/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */

/* Mutter main() */

/*
 * Copyright (C) 2001 Havoc Pennington
 * Copyright (C) 2006 Elijah Newren
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program 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
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

/**
 * SECTION:main
 * @title: Main
 * @short_description: Program startup.
 *
 * Functions which parse the command-line arguments, create the display,
 * kick everything off and then close down Mutter when it's time to go.
 *
 *
 *
 * Mutter - a boring window manager for the adult in you
 *
 * Many window managers are like Marshmallow Froot Loops; Mutter
 * is like Frosted Flakes: it's still plain old corn, but dusted
 * with some sugar.
 *
 * The best way to get a handle on how the whole system fits together
 * is discussed in doc/code-overview.txt; if you're looking for functions
 * to investigate, read main(), meta_display_open(), and event_callback().
 */

#define _GNU_SOURCE
#define _XOPEN_SOURCE /* for putenv() and some signal-related functions */

#include <config.h>
#include <meta/main.h>
#include "util-private.h"
#include "display-private.h"
#include <meta/errors.h>
#include "ui.h"
#include <meta/prefs.h>
#include <meta/compositor.h>

#include <glib-object.h>
#include <glib-unix.h>

#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <locale.h>
#include <time.h>
#include <unistd.h>

#include <clutter/clutter.h>

#ifdef HAVE_INTROSPECTION
#include <girepository.h>
#endif

#include "x11/session.h"

#include "wayland/meta-wayland.h"
#include "backends/meta-backend.h"

/*
 * The exit code we'll return to our parent process when we eventually die.
 */
static MetaExitCode meta_exit_code = META_EXIT_SUCCESS;

/*
 * Handle on the main loop, so that we have an easy way of shutting Mutter
 * down.
 */
static GMainLoop *meta_main_loop = NULL;

static void prefs_changed_callback (MetaPreference pref,
                                    gpointer       data);

/**
 * meta_print_compilation_info:
 *
 * Prints a list of which configure script options were used to
 * build this copy of Mutter. This is actually always called
 * on startup, but it's all no-op unless we're in verbose mode
 * (see meta_set_verbose()).
 */
static void
meta_print_compilation_info (void)
{
#ifdef HAVE_RANDR
  meta_verbose ("Compiled with randr extension\n");
#else
  meta_verbose ("Compiled without randr extension\n");
#endif
#ifdef HAVE_STARTUP_NOTIFICATION
  meta_verbose ("Compiled with startup notification\n");
#else
  meta_verbose ("Compiled without startup notification\n");
#endif
}

/**
 * meta_print_self_identity:
 *
 * Prints the version number, the current timestamp (not the
 * build date), the locale, the character encoding, and a list
 * of configure script options that were used to build this
 * copy of Mutter. This is actually always called
 * on startup, but it's all no-op unless we're in verbose mode
 * (see meta_set_verbose()).
 */
static void
meta_print_self_identity (void)
{
  char buf[256];
  GDate d;
  const char *charset;

  /* Version and current date. */
  g_date_clear (&d, 1);
  g_date_set_time_t (&d, time (NULL));
  g_date_strftime (buf, sizeof (buf), "%x", &d);
  meta_verbose ("Mutter version %s running on %s\n",
    VERSION, buf);

  /* Locale and encoding. */
  g_get_charset (&charset);
  meta_verbose ("Running in locale \"%s\" with encoding \"%s\"\n",
    setlocale (LC_ALL, NULL), charset);

  /* Compilation settings. */
  meta_print_compilation_info ();
}

/*
 * The set of possible options that can be set on Mutter's
 * command line.
 */
static gchar    *opt_save_file;
static gchar    *opt_display_name;
static gchar    *opt_client_id;
static gboolean  opt_replace_wm;
static gboolean  opt_disable_sm;
static gboolean  opt_sync;
static gboolean  opt_wayland;
#ifdef HAVE_NATIVE_BACKEND
static gboolean  opt_display_server;
#endif

static GOptionEntry meta_options[] = {
  {
    "sm-disable", 0, 0, G_OPTION_ARG_NONE,
    &opt_disable_sm,
    N_("Disable connection to session manager"),
    NULL
  },
  {
    "replace", 'r', 0, G_OPTION_ARG_NONE,
    &opt_replace_wm,
    N_("Replace the running window manager"),
    NULL
  },
  {
    "sm-client-id", 0, 0, G_OPTION_ARG_STRING,
    &opt_client_id,
    N_("Specify session management ID"),
    "ID"
  },
  {
    "display", 'd', 0, G_OPTION_ARG_STRING,
    &opt_display_name, N_("X Display to use"),
    "DISPLAY"
  },
  {
    "sm-save-file", 0, 0, G_OPTION_ARG_FILENAME,
    &opt_save_file,
    N_("Initialize session from savefile"),
    "FILE"
  },
  {
    "sync", 0, 0, G_OPTION_ARG_NONE,
    &opt_sync,
    N_("Make X calls synchronous"),
    NULL
  },
  {
    "wayland", 0, 0, G_OPTION_ARG_NONE,
    &opt_wayland,
    N_("Run as a wayland compositor"),
    NULL
  },
#ifdef HAVE_NATIVE_BACKEND
  {
    "display-server", 0, 0, G_OPTION_ARG_NONE,
    &opt_display_server,
    N_("Run as a full display server, rather than nested")
  },
#endif
  {NULL}
};

/**
 * meta_get_option_context: (skip)
 *
 * Returns a #GOptionContext initialized with mutter-related options.
 * Parse the command-line args with this before calling meta_init().
 *
 * Return value: the #GOptionContext
 */
GOptionContext *
meta_get_option_context (void)
{
  GOptionContext *ctx;

  if (setlocale (LC_ALL, "") == NULL)
    meta_warning ("Locale not understood by C library, internationalization will not work\n");
  bindtextdomain (GETTEXT_PACKAGE, MUTTER_LOCALEDIR);
  bind_textdomain_codeset (GETTEXT_PACKAGE, "UTF-8");

  ctx = g_option_context_new (NULL);
  g_option_context_add_main_entries (ctx, meta_options, GETTEXT_PACKAGE);
  return ctx;
}

/**
 * meta_select_display:
 *
 * Selects which display Mutter should use. It first tries to use
 * @display_name as the display. If @display_name is %NULL then
 * try to use the environment variable MUTTER_DISPLAY. If that
 * also is %NULL, use the default - :0.0
 */
static void
meta_select_display (char *display_arg)
{
  const char *display_name;

  if (display_arg)
    display_name = (const char *) display_arg;
  else
    display_name = g_getenv ("MUTTER_DISPLAY");

  if (display_name)
    g_setenv ("DISPLAY", display_name, TRUE);
}

static void
meta_finalize (void)
{
  MetaDisplay *display = meta_get_display ();

  if (display)
    meta_display_close (display,
                        CurrentTime); /* I doubt correct timestamps matter here */

  if (meta_is_wayland_compositor ())
    meta_wayland_finalize ();
}

static gboolean
on_sigterm (gpointer user_data)
{
  meta_quit (EXIT_SUCCESS);

  return G_SOURCE_REMOVE;
}

/**
 * meta_init: (skip)
 *
 * Initialize mutter. Call this after meta_get_option_context() and
 * meta_plugin_manager_set_plugin_type(), and before meta_run().
 */
void
meta_init (void)
{
  struct sigaction act;
  sigset_t empty_mask;
  ClutterSettings *clutter_settings;

  sigemptyset (&empty_mask);
  act.sa_handler = SIG_IGN;
  act.sa_mask    = empty_mask;
  act.sa_flags   = 0;
  if (sigaction (SIGPIPE,  &act, NULL) < 0)
    g_printerr ("Failed to register SIGPIPE handler: %s\n",
                g_strerror (errno));
#ifdef SIGXFSZ
  if (sigaction (SIGXFSZ,  &act, NULL) < 0)
    g_printerr ("Failed to register SIGXFSZ handler: %s\n",
                g_strerror (errno));
#endif

  g_unix_signal_add (SIGTERM, on_sigterm, NULL);

  if (g_getenv ("MUTTER_VERBOSE"))
    meta_set_verbose (TRUE);
  if (g_getenv ("MUTTER_DEBUG"))
    meta_set_debugging (TRUE);

#if defined(CLUTTER_WINDOWING_EGL) && defined(HAVE_NATIVE_BACKEND)
  if (opt_display_server)
    clutter_set_windowing_backend (CLUTTER_WINDOWING_EGL);
#endif

  meta_set_is_wayland_compositor (opt_wayland);

  if (g_get_home_dir ())
    if (chdir (g_get_home_dir ()) < 0)
      meta_warning ("Could not change to home directory %s.\n",
                    g_get_home_dir ());

  meta_print_self_identity ();

#ifdef HAVE_INTROSPECTION
  g_irepository_prepend_search_path (MUTTER_PKGLIBDIR);
#endif

  if (meta_is_wayland_compositor ())
    {
      /* NB: When running as a hybrid wayland compositor we run our own headless X
       * server so the user can't control the X display to connect too. */
      meta_wayland_init ();
    }
  else
    meta_select_display (opt_display_name);

  meta_set_syncing (opt_sync || (g_getenv ("MUTTER_SYNC") != NULL));

  if (opt_replace_wm)
    meta_set_replace_current_wm (TRUE);

  if (opt_save_file && opt_client_id)
    meta_fatal ("Can't specify both SM save file and SM client id\n");

  meta_main_loop = g_main_loop_new (NULL, FALSE);

  meta_ui_init ();

  /* If we are running with wayland then we don't wait until we have
   * an X connection before initializing clutter we instead initialize
   * it earlier since we need to initialize the GL driver so the driver
   * can register any needed wayland extensions. */
  if (!meta_is_wayland_compositor ())
    {
      /*
       * Clutter can only be initialized after the UI.
       */
      meta_clutter_init ();
    }

  /*
   * XXX: We cannot handle high dpi scaling yet, so fix the scale to 1
   * for now.
   */
  clutter_settings = clutter_settings_get_default ();
  g_object_set (clutter_settings, "window-scaling-factor", 1, NULL);
}

/**
 * meta_register_with_session:
 *
 * Registers mutter with the session manager.  Call this after completing your own
 * initialization.
 *
 * This should be called when the session manager can safely continue to the
 * next phase of startup and potentially display windows.
 */
void
meta_register_with_session (void)
{
  if (!opt_disable_sm)
    {
      if (opt_client_id == NULL)
        {
          const gchar *desktop_autostart_id;

          desktop_autostart_id = g_getenv ("DESKTOP_AUTOSTART_ID");

          if (desktop_autostart_id != NULL)
            opt_client_id = g_strdup (desktop_autostart_id);
        }

      /* Unset DESKTOP_AUTOSTART_ID in order to avoid child processes to
       * use the same client id. */
      g_unsetenv ("DESKTOP_AUTOSTART_ID");

      meta_session_init (opt_client_id, opt_save_file);
    }
  /* Free memory possibly allocated by the argument parsing which are
   * no longer needed.
   */
  g_free (opt_save_file);
  g_free (opt_display_name);
  g_free (opt_client_id);
}

/**
 * meta_run: (skip)
 *
 * Runs mutter. Call this after completing initialization that doesn't require
 * an event loop.
 *
 * Return value: mutter's exit status
 */
int
meta_run (void)
{
  /* Load prefs */
  meta_prefs_init ();
  meta_prefs_add_listener (prefs_changed_callback, NULL);

  meta_ui_set_current_theme (meta_prefs_get_theme ());

  /* Try to find some theme that'll work if the theme preference
   * doesn't exist.  First try Simple (the default theme) then just
   * try anything in the themes directory.
   */
  if (!meta_ui_have_a_theme ())
    meta_ui_set_current_theme ("Simple");

  if (!meta_ui_have_a_theme ())
    {
      const char *dir_entry = NULL;
      GError *err = NULL;
      GDir   *themes_dir = NULL;

      if (!(themes_dir = g_dir_open (MUTTER_DATADIR"/themes", 0, &err)))
        {
          meta_fatal (_("Failed to scan themes directory: %s\n"), err->message);
          g_error_free (err);
        }
      else
        {
          while (((dir_entry = g_dir_read_name (themes_dir)) != NULL) &&
                 (!meta_ui_have_a_theme ()))
            {
              meta_ui_set_current_theme (dir_entry);
            }

          g_dir_close (themes_dir);
        }
    }

  if (!meta_ui_have_a_theme ())
    meta_fatal (_("Could not find a theme! Be sure %s exists and contains the usual themes.\n"),
                MUTTER_DATADIR"/themes");

  if (!meta_display_open ())
    meta_exit (META_EXIT_ERROR);

  g_main_loop_run (meta_main_loop);

  meta_finalize ();

  return meta_exit_code;
}

/**
 * meta_quit:
 * @code: The success or failure code to return to the calling process.
 *
 * Stops Mutter. This tells the event loop to stop processing; it is
 * rather dangerous to use this because this will leave the user with
 * no window manager. We generally do this only if, for example, the
 * session manager asks us to; we assume the session manager knows
 * what it's talking about.
 */
void
meta_quit (MetaExitCode code)
{
  if (g_main_loop_is_running (meta_main_loop))
    {
      meta_exit_code = code;
      g_main_loop_quit (meta_main_loop);
    }
}

/**
 * prefs_changed_callback:
 * @pref:  Which preference has changed
 * @data:  Arbitrary data (which we ignore)
 *
 * Called on pref changes. (One of several functions of its kind and purpose.)
 *
 * FIXME: Why are these particular prefs handled in main.c and not others?
 *        Should they be?
 */
static void
prefs_changed_callback (MetaPreference pref,
                        gpointer       data)
{
  switch (pref)
    {
    case META_PREF_THEME:
    case META_PREF_DRAGGABLE_BORDER_WIDTH:
      meta_ui_set_current_theme (meta_prefs_get_theme ());
      meta_display_retheme_all ();
      break;

    default:
      /* handled elsewhere or otherwise */
      break;
    }
}