      return Status::OK();
    }
    Status PositionedAppend(const Slice& data, uint64_t) override {
      if (io_error_) {
        return Status::IOError("Fake IO error");
      }
      return Status::OK();
    }
    Status Close() override { return Status::OK(); }
    Status Flush() override { return Status::OK(); }
    Status Sync() override { return Status::OK(); }
    void Setuse_direct_io(bool val) { use_direct_io_ = val; }
    void SetIOError(bool val) { io_error_ = val; }

   protected:
    bool use_direct_io_;
    bool io_error_;
  };
  unique_ptr<FakeWF> wf(new FakeWF());
  wf->Setuse_direct_io(true);
  unique_ptr<WritableFileWriter> writer(
      new WritableFileWriter(std::move(wf), EnvOptions()));

  ASSERT_OK(writer->Append(std::string(2 * kMb, 'a')));

  // Next call to WritableFile::Append() should fail
  dynamic_cast<FakeWF*>(writer->writable_file())->SetIOError(true);
  ASSERT_NOK(writer->Append(std::string(2 * kMb, 'b')));
}

class ReadaheadRandomAccessFileTest
    : public testing::Test,
      public testing::WithParamInterface<size_t> {
 public:
  static std::vector<size_t> GetReadaheadSizeList() {
    return {1lu << 12, 1lu << 16};
  }
  virtual void SetUp() override {
    readahead_size_ = GetParam();
    scratch_.reset(new char[2 * readahead_size_]);
    ResetSourceStr();
  }
  ReadaheadRandomAccessFileTest() : control_contents_() {}
  std::string Read(uint64_t offset, size_t n) {
    Slice result;
    test_read_holder_->Read(offset, n, &result, scratch_.get());
    return std::string(result.data(), result.size());
  }
  void ResetSourceStr(const std::string& str = "") {
    auto write_holder = std::unique_ptr<WritableFileWriter>(
        test::GetWritableFileWriter(new test::StringSink(&control_contents_)));
    write_holder->Append(Slice(str));
    write_holder->Flush();
    auto read_holder = std::unique_ptr<RandomAccessFile>(
        new test::StringSource(control_contents_));
    test_read_holder_ =
        NewReadaheadRandomAccessFile(std::move(read_holder), readahead_size_);
  }
  size_t GetReadaheadSize() const { return readahead_size_; }

 private:
  size_t readahead_size_;
  Slice control_contents_;
  std::unique_ptr<RandomAccessFile> test_read_holder_;
  std::unique_ptr<char[]> scratch_;
};

TEST_P(ReadaheadRandomAccessFileTest, EmptySourceStrTest) {
  ASSERT_EQ("", Read(0, 1));
  ASSERT_EQ("", Read(0, 0));
  ASSERT_EQ("", Read(13, 13));
}

TEST_P(ReadaheadRandomAccessFileTest, SourceStrLenLessThanReadaheadSizeTest) {
  std::string str = "abcdefghijklmnopqrs";
  ResetSourceStr(str);
  ASSERT_EQ(str.substr(3, 4), Read(3, 4));
  ASSERT_EQ(str.substr(0, 3), Read(0, 3));
  ASSERT_EQ(str, Read(0, str.size()));
  ASSERT_EQ(str.substr(7, std::min(static_cast<int>(str.size()) - 7, 30)),
            Read(7, 30));
  ASSERT_EQ("", Read(100, 100));
}

TEST_P(ReadaheadRandomAccessFileTest,
       SourceStrLenCanBeGreaterThanReadaheadSizeTest) {
  Random rng(42);
  for (int k = 0; k < 100; ++k) {
    size_t strLen = k * GetReadaheadSize() +
                    rng.Uniform(static_cast<int>(GetReadaheadSize()));
    std::string str =
        test::RandomHumanReadableString(&rng, static_cast<int>(strLen));
    ResetSourceStr(str);
    for (int test = 1; test <= 100; ++test) {
      size_t offset = rng.Uniform(static_cast<int>(strLen));
      size_t n = rng.Uniform(static_cast<int>(GetReadaheadSize()));
      ASSERT_EQ(str.substr(offset, std::min(n, str.size() - offset)),
                Read(offset, n));
    }
  }
}

TEST_P(ReadaheadRandomAccessFileTest, NExceedReadaheadTest) {
  Random rng(7);
  size_t strLen = 4 * GetReadaheadSize() +
                  rng.Uniform(static_cast<int>(GetReadaheadSize()));
  std::string str =
      test::RandomHumanReadableString(&rng, static_cast<int>(strLen));
  ResetSourceStr(str);
  for (int test = 1; test <= 100; ++test) {
    size_t offset = rng.Uniform(static_cast<int>(strLen));
    size_t n =
        GetReadaheadSize() + rng.Uniform(static_cast<int>(GetReadaheadSize()));
    ASSERT_EQ(str.substr(offset, std::min(n, str.size() - offset)),
              Read(offset, n));
  }
}

INSTANTIATE_TEST_CASE_P(
    EmptySourceStrTest, ReadaheadRandomAccessFileTest,
    ::testing::ValuesIn(ReadaheadRandomAccessFileTest::GetReadaheadSizeList()));
INSTANTIATE_TEST_CASE_P(
    SourceStrLenLessThanReadaheadSizeTest, ReadaheadRandomAccessFileTest,
    ::testing::ValuesIn(ReadaheadRandomAccessFileTest::GetReadaheadSizeList()));
INSTANTIATE_TEST_CASE_P(
    SourceStrLenCanBeGreaterThanReadaheadSizeTest,
    ReadaheadRandomAccessFileTest,
    ::testing::ValuesIn(ReadaheadRandomAccessFileTest::GetReadaheadSizeList()));
INSTANTIATE_TEST_CASE_P(
    NExceedReadaheadTest, ReadaheadRandomAccessFileTest,
    ::testing::ValuesIn(ReadaheadRandomAccessFileTest::GetReadaheadSizeList()));

}  // namespace rocksdb

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