#include "udp.h"
#include "eth.h"
#include "ipv4.h"
#include "net.h"
#include "parse_buffer.h"

namespace udp {

void handle(std::span<const uint8_t> frame, span_writer& tx) {
    parse_buffer pb(frame);
    auto* eth_hdr = pb.consume<eth::header>();
    auto* ip = pb.consume<ipv4::header>();
    if (!ip) return;

    size_t options_len = ip->header_len() - sizeof(ipv4::header);
    if (options_len > 0 && !pb.skip(options_len)) return;

    auto* uhdr = pb.consume<header>();
    if (!uhdr) return;
    if (uhdr->dst_port != PICOMAP_PORT_BE) return;

    size_t udp_len = __builtin_bswap16(uhdr->length);
    if (udp_len < sizeof(header)) return;
    size_t payload_len = udp_len - sizeof(header);
    if (pb.remaining_size() < payload_len) return;

    address from{eth_hdr->src, ip->src, uhdr->src_port};
    client::handler(pb.remaining().subspan(0, payload_len), from);
}

} // namespace udp