/* 
 * FreeSWITCH Modular Media Switching Software Library / Soft-Switch Application
 * Copyright (C) 2005-2010, Anthony Minessale II <anthm@freeswitch.org>
 *
 * Version: MPL 1.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is FreeSWITCH Modular Media Switching Software Library / Soft-Switch Application
 *
 * The Initial Developer of the Original Code is
 * Anthony Minessale II <anthm@freeswitch.org>
 * Portions created by the Initial Developer are Copyright (C)
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 * 
 * Anthony Minessale II <anthm@freeswitch.org>
 * Neal Horman <neal at wanlink dot com>
 *
 *
 * mod_distributor.c -- Framework Demo Module
 *
 */
#include <switch.h>

/* Prototypes */
SWITCH_MODULE_SHUTDOWN_FUNCTION(mod_distributor_shutdown);
SWITCH_MODULE_RUNTIME_FUNCTION(mod_distributor_runtime);
SWITCH_MODULE_LOAD_FUNCTION(mod_distributor_load);

/* SWITCH_MODULE_DEFINITION(name, load, shutdown, runtime) 
 * Defines a switch_loadable_module_function_table_t and a static const char[] modname
 */
SWITCH_MODULE_DEFINITION(mod_distributor, mod_distributor_load, mod_distributor_shutdown, NULL);


struct dist_node {
	char *name;
	int weight;
	int cur_weight;
	struct dist_node *next;
};

struct dist_list {
	char *name;
	int target_weight;
	int last;
	int node_count;
	struct dist_node *lastnode;
	struct dist_node *nodes;
	struct dist_list *next;
};


static void destroy_node(struct dist_node *node)
{
	struct dist_node *old;
	while (node) {
		old = node;
		node = node->next;
		if (old->name) {
			free(old->name);
		}
		free(old);
	}
}

static void destroy_list(struct dist_list *list)
{
	struct dist_list *old;

	while (list) {
		old = list;
		list = list->next;
		destroy_node(old->nodes);
		if (old->name) {
			free(old->name);
		}
		free(old);
	}
}

static struct {
	switch_mutex_t *mod_lock;
	switch_memory_pool_t *pool;
	struct dist_list *list;
} globals;



static int load_config(int reloading)
{
	struct dist_list *main_list = NULL, *new_list, *old_list = NULL, *lp = NULL;
	switch_status_t status = SWITCH_STATUS_FALSE;
	char *cf = "distributor.conf";
	switch_xml_t cfg, xml, lists, list, param;


	if (!(xml = switch_xml_open_cfg(cf, &cfg, NULL))) {
		switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_ERROR, "Open of %s failed\n", cf);
		return SWITCH_STATUS_TERM;
	}

	if (!(lists = switch_xml_child(cfg, "lists"))) {
		switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_ERROR, "Can't find any lists!\n");
		return status;
	}

	switch_mutex_lock(globals.mod_lock);

	for (list = switch_xml_child(lists, "list"); list; list = list->next) {
		const char *name = switch_xml_attr(list, "name");
		const char *tweight = switch_xml_attr(list, "total-weight");
		struct dist_node *node, *np = NULL;
		int target_weight = 10;
		int accum = 0;

		if (zstr(name)) {
			switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_ERROR, "Missing NAME!\n");
			continue;
		}

		if (!zstr(tweight)) {
			target_weight = atoi(tweight);
		}

		switch_zmalloc(new_list, sizeof(*new_list));

		new_list->name = strdup(name);
		new_list->last = -1;
		new_list->target_weight = target_weight;

		if (lp) {
			lp->next = new_list;
		} else {
			main_list = new_list;
		}

		lp = new_list;

		for (param = switch_xml_child(list, "node"); param; param = param->next) {
			char *name = (char *) switch_xml_attr_soft(param, "name");
			char *weight_val = (char *) switch_xml_attr_soft(param, "weight");
			int weight = 0, tmp;

			if ((tmp = atoi(weight_val)) < 1) {
				switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_WARNING, "Weight %d value incorrect, must be > 0\n", tmp);
				continue;
			}

			if (tmp >= lp->target_weight) {
				switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_WARNING, "Weight %d value incorrect, must be less than %d\n", tmp, lp->target_weight);
				continue;
			}

			if (accum + tmp > lp->target_weight) {
				switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_WARNING, "Target Weight %d already met, ignoring subsequent entries.\n",
								  lp->target_weight);
				continue;
			}

			accum += tmp;

			weight = lp->target_weight - tmp;

			if (weight < 0 || weight > lp->target_weight) {
				switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_WARNING, "Weight %d value incorrect, must be between 1 and %d\n", weight,
								  lp->target_weight);
				continue;
			}

			switch_zmalloc(node, sizeof(*node));
			node->name = strdup(name);
			node->weight = node->cur_weight = weight;


			if (np) {
				np->next = node;
			} else {
				lp->nodes = node;
			}

			np = node;
			lp->node_count++;
		}

		if (accum < lp->target_weight) {
			struct dist_node *np1;
			int remain = lp->target_weight - accum;
			int ea = remain / lp->node_count ? lp->node_count : 1;

			switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_WARNING, "Total weight does not add up to total weight %d\n", lp->target_weight);

			for (np1 = lp->nodes; np1; np1 = np1->next) {
				np1->weight += lp->target_weight - ea;
			}

		}

	}

	if (main_list) {
		old_list = globals.list;
		globals.list = main_list;
		status = SWITCH_STATUS_SUCCESS;
	}

	switch_mutex_unlock(globals.mod_lock);

	if (old_list) {
		destroy_list(old_list);
	}


	if (xml) {
		switch_xml_free(xml);
	}

	return status;
}

static int reset_list(struct dist_list *list)
{
	struct dist_node *np;

	for (np = list->nodes; np; np = np->next) {
		np->cur_weight = np->weight;
	}
	list->last = -1;
	list->lastnode = NULL;
	return 0;
}

static struct dist_node *find_next(struct dist_list *list)
{
	struct dist_node *np, *match = NULL;
	int x = 0, mx = 0;
	int matches = 0, loops = 0;

	for (;;) {

		if (++loops > 1000) {
			break;
		}

		x = 0;
		if (list->last >= list->node_count) {
			list->last = -1;
		}
		match = NULL;
		for (np = list->nodes; np; np = np->next) {
			if (np->cur_weight < list->target_weight) {
				switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_DEBUG, "%s %d/%d\n", np->name, np->cur_weight, list->target_weight);
				matches++;
				if (!match && x > list->last) {
					match = np;
					mx = x;
				}
			}
			x++;
		}

		if (match) {
			match->cur_weight++;
			list->lastnode = match;
			list->last = mx;
			switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_DEBUG, "Choose %s\n", match->name);
			return match;
		}

		if (matches) {
			list->last = -1;
		} else {
			reset_list(list);
		}

	}

	return NULL;
}


static char *dist_engine(const char *name)
{
	struct dist_node *np = NULL;
	struct dist_list *lp;
	char *str = NULL;

	switch_mutex_lock(globals.mod_lock);
	for (lp = globals.list; lp; lp = lp->next) {
		if (!strcasecmp(name, lp->name)) {
			np = find_next(lp);
			break;
		}
	}

	if (np) {
		str = strdup(np->name);
	}
	switch_mutex_unlock(globals.mod_lock);

	return str;

}

SWITCH_STANDARD_APP(distributor_exec)
{
	switch_channel_t *channel = switch_core_session_get_channel(session);
	char *ret = NULL;

	if (zstr(data)) {
		switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_WARNING, "distributor requires an argument\n");
		return;
	}

	if ((ret = dist_engine(data))) {
		switch_channel_set_variable(channel, "DISTRIBUTOR", ret);
		free(ret);
	}
}

SWITCH_STANDARD_API(distributor_function)
{
	char *ret = NULL;

	if (!zstr(cmd) && (ret = dist_engine(cmd))) {
		stream->write_function(stream, "%s", ret);
		free(ret);
	} else {
		stream->write_function(stream, "-err");
	}

	return SWITCH_STATUS_SUCCESS;

}


SWITCH_STANDARD_API(distributor_ctl_function)
{

	if (!zstr(cmd) && !strcasecmp(cmd, "reload")) {
		if (load_config(SWITCH_TRUE) == SWITCH_STATUS_SUCCESS) {
			stream->write_function(stream, "+ok reloaded.\n");
			return SWITCH_STATUS_SUCCESS;
		}
	}

	stream->write_function(stream, "-error!\n");

	return SWITCH_STATUS_SUCCESS;
}

/* Macro expands to: switch_status_t mod_distributor_load(switch_loadable_module_interface_t **module_interface, switch_memory_pool_t *pool) */
SWITCH_MODULE_LOAD_FUNCTION(mod_distributor_load)
{
	switch_api_interface_t *api_interface;
	switch_application_interface_t *app_interface;

	*module_interface = switch_loadable_module_create_module_interface(pool, modname);

	memset(&globals, 0, sizeof(globals));
	switch_mutex_init(&globals.mod_lock, SWITCH_MUTEX_NESTED, pool);
	globals.pool = pool;

	load_config(SWITCH_FALSE);


	SWITCH_ADD_API(api_interface, "distributor", "Distributor API", distributor_function, "<list name>");
	SWITCH_ADD_API(api_interface, "distributor_ctl", "Distributor API", distributor_ctl_function, "[reload]");
	SWITCH_ADD_APP(app_interface, "distributor", "Distributor APP", "Distributor APP", distributor_exec, "<list name>",
				   SAF_SUPPORT_NOMEDIA | SAF_ROUTING_EXEC);


	/* indicate that the module should continue to be loaded */
	return SWITCH_STATUS_SUCCESS;
}

/*
  Called when the system shuts down
  Macro expands to: switch_status_t mod_distributor_shutdown() */
SWITCH_MODULE_SHUTDOWN_FUNCTION(mod_distributor_shutdown)
{
	switch_mutex_lock(globals.mod_lock);
	destroy_list(globals.list);
	switch_mutex_unlock(globals.mod_lock);
	return SWITCH_STATUS_SUCCESS;
}

/* For Emacs:
 * Local Variables:
 * mode:c
 * indent-tabs-mode:t
 * tab-width:4
 * c-basic-offset:4
 * End:
 * For VIM:
 * vim:set softtabstop=4 shiftwidth=4 tabstop=4
 */