/*
 * Asterisk -- A telephony toolkit for Linux.
 *
 * Check if Channel is Available
 * 
 * Copyright (C) 2003, Digium
 *
 * Mark Spencer <markster@digium.com>
 * James Golovich <james@gnuinter.net>
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License
 *
 */

#include <asterisk/lock.h>
#include <asterisk/file.h>
#include <asterisk/logger.h>
#include <asterisk/channel.h>
#include <asterisk/pbx.h>
#include <asterisk/module.h>
#include <asterisk/app.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <sys/ioctl.h>

static char *tdesc = "Check if channel is available";

static char *app = "ChanIsAvail";

static char *synopsis = "Check if channel is available";

static char *descrip = 
"  ChanIsAvail(Technology/resource[&Technology2/resource2...]): \n"
"Checks is any of the requested channels are available.  If none\n"
"of the requested channels are available the new priority will be\n"
"n+101 (unless such a priority does not exist or on error, in which\n"
"case ChanIsAvail will return -1).  If any of the requested channels\n"
"are available, the next priority will be n+1, the channel variable\n"
"${AVAILCHAN} will be set to the name of the available channel and\n"
"the ChanIsAvail app will return 0.  ${AVAILORIGCHAN} is\n"
"the canonical channel name that was used to create the channel.\n";

STANDARD_LOCAL_USER;

LOCAL_USER_DECL;

static int chanavail_exec(struct ast_channel *chan, void *data)
{
	int res=-1;
	struct localuser *u;
	char info[512], tmp[512], *peers, *tech, *number, *rest, *cur;
	struct ast_channel *tempchan;

	if (!data) {
		ast_log(LOG_WARNING, "ChanIsAvail requires an argument (Zap/1&Zap/2)\n");
		return -1;
	}
	LOCAL_USER_ADD(u);

	strncpy(info, (char *)data, sizeof(info)-1);
	peers = info;
	if (peers) {
		cur = peers;
		do {
			/* remember where to start next time */
			rest = strchr(cur, '&');
			if (rest) {
				*rest = 0;
				rest++;
			}
			tech = cur;
			number = strchr(tech, '/');
			if (!number) {
				ast_log(LOG_WARNING, "ChanIsAvail argument takes format ([technology]/[device])\n");
				return -1;
			}
			*number = '\0';
			number++;
			if ((tempchan = ast_request(tech, chan->nativeformats, number))) {
					pbx_builtin_setvar_helper(chan, "AVAILCHAN", tempchan->name);
					/* Store the originally used channel too */
					snprintf(tmp, sizeof(tmp), "%s/%s", tech, number);
					pbx_builtin_setvar_helper(chan, "AVAILORIGCHAN", tmp);
					ast_hangup(tempchan);
					tempchan = NULL;
					res = 1;
					break;
			}
			cur = rest;
		} while (cur);
	}

	if (res < 1) {
		pbx_builtin_setvar_helper(chan, "AVAILCHAN", "");
		pbx_builtin_setvar_helper(chan, "AVAILORIGCHAN", "");
		if (ast_exists_extension(chan, chan->context, chan->exten, chan->priority + 101, chan->callerid))
			chan->priority+=100;
		else
			return -1;
	}

	LOCAL_USER_REMOVE(u);
	return 0;
}

int unload_module(void)
{
	STANDARD_HANGUP_LOCALUSERS;
	return ast_unregister_application(app);
}

int load_module(void)
{
	return ast_register_application(app, chanavail_exec, synopsis, descrip);
}

char *description(void)
{
	return tdesc;
}

int usecount(void)
{
	int res;
	STANDARD_USECOUNT(res);
	return res;
}

char *key()
{
	return ASTERISK_GPL_KEY;
}