#include <stddef.h>
#include "global_state.h"
#include "dynmem.h"

#include "prefab/prefab.h"

EthState gEthState;

static void register_packet_parsers() {
    PcktClassDesc cdesc;
    // Ethernet frame parser
    cdesc.class = 0;
    cdesc.containerClass = 0;
    cdesc.procFun = parse_ethernet;
    cdesc.propertySize = sizeof(EthernetProps);
    packreg_add(E.pcktReg, &cdesc);

    // IPv4 packet parser
    cdesc.class = ETH_IPv4_PACKET_CLASS;
    cdesc.containerClass = 0;
    cdesc.procFun = parse_ipv4;
    cdesc.propertySize = sizeof(IPv4Props);
    packreg_add(E.pcktReg, &cdesc);

    // UDP packet parser
    cdesc.class = ETH_UDP_PACKET_CLASS;
    cdesc.containerClass = ETH_IPv4_PACKET_CLASS;
    cdesc.procFun = parse_udp;
    cdesc.propertySize = sizeof(UDPProps);
    packreg_add(E.pcktReg, &cdesc);
}

void ethlib_init() {
    dynmem_init(); // initialize dynamic memory subsystem
    E.pcktReg = packreg_new(); // create new packet registry
    register_packet_parsers(); // register packet parsers
}

typedef struct PcktHeaderElement_ {
    struct PcktHeaderElement_ * next, * prev; ///< Next and previous header in the linked list
    PcktProps props; ///< Properties (allocated to appropriate size)
} PcktHeaderElement;

#define ETH_PCKT_HEADER_ELEMENT_HEAD_SIZE (2 * sizeof(PcktHeaderElement *))

void process_raw_packet(const uint8_t * data, uint32_t size) {
    uint16_t ownClass = 0, containerClass = 0; // Ethernet...
    uint16_t offset = 0;
    PcktHeaderElement * lastHeader = NULL;
    do {
        // get packet descriptor
        const PcktClassDesc * cdesc = packreg_get_by_class(E.pcktReg, ownClass, containerClass);
        if (cdesc == NULL) {
            break;
        }

        // allocate property object
        PcktHeaderElement * header = (PcktHeaderElement *) dynmem_alloc(ETH_PCKT_HEADER_ELEMENT_HEAD_SIZE + cdesc->propertySize);
        header->props.ownPacketClass = ownClass;
        header->props.propSize = cdesc->propertySize;
        header->prev = lastHeader;
        if (lastHeader) {
            lastHeader->next = header;
        }

        // call parsing function
        cdesc->procFun(data + offset, size - offset, &header->props);
        uint16_t containedClass = header->props.containedPacketClass;
        if (containedClass != 0) {
            containerClass = ownClass;
            offset += header->props.headerSize;
            //dynmem_free(props);
        }
        ownClass = containedClass;
        lastHeader = header;
    } while (ownClass != 0);

    // TODO process innermost packet

    return;
}