/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2005, Digium, Inc.
 *
 * 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
 *
 * \author Mark Spencer <markster@digium.com>
 *
 * \brief Local Proxy Channel
 * 
 * \ingroup channel_drivers
 */

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <errno.h>
#include <stdlib.h>
#include <fcntl.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/signal.h>

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision$")

#include "asterisk/lock.h"
#include "asterisk/channel.h"
#include "asterisk/config.h"
#include "asterisk/logger.h"
#include "asterisk/module.h"
#include "asterisk/pbx.h"
#include "asterisk/options.h"
#include "asterisk/lock.h"
#include "asterisk/sched.h"
#include "asterisk/io.h"
#include "asterisk/rtp.h"
#include "asterisk/acl.h"
#include "asterisk/callerid.h"
#include "asterisk/file.h"
#include "asterisk/cli.h"
#include "asterisk/app.h"
#include "asterisk/musiconhold.h"
#include "asterisk/manager.h"
#include "asterisk/stringfields.h"

static const char tdesc[] = "Local Proxy Channel Driver";

#define IS_OUTBOUND(a,b) (a == b->chan ? 1 : 0)

static struct ast_channel *local_request(const char *type, int format, void *data, int *cause);
static int local_digit(struct ast_channel *ast, char digit);
static int local_call(struct ast_channel *ast, char *dest, int timeout);
static int local_hangup(struct ast_channel *ast);
static int local_answer(struct ast_channel *ast);
static struct ast_frame *local_read(struct ast_channel *ast);
static int local_write(struct ast_channel *ast, struct ast_frame *f);
static int local_indicate(struct ast_channel *ast, int condition);
static int local_fixup(struct ast_channel *oldchan, struct ast_channel *newchan);
static int local_sendhtml(struct ast_channel *ast, int subclass, const char *data, int datalen);

/* PBX interface structure for channel registration */
static const struct ast_channel_tech local_tech = {
	.type = "Local",
	.description = tdesc,
	.capabilities = -1,
	.requester = local_request,
	.send_digit = local_digit,
	.call = local_call,
	.hangup = local_hangup,
	.answer = local_answer,
	.read = local_read,
	.write = local_write,
	.exception = local_read,
	.indicate = local_indicate,
	.fixup = local_fixup,
	.send_html = local_sendhtml,
};

struct local_pvt {
	ast_mutex_t lock;			/* Channel private lock */
	char context[AST_MAX_CONTEXT];		/* Context to call */
	char exten[AST_MAX_EXTENSION];		/* Extension to call */
	int reqformat;				/* Requested format */
	int glaredetect;			/* Detect glare on hangup */
	int cancelqueue;			/* Cancel queue */
	int alreadymasqed;			/* Already masqueraded */
	int launchedpbx;			/* Did we launch the PBX */
	int nooptimization;			/* Don't leave masq state */
	struct ast_channel *owner;		/* Master Channel */
	struct ast_channel *chan;		/* Outbound channel */
	AST_LIST_ENTRY(local_pvt) list;		/* Next entity */
};

static AST_LIST_HEAD_STATIC(locals, local_pvt);

static int local_queue_frame(struct local_pvt *p, int isoutbound, struct ast_frame *f, struct ast_channel *us)
{
	struct ast_channel *other;
retrylock:		
	/* Recalculate outbound channel */
	if (isoutbound) {
		other = p->owner;
	} else {
		other = p->chan;
	}
	/* Set glare detection */
	p->glaredetect = 1;
	if (p->cancelqueue) {
		/* We had a glare on the hangup.  Forget all this business,
		return and destroy p.  */
		ast_mutex_unlock(&p->lock);
		ast_mutex_destroy(&p->lock);
		free(p);
		return -1;
	}
	if (!other) {
		p->glaredetect = 0;
		return 0;
	}
	if (ast_mutex_trylock(&other->lock)) {
		/* Failed to lock.  Release main lock and try again */
		ast_mutex_unlock(&p->lock);
		if (us) {
			if (ast_mutex_unlock(&us->lock)) {
				ast_log(LOG_WARNING, "%s wasn't locked while sending %d/%d\n",
					us->name, f->frametype, f->subclass);
				us = NULL;
			}
		}
		/* Wait just a bit */
		usleep(1);
		/* Only we can destroy ourselves, so we can't disappear here */
		if (us)
			ast_mutex_lock(&us->lock);
		ast_mutex_lock(&p->lock);
		goto retrylock;
	}
	ast_queue_frame(other, f);
	ast_mutex_unlock(&other->lock);
	p->glaredetect = 0;
	return 0;
}

static int local_answer(struct ast_channel *ast)
{
	struct local_pvt *p = ast->tech_pvt;
	int isoutbound;
	int res = -1;

	ast_mutex_lock(&p->lock);
	isoutbound = IS_OUTBOUND(ast, p);
	if (isoutbound) {
		/* Pass along answer since somebody answered us */
		struct ast_frame answer = { AST_FRAME_CONTROL, AST_CONTROL_ANSWER };
		res = local_queue_frame(p, isoutbound, &answer, ast);
	} else
		ast_log(LOG_WARNING, "Huh?  Local is being asked to answer?\n");
	ast_mutex_unlock(&p->lock);
	return res;
}

static void check_bridge(struct local_pvt *p, int isoutbound)
{
	if (p->alreadymasqed || p->nooptimization)
		return;
	if (!p->chan || !p->owner)
		return;
	if (isoutbound&& p->chan->_bridge /* Not ast_bridged_channel!  Only go one step! */ && !p->owner->readq) {
		/* Masquerade bridged channel into owner */
		/* Lock everything we need, one by one, and give up if
		   we can't get everything.  Remember, we'll get another
		   chance in just a little bit */
		if (!ast_mutex_trylock(&(p->chan->_bridge)->lock)) {
			if (!p->chan->_bridge->_softhangup) {
				if (!ast_mutex_trylock(&p->owner->lock)) {
					if (!p->owner->_softhangup) {
						ast_channel_masquerade(p->owner, p->chan->_bridge);
						p->alreadymasqed = 1;
					}
					ast_mutex_unlock(&p->owner->lock);
				}
				ast_mutex_unlock(&(p->chan->_bridge)->lock);
			}
		}
	} else if (!isoutbound && p->owner && p->owner->_bridge && p->chan && !p->chan->readq) {
		/* Masquerade bridged channel into chan */
		if (!ast_mutex_trylock(&(p->owner->_bridge)->lock)) {
			if (!p->owner->_bridge->_softhangup) {
				if (!ast_mutex_trylock(&p->chan->lock)) {
					if (!p->chan->_softhangup) {
						ast_channel_masquerade(p->chan, p->owner->_bridge);
						p->alreadymasqed = 1;
					}
					ast_mutex_unlock(&p->chan->lock);
				}
			}
			ast_mutex_unlock(&(p->owner->_bridge)->lock);
		}
	}
}

static struct ast_frame  *local_read(struct ast_channel *ast)
{
	return &ast_null_frame;
}

static int local_write(struct ast_channel *ast, struct ast_frame *f)
{
	struct local_pvt *p = ast->tech_pvt;
	int res = -1;
	int isoutbound;

	/* Just queue for delivery to the other side */
	ast_mutex_lock(&p->lock);
	isoutbound = IS_OUTBOUND(ast, p);
	if (f && (f->frametype == AST_FRAME_VOICE)) 
		check_bridge(p, isoutbound);
	if (!p->alreadymasqed)
		res = local_queue_frame(p, isoutbound, f, ast);
	else {
		ast_log(LOG_DEBUG, "Not posting to queue since already masked on '%s'\n", ast->name);
		res = 0;
	}
	ast_mutex_unlock(&p->lock);
	return res;
}

static int local_fixup(struct ast_channel *oldchan, struct ast_channel *newchan)
{
	struct local_pvt *p = newchan->tech_pvt;
	ast_mutex_lock(&p->lock);

	if ((p->owner != oldchan) && (p->chan != oldchan)) {
		ast_log(LOG_WARNING, "Old channel wasn't %p but was %p/%p\n", oldchan, p->owner, p->chan);
		ast_mutex_unlock(&p->lock);
		return -1;
	}
	if (p->owner == oldchan)
		p->owner = newchan;
	else
		p->chan = newchan;
	ast_mutex_unlock(&p->lock);
	return 0;
}

static int local_indicate(struct ast_channel *ast, int condition)
{
	struct local_pvt *p = ast->tech_pvt;
	int res = -1;
	struct ast_frame f = { AST_FRAME_CONTROL, };
	int isoutbound;

	/* Queue up a frame representing the indication as a control frame */
	ast_mutex_lock(&p->lock);
	isoutbound = IS_OUTBOUND(ast, p);
	f.subclass = condition;
	res = local_queue_frame(p, isoutbound, &f, ast);
	ast_mutex_unlock(&p->lock);
	return res;
}

static int local_digit(struct ast_channel *ast, char digit)
{
	struct local_pvt *p = ast->tech_pvt;
	int res = -1;
	struct ast_frame f = { AST_FRAME_DTMF, };
	int isoutbound;

	ast_mutex_lock(&p->lock);
	isoutbound = IS_OUTBOUND(ast, p);
	f.subclass = digit;
	res = local_queue_frame(p, isoutbound, &f, ast);
	ast_mutex_unlock(&p->lock);
	return res;
}

static int local_sendhtml(struct ast_channel *ast, int subclass, const char *data, int datalen)
{
	struct local_pvt *p = ast->tech_pvt;
	int res = -1;
	struct ast_frame f = { AST_FRAME_HTML, };
	int isoutbound;

	ast_mutex_lock(&p->lock);
	isoutbound = IS_OUTBOUND(ast, p);
	f.subclass = subclass;
	f.data = (char *)data;
	f.datalen = datalen;
	res = local_queue_frame(p, isoutbound, &f, ast);
	ast_mutex_unlock(&p->lock);
	return res;
}

/*! \brief Initiate new call, part of PBX interface 
 * 	dest is the dial string */
static int local_call(struct ast_channel *ast, char *dest, int timeout)
{
	struct local_pvt *p = ast->tech_pvt;
	int res;
	struct ast_var_t *varptr = NULL, *new;
	size_t len, namelen;
	
	ast_mutex_lock(&p->lock);

	p->chan->cid.cid_num = ast_strdup(p->owner->cid.cid_num);
	p->chan->cid.cid_name = ast_strdup(p->owner->cid.cid_name);
	p->chan->cid.cid_rdnis = ast_strdup(p->owner->cid.cid_rdnis);
	p->chan->cid.cid_ani = ast_strdup(p->owner->cid.cid_ani);

	ast_string_field_set(p->chan, language, p->owner->language);
	ast_string_field_set(p->chan, accountcode, p->owner->accountcode);
	p->chan->cdrflags = p->owner->cdrflags;

	/* copy the channel variables from the incoming channel to the outgoing channel */
	/* Note that due to certain assumptions, they MUST be in the same order */
	AST_LIST_TRAVERSE(&p->owner->varshead, varptr, entries) {
		namelen = strlen(varptr->name);
		len = sizeof(struct ast_var_t) + namelen + strlen(varptr->value) + 2;
		if ((new = ast_calloc(1, len))) {
			memcpy(new, varptr, len);
			new->value = &(new->name[0]) + namelen + 1;
			AST_LIST_INSERT_TAIL(&p->chan->varshead, new, entries);
		}
	}

	p->launchedpbx = 1;

	/* Start switch on sub channel */
	res = ast_pbx_start(p->chan);
	ast_mutex_unlock(&p->lock);
	return res;
}

#if 0
static void local_destroy(struct local_pvt *p)
{
	struct local_pvt *cur;

	AST_LIST_LOCK(&locals);
	AST_LIST_TRAVERSE_SAFE_BEGIN(&locals, cur, list) {
		if (cur == p) {
			AST_LIST_REMOVE_CURRENT(&locals, list);
			ast_mutex_destroy(&cur->lock);
			free(cur);
			break;
		}
	}
	AST_LIST_TRAVERSE_SAFE_END
	AST_LIST_UNLOCK(&locals);
	if (!cur)
		ast_log(LOG_WARNING, "Unable ot find local '%s@%s' in local list\n", p->exten, p->context);
}
#endif

/*! \brief Hangup a call through the local proxy channel */
static int local_hangup(struct ast_channel *ast)
{
	struct local_pvt *p = ast->tech_pvt;
	int isoutbound;
	struct ast_frame f = { AST_FRAME_CONTROL, AST_CONTROL_HANGUP };
	struct ast_channel *ochan = NULL;
	int glaredetect;

	ast_mutex_lock(&p->lock);
	isoutbound = IS_OUTBOUND(ast, p);
	if (isoutbound) {
		const char *status = pbx_builtin_getvar_helper(p->chan, "DIALSTATUS");
		if ((status) && (p->owner))
			pbx_builtin_setvar_helper(p->owner, "CHANLOCALSTATUS", status);
		p->chan = NULL;
		p->launchedpbx = 0;
	} else
		p->owner = NULL;
	ast->tech_pvt = NULL;
	
	ast_atomic_fetchadd_int(&__mod_desc->usecnt, -1);
	
	if (!p->owner && !p->chan) {
		/* Okay, done with the private part now, too. */
		glaredetect = p->glaredetect;
		/* If we have a queue holding, don't actually destroy p yet, but
		   let local_queue do it. */
		if (p->glaredetect)
			p->cancelqueue = 1;
		ast_mutex_unlock(&p->lock);
		/* Remove from list */
		AST_LIST_LOCK(&locals);
		AST_LIST_REMOVE(&locals, p, list);
		AST_LIST_UNLOCK(&locals);
		/* Grab / release lock just in case */
		ast_mutex_lock(&p->lock);
		ast_mutex_unlock(&p->lock);
		/* And destroy */
		if (!glaredetect) {
			ast_mutex_destroy(&p->lock);
			free(p);
		}
		return 0;
	}
	if (p->chan && !p->launchedpbx)
		/* Need to actually hangup since there is no PBX */
		ochan = p->chan;
	else
		local_queue_frame(p, isoutbound, &f, NULL);
	ast_mutex_unlock(&p->lock);
	if (ochan)
		ast_hangup(ochan);
	return 0;
}

/*! \brief Create a call structure */
static struct local_pvt *local_alloc(const char *data, int format)
{
	struct local_pvt *tmp;
	char *c;
	char *opts;

	if (!(tmp = ast_calloc(1, sizeof(*tmp))))
		return NULL;
	
	ast_mutex_init(&tmp->lock);
	ast_copy_string(tmp->exten, data, sizeof(tmp->exten));
	opts = strchr(tmp->exten, '/');
	if (opts) {
		*opts++ = '\0';
		if (strchr(opts, 'n'))
			tmp->nooptimization = 1;
	}
	c = strchr(tmp->exten, '@');
	if (c)
		*c++ = '\0';
	ast_copy_string(tmp->context, c ? c : "default", sizeof(tmp->context));
	tmp->reqformat = format;
	if (!ast_exists_extension(NULL, tmp->context, tmp->exten, 1, NULL)) {
		ast_log(LOG_NOTICE, "No such extension/context %s@%s creating local channel\n", tmp->exten, tmp->context);
		ast_mutex_destroy(&tmp->lock);
		free(tmp);
		tmp = NULL;
	} else {
		/* Add to list */
		AST_LIST_LOCK(&locals);
		AST_LIST_INSERT_HEAD(&locals, tmp, list);
		AST_LIST_UNLOCK(&locals);
	}
	
	return tmp;
}

/*! \brief Start new local channel */
static struct ast_channel *local_new(struct local_pvt *p, int state)
{
	struct ast_channel *tmp, *tmp2;
	int randnum = ast_random() & 0xffff;

	tmp = ast_channel_alloc(1);
	tmp2 = ast_channel_alloc(1);
	if (!tmp || !tmp2) {
		if (tmp)
			ast_channel_free(tmp);
		if (tmp2)
			ast_channel_free(tmp2);
		ast_log(LOG_WARNING, "Unable to allocate channel structure(s)\n");
		return NULL;
	} 

	tmp2->tech = tmp->tech = &local_tech;
	tmp->nativeformats = p->reqformat;
	tmp2->nativeformats = p->reqformat;
	ast_string_field_build(tmp, name, "Local/%s@%s-%04x,1", p->exten, p->context, randnum);
	ast_string_field_build(tmp2, name, "Local/%s@%s-%04x,2", p->exten, p->context, randnum);
	ast_setstate(tmp, state);
	ast_setstate(tmp2, AST_STATE_RING);
	tmp->writeformat = p->reqformat;
	tmp2->writeformat = p->reqformat;
	tmp->rawwriteformat = p->reqformat;
	tmp2->rawwriteformat = p->reqformat;
	tmp->readformat = p->reqformat;
	tmp2->readformat = p->reqformat;
	tmp->rawreadformat = p->reqformat;
	tmp2->rawreadformat = p->reqformat;
	tmp->tech_pvt = p;
	tmp2->tech_pvt = p;
	p->owner = tmp;
	p->chan = tmp2;
	ast_atomic_fetchadd_int(&__mod_desc->usecnt, +2);	/* we allocate 2 new channels */
	ast_update_use_count();
	ast_copy_string(tmp->context, p->context, sizeof(tmp->context));
	ast_copy_string(tmp2->context, p->context, sizeof(tmp2->context));
	ast_copy_string(tmp2->exten, p->exten, sizeof(tmp->exten));
	tmp->priority = 1;
	tmp2->priority = 1;

	return tmp;
}


/*! \brief Part of PBX interface */
static struct ast_channel *local_request(const char *type, int format, void *data, int *cause)
{
	struct local_pvt *p;
	struct ast_channel *chan = NULL;

	p = local_alloc(data, format);
	if (p)
		chan = local_new(p, AST_STATE_DOWN);
	return chan;
}

/*! \brief CLI command "local show channels" */
static int locals_show(int fd, int argc, char **argv)
{
	struct local_pvt *p;

	if (argc != 3)
		return RESULT_SHOWUSAGE;
	if (AST_LIST_EMPTY(&locals))
		ast_cli(fd, "No local channels in use\n");
	AST_LIST_LOCK(&locals);
	AST_LIST_TRAVERSE(&locals, p, list) {
		ast_mutex_lock(&p->lock);
		ast_cli(fd, "%s -- %s@%s\n", p->owner ? p->owner->name : "<unowned>", p->exten, p->context);
		ast_mutex_unlock(&p->lock);
	}
	AST_LIST_UNLOCK(&locals);
	return RESULT_SUCCESS;
}

static char show_locals_usage[] = 
"Usage: local show channels\n"
"       Provides summary information on active local proxy channels.\n";

static struct ast_cli_entry cli_show_locals = {
	{ "local", "show", "channels", NULL }, locals_show, 
	"Show status of local channels", show_locals_usage, NULL };

/*! \brief Load module into PBX, register channel */
static int load_module(void *mod)
{
	__mod_desc = mod;

	/* Make sure we can register our channel type */
	if (ast_channel_register(&local_tech)) {
		ast_log(LOG_ERROR, "Unable to register channel class 'Local'\n");
		return -1;
	}
	ast_cli_register(&cli_show_locals);
	return 0;
}

/*! \brief Unload the local proxy channel from Asterisk */
static int unload_module(void *mod)
{
	struct local_pvt *p;

	/* First, take us out of the channel loop */
	ast_cli_unregister(&cli_show_locals);
	ast_channel_unregister(&local_tech);
	if (!AST_LIST_LOCK(&locals)) {
		/* Hangup all interfaces if they have an owner */
		AST_LIST_TRAVERSE(&locals, p, list) {
			if (p->owner)
				ast_softhangup(p->owner, AST_SOFTHANGUP_APPUNLOAD);
		}
		AST_LIST_UNLOCK(&locals);
		AST_LIST_HEAD_DESTROY(&locals);
	} else {
		ast_log(LOG_WARNING, "Unable to lock the monitor\n");
		return -1;
	}		
	return 0;
}

static const char *key(void)
{
	return ASTERISK_GPL_KEY;
}

static const char *description(void)
{
	return "Local Proxy Channel";
}

STD_MOD(MOD_1, NULL, NULL, NULL);
