#include <assert.h>

#include "session_def.h"
#include "session_utils.h"
#include "session_manager.h"

#define EX_KEY_MAX_LEN 64

struct session_exdata_schema
{
    char key[EX_KEY_MAX_LEN];
    session_ex_free_cb *free_cb;
    void *args;
};

struct session_exdata_manager
{
    struct session_exdata_schema schemas[EX_DATA_MAX_COUNT];
    uint8_t count;
};

static struct session_exdata_manager g_ex_manager = {};

/******************************************************************************
 * session set/get
 ******************************************************************************/

void session_init(struct session *sess)
{
    memset(sess, 0, sizeof(struct session));
}

void session_set_id(struct session *sess, uint64_t id)
{
    sess->id = id;
}

uint64_t session_get_id(const struct session *sess)
{
    return sess->id;
}

void session_set_tuple6(struct session *sess, const struct tuple6 *tuple)
{
    memcpy(&sess->tuple, tuple, sizeof(struct tuple6));
}

const struct tuple6 *session_get_tuple6(const struct session *sess)
{
    return &sess->tuple;
}

void session_set_tuple_direction(struct session *sess, enum flow_direction dir)
{
    sess->tuple_dir = dir;
}

enum flow_direction session_get_tuple6_direction(const struct session *sess)
{
    return sess->tuple_dir;
}

const char *session_get0_readable_addr(const struct session *sess)
{
    return sess->tuple_str;
}

void session_set_direction(struct session *sess, enum session_direction dir)
{
    sess->sess_dir = dir;
}

enum session_direction session_get_direction(const struct session *sess)
{
    return sess->sess_dir;
}

void session_set_current_flow_direction(struct session *sess, enum flow_direction dir)
{
    sess->flow_dir = dir;
}

enum flow_direction session_get_current_flow_direction(const struct session *sess)
{
    return sess->flow_dir;
}

void session_set_current_state(struct session *sess, enum session_state state)
{
    sess->state = state;
}

enum session_state session_get_current_state(const struct session *sess)
{
    return sess->state;
}

void session_set_type(struct session *sess, enum session_type type)
{
    sess->type = type;
}

enum session_type session_get_type(const struct session *sess)
{
    return sess->type;
}

void session_set_duplicate_traffic(struct session *sess)
{
    sess->dup = 1;
}

int session_has_duplicate_traffic(const struct session *sess)
{
    return sess->dup;
}

void session_set_closing_reason(struct session *sess, enum closing_reason reason)
{
    sess->reason = reason;
}

enum closing_reason session_get_closing_reason(const struct session *sess)
{
    return sess->reason;
}

void session_inc_stat(struct session *sess, enum flow_direction dir, enum session_stat stat, uint64_t val)
{
    sess->stats[dir][stat] += val;
}

uint64_t session_get_stat(const struct session *sess, enum flow_direction dir, enum session_stat stat)
{
    return sess->stats[dir][stat];
}

void session_set_timestamp(struct session *sess, enum session_timestamp type, uint64_t value)
{
    sess->timestamps[type] = value;
}

uint64_t session_get_timestamp(const struct session *sess, enum session_timestamp type)
{
    return sess->timestamps[type];
}

void session_clear_sids(struct session *sess, enum flow_direction dir)
{
    memset(&sess->sids[dir], 0, sizeof(struct sids));
}

void session_set_sids(struct session *sess, enum flow_direction dir, const struct sids *sids)
{
    sess->sids[dir] = *sids;
}

const struct sids *session_get_sids(const struct session *sess, enum flow_direction dir)
{
    return &sess->sids[dir];
}

void session_clear_route_ctx(struct session *sess, enum flow_direction dir)
{
    memset(&sess->route_ctx[dir], 0, sizeof(struct route_ctx));
}

void session_set_route_ctx(struct session *sess, enum flow_direction dir, const struct route_ctx *ctx)
{
    sess->route_ctx[dir] = *ctx;
}

const struct route_ctx *session_get_route_ctx(const struct session *sess, enum flow_direction dir)
{
    return &sess->route_ctx[dir];
}

void session_set_first_packet(struct session *sess, enum flow_direction dir, const struct packet *pkt)
{
    sess->first_pkt[dir] = pkt;
}

const struct packet *session_get_first_packet(const struct session *sess, enum flow_direction dir)
{
    return sess->first_pkt[dir];
}

void session_set_current_packet(struct session *sess, const struct packet *pkt)
{
    sess->curr_pkt = pkt;
}

const struct packet *session_get0_current_packet(const struct session *sess)
{
    return sess->curr_pkt;
}

int session_is_symmetric(const struct session *sess, unsigned char *flag)
{
    int is_symmetric = 0;
    if (sess->first_pkt[FLOW_DIRECTION_C2S] && sess->first_pkt[FLOW_DIRECTION_S2C])
    {
        if (flag)
        {
            *flag = (SESSION_SEEN_C2S_FLOW | SESSION_SEEN_S2C_FLOW);
        }
        is_symmetric = 1;
    }
    else if (sess->first_pkt[FLOW_DIRECTION_C2S])
    {
        if (flag)
        {
            *flag = SESSION_SEEN_C2S_FLOW;
        }
    }
    else if (sess->first_pkt[FLOW_DIRECTION_S2C])
    {
        if (flag)
        {
            *flag = SESSION_SEEN_S2C_FLOW;
        }
    }
    return is_symmetric;
}

void session_set_user_data(struct session *sess, void *user_data)
{
    sess->user_data = user_data;
}

void *session_get_user_data(const struct session *sess)
{
    return sess->user_data;
}

struct tcp_segment *session_get_tcp_segment(struct session *sess)
{
    enum flow_direction dir = session_get_current_flow_direction(sess);
    struct tcp_half *half = &sess->tcp_halfs[dir];

    if (half->in_order.data != NULL && half->in_order.len > 0 && half->in_order_ref == 0)
    {
        half->in_order_ref++;
        return &half->in_order;
    }
    else
    {
        struct tcp_segment *seg = tcp_reassembly_pop(half->assembler);
        if (seg)
        {
            session_inc_stat(sess, dir, STAT_TCP_SEGMENTS_REORDERED, 1);
            session_inc_stat(sess, dir, STAT_TCP_PAYLOADS_REORDERED, seg->len);

            // TODO
            sess->mgr_stat->nr_tcp_seg_reorded++;
        }
        return seg;
    }
}

void session_free_tcp_segment(struct session *sess, struct tcp_segment *seg)
{
    if (seg == NULL)
    {
        return;
    }

    enum flow_direction dir = session_get_current_flow_direction(sess);
    struct tcp_half *half = &sess->tcp_halfs[dir];

    if (seg == &half->in_order)
    {
        half->in_order.data = NULL;
        half->in_order.len = 0;
        return;
    }
    else
    {
        session_inc_stat(sess, dir, STAT_TCP_SEGMENTS_RELEASED, 1);
        session_inc_stat(sess, dir, STAT_TCP_PAYLOADS_RELEASED, seg->len);
        sess->mgr_stat->nr_tcp_seg_released++;

        tcp_segment_free(seg);
    }
}

/******************************************************************************
 * session ex data
 ******************************************************************************/

/*
 * the exdata prodoced by user, and comsumed by same user.
 * so, the exdata is not shared by different user.
 * otherwise, the exdata need dup by refer count, and free by refer count.
 *
 * if key exist, not allow update, return original index.
 */
uint8_t session_get_ex_new_index(const char *key, session_ex_free_cb *free_cb, void *args)
{
    if (g_ex_manager.count >= EX_DATA_MAX_COUNT)
    {
        abort();
        return EX_DATA_MAX_COUNT;
    }

    for (uint8_t i = 0; i < g_ex_manager.count; i++)
    {
        if (strcmp(g_ex_manager.schemas[i].key, key) == 0)
        {
            return i;
        }
    }

    uint8_t idx = g_ex_manager.count;
    g_ex_manager.count++;

    struct session_exdata_schema *schema = &g_ex_manager.schemas[idx];
    strncpy(schema->key, key, EX_KEY_MAX_LEN);
    schema->free_cb = free_cb;
    schema->args = args;

    return idx;
}

/*
 * Support update ex_data.
 *
 * if key exist: run free_cb free old value, then set new value.
 *     if not run free_cb, old value will be memory leak.
 *     if not allow update, new value will be memory leak.
 * if key not exist: set new value.
 */
void session_set_ex_data(struct session *sess, uint8_t idx, void *val)
{
    if (idx >= g_ex_manager.count)
    {
        assert(0);
        return;
    }

    session_free_ex_data(sess, idx);
    sess->ex_data[idx] = val;
}

void *session_get0_ex_data(const struct session *sess, uint8_t idx)
{
    if (idx >= g_ex_manager.count)
    {
        assert(0);
        return NULL;
    }

    return sess->ex_data[idx];
}

/*
 * after set ex_data, the owner of ex_data is session, so user should not free it directly.
 * if user want to free ex_data, should use session_free_ex_data.
 */
void session_free_ex_data(struct session *sess, uint8_t idx)
{
    if (idx >= g_ex_manager.count)
    {
        assert(0);
        return;
    }

    struct session_exdata_schema *schema = &g_ex_manager.schemas[idx];
    if (schema->free_cb != NULL && sess->ex_data[idx] != NULL)
    {
        printf("free ex_data, idx: %d, key: %s, val: %p\n", idx, schema->key, sess->ex_data[idx]);
        schema->free_cb(sess, idx, sess->ex_data[idx], schema->args);
    }

    sess->ex_data[idx] = NULL;
}

void session_free_all_ex_data(struct session *sess)
{
    if (sess)
    {
        for (uint8_t i = 0; i < g_ex_manager.count; i++)
        {
            session_free_ex_data(sess, i);
        }
    }
}

/******************************************************************************
 * to string
 ******************************************************************************/

const char *closing_reason_to_str(enum closing_reason reason)
{
    switch (reason)
    {
    case CLOSING_BY_TIMEOUT:
        return "closing by timeout";
    case CLOSING_BY_LRU_EVICTED:
        return "closing by lru evicted";
    case CLOSING_BY_PORT_REUSE_EVICTED:
        return "closing by port reuse evicted";
    case CLOSING_BY_CLIENT_FIN:
        return "closing by client FIN";
    case CLOSING_BY_CLIENT_RST:
        return "closing by client RST";
    case CLOSING_BY_SERVER_FIN:
        return "closing by server FIN";
    case CLOSING_BY_SERVER_RST:
        return "closing by server RST";
    default:
        return "unknown";
    }
}

const char *session_state_to_str(enum session_state state)
{
    switch (state)
    {
    case SESSION_STATE_INIT:
        return "init";
    case SESSION_STATE_OPENING:
        return "opening";
    case SESSION_STATE_ACTIVE:
        return "active";
    case SESSION_STATE_CLOSING:
        return "closing";
    case SESSION_STATE_DISCARD:
        return "discard";
    case SESSION_STATE_CLOSED:
        return "closed";
    default:
        return "unknown";
    }
}

const char *session_type_to_str(enum session_type type)
{
    switch (type)
    {
    case SESSION_TYPE_TCP:
        return "TCP";
    case SESSION_TYPE_UDP:
        return "UDP";
    default:
        return "unknown";
    }
}

const char *flow_direction_to_str(enum flow_direction dir)
{
    switch (dir)
    {
    case FLOW_DIRECTION_C2S:
        return "C2S";
    case FLOW_DIRECTION_S2C:
        return "S2C";
    default:
        return "unknown";
    }
}

static void tcp_flags_to_str(uint8_t flags, char *buffer, size_t len)
{
    int used = 0;

    if (flags & TH_SYN)
    {
        used += snprintf(buffer + used, len - used, "SYN ");
    }
    if (flags & TH_ACK)
    {
        used += snprintf(buffer + used, len - used, "ACK ");
    }
    if (flags & TH_FIN)
    {
        used += snprintf(buffer + used, len - used, "FIN ");
    }
    if (flags & TH_RST)
    {
        used += snprintf(buffer + used, len - used, "RST ");
    }
}

int session_to_str(const struct session *sess, int bref, char *buff, int size)
{
    memset(buff, 0, size);
    char flags[64] = {0};
    int used = 0;

    if (bref)
    {
        used += snprintf(buff + used, size - used, "session id: %lu, addr: %s, type: %s, state: %s, dir: %s, c2s_rx_pkts: %lu, s2c_rx_pkts: %lu",
                         session_get_id(sess),
                         session_get0_readable_addr(sess),
                         session_type_to_str(session_get_type(sess)),
                         session_state_to_str(session_get_current_state(sess)),
                         flow_direction_to_str(session_get_current_flow_direction(sess)),
                         session_get_stat(sess, FLOW_DIRECTION_C2S, STAT_RAW_PACKETS_RECEIVED),
                         session_get_stat(sess, FLOW_DIRECTION_S2C, STAT_RAW_PACKETS_RECEIVED));
    }
    else
    {
        used += snprintf(buff + used, size - used, "{");
        used += snprintf(buff + used, size - used, "\"id\":%" PRIu64 ",", session_get_id(sess));
        used += snprintf(buff + used, size - used, "\"start_timestamp_ms\":%" PRIu64 ",", session_get_timestamp(sess, SESSION_TIMESTAMP_START));
        used += snprintf(buff + used, size - used, "\"last_timestamp_ms\":%" PRIu64 ",", session_get_timestamp(sess, SESSION_TIMESTAMP_LAST));
        used += snprintf(buff + used, size - used, "\"tuple\":\"%s\",", session_get0_readable_addr(sess));
        used += snprintf(buff + used, size - used, "\"type\":\"%s\",", session_type_to_str(session_get_type(sess)));
        used += snprintf(buff + used, size - used, "\"state\":\"%s\",", session_state_to_str(session_get_current_state(sess)));
        used += snprintf(buff + used, size - used, "\"closing_reason\":\"%s\",", closing_reason_to_str(session_get_closing_reason(sess)));
        used += snprintf(buff + used, size - used, "\"duplicate_traffic\":%d,", session_has_duplicate_traffic(sess));
        used += snprintf(buff + used, size - used, "\"current_packet\":\"%p\",", session_get0_current_packet(sess));

        const char *str[] = {"c2s", "s2c"};
        enum flow_direction dir[] = {FLOW_DIRECTION_C2S, FLOW_DIRECTION_S2C};
        for (int i = 0; i < 2; i++)
        {
            // raw packets
            used += snprintf(buff + used, size - used, "\"%s_raw_packets_received\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_RAW_PACKETS_RECEIVED));
            used += snprintf(buff + used, size - used, "\"%s_raw_bytes_received\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_RAW_BYTES_RECEIVED));

            used += snprintf(buff + used, size - used, "\"%s_raw_packets_transmitted\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_RAW_PACKETS_TRANSMITTED));
            used += snprintf(buff + used, size - used, "\"%s_raw_bytes_transmitted\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_RAW_BYTES_TRANSMITTED));

            used += snprintf(buff + used, size - used, "\"%s_raw_packets_dropped\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_RAW_PACKETS_DROPPED));
            used += snprintf(buff + used, size - used, "\"%s_raw_bytes_dropped\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_RAW_BYTES_DROPPED));

            // duplicate packets
            used += snprintf(buff + used, size - used, "\"%s_duplicate_packets_bypass\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_DUPLICATE_PACKETS_BYPASS));
            used += snprintf(buff + used, size - used, "\"%s_duplicate_bytes_bypass\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_DUPLICATE_BYTES_BYPASS));

            // injected packets
            used += snprintf(buff + used, size - used, "\"%s_injected_packets_failed\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_INJECTED_PACKETS_FAILED));
            used += snprintf(buff + used, size - used, "\"%s_injected_packets_success\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_INJECTED_PACKETS_SUCCESS));
            used += snprintf(buff + used, size - used, "\"%s_injected_bytes_success\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_INJECTED_BYTES_SUCCESS));

            // control packets
            used += snprintf(buff + used, size - used, "\"%s_control_packets_received\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_CONTROL_PACKETS_RECEIVED));
            used += snprintf(buff + used, size - used, "\"%s_control_bytes_received\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_CONTROL_BYTES_RECEIVED));

            used += snprintf(buff + used, size - used, "\"%s_control_packets_transmitted\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_CONTROL_PACKETS_TRANSMITTED));
            used += snprintf(buff + used, size - used, "\"%s_control_bytes_transmitted\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_CONTROL_BYTES_TRANSMITTED));

            used += snprintf(buff + used, size - used, "\"%s_control_packets_dropped\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_CONTROL_PACKETS_DROPPED));
            used += snprintf(buff + used, size - used, "\"%s_control_bytes_dropped\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_CONTROL_BYTES_DROPPED));

            if (session_get_type(sess) == SESSION_TYPE_TCP)
            {
                used += snprintf(buff + used, size - used, "\"%s_tcp_last_seq\":%u,", str[i], sess->tcp_halfs[dir[i]].seq);
                used += snprintf(buff + used, size - used, "\"%s_tcp_last_ack\":%u,", str[i], sess->tcp_halfs[dir[i]].ack);
                memset(flags, 0, sizeof(flags));
                tcp_flags_to_str(sess->tcp_halfs[dir[i]].flags, flags, sizeof(flags));
                used += snprintf(buff + used, size - used, "\"%s_tcp_flags\":\"%s\",", str[i], flags);

                used += snprintf(buff + used, size - used, "\"%s_tcp_segments_received\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_TCP_SEGMENTS_RECEIVED));
                used += snprintf(buff + used, size - used, "\"%s_tcp_payloads_received\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_TCP_PAYLOADS_RECEIVED));

                used += snprintf(buff + used, size - used, "\"%s_tcp_segments_expired\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_TCP_SEGMENTS_EXPIRED));
                used += snprintf(buff + used, size - used, "\"%s_tcp_payloads_expired\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_TCP_PAYLOADS_EXPIRED));

                used += snprintf(buff + used, size - used, "\"%s_tcp_segments_retransmit\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_TCP_SEGMENTS_RETRANSMIT));
                used += snprintf(buff + used, size - used, "\"%s_tcp_payloads_retransmit\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_TCP_PAYLOADS_RETRANSMIT));

                used += snprintf(buff + used, size - used, "\"%s_tcp_segments_overlap\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_TCP_SEGMENTS_OVERLAP));
                used += snprintf(buff + used, size - used, "\"%s_tcp_payloads_overlap\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_TCP_PAYLOADS_OVERLAP));

                used += snprintf(buff + used, size - used, "\"%s_tcp_segments_nospace\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_TCP_SEGMENTS_NOSPACE));
                used += snprintf(buff + used, size - used, "\"%s_tcp_payloads_nospace\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_TCP_PAYLOADS_NOSPACE));

                used += snprintf(buff + used, size - used, "\"%s_tcp_segments_inorder\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_TCP_SEGMENTS_INORDER));
                used += snprintf(buff + used, size - used, "\"%s_tcp_payloads_inorder\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_TCP_PAYLOADS_INORDER));

                used += snprintf(buff + used, size - used, "\"%s_tcp_segments_reordered\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_TCP_SEGMENTS_REORDERED));
                used += snprintf(buff + used, size - used, "\"%s_tcp_payloads_reordered\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_TCP_PAYLOADS_REORDERED));

                used += snprintf(buff + used, size - used, "\"%s_tcp_segments_buffered\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_TCP_SEGMENTS_BUFFERED));
                used += snprintf(buff + used, size - used, "\"%s_tcp_payloads_buffered\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_TCP_PAYLOADS_BUFFERED));

                used += snprintf(buff + used, size - used, "\"%s_tcp_segments_released\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_TCP_SEGMENTS_RELEASED));
                used += snprintf(buff + used, size - used, "\"%s_tcp_payloads_released\":%" PRIu64 ",", str[i], session_get_stat(sess, dir[i], STAT_TCP_PAYLOADS_RELEASED));
            }

            used += snprintf(buff + used, size - used, "\"%s_first_packet\":\"%p\"", str[i], session_get_first_packet(sess, dir[i]));
            if (i == 0)
            {
                used += snprintf(buff + used, size - used, ",");
            }
        }
        used += snprintf(buff + used, size - used, "}");
    }

    return used;
}