#include <time.h>
#include <setjmp.h>
#include "pthread_impl.h"

struct ksigevent {
  union sigval sigev_value;
  int sigev_signo;
  int sigev_notify;
  int sigev_tid;
};

struct start_args {
  pthread_barrier_t b;
  struct sigevent* sev;
};

static void dummy_1(pthread_t self) {}
weak_alias(dummy_1, __pthread_tsd_run_dtors);

void __reset_tls();

static void cleanup_fromsig(void* p) {
  pthread_t self = __pthread_self();
  __pthread_tsd_run_dtors(self);
  self->cancel = 0;
  self->cancelbuf = 0;
  self->canceldisable = 0;
  self->cancelasync = 0;
  self->unblock_cancel = 0;
  __reset_tls();
  longjmp(p, 1);
}

static void timer_handler(int sig, siginfo_t* si, void* ctx) {
  pthread_t self = __pthread_self();
  jmp_buf jb;
  void (*notify)(union sigval) = (void (*)(union sigval))self->start;
  union sigval val = {.sival_ptr = self->start_arg};

  if (!setjmp(jb) && si->si_code == SI_TIMER) {
    pthread_cleanup_push(cleanup_fromsig, jb);
    notify(val);
    pthread_cleanup_pop(1);
  }
}

static void install_handler() {
  struct sigaction sa = {.sa_sigaction = timer_handler,
                         .sa_flags = SA_SIGINFO | SA_RESTART};
  __libc_sigaction(SIGTIMER, &sa, 0);
}

static void* start(void* arg) {
  pthread_t self = __pthread_self();
  struct start_args* args = arg;
  int id;

  /* Reuse no-longer-needed thread structure fields to avoid
   * needing the timer address in the signal handler. */
  self->start = (void* (*)(void*))args->sev->sigev_notify_function;
  self->start_arg = args->sev->sigev_value.sival_ptr;

  pthread_barrier_wait(&args->b);
  if ((id = self->timer_id) >= 0) {
    __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, SIGTIMER_SET, 0, _NSIG / 8);
    __wait(&self->timer_id, 0, id, 1);
    __syscall(SYS_timer_delete, id);
  }
  return 0;
}

int timer_create(clockid_t clk,
                 struct sigevent* restrict evp,
                 timer_t* restrict res) {
  static pthread_once_t once = PTHREAD_ONCE_INIT;
  pthread_t td;
  pthread_attr_t attr;
  int r;
  struct start_args args;
  struct ksigevent ksev, *ksevp = 0;
  int timerid;
  sigset_t set;

  switch (evp ? evp->sigev_notify : SIGEV_SIGNAL) {
    case SIGEV_NONE:
    case SIGEV_SIGNAL:
      if (evp) {
        ksev.sigev_value = evp->sigev_value;
        ksev.sigev_signo = evp->sigev_signo;
        ksev.sigev_notify = evp->sigev_notify;
        ksev.sigev_tid = 0;
        ksevp = &ksev;
      }
      if (syscall(SYS_timer_create, clk, ksevp, &timerid) < 0)
        return -1;
      *res = (void*)(intptr_t)timerid;
      break;
    case SIGEV_THREAD:
      pthread_once(&once, install_handler);
      if (evp->sigev_notify_attributes)
        attr = *evp->sigev_notify_attributes;
      else
        pthread_attr_init(&attr);
      pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
      pthread_barrier_init(&args.b, 0, 2);
      args.sev = evp;

      __block_app_sigs(&set);
      r = pthread_create(&td, &attr, start, &args);
      __restore_sigs(&set);
      if (r) {
        errno = r;
        return -1;
      }

      ksev.sigev_value.sival_ptr = 0;
      ksev.sigev_signo = SIGTIMER;
      ksev.sigev_notify = 4; /* SIGEV_THREAD_ID */
      ksev.sigev_tid = td->tid;
      if (syscall(SYS_timer_create, clk, &ksev, &timerid) < 0)
        timerid = -1;
      td->timer_id = timerid;
      pthread_barrier_wait(&args.b);
      if (timerid < 0)
        return -1;
      *res = (void*)(INTPTR_MIN | (uintptr_t)td >> 1);
      break;
    default:
      errno = EINVAL;
      return -1;
  }

  return 0;
}