/*************************************************************************
 * Copyright (C) 2009-2014 Tavian Barnes <tavianator@tavianator.com>     *
 *                                                                       *
 * This file is part of The Dimension Library.                           *
 *                                                                       *
 * The Dimension Library is free software; you can redistribute it and/  *
 * or modify it under the terms of the GNU Lesser General Public License *
 * as published by the Free Software Foundation; either version 3 of the *
 * License, or (at your option) any later version.                       *
 *                                                                       *
 * The Dimension Library is distributed in the hope that it will be      *
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty   *
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU  *
 * Lesser General Public License for more details.                       *
 *                                                                       *
 * You should have received a copy of the GNU Lesser General Public      *
 * License along with this program.  If not, see                         *
 * <http://www.gnu.org/licenses/>.                                       *
 *************************************************************************/

/**
 * @file
 * Error handling.
 */

#include "internal.h"
#include "internal/platform.h"
#include <errno.h>
#include <pthread.h>
#include <stdatomic.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/// Report internal errors in this file.
#define DMNSN_LOCAL_ERROR(str)                          \
  do {                                                  \
    fprintf(stderr, "Dimension ERROR: %s, %s:%u: %s\n", \
            DMNSN_FUNC, __FILE__, __LINE__, (str));     \
    abort();                                            \
  } while (0)

/// The default fatal error handler.
static void dmnsn_default_fatal_error_fn(void);

/// The current fatal error handler.
static atomic(dmnsn_fatal_error_fn *) dmnsn_fatal = ATOMIC_VAR_INIT(dmnsn_default_fatal_error_fn);

/// The current resilience.
static atomic_bool dmnsn_always_die = ATOMIC_VAR_INIT(false);

void
dmnsn_report_impl(bool die, const char *func, const char *file, unsigned int line, const char *str)
{
  // Save the value of errno
  int err = errno;

  bool always_die = atomic_load(&dmnsn_always_die);

  // Print the diagnostic string
  fprintf(stderr, "Dimension %s: %s, %s:%u: %s\n",
          die ? "ERROR" : "WARNING", func, file, line, str);

  // Print the value of errno
  if (err != 0) {
    fprintf(stderr, "Last error: %d", err);
#if DMNSN_STRERROR_R
    char errbuf[256];
    if (strerror_r(err, errbuf, 256) == 0) {
      fprintf(stderr, " (%s)", errbuf);
    }
#elif DMNSN_SYS_ERRLIST
    if (err >= 0 && err < sys_nerr) {
      fprintf(stderr, " (%s)", sys_errlist[err]);
    }
#endif
    fprintf(stderr, "\n");
  }

  // Print a stack trace to standard error
  dmnsn_backtrace(stderr);

  // Call the fatal error handler if needed
  if (die || always_die) {
    static __thread bool thread_exiting = false;

    if (thread_exiting) {
      if (die) {
        // Prevent infinite recursion if the fatal error function itself calls
        // dmnsn_error() (not dmnsn_warning())
        DMNSN_LOCAL_ERROR("Error raised while in error handler, aborting.");
      }
    } else {
      thread_exiting = true;

      dmnsn_fatal_error_fn *fatal = dmnsn_get_fatal_error_fn();
      fatal();
      DMNSN_LOCAL_ERROR("Fatal error handler didn't exit.");
    }
  }
}

void
dmnsn_report_warning(const char *func, const char *file, unsigned int line, const char *str)
{
  dmnsn_report_impl(false, func, file, line, str);
}

DMNSN_NORETURN
dmnsn_report_error(const char *func, const char *file, unsigned int line, const char *str)
{
  dmnsn_report_impl(true, func, file, line, str);
  DMNSN_UNREACHABLE();
}

void
dmnsn_die_on_warnings(bool always_die)
{
  atomic_store(&dmnsn_always_die, always_die);
}

dmnsn_fatal_error_fn *
dmnsn_get_fatal_error_fn(void)
{
  dmnsn_fatal_error_fn *fatal = atomic_load(&dmnsn_fatal);
  return fatal;
}

void
dmnsn_set_fatal_error_fn(dmnsn_fatal_error_fn *fatal)
{
  atomic_store(&dmnsn_fatal, fatal);
}

static void
dmnsn_default_fatal_error_fn(void)
{
  if (dmnsn_is_main_thread()) {
    exit(EXIT_FAILURE);
  } else {
    pthread_exit(NULL);
  }
}