/* SPDX-License-Identifier: Unlicense */

#include "proto_io.h"

#include <arpa/inet.h>
#include <errno.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <stdio.h>

static unsigned char g_udp_buffer[UINT16_MAX + 1u];

int ReceiveFrame(int fd, struct frame *frame)
{
    frame->type = FT_NONE;
    struct sockaddr_in source_address;
    socklen_t source_address_len = sizeof(source_address);
    int const length = recvfrom(
            fd,
            g_udp_buffer,
            sizeof(g_udp_buffer) - 1,
            0,
            (struct sockaddr*)&source_address,
            &source_address_len);
    if (length == 0) {
        return -EWOULDBLOCK;
    }
    if (length < 0) {
        int const err = errno;
        if (err != EWOULDBLOCK) {
            perror("recvfrom failed");
        }
        return -err;
    }
    uint32_t const addr = ntohl(source_address.sin_addr.s_addr);
    uint16_t const port = ntohs(source_address.sin_port);
    if (length) {
        *frame = ParseFrame(g_udp_buffer, length);
        frame->addr = addr;
        frame->port = port;
    }
    if (LOG_TRACE) {
        uint8_t const a0 = addr >> 24;
        uint8_t const a1 = addr >> 16;
        uint8_t const a2 = addr >> 8;
        uint8_t const a3 = addr;
        fprintf(stderr, "Received from %u.%u.%u.%u:%u\n", a0, a1, a2, a3, port);
    }
    return 0;
}

int SendFrame(int const fd, struct frame const *const frame)
{
    g_udp_buffer[0] = frame->type;
    struct sockaddr_in const sockaddr = {
        .sin_family = AF_INET,
        .sin_port = htons(frame->port),
        .sin_addr.s_addr = htonl(frame->addr),
    };
    if (LOG_TRACE) {
        uint32_t const addr = frame->addr;
        uint16_t const port = frame->port;
        uint8_t const a0 = addr >> 24;
        uint8_t const a1 = addr >> 16;
        uint8_t const a2 = addr >> 8;
        uint8_t const a3 = addr;
        fprintf(stderr, "Sending to %u.%u.%u.%u:%u\n", a0, a1, a2, a3, port);
    }
    size_t const size = SerializeFrame(g_udp_buffer, UINT16_MAX + 1u, frame);
    ssize_t const ret = sendto(
            fd, g_udp_buffer, size, 0, (struct sockaddr const *)&sockaddr, sizeof(sockaddr));
    if (ret < 0) {
        int const err = errno;
        perror("sendto failed");
        return -err;
    }
    return 0;
}