/* Pinos
 * Copyright (C) 2016 Axis Communications <dev-gstreamer@axis.com>
 * @author Linus Svensson <linus.svensson@axis.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <dlfcn.h>

#include "pinos/client/pinos.h"
#include "pinos/client/utils.h"
#include "pinos/server/module.h"

#define PINOS_SYMBOL_MODULE_INIT "pinos__module_init"

typedef struct
{
  PinosModule this;

  void *hnd;
} PinosModuleImpl;

static char *
find_module (const char * path, const char *name)
{
  gchar *filename;
  GDir *dir;
  const gchar *entry;
  GError *err = NULL;

  filename = g_strconcat (path, G_DIR_SEPARATOR_S, name, ".", G_MODULE_SUFFIX, NULL);

  if (g_file_test (filename, G_FILE_TEST_IS_REGULAR)) {
    /* found a regular file with name */
    return filename;
  }

  g_clear_pointer (&filename, g_free);

  /* now recurse down in subdirectories and look for it there */

  dir = g_dir_open (path, 0, &err);
  if (dir == NULL) {
    pinos_log_warn ("could not open %s: %s", path, err->message);
    g_error_free (err);
    return NULL;
  }

  while ((entry = g_dir_read_name (dir))) {
    gchar *newpath;

    newpath = g_build_filename (path, entry, NULL);
    if (g_file_test (newpath, G_FILE_TEST_IS_DIR)) {
      filename = find_module (newpath, name);
    }
    g_free (newpath);

    if (filename != NULL)
      break;
  }

  g_dir_close (dir);

  return filename;
}

/**
 * pinos_module_load:
 * @core: a #PinosCore
 * @name: name of the module to load
 * @args: A string with arguments for the module
 * @err: Return location for an error string, or %NULL
 *
 * Load module with @name.
 *
 * Returns: A #PinosModule if the module could be loaded, or %NULL on failure.
 */
PinosModule *
pinos_module_load (PinosCore    *core,
                   const gchar  *name,
                   const gchar  *args,
                   char        **err)
{
  PinosModule *this;
  PinosModuleImpl *impl;
  void *hnd;
  char *filename = NULL;
  const char *module_dir;
  PinosModuleInitFunc init_func;

  module_dir = getenv ("PINOS_MODULE_DIR");
  if (module_dir != NULL) {
    char **l;
    int i, n_paths;

    pinos_log_debug ("PINOS_MODULE_DIR set to: %s", module_dir);

    l = pinos_split_strv (module_dir, G_SEARCHPATH_SEPARATOR_S, 0, &n_paths);
    for (i = 0; l[i] != NULL; i++) {
      filename = find_module (l[i], name);
      if (filename != NULL)
        break;
    }
    pinos_free_strv (l);
  } else {
    pinos_log_debug ("moduledir set to: %s", MODULEDIR);

    filename = find_module (MODULEDIR, name);
  }

  if (filename == NULL)
    goto not_found;

  pinos_log_debug ("trying to load module: %s (%s)", name, filename);

  hnd = dlopen (filename, RTLD_NOW | RTLD_LOCAL);
  free (filename);

  if (hnd == NULL)
    goto open_failed;

  if ((init_func = dlsym (hnd, PINOS_SYMBOL_MODULE_INIT)) == NULL)
    goto no_pinos_module;

  impl = calloc (1, sizeof (PinosModuleImpl));
  impl->hnd = hnd;

  this = &impl->this;
  this->name = strdup (name);
  this->core = core;

  if (!init_func (this, (gchar *) args))
    goto init_failed;

  pinos_log_debug ("loaded module: %s", this->name);

  return this;

not_found:
  {
    asprintf (err, "No module \"%s\" was found", name);
    return NULL;
  }
open_failed:
  {
    asprintf (err, "Failed to open module: %s", dlerror ());
    return NULL;
  }
no_pinos_module:
  {
    asprintf (err, "\"%s\" is not a pinos module", name);
    dlclose (hnd);
    return NULL;
  }
init_failed:
  {
    asprintf (err, "\"%s\" failed to initialize", name);
    pinos_module_destroy (this);
    return NULL;
  }
}

void
pinos_module_destroy (PinosModule *this)
{
  PinosModuleImpl *impl = SPA_CONTAINER_OF (this, PinosModuleImpl, this);

  pinos_signal_emit (&this->destroy_signal, this);

  free (this->name);
  dlclose (impl->hnd);
  free (impl);
}