/*
   Copyright (c) 2016, Facebook, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02111-1301 USA */

#pragma once

/* C++ standard header files */
#include <atomic>
#include <condition_variable>
#include <mutex>
#include <queue>
#include <stack>
#include <string>
#include <thread>
#include <utility>
#include <vector>

/* RocksDB header files */
#include "rocksdb/db.h"
#include "rocksdb/sst_file_writer.h"

/* MyRocks header files */
#include "./rdb_utils.h"

namespace myrocks {

class Rdb_sst_file_ordered {
 private:
  class Rdb_sst_file {
   private:
    Rdb_sst_file(const Rdb_sst_file &p) = delete;
    Rdb_sst_file &operator=(const Rdb_sst_file &p) = delete;

    rocksdb::DB *const m_db;
    rocksdb::ColumnFamilyHandle *const m_cf;
    const rocksdb::DBOptions &m_db_options;
    rocksdb::SstFileWriter *m_sst_file_writer;
    const std::string m_name;
    const bool m_tracing;
    const rocksdb::Comparator *m_comparator;

    std::string generateKey(const std::string &key);

   public:
    Rdb_sst_file(rocksdb::DB *const db, rocksdb::ColumnFamilyHandle *const cf,
                 const rocksdb::DBOptions &db_options, const std::string &name,
                 const bool tracing);
    ~Rdb_sst_file();

    rocksdb::Status open();
    rocksdb::Status put(const rocksdb::Slice &key, const rocksdb::Slice &value);
    rocksdb::Status commit();

    inline const std::string get_name() const { return m_name; }
    inline int compare(rocksdb::Slice key1, rocksdb::Slice key2) {
      return m_comparator->Compare(key1, key2);
    }
  };

  class Rdb_sst_stack {
   private:
    char *m_buffer;
    size_t m_buffer_size;
    size_t m_offset;
    std::stack<std::tuple<size_t, size_t, size_t>> m_stack;

   public:
    explicit Rdb_sst_stack(size_t max_size)
        : m_buffer(nullptr), m_buffer_size(max_size) {}
    ~Rdb_sst_stack() { delete[] m_buffer; }

    void reset() { m_offset = 0; }
    bool empty() { return m_stack.empty(); }
    void push(const rocksdb::Slice &key, const rocksdb::Slice &value);
    std::pair<rocksdb::Slice, rocksdb::Slice> top();
    void pop() { m_stack.pop(); }
    size_t size() { return m_stack.size(); }
  };

  bool m_use_stack;
  bool m_first;
  std::string m_first_key;
  std::string m_first_value;
  Rdb_sst_stack m_stack;
  Rdb_sst_file m_file;

  rocksdb::Status apply_first();

 public:
  Rdb_sst_file_ordered(rocksdb::DB *const db,
                       rocksdb::ColumnFamilyHandle *const cf,
                       const rocksdb::DBOptions &db_options,
                       const std::string &name, const bool tracing,
                       size_t max_size);

  inline rocksdb::Status open() { return m_file.open(); }
  rocksdb::Status put(const rocksdb::Slice &key, const rocksdb::Slice &value);
  rocksdb::Status commit();
  inline const std::string get_name() const { return m_file.get_name(); }
};

class Rdb_sst_info {
 private:
  Rdb_sst_info(const Rdb_sst_info &p) = delete;
  Rdb_sst_info &operator=(const Rdb_sst_info &p) = delete;

  rocksdb::DB *const m_db;
  rocksdb::ColumnFamilyHandle *const m_cf;
  const rocksdb::DBOptions &m_db_options;
  uint64_t m_curr_size;
  uint64_t m_max_size;
  uint32_t m_sst_count;
  std::atomic<int> m_background_error;
  bool m_done;
  std::string m_prefix;
  static std::atomic<uint64_t> m_prefix_counter;
  static std::string m_suffix;
  mysql_mutex_t m_commit_mutex;
  Rdb_sst_file_ordered *m_sst_file;

  // List of committed SST files - we'll ingest them later in one single batch
  std::vector<std::string> m_committed_files;

  const bool m_tracing;
  bool m_print_client_error;

  int open_new_sst_file();
  void close_curr_sst_file();
  void commit_sst_file(Rdb_sst_file_ordered *sst_file);

  void set_error_msg(const std::string &sst_file_name,
                     const rocksdb::Status &s);

 public:
  Rdb_sst_info(rocksdb::DB *const db, const std::string &tablename,
               const std::string &indexname,
               rocksdb::ColumnFamilyHandle *const cf,
               const rocksdb::DBOptions &db_options, const bool tracing);
  ~Rdb_sst_info();

  /*
    This is the unit of work returned from Rdb_sst_info::finish and represents
    a group of SST to be ingested atomically with other Rdb_sst_commit_info.
    This is always local to the bulk loading complete operation so no locking
    is required
   */
  class Rdb_sst_commit_info {
   public:
    Rdb_sst_commit_info() : m_committed(true), m_cf(nullptr) {}

    Rdb_sst_commit_info(Rdb_sst_commit_info &&rhs) noexcept
        : m_committed(rhs.m_committed),
          m_cf(rhs.m_cf),
          m_committed_files(std::move(rhs.m_committed_files)) {
      rhs.m_committed = true;
      rhs.m_cf = nullptr;
    }

    Rdb_sst_commit_info &operator=(Rdb_sst_commit_info &&rhs) noexcept {
      reset();

      m_cf = rhs.m_cf;
      m_committed_files = std::move(rhs.m_committed_files);
      m_committed = rhs.m_committed;

      rhs.m_committed = true;
      rhs.m_cf = nullptr;

      return *this;
    }

    Rdb_sst_commit_info(const Rdb_sst_commit_info &) = delete;
    Rdb_sst_commit_info &operator=(const Rdb_sst_commit_info &) = delete;

    ~Rdb_sst_commit_info() { reset(); }

    void reset() {
      if (!m_committed) {
        for (auto sst_file : m_committed_files) {
          // In case something went wrong attempt to delete the temporary file.
          // If everything went fine that file will have been renamed and this
          // function call will fail.
          std::remove(sst_file.c_str());
        }
      }
      m_committed_files.clear();
      m_cf = nullptr;
      m_committed = true;
    }

    bool has_work() const {
      return m_cf != nullptr && m_committed_files.size() > 0;
    }

    void init(rocksdb::ColumnFamilyHandle *cf,
              std::vector<std::string> &&files) {
      DBUG_ASSERT(m_cf == nullptr && m_committed_files.size() == 0 &&
                  m_committed);
      m_cf = cf;
      m_committed_files = std::move(files);
      m_committed = false;
    }

    rocksdb::ColumnFamilyHandle *get_cf() const { return m_cf; }

    const std::vector<std::string> &get_committed_files() const {
      return m_committed_files;
    }

    void commit() { m_committed = true; }

   private:
    bool m_committed;
    rocksdb::ColumnFamilyHandle *m_cf;
    std::vector<std::string> m_committed_files;
  };

  int put(const rocksdb::Slice &key, const rocksdb::Slice &value);
  int finish(Rdb_sst_commit_info *commit_info, bool print_client_error = true);

  bool is_done() const { return m_done; }

  bool have_background_error() { return m_background_error != 0; }

  int get_and_reset_background_error() {
    int ret = m_background_error;
    while (!m_background_error.compare_exchange_weak(ret, HA_EXIT_SUCCESS)) {
      // Do nothing
    }

    return ret;
  }

  void set_background_error(int code) {
    int expected = HA_EXIT_SUCCESS;
    // Only assign 'code' into the error if it is already 0, otherwise ignore it
    m_background_error.compare_exchange_strong(expected, code);
  }

  /** Return the list of committed files later to be ingested **/
  const std::vector<std::string> &get_committed_files() {
    return m_committed_files;
  }

  rocksdb::ColumnFamilyHandle *get_cf() const { return m_cf; }

  static void init(const rocksdb::DB *const db);

  static void report_error_msg(const rocksdb::Status &s,
                               const char *sst_file_name);
};

}  // namespace myrocks