/*
* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 1999 - 2005, Digium, Inc.
*
* Mark Spencer <markster@digium.com>
* James Golovich <james@gnuinter.net>
*
* See http://www.asterisk.org for more information about
* the Asterisk project. Please do not directly contact
* any of the maintainers of this project for assistance;
* the project provides a web site, mailing lists and IRC
* channels for your use.
*
* This program is free software, distributed under the terms of
* the GNU General Public License Version 2. See the LICENSE file
* at the top of the source tree.
*/

/*! \file
 * 
 * \brief Check if Channel is Available
 * 
 * \author Mark Spencer <markster@digium.com>
 * \author James Golovich <james@gnuinter.net>

 * \ingroup applications
 */

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision$")

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <sys/ioctl.h>

#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 "asterisk/devicestate.h"
#include "asterisk/options.h"

static char *app = "ChanIsAvail";

static char *synopsis = "Check channel availability";

static char *descrip = 
"  ChanIsAvail(Technology/resource[&Technology2/resource2...][|options]): \n"
"This application will check to see if any of the specified channels are\n"
"available. Note that the AVAILSTATUS variable is used for both device state\n"
"and cause code. It is therefore possible for it to give a value that may\n"
"indicate a device is available when it is not. It is suggested that the\n"
"AVAILORIGCHAN variable is used instead to see whether a device is available\n"
"or not.\n"
"The following variables will be set by this application:\n"
"  ${AVAILCHAN}     - the name of the available channel, if one exists\n"
"  ${AVAILORIGCHAN} - the canonical channel name that was used to create the channel\n"
"  ${AVAILSTATUS}   - the status code for the available channel\n"
"  Options:\n"
"    s - Consider the channel unavailable if the channel is in use at all\n"
"    j - Support jumping to priority n+101 if no channel is available\n";


static int chanavail_exec(struct ast_channel *chan, void *data)
{
	int res=-1, inuse=-1, option_state=0, priority_jump=0;
	int status;
	struct ast_module_user *u;
	char *info, tmp[512], trychan[512], *peers, *tech, *number, *rest, *cur;
	struct ast_channel *tempchan;
	AST_DECLARE_APP_ARGS(args,
		AST_APP_ARG(reqchans);
		AST_APP_ARG(options);
	);

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

	u = ast_module_user_add(chan);

	info = ast_strdupa(data); 

	AST_STANDARD_APP_ARGS(args, info);

	if (args.options) {
		if (strchr(args.options, 's'))
			option_state = 1;
		if (strchr(args.options, 'j'))
			priority_jump = 1;
	}
	peers = args.reqchans;
	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");
				ast_module_user_remove(u);
				return -1;
			}
			*number = '\0';
			number++;
			
			if (option_state) {
				/* If the pbx says in use then don't bother trying further.
				   This is to permit testing if someone's on a call, even if the 
	 			   channel can permit more calls (ie callwaiting, sip calls, etc).  */
                               
				snprintf(trychan, sizeof(trychan), "%s/%s",cur,number);
				status = inuse = ast_device_state(trychan);
			}
			if ((inuse <= 1) && (tempchan = ast_request(tech, chan->nativeformats, number, &status))) {
					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);
					snprintf(tmp, sizeof(tmp), "%d", status);
					pbx_builtin_setvar_helper(chan, "AVAILSTATUS", tmp);
					ast_hangup(tempchan);
					tempchan = NULL;
					res = 1;
					break;
			} else {
				snprintf(tmp, sizeof(tmp), "%d", status);
				pbx_builtin_setvar_helper(chan, "AVAILSTATUS", tmp);
			}
			cur = rest;
		} while (cur);
	}
	if (res < 1) {
		pbx_builtin_setvar_helper(chan, "AVAILCHAN", "");
		pbx_builtin_setvar_helper(chan, "AVAILORIGCHAN", "");
		if (priority_jump || ast_opt_priority_jumping) {
			if (ast_goto_if_exists(chan, chan->context, chan->exten, chan->priority + 101)) {
				ast_module_user_remove(u);
				return -1;
			}
		}
	}

	ast_module_user_remove(u);
	return 0;
}

static int unload_module(void)
{
	int res = 0;

	res = ast_unregister_application(app);

	ast_module_user_hangup_all();
	
	return res;
}

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

AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Check channel availability");