#ifndef ETHERLIB_TCP_SEGMENT_H
#define ETHERLIB_TCP_SEGMENT_H

#include <stdint.h>
#include "../../packet_sieve.h"

#define ETH_TCP_PACKET_CLASS (6)
#define ETH_TCP_HEADER_SIZE (20)

#define TCP_MAX_OPT_VAL_LEN (8)

/**
 * TCP option kinds.
 */
typedef enum {
    TCP_OPT_KIND_EOL = 0, // End of Operation List Option
    TCP_OPT_KIND_NOP = 1, // No-Operation
    TCP_OPT_KIND_MSS = 2  // Maximum Segment Size
} TcpOptionKind;

/**
 * TCP options
 */
typedef struct TcpOption_ {
    uint8_t kind; ///< Kind of the specific option (~type)
    uint8_t size; ///< Size of value (NOT including 'kind' and 'length' fields) [=TCP opt length - 2]
    struct TcpOption_ * next; ///< Next option in the list
    uint8_t value[]; ///< Value
} TcpOption;

/**
 * Allocate new TCP option.
 * @param kind kind of TCP option.
 * @param size size of value
 * @return pointer to newly allocated option
 */
TcpOption * tcpopt_new(uint32_t kind, uint32_t size);

/**
 * TCP segment flags
 */
typedef enum {
    TCP_FLAG_FIN = 0x01,
    TCP_FLAG_SYN = 0x02,
    TCP_FLAG_RESET = 0x04,
    TCP_FLAG_PUSH = 0x08,
    TCP_FLAG_ACK = 0x10,
    TCP_FLAG_URGENT = 0x20,
    TCP_FLAG_ECNECHO = 0x40,
    TCP_FLAG_CWR = 0x80,
    TCP_FLAG_NONCE = 0x100
} TcpFlag;

/**
 * TCP connection block states.
 */
typedef enum {
    TCP_STATE_CLOSED = 0,
    TCP_STATE_LISTEN,
    TCP_STATE_SYN_RCVD,
    TCP_STATE_SYN_SENT,
    TCP_STATE_ESTAB,
    TCP_STATE_FIN_WAIT_1,
    TCP_STATE_FIN_WAIT_2,
    TCP_STATE_CLOSE_WAIT,
    TCP_STATE_CLOSING,
    TCP_STATE_LAST_ACK,
    TCP_STATE_TIME_WAIT
} TcpConnectionState;

/**
 * TCP segment properties.
 */
typedef struct {
    PcktPropsHeader
    uint16_t SourcePort; ///< Source port
    uint16_t DestinationPort; ///< Destination port
    uint32_t SequenceNumber; ///< TCP sequence number
    uint32_t AcknowledgementNumber; ///< TCP ack. number
    uint8_t DataOffset; ///< Data offset in 32-bits (4 bit-long field)
    uint16_t Flags; ///< TCP flags (9-bit, 8 + 4, but upper 3 is reserved)
    uint16_t Window; ///< TCP window
    uint16_t Checksum; ///< Checksum
    uint16_t UrgentPtr; ///< Urgent pointer
    TcpOption * options; ///< Linked list of TCP options
} TcpProps;

struct EthInterface_;

/**
 * Parse raw TCP segments.
 * @param hdr pointer to the TCP packet header
 * @param size total packet size
 * @param pcktHdrLe pointer to property storage
 * @return 0 on success or -1 on failure
 */
int parse_tcp(const uint8_t *hdr, uint32_t size, PcktHeaderElement *pcktHdrLe, struct EthInterface_ *intf, PcktProcFnPassbackData *pb);

/**
 * Insert TCP header.
 * @param hdr space where the header is to be inserted
 * @param headers linked list of header, top is always relevant
 */
void insert_tcp_header(uint8_t * hdr, const PcktHeaderElement * headers);

/**
 * Get the flattened size of the option chain.
 * @param optLe list of TCP options
 * @return flattened size of options
 */
uint32_t tcp_get_options_size(TcpOption * optLe);

/**
 * Get TCP option by filtering against kind field.
 * @param kind option kind to lookup
 * @param opt linked list of options
 * @return pointer to option OR NULL if not found
 */
TcpOption * tcp_get_option_by_kind(TcpOption * opt, uint16_t kind);

#endif //ETHERLIB_TCP_SEGMENT_H