/*
 * Copyright (C) 2013 Konstantin Mosesov
 *
 * This file is part of Kamailio, a free SIP server.
 *
 * This file is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version
 *
 *
 * This file is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#include "../../core/str.h"
#include "../../core/sr_module.h"

#include <string.h>
#include <jni.h>

#include "global.h"
#include "java_iface.h"
#include "utils.h"
#include "app_java_mod.h"
#include "java_iface.h"
#include "java_support.h"
#include "java_native_methods.h"
#include "java_msgobj.h"
#include "java_sig_parser.h"

/*
    example of java prototype: public int method_name();
    example of kamailio invocation: java_method_exec("method_name", "V");
*/
int j_nst_exec_0(struct sip_msg *msgp, char *method_name, char *signature)
{
	return java_exec(msgp, 0, 0, method_name, signature, NULL);
}
/*
    example of java prototype: public int method_name(int param);
    example of kamailio invocation: java_method_exec("method_name", "I", "5");
*/
int j_nst_exec_1(
		struct sip_msg *msgp, char *method_name, char *signature, char *param)
{
	return java_exec(msgp, 0, 0, method_name, signature, param);
}
/*
    example of java prototype: public synchronized int method_name();
    example of kamailio invocation: java_s_method_exec("method_name", "V");
*/
int j_s_nst_exec_0(struct sip_msg *msgp, char *method_name, char *signature)
{
	return java_exec(msgp, 0, 1, method_name, signature, NULL);
}
/*
    example of java prototype: public synchronized int method_name(int param);
    example of kamailio invocation: java_s_method_exec("method_name", "I", "5");
*/
int j_s_nst_exec_1(
		struct sip_msg *msgp, char *method_name, char *signature, char *param)
{
	return java_exec(msgp, 0, 1, method_name, signature, param);
}


/*
    example of java prototype: public static int method_name();
    example of kamailio invocation: java_staticmethod_exec("method_name", "V");
*/
int j_st_exec_0(struct sip_msg *msgp, char *method_name, char *signature)
{
	return java_exec(msgp, 1, 0, method_name, signature, NULL);
}
/*
    example of java prototype: public static int method_name(int param);
    example of kamailio invocation: java_staticmethod_exec("method_name", "I", "5");
*/
int j_st_exec_1(
		struct sip_msg *msgp, char *method_name, char *signature, char *param)
{
	return java_exec(msgp, 1, 0, method_name, signature, param);
}
/*
    example of java prototype: public static synchronized int method_name();
    example of kamailio invocation: java_s_staticmethod_exec("method_name", "V");
*/
int j_s_st_exec_0(struct sip_msg *msgp, char *method_name, char *signature)
{
	return java_exec(msgp, 1, 1, method_name, signature, NULL);
}
/*
    example of java prototype: public static synchronized int method_name(int param);
    example of kamailio invocation: java_s_staticmethod_exec("method_name", "I", "5");
*/
int j_s_st_exec_1(
		struct sip_msg *msgp, char *method_name, char *signature, char *param)
{
	return java_exec(msgp, 1, 1, method_name, signature, param);
}


int java_exec(struct sip_msg *msgp, int is_static, int is_synchronized,
		char *method_name, char *signature, char *param)
{
	char *retval_sig;
	char *cs;
	size_t cslen;
	jint retval;
	int locked;
	jfieldID fid;
	jclass cls;
	jmethodID invk_method, invk_method_ref;
	jvalue *jparam;
	int r;

	if(signature == NULL || !strcmp(signature, "")) {
		LM_ERR("%s: java_method_exec(): signature is empty or invalid.\n",
				APP_NAME);
		return -1;
	}

	if(param == NULL && strcmp(signature, "V")) {
		LM_ERR("%s: java_method_exec(): no parameter (parameter is NULL) but "
			   "signature '%s' is not equals to 'V'.\n",
				APP_NAME, signature);
		return -1;
	}

	if(is_sig_allowed(signature) == 0) {
		LM_ERR("%s: java_method_exec(): error: signature '%s' isn't supported "
			   "yet.\n",
				APP_NAME, signature);
		return -1;
	}

	if(!strcmp(signature, "V")) {
		signature = "";
	}

	retval_sig = "I";

	cslen = strlen(signature) + 2 + 1
			+ 1; // '(' + 'signature' + ')' + 'return signature' + null terminator
	cs = (char *)pkg_malloc((cslen+1) * sizeof(char));
	if(!cs) {
		LM_ERR("%s: pkg_malloc() has failed. Can't allocate %lu bytes. Not "
			   "enough memory!\n",
				APP_NAME, (unsigned long)cslen);
		return -1;
	}
	r = snprintf(cs, cslen, "(%s)%s", signature, retval_sig);
	if(r<0 || r>cslen) {
		LM_ERR("building cs value failed\n");
		pkg_free(cs);
		return -1;
	}
	cs[cslen] = '\0';

	// attach to current thread
	(*_aj_jvm)->AttachCurrentThread(_aj_jvm, (void **)&_aj_env, NULL);
	if((*_aj_env)->ExceptionCheck(_aj_env)) {
		handle_exception();
		return -1;
	}

	cls = (*_aj_env)->GetObjectClass(_aj_env, KamailioClassInstance);
	if((*_aj_env)->ExceptionCheck(_aj_env)) {
		handle_exception();
		(*_aj_jvm)->DetachCurrentThread(_aj_jvm);
		return -1;
	}
	fid = (*_aj_env)->GetFieldID(_aj_env, cls, "mop", "I");
	if(!fid) {
		handle_exception();
		(*_aj_jvm)->DetachCurrentThread(_aj_jvm);
		return -1;
	}

	_aj_msg = msgp;

	// find a method by signature
	invk_method = is_static
						  ? (*_aj_env)->GetStaticMethodID(
									_aj_env, KamailioClassRef, method_name, cs)
						  : (*_aj_env)->GetMethodID(
									_aj_env, KamailioClassRef, method_name, cs);
	if(!invk_method || (*_aj_env)->ExceptionCheck(_aj_env)) {
		handle_exception();
		(*_aj_jvm)->DetachCurrentThread(_aj_jvm);
		return -1;
	}

	pkg_free(cs);

	// keep local reference to method
	invk_method_ref = (*_aj_env)->NewLocalRef(_aj_env, invk_method);
	if(!invk_method_ref || (*_aj_env)->ExceptionCheck(_aj_env)) {
		handle_exception();
		(*_aj_env)->DeleteLocalRef(_aj_env, invk_method_ref);
		(*_aj_jvm)->DetachCurrentThread(_aj_jvm);
		return -1;
	}

	retval = -1;

	if(is_synchronized) {
		if((*_aj_env)->MonitorEnter(_aj_env, invk_method_ref) != JNI_OK) {
			locked = 0;
			LM_ERR("%s: MonitorEnter() has failed! Can't synchronize!\n",
					APP_NAME);
		} else {
			locked = 1;
		}
	}

	if(param == NULL) {
		retval = is_static
						 ? (int)(*_aj_env)->CallStaticIntMethod(
								   _aj_env, KamailioClassRef, invk_method_ref)
						 : (int)(*_aj_env)->CallIntMethod(_aj_env,
								   KamailioClassInstanceRef, invk_method_ref);
	} else {
		jparam = get_value_by_sig_type(signature, param);
		if(jparam == NULL) {
			(*_aj_env)->DeleteLocalRef(_aj_env, invk_method_ref);
			(*_aj_env)->DeleteLocalRef(_aj_env, invk_method);
			(*_aj_jvm)->DetachCurrentThread(_aj_jvm);
			return -1;
		}

		retval = is_static
						 ? (int)(*_aj_env)->CallStaticIntMethod(_aj_env,
								   KamailioClassRef, invk_method_ref, *jparam)
						 : (int)(*_aj_env)->CallIntMethod(_aj_env,
								   KamailioClassInstanceRef, invk_method_ref,
								   *jparam);
	}

	if((*_aj_env)->ExceptionCheck(_aj_env)) {
		LM_ERR("%s: %s(): %s() has failed. See exception below.\n", APP_NAME,
				(is_static ? (is_synchronized ? "java_s_staticmethod_exec"
											  : "java_staticmethod_exec")
						   : (is_synchronized ? "java_s_method_exec"
											  : "java_method_exec")),
				is_static ? "CallStaticIntMethod" : "CallIntMethod");

		handle_exception();

		(*_aj_env)->DeleteLocalRef(_aj_env, invk_method_ref);
		(*_aj_env)->DeleteLocalRef(_aj_env, invk_method);
		(*_aj_jvm)->DetachCurrentThread(_aj_jvm);

		return -1;
	}

	if(is_synchronized && locked) {
		if((*_aj_env)->MonitorExit(_aj_env, invk_method_ref) != JNI_OK) {
			LM_ERR("%s: MonitorExit() has failed! Can't synchronize!\n",
					APP_NAME);
		}
	}

	(*_aj_env)->DeleteLocalRef(_aj_env, invk_method_ref);
	(*_aj_env)->DeleteLocalRef(_aj_env, invk_method);
	(*_aj_jvm)->DetachCurrentThread(_aj_jvm);

	return retval;
}