/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2019, CyCore Systems, Inc
 *
 * Seán C McCord <scm@cycoresys.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 Seán C McCord <scm@cycoresys.com>
 *
 * \brief AudioSocket Channel
 *
 * \ingroup channel_drivers
 */

/*** MODULEINFO
	<depend>res_audiosocket</depend>
	<support_level>extended</support_level>
 ***/


#include "asterisk.h"
#include <uuid/uuid.h>

#include "asterisk/channel.h"
#include "asterisk/module.h"
#include "asterisk/res_audiosocket.h"
#include "asterisk/pbx.h"
#include "asterisk/acl.h"
#include "asterisk/app.h"
#include "asterisk/causes.h"
#include "asterisk/format_cache.h"

#define FD_OUTPUT 1	/* A fd of -1 means an error, 0 is stdin */

struct audiosocket_instance {
	int svc;	  /* The file descriptor for the AudioSocket instance */
	char server[50];  /* The IP/port of the server the instance is connected to */
	char id[38];	  /* The UUID identifying this AudioSocket instance */
} audiosocket_instance;

/* Forward declarations */
static struct ast_channel *audiosocket_request(const char *type,
	struct ast_format_cap *cap, const struct ast_assigned_ids *assignedids,
	const struct ast_channel *requestor, const char *data, int *cause);
static int audiosocket_call(struct ast_channel *ast, const char *dest, int timeout);
static int audiosocket_hangup(struct ast_channel *ast);
static struct ast_frame *audiosocket_read(struct ast_channel *ast);
static int audiosocket_write(struct ast_channel *ast, struct ast_frame *f);
static int audiosocket_send_dtmf(struct ast_channel *ast, char digit, unsigned int duration);

/* AudioSocket channel driver declaration */
static struct ast_channel_tech audiosocket_channel_tech = {
	.type = "AudioSocket",
	.description = "AudioSocket Channel Driver",
	.requester = audiosocket_request,
	.call = audiosocket_call,
	.hangup = audiosocket_hangup,
	.read = audiosocket_read,
	.write = audiosocket_write,
	.send_digit_end = audiosocket_send_dtmf,
};

/*! \brief Function called when we should read a frame from the channel */
static struct ast_frame *audiosocket_read(struct ast_channel *ast)
{
	struct audiosocket_instance *instance;
	struct ast_frame *frame;
	int hangup;


	/* The channel should always be present from the API */
	instance = ast_channel_tech_pvt(ast);
	if (instance == NULL || instance->svc < FD_OUTPUT) {
		return NULL;
	}

	frame = ast_audiosocket_receive_frame_with_hangup(instance->svc, &hangup);
	if (!frame && !hangup) {
		ast_log(LOG_ERROR, "Failed to receive frame from AudioSocket server '%s'"
			" connected to channel '%s'\n", instance->server, ast_channel_name(ast));
	}
	return frame;
}

/*! \brief Function called when we should write a frame to the channel */
static int audiosocket_write(struct ast_channel *ast, struct ast_frame *f)
{
	struct audiosocket_instance *instance;

	/* The channel should always be present from the API */
	instance = ast_channel_tech_pvt(ast);
	if (instance == NULL || instance->svc < 1) {
		return -1;
	}

	if (ast_audiosocket_send_frame(instance->svc, f)) {
		ast_log(LOG_ERROR, "Failed to forward frame from channel '%s' to AudioSocket server '%s'\n",
				ast_channel_name(ast), instance->server);
		return -1;
	}
	return 0;
}

/*! \brief Function called when we should write a DTMF frame to the channel */
static int audiosocket_send_dtmf(struct ast_channel *ast, char digit, unsigned int duration)
{
	struct audiosocket_instance *instance;
	struct ast_frame f;

	/* The channel should always be present from the API */
	instance = ast_channel_tech_pvt(ast);
	if (instance == NULL || instance->svc < 1) {
		return -1;
	}

	f.frametype = AST_FRAME_DTMF;
	f.subclass.integer = digit;
	f.len = duration;

	if (ast_audiosocket_send_frame(instance->svc, &f)) {
		ast_log(LOG_ERROR, "Failed to forward DTMF frame from channel '%s' to AudioSocket server '%s'\n",
				ast_channel_name(ast), instance->server);
		return -1;
	}
	return 0;
}

/*! \brief Function called when we should actually call the destination */
static int audiosocket_call(struct ast_channel *ast, const char *dest, int timeout)
{
	struct audiosocket_instance *instance = ast_channel_tech_pvt(ast);

	ast_queue_control(ast, AST_CONTROL_ANSWER);

	return ast_audiosocket_init(instance->svc, instance->id);
}

/*! \brief Function called when we should hang the channel up */
static int audiosocket_hangup(struct ast_channel *ast)
{
	struct audiosocket_instance *instance;

	/* The channel should always be present from the API */
	instance = ast_channel_tech_pvt(ast);
	if (instance != NULL && instance->svc > 0) {
		close(instance->svc);
	}

	ast_channel_tech_pvt_set(ast, NULL);
	ast_free(instance);

	return 0;
}

enum {
	OPT_AUDIOSOCKET_CODEC = (1 << 0),
};

enum {
	OPT_ARG_AUDIOSOCKET_CODEC = (1 << 0),
	OPT_ARG_ARRAY_SIZE
};

AST_APP_OPTIONS(audiosocket_options, BEGIN_OPTIONS
	AST_APP_OPTION_ARG('c', OPT_AUDIOSOCKET_CODEC, OPT_ARG_AUDIOSOCKET_CODEC),
END_OPTIONS );

/*! \brief Function called when we should prepare to call the unicast destination */
static struct ast_channel *audiosocket_request(const char *type,
	struct ast_format_cap *cap, const struct ast_assigned_ids *assignedids,
	const struct ast_channel *requestor, const char *data, int *cause)
{
	char *parse;
	struct audiosocket_instance *instance = NULL;
	struct ast_sockaddr address;
	struct ast_channel *chan;
	struct ast_format_cap *caps = NULL;
	struct ast_format *fmt = NULL;
	uuid_t uu;
	int fd = -1;
	AST_DECLARE_APP_ARGS(args,
		AST_APP_ARG(destination);
		AST_APP_ARG(idStr);
		AST_APP_ARG(options);
	);
	struct ast_flags opts = { 0, };
	char *opt_args[OPT_ARG_ARRAY_SIZE];

	if (ast_strlen_zero(data)) {
		ast_log(LOG_ERROR, "Destination is required for the 'AudioSocket' channel\n");
		goto failure;
	}
	parse = ast_strdupa(data);
	AST_NONSTANDARD_APP_ARGS(args, parse, '/');

	if (ast_strlen_zero(args.destination)) {
		ast_log(LOG_ERROR, "Destination is required for the 'AudioSocket' channel\n");
		goto failure;
	}
	if (ast_sockaddr_resolve_first_af
		(&address, args.destination, PARSE_PORT_REQUIRE, AST_AF_UNSPEC)) {
		ast_log(LOG_ERROR, "Destination '%s' could not be parsed\n", args.destination);
		goto failure;
	}

	if (ast_strlen_zero(args.idStr)) {
		ast_log(LOG_ERROR, "UUID is required for the 'AudioSocket' channel\n");
		goto failure;
	}
	if (uuid_parse(args.idStr, uu)) {
		ast_log(LOG_ERROR, "Failed to parse UUID '%s'\n", args.idStr);
		goto failure;
	}

	if (!ast_strlen_zero(args.options)
		&& ast_app_parse_options(audiosocket_options, &opts, opt_args,
			ast_strdupa(args.options))) {
		ast_log(LOG_ERROR, "'AudioSocket' channel options '%s' parse error\n",
			args.options);
		goto failure;
	}

	if (ast_test_flag(&opts, OPT_AUDIOSOCKET_CODEC)
		&& !ast_strlen_zero(opt_args[OPT_ARG_AUDIOSOCKET_CODEC])) {
		fmt = ast_format_cache_get(opt_args[OPT_ARG_AUDIOSOCKET_CODEC]);
		if (!fmt) {
			ast_log(LOG_ERROR, "Codec '%s' not found for AudioSocket connection to '%s'\n",
				opt_args[OPT_ARG_AUDIOSOCKET_CODEC], args.destination);
			goto failure;
		}
	} else {
		fmt = ast_format_cap_get_format(cap, 0);
		if (!fmt) {
			ast_log(LOG_ERROR, "No codec available for AudioSocket connection to '%s'\n",
				args.destination);
			goto failure;
		}
	}

	caps = ast_format_cap_alloc(AST_FORMAT_CAP_FLAG_DEFAULT);
	if (!caps) {
		goto failure;
	}

	instance = ast_calloc(1, sizeof(*instance));
	if (!instance) {
		ast_log(LOG_ERROR, "Failed to allocate AudioSocket channel pvt\n");
		goto failure;
	}
	ast_copy_string(instance->id, args.idStr, sizeof(instance->id));

	if ((fd = ast_audiosocket_connect(args.destination, NULL)) < 0) {
		goto failure;
	}
	/* Make a copy of the server address for display in error messages. */
	ast_copy_string(instance->server, args.destination, sizeof(instance->server));
	instance->svc = fd;

	chan = ast_channel_alloc(1, AST_STATE_DOWN, "", "", "", "", "", assignedids,
		requestor, 0, "AudioSocket/%s-%s", args.destination, args.idStr);
	if (!chan) {
		goto failure;
	}
	ast_channel_set_fd(chan, 0, fd);
	/* Prevent device state caching as this channel involves ephemeral destinations or sources */
	ast_set_flag(ast_channel_flags(chan), AST_FLAG_DISABLE_DEVSTATE_CACHE);

	ast_channel_tech_set(chan, &audiosocket_channel_tech);

	ast_format_cap_append(caps, fmt, 0);
	ast_channel_nativeformats_set(chan, caps);
	ast_channel_set_writeformat(chan, fmt);
	ast_channel_set_rawwriteformat(chan, fmt);
	ast_channel_set_readformat(chan, fmt);
	ast_channel_set_rawreadformat(chan, fmt);

	ast_channel_tech_pvt_set(chan, instance);

	pbx_builtin_setvar_helper(chan, "AUDIOSOCKET_UUID", args.idStr);
	pbx_builtin_setvar_helper(chan, "AUDIOSOCKET_SERVICE", args.destination);

	ast_channel_unlock(chan);

	ao2_ref(fmt, -1);
	ao2_ref(caps, -1);
	return chan;

failure:
	*cause = AST_CAUSE_FAILURE;
	ao2_cleanup(fmt);
	ao2_cleanup(caps);
	if (instance != NULL) {
		ast_free(instance);
		if (fd >= 0) {
			close(fd);
		}
	}

	return NULL;
}

/*! \brief Function called when our module is unloaded */
static int unload_module(void)
{
	ast_channel_unregister(&audiosocket_channel_tech);
	ao2_cleanup(audiosocket_channel_tech.capabilities);
	audiosocket_channel_tech.capabilities = NULL;

	return 0;
}

/*! \brief Function called when our module is loaded */
static int load_module(void)
{
	if (!(audiosocket_channel_tech.capabilities = ast_format_cap_alloc(AST_FORMAT_CAP_FLAG_DEFAULT))) {
		return AST_MODULE_LOAD_DECLINE;
	}
	ast_format_cap_append_by_type(audiosocket_channel_tech.capabilities, AST_MEDIA_TYPE_UNKNOWN);
	if (ast_channel_register(&audiosocket_channel_tech)) {
		ast_log(LOG_ERROR, "Unable to register channel class AudioSocket");
		ao2_ref(audiosocket_channel_tech.capabilities, -1);
		audiosocket_channel_tech.capabilities = NULL;
		return AST_MODULE_LOAD_DECLINE;
	}

	return AST_MODULE_LOAD_SUCCESS;
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "AudioSocket Channel",
	.support_level = AST_MODULE_SUPPORT_EXTENDED,
	.load = load_module,
	.unload = unload_module,
	.load_pri = AST_MODPRI_CHANNEL_DRIVER,
	.requires = "res_audiosocket",
);
