#ifndef _SESSION_MANAGER_H
#define _SESSION_MANAGER_H

#ifdef __cpluscplus
extern "C"
{
#endif

#include "session.h"

#ifndef SESSION_LOG_ERROR
#define SESSION_LOG_ERROR(format, ...) \
    fprintf(stderr, "ERROR (session), " format "\n", ##__VA_ARGS__);
#endif
#ifndef SESSION_LOG_DEBUG
#define SESSION_LOG_DEBUG(format, ...) \
    fprintf(stderr, "DEBUG (session), " format "\n", ##__VA_ARGS__);
#endif

struct session_manager_config
{
    // max session number
    uint64_t max_tcp_session_num;
    uint64_t max_udp_session_num;

    // session overload
    uint8_t tcp_overload_evict_old_sess; // 1: evict old session, 0: bypass new session
    uint8_t udp_overload_evict_old_sess; // 1: evict old session, 0: bypass new session

    // TCP timeout
    uint64_t tcp_timeout_init;        // seconds, Range: 1-60
    uint64_t tcp_timeout_handshake;   // seconds, Range: 1-60
    uint64_t tcp_timeout_data;        // seconds, Range: 1-15,999,999
    uint64_t tcp_timeout_half_closed; // seconds, Range: 1-604,800
    uint64_t tcp_timeout_time_wait;   // seconds, Range: 1-600
    uint64_t tcp_timeout_discard;     // seconds, Range: 1-15,999,999

    // UDP timeout
    uint64_t udp_timeout_data; // seconds, Range: 1-15,999,999

    // TCP duplicate packet filter
    uint8_t tcp_dupkt_filter_enable;
    uint64_t tcp_dupkt_filter_capacity;
    uint64_t tcp_dupkt_filter_timeout; // seconds, Range: 1-60
    double tcp_dupkt_filter_error_rate;

    // UDP eviction filter
    uint8_t udp_eviction_filter_enable;
    uint64_t udp_eviction_filter_capacity;
    uint64_t udp_eviction_filter_timeout; // seconds, Range: 1-60
    double udp_eviction_filter_error_rate;
};

struct session_manager;
struct session_manager *session_manager_create(struct session_manager_config *config);
void session_manager_destroy(struct session_manager *mgr);

// only use the packet six-tuple to find the session, not update it
struct session *session_manager_lookup_sesssion(struct session_manager *mgr, const struct packet *pkt);
/*
 * Return NULL in the following cases:
 *      1.not a TCP or UDP packet
 *      2.TCP packet miss session but no syn packet seen
 *      3.TCP duplicate packet
 *      4.TCP discards packets
 *      5.UDP evict packet
 * pakcet will not update the session and needs to be fast forwarded
 */
struct session *session_manager_update_session(struct session_manager *mgr, const struct packet *pkt);
struct session *session_manager_get_expired_session(struct session_manager *mgr);
struct session *session_manager_get_evicted_session(struct session_manager *mgr);
// return  0: have already timeout session
// return >0: next expire interval
uint64_t session_manager_get_expire_interval(struct session_manager *mgr);

struct session_counter
{
    uint64_t tcp_sess_num;
    uint64_t tcp_opening_sess_num;
    uint64_t tcp_active_sess_num;
    uint64_t tcp_closing_sess_num;

    uint64_t udp_sess_num;
    uint64_t udp_opening_sess_num;
    uint64_t udp_active_sess_num;
    uint64_t udp_closing_sess_num;

    uint64_t tcp_overload_evict_old_sess_num;
    uint64_t tcp_overload_evict_new_sess_num;
    uint64_t udp_overload_evict_old_sess_num;
    uint64_t udp_overload_evict_new_sess_num;
};

void session_manager_get_session_counter(struct session_manager *mgr, struct session_counter *out);
void session_manager_print_status(struct session_manager *mgr);

#ifdef __cpluscplus
}
#endif

#endif