/*
 * CallWeaver -- An open source telephony toolkit.
 *
 * Copyright (c) 2004-2005 Tilghman Lesher <app_stack_v002@the-tilghman.com>.
 *
 * This code is released by the author with no restrictions on usage.
 *
 * See http://www.callweaver.org for more information about
 * the CallWeaver 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 Stack applications Gosub, Return, etc.
 * 
 * \ingroup applications
 */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>

#include "callweaver.h"

#include "callweaver/options.h"
#include "callweaver/logger.h"
#include "callweaver/channel.h"
#include "callweaver/chanvars.h"
#include "callweaver/pbx.h"
#include "callweaver/module.h"
#include "callweaver/config.h"

#define STACKVAR	"~GOSUB~STACK~"

static const char tdesc[] = "Stack Routines";

static void *gosub_app;
static void *gosubif_app;
static void *return_app;
static void *pop_app;

static const char gosub_name[] = "Gosub";
static const char gosubif_name[] = "GosubIf";
static const char return_name[] = "Return";
static const char pop_name[] = "StackPop";

static const char gosub_synopsis[] = "Jump to label, saving return address";
static const char gosubif_synopsis[] = "Jump to label, saving return address";
static const char return_synopsis[] = "Return from gosub routine";
static const char pop_synopsis[] = "Remove one address from gosub stack";

static const char gosub_syntax[] = "Gosub([[context, ]exten, ]label|priority[(arg,...)])";
static const char gosubif_syntax[] = "GosubIf(condition ? [[context, ]exten, ]label|priority[(arg, ...)] [: [[context, ]exten, ]label|priority][(arg, ...)])";
static const char return_syntax[] = "Return()";
static const char pop_syntax[] = "StackPop()";

static const char gosub_descrip[] =
"  Jumps to the label specified, saving the return address.\n"
"  Returns 0 if the label exists or -1 otherwise.\n";
static const char gosubif_descrip[] =
"  If the condition is true, then jump to labeliftrue.  If false, jumps to\n"
"labeliffalse, if specified.  In either case, a jump saves the return point\n"
"in the dialplan, to be returned to with a Return.\n"
"  Returns 0 if the label exists or -1 otherwise.\n";
static const char return_descrip[] =
"  Jumps to the last label in the stack, removing it.\n"
"  Returns 0 if there's a label in the stack or -1 otherwise.\n";
static const char pop_descrip[] =
"  Removes last label in the stack, discarding it.\n"
"  Always returns 0, even if the stack is empty.\n";


static int pop_exec(struct cw_channel *chan, int argc, char **argv, struct cw_dynstr *result)
{
	CW_UNUSED(argv);
	CW_UNUSED(result);

	if (argc != 0)
		return cw_function_syntax(pop_syntax);

	pbx_builtin_setvar_helper(chan, STACKVAR, NULL);

	return 0;
}

static int return_exec(struct cw_channel *chan, int argc, char **argv, struct cw_dynstr *result)
{
	struct cw_dynargs args = CW_DYNARRAY_INIT;
	char buf[3 + 3 + 1];
	struct cw_var_t *var;
	int i, res;

	CW_UNUSED(argv);
	CW_UNUSED(result);

	if (argc != 0)
		return cw_function_syntax(return_syntax);

	res = -1;

	if ((var = pbx_builtin_getvar_helper(chan, cw_hash_var_name(STACKVAR), STACKVAR))) {
		pbx_builtin_setvar_helper(chan, STACKVAR, NULL);

		/* No one else should be messing with our stack frame so we can safely trash it */
		cw_split_args(&args, (char *)var->value, ",", '\0', NULL);

		if (!args.error) {
			memcpy(buf, "ARG", 3);
			for (i = atoi(args.data[3]); i; i--) {
				sprintf(buf+3, "%d", i+1);
				pbx_builtin_setvar_helper(chan, buf, NULL);
			}

			if (!cw_explicit_goto(chan, args.data[0], args.data[1], args.data[2]))
				res = 0;
			else
				cw_log(CW_LOG_WARNING, "No statement after Gosub to return to?\n");
		}

		cw_dynargs_free(&args);
		cw_object_put(var);
	} else
		cw_log(CW_LOG_ERROR, "Return without Gosub: stack is empty\n");


	return res;
}

static int gosub_exec(struct cw_channel *chan, int argc, char **argv, struct cw_dynstr *result)
{
	char buf[3 + 1 + CW_MAX_CONTEXT + 1 + CW_MAX_EXTENSION + 1 + 11 + 11];
	char *context, *exten, *priority, *p, *q;
	int i, res;

	CW_UNUSED(result);

	priority = p = q = NULL;
	if (argc) {
		for (i = 0; i < 3 && i < argc; i++) {
			if ((p = strchr(argv[i], '('))) {
				i++;
				*(p++) = '\0';
				break;
			}
		}

		priority = argv[i - 1];
		exten = (i > 1 ? argv[i - 2] : NULL);
		context = (i > 2 ? argv[i - 3] : NULL);

		if (p) {
			argv[i - 1] = p;
			argv = &argv[i - 1];
			argc = argc - (i - 1);
			q = &argv[argc - 1][strlen(argv[argc - 1]) - 1];
		} else
			argc -= i;
	}

	if (!priority || (!p && argc) || (q && *q != ')'))
		return cw_function_syntax(gosub_syntax);

	if (q)
		*q = '\0';

	i = snprintf(buf, sizeof(buf), "\"%s\",\"%s\",%d", chan->context, chan->exten, chan->priority + 1);

	res = -1;

	if (!cw_explicit_goto(chan, context, exten, priority)) {
		snprintf(buf + i, sizeof(buf) - i, ",%d", argc);
		pbx_builtin_pushvar_helper(chan, STACKVAR, buf);

		memcpy(buf, "ARG", 3);
		for (i = 0; i < argc; i++) {
			sprintf(buf + sizeof("ARG") - 1, "%d", i + 1);
			pbx_builtin_pushvar_helper(chan, buf, argv[i]);
		}

		res = 0;
	}

	return res;
}

static int gosubif_exec(struct cw_channel *chan, int argc, char **argv, struct cw_dynstr *result)
{
	char *s, *q;
	int i;

	CW_UNUSED(result);

	/* First argument is "<condition ? ..." */
	if (argc < 1 || !(s = strchr(argv[0], '?')))
		return cw_function_syntax(gosubif_syntax);

	/* Trim trailing space from the condition */
	q = s;
	do { *(q--) = '\0'; } while (q >= argv[0] && isspace(*q));

	do { *(s++) = '\0'; } while (isspace(*s));

	if (pbx_checkcondition(argv[0])) {
		/* True: we want everything between '?' and ':' */
		argv[0] = s;
		for (i = 0; i < argc; i++) {
			if ((s = strchr(argv[i], ':'))) {
				do { *(s--) = '\0'; } while (s >= argv[i] && isspace(*s));
				argc = i + 1;
				break;
			}
		}
		return gosub_exec(chan, argc, argv, NULL);
	} else {
		/* False: we want everything after ':' (if anything) */
		argv[0] = s;
		for (i = 0; i < argc; i++) {
			if ((s = strchr(argv[i], ':'))) {
				do { *(s++) = '\0'; } while (isspace(*s));
				argv[i] = s;
				return gosub_exec(chan, argc - i, argv + i, NULL);
			}
		}
		/* No ": ..." so we just drop through */
		return 0;
	}
}

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

	res |= cw_unregister_function(return_app);
	res |= cw_unregister_function(pop_app);
	res |= cw_unregister_function(gosubif_app);
	res |= cw_unregister_function(gosub_app);

	return res;
}

static int load_module(void)
{
	pop_app = cw_register_function(pop_name, pop_exec, pop_synopsis, pop_syntax, pop_descrip);
	return_app = cw_register_function(return_name, return_exec, return_synopsis, return_syntax, return_descrip);
	gosubif_app = cw_register_function(gosubif_name, gosubif_exec, gosubif_synopsis, gosubif_syntax, gosubif_descrip);
	gosub_app = cw_register_function(gosub_name, gosub_exec, gosub_synopsis, gosub_syntax, gosub_descrip);

	return 0;
}


MODULE_INFO(load_module, NULL, unload_module, NULL, tdesc)