// Part of JoeyLib, Copyright (c) 2026 Scott Duensing, under the MIT License.
// See LICENSE.md for license information.
// SPDX-License-Identifier: MIT
//
// gateNet.c - sockets, waits, and the clock shared by the gates' serial
// and network peers, and received bytes shown printably (gateNet.h).

#define _DEFAULT_SOURCE

#include <arpa/inet.h>
#include <errno.h>
#include <limits.h>
#include <math.h>
#include <poll.h>
#include <signal.h>
#include <string.h>
#include <sys/socket.h>
#include <time.h>
#include <unistd.h>

#include "gateNet.h"
#include "toolFile.h"

#define MS_PER_SECOND  1000.0
#define NS_PER_SECOND  1000000000.0
#define WAIT_FOREVER   (-1)
// Bytes from SHOW_PRINTABLE up to (not including) SHOW_DELETE show as
// themselves.
#define SHOW_PRINTABLE 0x20u
#define SHOW_DELETE    0x7Fu


int gateNetAccept(int listener, double seconds, struct sockaddr_in *from) {
    struct sockaddr_in peer;
    socklen_t          peerLen;
    int                conn;

    if (!gateNetWait(listener, POLLIN, seconds)) {
        return -1;
    }
    peerLen = sizeof(peer);
    conn    = accept(listener, (struct sockaddr *)&peer, &peerLen);
    if (conn < 0) {
        toolFail("accept: %s", strerror(errno));
    }
    if (from != NULL) {
        *from = peer;
    }
    return conn;
}


int gateNetAcceptOne(uint16_t port, double seconds) {
    int listener;
    int conn;

    listener = gateNetListen(port, GATE_NET_ONE_PEER);
    conn     = gateNetAccept(listener, seconds, NULL);
    close(listener);
    return conn;
}


int gateNetListen(uint16_t port, int backlog) {
    struct sockaddr_in addr;
    int                fd;
    int                on;

    memset(&addr, 0, sizeof(addr));
    addr.sin_family      = AF_INET;
    addr.sin_port        = htons(port);
    addr.sin_addr.s_addr = inet_addr(GATE_NET_HOST);
    on                   = 1;
    fd                   = socket(AF_INET, SOCK_STREAM, 0);
    if (fd < 0 || setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) != 0 || bind(fd, (struct sockaddr *)&addr, sizeof(addr)) != 0 || listen(fd, backlog) != 0) {
        toolFail("cannot listen on %s:%u: %s", GATE_NET_HOST, (unsigned)port, strerror(errno));
    }
    return fd;
}


double gateNetNow(void) {
    struct timespec now;

    clock_gettime(CLOCK_MONOTONIC, &now);
    return (double)now.tv_sec + (double)now.tv_nsec / NS_PER_SECOND;
}


int32_t gateNetRecv(int fd, uint8_t *buf, size_t cap, double seconds) {
    ssize_t got;

    if (!gateNetWait(fd, POLLIN, seconds)) {
        return GATE_NET_IDLE;
    }
    got = read(fd, buf, cap);
    if (got == 0) {
        errno = 0;
    }
    return got > 0 ? (int32_t)got : GATE_NET_CLOSED;
}


bool gateNetSendAll(int fd, const void *data, size_t len) {
    const uint8_t *at;
    ssize_t        put;

    at = (const uint8_t *)data;
    while (len > 0u) {
        put = write(fd, at, len);
        if (put < 0 && errno == EINTR) {
            continue;
        }
        if (put <= 0) {
            return false;
        }
        at  += put;
        len -= (size_t)put;
    }
    return true;
}


void gateNetShowBytes(FILE *out, const void *data, size_t len) {
    const uint8_t *bytes;
    size_t         i;
    uint8_t        c;

    bytes = (const uint8_t *)data;
    fputc('"', out);
    for (i = 0; i < len; i++) {
        c = bytes[i];
        if (c == '"' || c == '\\') {
            fprintf(out, "\\%c", c);
        } else if (c == '\n') {
            fputs("\\n", out);
        } else if (c == '\r') {
            fputs("\\r", out);
        } else if (c == '\t') {
            fputs("\\t", out);
        } else if (c < SHOW_PRINTABLE || c >= SHOW_DELETE) {
            fprintf(out, "\\x%02x", c);
        } else {
            fputc(c, out);
        }
    }
    fputc('"', out);
}


void gateNetSleep(double seconds) {
    struct timespec left;

    if (seconds <= 0.0) {
        return;
    }
    left.tv_sec  = (time_t)seconds;
    left.tv_nsec = (long)((seconds - (double)left.tv_sec) * NS_PER_SECOND);
    while (nanosleep(&left, &left) != 0 && errno == EINTR) {
        // A signal cut the sleep short: sleep what is left of it.
    }
}


void gateNetStart(const char *toolName) {
    toolFileName(toolName);
    setvbuf(stdout, NULL, _IOLBF, 0);
    signal(SIGPIPE, SIG_IGN);
}


bool gateNetWait(int fd, short events, double seconds) {
    struct pollfd watch;
    double        ms;
    int           timeoutMs;
    int           ready;

    // Whole milliseconds, rounded up: never a shorter wait than asked.
    ms           = ceil(seconds * MS_PER_SECOND);
    timeoutMs    = ms >= (double)INT_MAX ? WAIT_FOREVER : (ms > 0.0 ? (int)ms : 0);
    watch.fd     = fd;
    watch.events = events;
    do {
        watch.revents = 0;
        ready         = poll(&watch, 1, timeoutMs);
    } while (ready < 0 && errno == EINTR);
    // An error is "ready": the read or write that follows reports it.
    return ready != 0;
}