#ifndef _PACKET_H
#define _PACKET_H

#ifdef __cplusplus
extern "C"
{
#endif

#include "tuple.h"

enum layer_type
{
    // L2 -- data link layer
    LAYER_TYPE_ETHER = 1 << 0,
    LAYER_TYPE_PPP = 1 << 1,
    LAYER_TYPE_HDLC = 1 << 2,
    LAYER_TYPE_L2 = (LAYER_TYPE_ETHER | LAYER_TYPE_PPP | LAYER_TYPE_HDLC),

    // L2 -- tunnel
    LAYER_TYPE_VLAN = 1 << 3,
    LAYER_TYPE_PPPOE = 1 << 4,
    LAYER_TYPE_MPLS = 1 << 5,
    LAYER_TYPE_L2_TUN = (LAYER_TYPE_VLAN | LAYER_TYPE_PPPOE | LAYER_TYPE_MPLS),

    // L3 -- network layer
    LAYER_TYPE_IPV4 = 1 << 6,
    LAYER_TYPE_IPV6 = 1 << 7,
    LAYER_TYPE_L3 = (LAYER_TYPE_IPV4 | LAYER_TYPE_IPV6),

    // L3 -- tunnel
    LAYER_TYPE_GRE = 1 << 8,
    LAYER_TYPE_L3_TUN = (LAYER_TYPE_GRE),

    // L4 -- transport layer
    LAYER_TYPE_UDP = 1 << 9,
    LAYER_TYPE_TCP = 1 << 10,
    LAYER_TYPE_L4 = (LAYER_TYPE_UDP | LAYER_TYPE_TCP),

    // L4 -- tunnel
    LAYER_TYPE_VXLAN = 1 << 11,
    LAYER_TYPE_GTPV1_U = 1 << 12,

    // ALL
    LAYER_TYPE_ALL = (LAYER_TYPE_L2 | LAYER_TYPE_L2_TUN | LAYER_TYPE_L3 | LAYER_TYPE_L3_TUN | LAYER_TYPE_L4 | LAYER_TYPE_VXLAN | LAYER_TYPE_GTPV1_U),
};

struct packet_layer
{
    enum layer_type type;
    const char *hdr_ptr; // header pointer
    const char *pld_ptr; // payload pointer
    uint16_t hdr_offset; // header offset from data_ptr
    uint16_t hdr_len;    // header length
    uint16_t pld_len;    // payload length
};

// return  0: found
// return -1: not found
int packet_get_innermost_tuple2(const struct packet *pkt, struct tuple2 *tuple);
int packet_get_outermost_tuple2(const struct packet *pkt, struct tuple2 *tuple);

// return  0: found
// return -1: not found
int packet_get_innermost_tuple4(const struct packet *pkt, struct tuple4 *tuple);
int packet_get_outermost_tuple4(const struct packet *pkt, struct tuple4 *tuple);

// return  0: found
// return -1: not found
int packet_get_innermost_tuple6(const struct packet *pkt, struct tuple6 *tuple);
int packet_get_outermost_tuple6(const struct packet *pkt, struct tuple6 *tuple);

const struct packet_layer *packet_get_innermost_layer(const struct packet *pkt, enum layer_type type);
const struct packet_layer *packet_get_outermost_layer(const struct packet *pkt, enum layer_type type);

/******************************************************************************
 * Utils
 ******************************************************************************/

int8_t packet_get_layers(const struct packet *pkt);
const struct packet_layer *packet_get_layer(const struct packet *pkt, int8_t idx);

const char *packet_get_data(const struct packet *pkt);
uint16_t packet_get_len(const struct packet *pkt);

const char *packet_get_payload(const struct packet *pkt);
uint16_t packet_get_payload_len(const struct packet *pkt);

int packet_need_drop(const struct packet *pkt);
void packet_set_drop(struct packet *pkt);

void packet_set_ctrl(struct packet *pkt);
int packet_is_ctrl(const struct packet *pkt);

void packet_set_direction(struct packet *pkt, int dir);
int packet_get_direction(const struct packet *pkt); // 1: E2I, 0: I2E

void packet_set_session_id(struct packet *pkt, uint64_t sess_id);
uint64_t packet_get_session_id(const struct packet *pkt);

void packet_set_sid_list(struct packet *pkt, uint16_t *sid, int num);
int packet_get_sid_list(const struct packet *pkt, uint16_t *sid, int num); // return number of sid
void packet_prepend_sid_list(struct packet *pkt, uint16_t *sid, int num);
void packet_append_sid_list(struct packet *pkt, uint16_t *sid, int num);

/*
 ******************************************************************************
 * Example: getting the innermost TCP layer
 ******************************************************************************
 *
 *    |<--------------------------- pkt->data_len -------------------------->|
 *    +----------+------+-----+-------+------+---------------+---------------+
 *    | Ethernet | IPv4 | UDP | GTP-U | IPv4 | TCP           | Payload       |
 *    +----------+------+-----+-------+------+---------------+---------------+
 *    ^                                      ^               ^
 *    |                                      |               |
 *    |<------------ hdr_offset ------------>|<-- hdr_len -->|<-- pld_len -->|
 *    |                                      |               |
 *    |                                      |               +-- pld_ptr
 *    |                                      +-- hdr_ptr
 *    +-- data_ptr
 *
 *    const struct packet_layer *tcp_layer = packet_get_innermost_layer(pkt, LAYER_TYPE_TCP);
 *    const struct tcphdr *hdr = (const struct tcphdr *)tcp_layer->hdr_ptr;
 *    uint16_t src_port = ntohs(hdr->th_sport);
 *    uint16_t dst_port = ntohs(hdr->th_dport);
 *    uint32_t seq = ntohl(hdr->th_seq);
 *    uint32_t ack = ntohl(hdr->th_ack);
 *
 ******************************************************************************
 * Example: foreach layer in packet
 ******************************************************************************
 *
 *    // inorder
 *    int8_t layers = packet_get_layers(pkt);
 *    for (int8_t i = 0; i < layers; i++)
 *    {
 *        const struct packet_layer *layer = packet_get_layer(pkt, i);
 *        printf("layer[%d]: type=%d, hdr_offset=%d, hdr_len=%d, pld_len=%d\n", i, layer->type, layer->hdr_offset, layer->hdr_len, layer->pld_len);
 *    }
 *
 *    // reverse
 *    for (int8_t i = layers - 1; i >= 0; i--)
 *    {
 *        const struct packet_layer *layer = packet_get_layer(pkt, i);
 *        printf("layer[%d]: type=%d, hdr_offset=%d, hdr_len=%d, pld_len=%d\n", i, layer->type, layer->hdr_offset, layer->hdr_len, layer->pld_len);
 *    }
 */

#ifdef __cplusplus
}
#endif

#endif