#define _ALL_SOURCE
#include "libc.h"
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <syslog.h>
#include <threads.h>
#include <time.h>
#include <unistd.h>

static mtx_t lock = MTX_INIT;
static char log_ident[32];
static int log_opt;
static int log_facility = LOG_USER;
static int log_mask = 0xff;
static int log_fd = -1;

int setlogmask(int maskpri) {
    mtx_lock(&lock);
    int ret = log_mask;
    if (maskpri)
        log_mask = maskpri;
    mtx_unlock(&lock);
    return ret;
}

static const struct {
    short sun_family;
    char sun_path[9];
} log_addr = {AF_UNIX, "/dev/log"};

void closelog(void) {
    mtx_lock(&lock);
    close(log_fd);
    log_fd = -1;
    mtx_unlock(&lock);
}

static void __openlog(void) {
    log_fd = socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0);
    if (log_fd >= 0)
        connect(log_fd, (void*)&log_addr, sizeof log_addr);
}

void openlog(const char* ident, int opt, int facility) {
    mtx_lock(&lock);

    if (ident) {
        size_t n = strnlen(ident, sizeof log_ident - 1);
        memcpy(log_ident, ident, n);
        log_ident[n] = 0;
    } else {
        log_ident[0] = 0;
    }
    log_opt = opt;
    log_facility = facility;

    if ((opt & LOG_NDELAY) && log_fd < 0)
        __openlog();

    mtx_unlock(&lock);
}

static int is_lost_conn(int e) {
    return e == ECONNREFUSED || e == ECONNRESET || e == ENOTCONN || e == EPIPE;
}

static void _vsyslog(int priority, const char* message, va_list ap) {
    char timebuf[16];
    time_t now;
    struct tm tm;
    char buf[1024];
    int errno_save = errno;
    int pid;
    int l, l2;
    int hlen;
    int fd;

    if (log_fd < 0)
        __openlog();

    if (!(priority & LOG_FACMASK))
        priority |= log_facility;

    now = time(NULL);
    gmtime_r(&now, &tm);
    strftime(timebuf, sizeof timebuf, "%b %e %T", &tm);

    pid = (log_opt & LOG_PID) ? getpid() : 0;
    l = snprintf(buf, sizeof buf, "<%d>%s %n%s%s%.0d%s: ", priority, timebuf, &hlen, log_ident,
                 pid ? "[" : "", pid, pid ? "]" : "");
    errno = errno_save;
    l2 = vsnprintf(buf + l, sizeof buf - l, message, ap);
    if (l2 >= 0) {
        if ((size_t)l2 >= sizeof(buf) - l)
            l = sizeof(buf) - 1;
        else
            l += l2;
        if (buf[l - 1] != '\n')
            buf[l++] = '\n';
        if (send(log_fd, buf, l, 0) < 0 &&
            (!is_lost_conn(errno) || connect(log_fd, (void*)&log_addr, sizeof log_addr) < 0 ||
             send(log_fd, buf, l, 0) < 0) &&
            (log_opt & LOG_CONS)) {
            fd = open("/dev/console", O_WRONLY | O_NOCTTY | O_CLOEXEC);
            if (fd >= 0) {
                dprintf(fd, "%.*s", l - hlen, buf + hlen);
                close(fd);
            }
        }
        if (log_opt & LOG_PERROR)
            dprintf(2, "%.*s", l - hlen, buf + hlen);
    }
}

void __vsyslog(int priority, const char* message, va_list ap) {
    if (!(log_mask & LOG_MASK(priority & 7)) || (priority & ~0x3ff))
        return;
    mtx_lock(&lock);
    _vsyslog(priority, message, ap);
    mtx_unlock(&lock);
}

void syslog(int priority, const char* message, ...) {
    va_list ap;
    va_start(ap, message);
    __vsyslog(priority, message, ap);
    va_end(ap);
}

weak_alias(__vsyslog, vsyslog);