/* Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.

   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 St, Fifth Floor, Boston, MA 02110-1301  USA */

#ifndef CONNECTION_DELAY_H
#define CONNECTION_DELAY_H

#include <lf.h>                         /* LF Hash */
#include <my_global.h>
#include <my_atomic.h>                  /* my_atomic_* */
#include <mysql_com.h>                  /* USERNAME_LENGTH */
#include "table.h"                      /* TABLE_LIST */

#include "connection_control_interfaces.h" /* Observer interface */
#include "connection_delay_api.h"       /* Constants */
#include "connection_control_data.h"    /* variables and status */
#include "connection_control_memory.h"  /* Connection_control_alloc */

namespace connection_control
{
  /**
    Class to store failed attempts information for a given user.
  */

  class Connection_event_record : public Connection_control_alloc
  {
  public:

    /**
      Constructor for Connection_event_record. Always initializes failed login count to 1.
    */
    Connection_event_record(const Sql_string &s)
      : m_count(1)
    {
      memset((void *)m_userhost, 0, sizeof(m_userhost));
      memcpy((void *)m_userhost, s.c_str(), s.length());
      m_length= s.length();
      m_count= 1;
    }

    /**
      Retrives failed login count for given user entry

      @returns Failed login count
    */
    int64 get_count() const
    {
      int64 result= my_atomic_load64((volatile int64*)&m_count);
      return result;
    }

    /** Increment failed login count for given user entry by 1 */
    void inc_count()
    {
      my_atomic_add64((volatile int64*)&m_count, 1);
    }

    /** Reset failed login count for given user entry */
    void reset_count()
    {
      my_atomic_store64(&m_count, 0);
    }

    /** Get user information */
    uchar * get_userhost() const
    {
      return const_cast<uchar *> (m_userhost);
    }

    /**  Get length information  */
    size_t get_length() const
    {
      return m_length;
    }

    /** Destructor */
    ~Connection_event_record()
    {
      m_count= DISABLE_THRESHOLD;
    }

  private:
    /* '<user>'@'<host>' */
    uchar m_userhost[1 + USERNAME_LENGTH + 3 + HOSTNAME_LENGTH + 1 + 1];
    /* Length of m_userhost */
    size_t m_length;
    /* connection event count */
    volatile int64 m_count;
  };


  /**
    Hash for a connection event.
    Stores information in Connection_event_record object for each user.
  */

  class Connection_delay_event : public Connection_event_records
  {
  public:

    /** Constructor. Also initializes the hash */
    Connection_delay_event();

    /** Destructor. Removes all entries from hash before destroying hash */
    ~Connection_delay_event()
    {
      reset_all();
      lf_hash_destroy(&m_entries);
    }

    void fill_IS_table(THD *thd, TABLE_LIST *tables);

    /* Overridden function */
    bool create_or_update_entry(const Sql_string &s);
    bool remove_entry(const Sql_string &s);
    bool match_entry(const Sql_string &s, void * value);
    void reset_all();

  private:
    /** Hash for storing Connection_event_record per user */
    LF_HASH m_entries;
  };


  /**
    Connection event action to enforce max failed login constraint
  */

  class Connection_delay_action : public Connection_event_observer,
                                  public Connection_control_alloc
  {
  public:

    Connection_delay_action(int64 threshold,
                            int64 min_delay,
                            int64 max_delay,
                            opt_connection_control *sys_vars,
                            size_t sys_vars_size,
                            stats_connection_control *status_vars,
                            size_t status_vars_size,
                            mysql_rwlock_t *lock);

    /** Destructor */
    ~Connection_delay_action()
    {
      deinit();
      m_lock= 0;
    }

    void init(Connection_event_coordinator_services *coordinator);

    /**
      Set threshold value.

      @param threshold [in]        New threshold value

      @returns whether threshold value was changed successfully or not
        @retval true  Success
        @retval false Failure. Invalid threshold value specified.
    */

    void set_threshold(int64 threshold)
    {
      my_atomic_store64(&m_threshold, threshold);
      /* Clear the hash */
      m_userhost_hash.reset_all();
    }

    /** Get threshold value */
    int64 get_threshold()
    {
      int64 result= my_atomic_load64(&m_threshold);
      return result;
    }

    /**
      Set min/max delay

      @param new_value [in]        New m_min_delay/m_max_delay value
      @param min [in]              true for m_min_delay. false otherwise.

      @returns whether m_min_delay/m_max_delay value was changed successfully or not
        @retval false  Success
        @retval true Failure. Invalid value specified.
    */

    bool set_delay(int64 new_value, bool min)
    {
      int64 current_max= get_max_delay();
      int64 current_min= get_min_delay();

      if (new_value < MIN_DELAY)
        return true;

      if ((min && new_value > current_max) ||
        (!min && new_value < current_min))
        return true;

      else
        min ? my_atomic_store64(&m_min_delay, new_value) :
        my_atomic_store64(&m_max_delay, new_value);
      return false;
    }

    /** Get max value */
    int64 get_max_delay()
    {
      int64 result= my_atomic_load64(&m_max_delay);
      return result;
    }

    /** Get min value */
    int64 get_min_delay()
    {
      int64 result= my_atomic_load64(&m_min_delay);
      return result;
    }

    void fill_IS_table(THD *thd,
                       TABLE_LIST *tables,
                       Item *cond);

    /** Overridden functions */
    bool notify_event(MYSQL_THD thd,
                      Connection_event_coordinator_services *coordinator,
                      const mysql_event_connection *connection_event,
                      Error_handler *error_handler);
    bool notify_sys_var(Connection_event_coordinator_services *coordinator,
                        opt_connection_control variable,
                        void *new_value,
                        Error_handler *error_handler);

  private:
    void deinit();
    void make_hash_key(MYSQL_THD thd, Sql_string &s);
    /**
      Generates wait time

      @param count [in] Proposed delay

      @returns wait time
    */

    inline ulonglong get_wait_time(int64 count)
    {
      int64 max_delay= get_max_delay();
      int64 min_delay= get_min_delay();
      int64 count_mili= count*1000;

      /*
        if count < 0 (can happen in edge cases
        we return max_delay.
        Otherwise, following equation will be used:
        wait_time = MIN(MIN(count, min_delay),
                        max_delay)
      */
      return (static_cast<ulonglong>((count_mili >= MIN_DELAY && count_mili < max_delay) ?
        (count_mili < min_delay ? min_delay : count_mili) :
                                  max_delay));
    }
    void conditional_wait(THD *thd,
                          ulonglong wait_time);

  private:
    /** Threshold value which triggers wait */
    volatile int64 m_threshold;
    /** Lower cap on delay to be generated */
    volatile int64 m_min_delay;
    /** Upper cap on delay to be generated */
    volatile int64 m_max_delay;
    /** System variables */
    std::vector<opt_connection_control> m_sys_vars;
    /** Status variables */
    std::vector<stats_connection_control> m_stats_vars;
    /** Hash to store failed attempts for each user entry */
    Connection_delay_event m_userhost_hash;
    /** RW lock */
    mysql_rwlock_t *m_lock;
  };
}
#endif /* !CONNECTION_DELAY_H */