/*
 * Copyright (c) 2020-2021, NVIDIA CORPORATION.
 *
 * 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.
 */
#pragma once

#include <rmm/cuda_stream_view.hpp>
#include <rmm/detail/error.hpp>
#include <rmm/mr/device/device_memory_resource.hpp>

#include <spdlog/common.h>
#include <spdlog/sinks/basic_file_sink.h>
#include <spdlog/sinks/ostream_sink.h>
#include <spdlog/spdlog.h>

#include <cstddef>
#include <memory>
#include <sstream>

namespace rmm::mr {
/**
 * @brief Resource that uses `Upstream` to allocate memory and logs information
 * about the requested allocation/deallocations.
 *
 * An instance of this resource can be constructed with an existing, upstream
 * resource in order to satisfy allocation requests and log
 * allocation/deallocation activity.
 *
 * @tparam Upstream Type of the upstream resource used for
 * allocation/deallocation.
 */
template <typename Upstream>
class logging_resource_adaptor final : public device_memory_resource {
 public:
  /**
   * @brief Construct a new logging resource adaptor using `upstream` to satisfy
   * allocation requests and logging information about each allocation/free to
   * the file specified by `filename`.
   *
   * The logfile will be written using CSV formatting.
   *
   * Clears the contents of `filename` if it already exists.
   *
   * Creating multiple `logging_resource_adaptor`s with the same `filename` will
   * result in undefined behavior.
   *
   * @throws `rmm::logic_error` if `upstream == nullptr`
   * @throws `spdlog::spdlog_ex` if opening `filename` failed
   *
   * @param upstream The resource used for allocating/deallocating device memory
   * @param filename Name of file to write log info. If not specified, retrieves
   * the file name from the environment variable "RMM_LOG_FILE".
   * @param auto_flush If true, flushes the log for every (de)allocation. Warning, this will degrade
   * performance.
   */
  logging_resource_adaptor(Upstream* upstream,
                           std::string const& filename = get_default_filename(),
                           bool auto_flush             = false)
    : logger_{std::make_shared<spdlog::logger>(
        "RMM",
        std::make_shared<spdlog::sinks::basic_file_sink_mt>(filename, true /*truncate file*/))},
      upstream_{upstream}
  {
    RMM_EXPECTS(nullptr != upstream, "Unexpected null upstream resource pointer.");

    init_logger(auto_flush);
  }

  /**
   * @brief Construct a new logging resource adaptor using `upstream` to satisfy
   * allocation requests and logging information about each allocation/free to
   * the ostream specified by `stream`.
   *
   * The logfile will be written using CSV formatting.
   *
   * @throws `rmm::logic_error` if `upstream == nullptr`
   *
   * @param upstream The resource used for allocating/deallocating device memory
   * @param stream The ostream to write log info.
   * @param auto_flush If true, flushes the log for every (de)allocation. Warning, this will degrade
   * performance.
   */
  logging_resource_adaptor(Upstream* upstream, std::ostream& stream, bool auto_flush = false)
    : logger_{std::make_shared<spdlog::logger>(
        "RMM", std::make_shared<spdlog::sinks::ostream_sink_mt>(stream))},
      upstream_{upstream}
  {
    RMM_EXPECTS(nullptr != upstream, "Unexpected null upstream resource pointer.");

    init_logger(auto_flush);
  }

  logging_resource_adaptor(Upstream* upstream,
                           spdlog::sinks_init_list sinks,
                           bool auto_flush = false)
    : logger_{std::make_shared<spdlog::logger>("RMM", sinks)}, upstream_{upstream}
  {
    RMM_EXPECTS(nullptr != upstream, "Unexpected null upstream resource pointer.");

    init_logger(auto_flush);
  }

  logging_resource_adaptor()                                = delete;
  ~logging_resource_adaptor() override                      = default;
  logging_resource_adaptor(logging_resource_adaptor const&) = delete;
  logging_resource_adaptor& operator=(logging_resource_adaptor const&) = delete;
  logging_resource_adaptor(logging_resource_adaptor&&) noexcept        = default;
  logging_resource_adaptor& operator=(logging_resource_adaptor&&) noexcept = default;

  /**
   * @brief Return pointer to the upstream resource.
   *
   * @return Upstream* Pointer to the upstream resource.
   */
  [[nodiscard]] Upstream* get_upstream() const noexcept { return upstream_; }

  /**
   * @brief Checks whether the upstream resource supports streams.
   *
   * @return true The upstream resource supports streams
   * @return false The upstream resource does not support streams.
   */
  [[nodiscard]] bool supports_streams() const noexcept override
  {
    return upstream_->supports_streams();
  }

  /**
   * @brief Query whether the resource supports the get_mem_info API.
   *
   * @return bool true if the upstream resource supports get_mem_info, false otherwise.
   */
  [[nodiscard]] bool supports_get_mem_info() const noexcept override
  {
    return upstream_->supports_get_mem_info();
  }

  /**
   * @brief Flush logger contents.
   */
  void flush() { logger_->flush(); }

  /**
   * @brief Return the CSV header string
   *
   * @return CSV formatted header string of column names
   */
  [[nodiscard]] std::string header() const
  {
    return std::string{"Thread,Time,Action,Pointer,Size,Stream"};
  }

 private:
  /**
   * @brief Return the value of the environment variable RMM_LOG_FILE.
   *
   * @throws `rmm::logic_error` if `RMM_LOG_FILE` is not set.
   *
   * @return The value of RMM_LOG_FILE as `std::string`.
   */
  static std::string get_default_filename()
  {
    auto* filename = std::getenv("RMM_LOG_FILE");
    RMM_EXPECTS(filename != nullptr,
                "RMM logging requested without an explicit file name, but RMM_LOG_FILE is unset");
    return std::string{filename};
  }

  /**
   * @brief Initialize the logger.
   */
  void init_logger(bool auto_flush)
  {
    if (auto_flush) { logger_->flush_on(spdlog::level::info); }
    logger_->set_pattern("%v");
    logger_->info(header());
    logger_->set_pattern("%t,%H:%M:%S.%f,%v");
  }

  /**
   * @brief Allocates memory of size at least `bytes` using the upstream
   * resource and logs the allocation.
   *
   * If the upstream allocation is successful logs the
   * following CSV formatted line to the file specified at construction:
   * ```
   * thread_id,*TIMESTAMP*,"allocate",*bytes*,*stream*
   * ```
   *
   * The returned pointer has at least 256B alignment.
   *
   * @throws `rmm::bad_alloc` if the requested allocation could not be fulfilled
   * by the upstream resource.
   *
   * @param bytes The size, in bytes, of the allocation
   * @param stream Stream on which to perform the allocation
   * @return void* Pointer to the newly allocated memory
   */
  void* do_allocate(std::size_t bytes, cuda_stream_view stream) override
  {
    auto const ptr = upstream_->allocate(bytes, stream);
    logger_->info("allocate,{},{},{}", ptr, bytes, fmt::ptr(stream.value()));
    return ptr;
  }

  /**
   * @brief Free allocation of size `bytes` pointed to by `ptr` and log the
   * deallocation.
   *
   * Every invocation of `logging_resource_adaptor::do_deallocate` will write
   * the following CSV formatted line to the file specified at construction:
   * ```
   * thread_id,*TIMESTAMP*,"free",*bytes*,*stream*
   * ```
   *
   * @throws Nothing.
   *
   * @param ptr Pointer to be deallocated
   * @param bytes Size of the allocation
   * @param stream Stream on which to perform the deallocation
   */
  void do_deallocate(void* ptr, std::size_t bytes, cuda_stream_view stream) override
  {
    logger_->info("free,{},{},{}", ptr, bytes, fmt::ptr(stream.value()));
    upstream_->deallocate(ptr, bytes, stream);
  }

  /**
   * @brief Compare the upstream resource to another.
   *
   * @throws Nothing.
   *
   * @param other The other resource to compare to
   * @return true If the two resources are equivalent
   * @return false If the two resources are not equal
   */
  [[nodiscard]] bool do_is_equal(device_memory_resource const& other) const noexcept override
  {
    if (this == &other) { return true; }
    auto const* cast = dynamic_cast<logging_resource_adaptor<Upstream> const*>(&other);
    if (cast != nullptr) { return upstream_->is_equal(*cast->get_upstream()); }
    return upstream_->is_equal(other);
  }

  /**
   * @brief Get free and available memory from upstream resource.
   *
   * @throws `rmm::cuda_error` if unable to retrieve memory info.
   *
   * @param stream Stream on which to get the mem info.
   * @return std::pair contaiing free_size and total_size of memory
   */
  [[nodiscard]] std::pair<std::size_t, std::size_t> do_get_mem_info(
    cuda_stream_view stream) const override
  {
    return upstream_->get_mem_info(stream);
  }

  // make_logging_adaptor needs access to private get_default_filename
  template <typename T>
  // NOLINTNEXTLINE(readability-redundant-declaration)
  friend logging_resource_adaptor<T> make_logging_adaptor(T* upstream,
                                                          std::string const& filename,
                                                          bool auto_flush);

  std::shared_ptr<spdlog::logger> logger_;  ///< spdlog logger object

  Upstream* upstream_;  ///< The upstream resource used for satisfying
                        ///< allocation requests
};

/**
 * @brief Convenience factory to return a `logging_resource_adaptor` around the
 * upstream resource `upstream`.
 *
 * @tparam Upstream Type of the upstream `device_memory_resource`.
 * @param upstream Pointer to the upstream resource
 * @param filename Name of the file to write log info. If not specified,
 * retrieves the log file name from the environment variable "RMM_LOG_FILE".
 */
template <typename Upstream>
logging_resource_adaptor<Upstream> make_logging_adaptor(
  Upstream* upstream,
  std::string const& filename = logging_resource_adaptor<Upstream>::get_default_filename(),
  bool auto_flush             = false)
{
  return logging_resource_adaptor<Upstream>{upstream, filename, auto_flush};
}

/**
 * @brief Convenience factory to return a `logging_resource_adaptor` around the
 * upstream resource `upstream`.
 *
 * @tparam Upstream Type of the upstream `device_memory_resource`.
 * @param upstream Pointer to the upstream resource
 * @param stream The ostream to write log info.
 */
template <typename Upstream>
logging_resource_adaptor<Upstream> make_logging_adaptor(Upstream* upstream,
                                                        std::ostream& stream,
                                                        bool auto_flush = false)
{
  return logging_resource_adaptor<Upstream>{upstream, stream, auto_flush};
}

}  // namespace rmm::mr
