/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2005, Digium, Inc.
 *
 * WaitForSilence Application by David C. Troy <dave@popvox.com>
 * Version 1.11 2006-06-29
 *
 * Modified by Frank Gorgas-Waller <frank@explido.us>
 * Version 1.12 2007-04-16
 *
 * Modified by Michael Cargile <mikec@vicidial.com>
 * Version 1.13 2008-10-09
 *
 * Mark Spencer <markster@digium.com>
 *
 * 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 Wait for Silence
 *   - Waits for up to 'x' milliseconds of silence, 'y' times \n
 *   - WaitForSilence(500,2) will wait for 1/2 second of silence, twice, and timing out after 60sec \n
 *   - WaitForSilence(1000,1) will wait for 1 second of silence, once, and timing out after 60sec \n
 *   - WaitForSilence(300,3,10) will wait for 300ms of silence, 3 times, and timing out after 10sec \n
 *   - WaitForSilence(300,3,0) will wait for 300ms of silence, 3 times, and never timing out \n
 *   - WaitForSilence(300|3|10|256) will wait for 300ms silence, 3 times, and timing out after 10sec but with 256 threshold \n
 *
 * \author David C. Troy <dave@popvox.com>
 *
 * \ingroup applications
 */

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 32846 $")

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#include "asterisk/file.h"
#include "asterisk/logger.h"
#include "asterisk/channel.h"
#include "asterisk/pbx.h"
#include "asterisk/dsp.h"
#include "asterisk/module.h"
#include "asterisk/options.h"

static char *tdesc = "Wait For Silence";
static char *app = "WaitForSilence";
static char *synopsis = "Waits for a specified amount of silence";
static char *descrip = 
"  WaitForSilence(silencerequired[|iterations][|timeout][|threshold]) \n"
"Wait for Silence: Waits for up to 'silencerequired' milliseconds of \n"
"silence, 'iterations' times or once if omitted. An optional timeout \n"
"specifies the number of seconds to return after, even if we do not receive\n"
"the specified amount of silence. If no time out is specified, one minute\n"
"will be assumed. To have it wait indefinitely specify 0 as the timeout. \n"
"This can cause an infinite loop on noisy lines. This is particularly useful\n"
"for reverse-911-type call broadcast applications where you need to wait for\n"
"an answering machine to complete its spiel before playing a message. The\n"
"timeout parameter is specified only to avoid an infinite loop in cases\n"
"where silence is never achieved. Typically you will want to include two\n"
"or more calls to WaitForSilence when dealing with an answering machine;\n"
"first waiting for the spiel to finish, then waiting for the beep, etc. The\n"
"threshold allows you to specify the maximum volume for silence. Raise the\n"
"threshold if you have noisy lines.\n\n"
"Examples:\n"
"  - WaitForSilence(1000) will wait for 1 second of silence, once, \n"
"     and return after 60 seconds, even if silence is not detected\n"
"  - WaitForSilence(500|2) will wait for 500ms of silence, twice,\n"
"     and return after 60 seconds, even if silence is not detected\n"
"  - WaitForSilence(300|3|10) will wait for 300ms silence, 3 times,\n"
"     and returns after 10 sec, even if silence is not detected\n"
"  - WaitForSilence(600|3|0) will wait for 600ms silence, 3 times,\n"
"     and will do so indefinitely.\n"
"  - WaitForSilence(1200|3|10|256) will wait for 1200ms silence, 3 times,\n"
"     on a more noisy line this will detect silence but might detect\n"
"     people talking very softly as silence as well and returns after\n"
"     10 sec, even if silence is not detected\n\n"
"Sets the channel variable WAITSTATUS with to one of these values:\n"
"SILENCE - if exited with silence detected\n"
"TIMEOUT - if exited without silence detected after timeout\n"
"ERROR   - if exited for some other reason usually a hangup\n";

STANDARD_LOCAL_USER;

LOCAL_USER_DECL;

static int do_waiting(struct ast_channel *chan, int silencereqd, time_t waitstart, int timeout, int silencethreshold) {
	struct ast_frame *f;
	int dspsilence = 0;
	int rfmt = 0;
	int res = 0;
	int loop_count = 1;
	struct ast_dsp *sildet;	 /* silence detector dsp */
 	time_t now;

	/* Back up the current readformat */
	rfmt = chan->readformat;

	/* Set to linear mode */
	res = ast_set_read_format(chan, AST_FORMAT_SLINEAR);
	if (res < 0) {
		ast_log(LOG_WARNING, "Unable to set channel to linear mode, giving up\n");
		return -1;
	}

	/* Create the silence detector */
	sildet = ast_dsp_new();
	if (!sildet) {
		ast_log(LOG_WARNING, "Unable to create silence detector :(\n");
		return -1;
	}
	ast_dsp_set_threshold(sildet, silencethreshold);

	/* Await silence... */
	f = NULL;
	for(;;) {
		/* Check if the channel wants to be hung up */
		if (ast_check_hangup(chan)) {
			if (option_verbose > 2)
				ast_verbose(VERBOSE_PREFIX_3 "Channel is hanging up. No point waiting.\n");
			pbx_builtin_setvar_helper(chan, "WAITSTATUS", "ERROR");
			ast_log(LOG_DEBUG, "WAITSTATUS was set to ERROR\n");
			f = NULL;
			break;
		}

		/* Start with no silence received */
		dspsilence = 0;

		/* Wait for a something to come */
		res = ast_waitfor(chan, silencereqd);

		if (res > 0) {
			/* Looks like we got a frame, so let's check it out */
			f = ast_read(chan);
			if (!f) {
				/* Got an error from ast_read(); let's exit */
				if (option_verbose > 2)
					ast_verbose(VERBOSE_PREFIX_3 "Got an error while reading from the channel. Probably disconnected. No point waiting.\n");
				pbx_builtin_setvar_helper(chan, "WAITSTATUS", "ERROR");
				ast_log(LOG_DEBUG, "WAITSTATUS was set to ERROR\n");
				break;
			}
			if (f && f->frametype == AST_FRAME_VOICE) { 
				/* got a voice frame */
				ast_dsp_silence(sildet, f, &dspsilence);
			}
			if (f) {
				/* clean up the frame no matter what type */
				ast_frfree(f);
			}
		} else {
			if (res == 0) {
				/* We waited and did not get a frame; sounds like digital silence or a muted digital channel */
				dspsilence = silencereqd;
			} else {
				/* Got an error from ast_waitfor(); let's exit */
				if (option_verbose > 2)
					ast_verbose(VERBOSE_PREFIX_3 "Got an error while waiting on the channel. No point waiting.\n");
				pbx_builtin_setvar_helper(chan, "WAITSTATUS", "ERROR");
				ast_log(LOG_DEBUG, "WAITSTATUS was set to ERROR\n");
				f = NULL;
				break;
			}
		}

		/* check to see if silencereqd has been reached */
		if (dspsilence >= silencereqd) {
			if (option_verbose > 2)
				ast_verbose(VERBOSE_PREFIX_3 "Exiting with %dms silence >= %dms required\n", dspsilence, silencereqd);
			/* Ended happily with silence */
			res = 1;
			pbx_builtin_setvar_helper(chan, "WAITSTATUS", "SILENCE");
			ast_log(LOG_DEBUG, "WAITSTATUS was set to SILENCE\n");
			break;
		}

		/* check if the timeout has been reached */
		if ( timeout && (difftime(time(&now),waitstart) >= timeout) ) {
			if (option_verbose > 2)
				ast_verbose(VERBOSE_PREFIX_3 "Timeout of %d seconds reached. Exiting\n", timeout);
			/* Ended unhappily with timeout */
			res = 0;
			pbx_builtin_setvar_helper(chan, "WAITSTATUS", "TIMEOUT");
			ast_log(LOG_DEBUG, "WAITSTATUS was set to TIMEOUT\n");
			break;
		}

		loop_count++;

		/* Lets not spam the logs */
		if (loop_count >= 11) {
			if ((option_verbose > 6) && (option_verbose <= 21))
				ast_verbose(VERBOSE_PREFIX_3 "Got %dms silence < %dms required\n", dspsilence, silencereqd);
			loop_count = 1;
		}

		/* They must really want us to spam the logs */
		if (option_verbose > 21)
			ast_verbose(VERBOSE_PREFIX_3 "Got %dms silence < %dms required\n", dspsilence, silencereqd);

	}

	/* restore the readformat */
	if (rfmt && ast_set_read_format(chan, rfmt)) {
		ast_log(LOG_WARNING, "Unable to restore format %s to channel '%s'\n", ast_getformatname(rfmt), chan->name);
	}

	/* Destroy the silence detector */
	ast_dsp_free(sildet);

	return res;
}

static int waitforsilence_exec(struct ast_channel *chan, void *data)
{
	int res = 1;
	struct localuser *u;
	int silencereqd = 1000;
	int timeout = 60;
	int iterations = 1, i;
	int silencethreshold = 128;
	time_t waitstart;

	LOCAL_USER_ADD(u);
	
	res = ast_answer(chan); /* Answer the channel */

	if (!data || ( 
		(sscanf(data, "%d|%d|%d|%d", &silencereqd, &iterations, &timeout, &silencethreshold) != 4) &&
		(sscanf(data, "%d|%d|%d", &silencereqd, &iterations, &timeout) != 3) &&
		(sscanf(data, "%d|%d", &silencereqd, &iterations) != 2) &&
		(sscanf(data, "%d", &silencereqd) != 1) 
		) ) {
		ast_log(LOG_WARNING, "Using default values of 1000ms, 1 iteration, 60 second timeout, and 128 threshold\n");
	}

	if (option_verbose > 2)
		ast_verbose(VERBOSE_PREFIX_3 "Waiting %d time(s) for %d ms silence with %d timeout %d threshold\n ", iterations, silencereqd, timeout, silencethreshold);

	time(&waitstart);
	res = 1;
	for (i=0; (i<iterations) && (res == 1); i++) {
		res = do_waiting(chan, silencereqd, waitstart, timeout, silencethreshold);
	}
	LOCAL_USER_REMOVE(u);
	if (res > 0)
		res = 0;
	return res;
}

int unload_module(void)
{
	int res;

	res = ast_unregister_application(app);
	
	STANDARD_HANGUP_LOCALUSERS;

	return res;
}

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

char *description(void)
{
	return tdesc;
}

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

char *key(void)
{
	return ASTERISK_GPL_KEY;
}