#ifndef _SESSION_H
#define _SESSION_H
/*
 * This file is distributed as part of the SkySQL Gateway.  It 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.
 *
 * 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 02110-1301 USA.
 *
 * Copyright SkySQL Ab 2013
 */

/**
 * @file session.h
 *
 * @verbatim
 * Revision History
 *
 * Date		Who			Description
 * 01-06-2013	Mark Riddoch		Initial implementation
 * 14-06-2013	Massimiliano Pinto	Added void *data to session
 *					for session specific data
 * 01-07-2013	Massimiliano Pinto	Removed backends pointer
 *					from struct session
 * 02-09-2013	Massimiliano Pinto	Added session ref counter
 * 29-05-2014	Mark Riddoch		Support for filter mechanism
 *					added
 *
 * @endverbatim
 */
#include <time.h>
#include <atomic.h>
#include <buffer.h>
#include <spinlock.h>
#include <skygw_utils.h>

struct dcb;
struct service;
struct filter_def;

/**
 * The session statistics structure
 */
typedef struct {
	time_t		connect;	/**< Time when the session was started */
} SESSION_STATS;

typedef enum {
    SESSION_STATE_ALLOC,            /*< for all sessions */
    SESSION_STATE_READY,            /*< for router session */
    SESSION_STATE_ROUTER_READY,     /*< for router session */
    SESSION_STATE_STOPPING,         /*< session and router are being closed */
    SESSION_STATE_LISTENER,         /*< for listener session */
    SESSION_STATE_LISTENER_STOPPED, /*< for listener session */
    SESSION_STATE_FREE              /*< for all sessions */
} session_state_t;

/**
 * The downstream element in the filter chain. This may refer to
 * another filter or to a router.
 */
typedef struct {
	void		*instance;
	void		*session;
	int		(*routeQuery)(void *instance, void *session,
					GWBUF *request);
} DOWNSTREAM;

/**
 * The upstream element in the filter chain. This may refer to
 * another filter or to the protocol implementation.
 */
typedef struct {
	void		*instance;
	void		*session;
	int		(*clientReply)(void *instance,
				void *session, GWBUF *response);
	int		(*error)(void *instance, void *session, void *);
} UPSTREAM;

/**
 * Structure used to track the filter instances and sessions of the filters
 * that are in use within a session.
 */
typedef struct {
	struct filter_def
			*filter;
	void		*instance;
	void		*session;
} SESSION_FILTER;

/**
 * The session status block
 *
 * A session status block is created for each user (client) connection
 * to the database, it links the descriptors, routing implementation
 * and originating service together for the client session.
 */
typedef struct session {
#if defined(SS_DEBUG)
        skygw_chk_t     ses_chk_top;
#endif
        SPINLOCK        ses_lock;
	session_state_t state;		/**< Current descriptor state */
	struct dcb	*client;	/**< The client connection */
	void 		*data;		/**< The session data */
	void		*router_session;/**< The router instance data */
	SESSION_STATS	stats;		/**< Session statistics */
	struct service	*service;	/**< The service this session is using */
	int		n_filters;	/**< Number of filter sessions */
	SESSION_FILTER	*filters;	/**< The filters in use within this session */
	DOWNSTREAM	head;		/**< Head of the filter chain */
	UPSTREAM	tail;		/**< The tail of the filter chain */
	struct session	*next;		/**< Linked list of all sessions */
	int		refcount;	/**< Reference count on the session */
#if defined(SS_DEBUG)
        skygw_chk_t     ses_chk_tail;
#endif
} SESSION;

#define SESSION_PROTOCOL(x, type)	DCB_PROTOCOL((x)->client, type)

/**
 * A convenience macro that can be used by the protocol modules to route
 * the incoming data to the first element in the pipeline of filters and
 * routers.
 */
#define	SESSION_ROUTE_QUERY(sess, buf) \
		((sess)->head.routeQuery)((sess)->head.instance, \
				(sess)->head.session, (buf))
/**
 * A convenience macro that can be used by the router modules to route
 * the replies to the first element in the pipeline of filters and
 * the protocol.
 */
#define	SESSION_ROUTE_REPLY(sess, buf) \
		((sess)->tail.clientReply)((sess)->tail.instance, \
				(sess)->tail.session, (buf))

SESSION	*session_alloc(struct service *, struct dcb *);
bool    session_free(SESSION *);
int	session_isvalid(SESSION *);
int	session_reply(void *inst, void *session, GWBUF *data);
char	*session_get_remote(SESSION *);
char	*session_getUser(SESSION *);
void	printAllSessions();
void	printSession(SESSION *);
void	dprintAllSessions(struct dcb *);
void	dprintSession(struct dcb *, SESSION *);
void	dListSessions(struct dcb *);
char	*session_state(int);
bool	session_link_dcb(SESSION *, struct dcb *);
SESSION* get_session_by_router_ses(void* rses);
#endif