/* hooks.c -- Hooks triggered by events
 * This file is part of redshift-ng.
 * 
 * redshift-ng 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 3 of the License, or
 * (at your option) any later version.
 * 
 * redshift-ng 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 redshift-ng.  If not, see <http://www.gnu.org/licenses/>.
 * 
 * Copyright (c) 2014  Jon Lund Steffensen <jonlst@gmail.com>
 */
#include "common.h"

#define MAX_HOOK_PATH  4096


/* Names of periods supplied to scripts. */
static const char *period_names[] = {
	"none",
	"daytime",
	"night",
	"transition"
};


/* Try to open the directory containing hooks. HP is a string
   of MAX_HOOK_PATH length that will be filled with the path
   of the returned directory. */
static DIR *
open_hooks_dir(char *hp)
{
	char *env;

#ifndef WINDOWS
	struct passwd *pwd;
#endif

	env = getenv("XDG_CONFIG_HOME");
	if (env && *env) {
		snprintf(hp, MAX_HOOK_PATH, "%s/redshift/hooks", env);
		return opendir(hp);
	}

	env = getenv("HOME");
	if (env && *env) {
		snprintf(hp, MAX_HOOK_PATH, "%s/.config/redshift/hooks", env);
		return opendir(hp);
	}

#ifndef WINDOWS
	pwd = getpwuid(getuid()); /* TODO check failure */
	snprintf(hp, MAX_HOOK_PATH, "%s/.config/redshift/hooks", pwd->pw_dir);
	return opendir(hp);
#else
	return NULL;
#endif
}

/* Run hooks with a signal that the period changed. */
void
hooks_signal_period_change(enum period prev_period, enum period period)
{
	char hooksdir_path[MAX_HOOK_PATH];
	DIR *hooks_dir;
	struct dirent *ent;
	char *hook_name;
	char hook_path[MAX_HOOK_PATH];
	int r;

	hooks_dir = open_hooks_dir(hooksdir_path);
	if (!hooks_dir)
		return;

	while ((ent = readdir(hooks_dir))) {
		/* Skip hidden and special files (., ..) */
		if (ent->d_name[0] == '\0' || ent->d_name[0] == '.')
			continue;

		hook_name = ent->d_name;
		snprintf(hook_path, sizeof(hook_path), "%s/%s", hooksdir_path, hook_name);

#ifndef WINDOWS
		/* Fork and exec the hook. We close stdout
		   so the hook cannot interfere with the normal
		   output. */
		switch (fork()) {
		case -1:
			weprintf("fork:");
			break;
		case 0:
			close(STDOUT_FILENO);

			r = execl(hook_path, hook_name,
			          "period-changed",
			          period_names[prev_period],
			          period_names[period], NULL);
			if (r < 0 && errno != EACCES)
				weprintf("execl %s:", hook_path);

			/* Only reached on error */
			_exit(1);
		default:
			/* SIGCHLD is ignored */
			break;
		}
#endif
	}
}