/* SPDX-License-Identifier: Apache-2.0
 *
 * Copyright © 2017-2021 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
 */

#include <assert.h>
#include <jni.h>
#include <stdlib.h>
#include <string.h>
#include <android/log.h>

#define TAG "WireGuard/GoBackend"

struct go_string { const char *str; long n; };
extern int wgTurnOn(struct go_string ifname, int tun_fd, struct go_string settings, void *eventHandler);
extern int wgTurnOnDhcp(struct go_string ifname, struct go_string lladdr, struct go_string settings, void *eventHandler);
extern void wgSetFd(int handle, int tun_fd);
extern void *wgTurnOff(int handle);
extern int wgGetSocketV4(int handle);
extern int wgGetSocketV6(int handle);
extern char *wgGetConfig(int handle);
extern char *wgVersion();
extern void wgOnEvent(void *eventHandler, const char *event);

static JavaVM *gVm;
static jclass gEventHandlerClass;
static jmethodID gOnEventMethod;

JNIEXPORT jint JNI_OnLoad(JavaVM *vm, void *reserved)
{
	JNIEnv* env;
	char buf[128];

	__android_log_write(ANDROID_LOG_ERROR, TAG, "JNI_OnLoad");

	gVm = vm;
	if ((*vm)->GetEnv(vm, (void**)&env, JNI_VERSION_1_6) != JNI_OK) {
		__android_log_write(ANDROID_LOG_ERROR, TAG, "GetEnv error");
		return JNI_ERR;
	}

	sprintf(buf, "GetEnv FindClass %p", (*env)->FindClass);
	__android_log_write(ANDROID_LOG_ERROR, TAG, buf);
	gEventHandlerClass = (*env)->FindClass(env, "com/wireguard/android/backend/EventHandler");
	sprintf(buf, "gEventHandlerClass %p", gEventHandlerClass);
	__android_log_write(ANDROID_LOG_ERROR, TAG, buf);

	gOnEventMethod = (*env)->GetMethodID(env, gEventHandlerClass, "onEvent", "(Ljava/lang/String;)V");
	sprintf(buf, "gOnEventMethod %p", gOnEventMethod);
	__android_log_write(ANDROID_LOG_ERROR, TAG, buf);
	//assert(gOnEventMethod);

	return JNI_VERSION_1_6;
}

JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgTurnOn(JNIEnv *env, jclass c, jstring ifname, jint tun_fd, jstring settings, jobject eventHandler)
{
	const char *ifname_str = (*env)->GetStringUTFChars(env, ifname, 0);
	size_t ifname_len = (*env)->GetStringUTFLength(env, ifname);
	const char *settings_str = (*env)->GetStringUTFChars(env, settings, 0);
	size_t settings_len = (*env)->GetStringUTFLength(env, settings);
	jobject event_handler = (*env)->NewGlobalRef(env, eventHandler);
	int ret = wgTurnOn((struct go_string){
		.str = ifname_str,
		.n = ifname_len
	}, tun_fd, (struct go_string){
		.str = settings_str,
		.n = settings_len
	}, event_handler);
	(*env)->ReleaseStringUTFChars(env, ifname, ifname_str);
	(*env)->ReleaseStringUTFChars(env, settings, settings_str);
	return ret;
}

JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgTurnOnDhcp(JNIEnv *env, jclass c, jstring ifname, jstring lladdr, jstring settings, jobject eventHandler)
{
	const char *ifname_str = (*env)->GetStringUTFChars(env, ifname, 0);
	size_t ifname_len = (*env)->GetStringUTFLength(env, ifname);
	const char *lladdr_str = (*env)->GetStringUTFChars(env, lladdr, 0);
	size_t lladdr_len = (*env)->GetStringUTFLength(env, lladdr);
	const char *settings_str = (*env)->GetStringUTFChars(env, settings, 0);
	size_t settings_len = (*env)->GetStringUTFLength(env, settings);
	jobject event_handler = (*env)->NewGlobalRef(env, eventHandler);
	int ret = wgTurnOnDhcp((struct go_string){
		.str = ifname_str,
		.n = ifname_len
	}, (struct go_string){
		.str = lladdr_str,
		.n = lladdr_len
	}, (struct go_string){
		.str = settings_str,
		.n = settings_len
	}, event_handler);
	(*env)->ReleaseStringUTFChars(env, ifname, ifname_str);
	(*env)->ReleaseStringUTFChars(env, lladdr, lladdr_str);
	(*env)->ReleaseStringUTFChars(env, settings, settings_str);
	return ret;
}

JNIEXPORT void JNICALL Java_com_wireguard_android_backend_GoBackend_wgSetFd(JNIEnv *env, jclass c, jint handle, jint tun_fd)
{
	wgSetFd(handle, tun_fd);
}

JNIEXPORT void JNICALL Java_com_wireguard_android_backend_GoBackend_wgTurnOff(JNIEnv *env, jclass c, jint handle)
{
	jobject event_handler = wgTurnOff(handle);
	if (event_handler)
		(*env)->DeleteGlobalRef(env, event_handler);
}

JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgGetSocketV4(JNIEnv *env, jclass c, jint handle)
{
	return wgGetSocketV4(handle);
}

JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgGetSocketV6(JNIEnv *env, jclass c, jint handle)
{
	return wgGetSocketV6(handle);
}

JNIEXPORT jstring JNICALL Java_com_wireguard_android_backend_GoBackend_wgGetConfig(JNIEnv *env, jclass c, jint handle)
{
	jstring ret;
	char *config = wgGetConfig(handle);
	if (!config)
		return NULL;
	ret = (*env)->NewStringUTF(env, config);
	free(config);
	return ret;
}

JNIEXPORT jstring JNICALL Java_com_wireguard_android_backend_GoBackend_wgVersion(JNIEnv *env, jclass c)
{
	jstring ret;
	char *version = wgVersion();
	if (!version)
		return NULL;
	ret = (*env)->NewStringUTF(env, version);
	free(version);
	return ret;
}

void wgOnEvent(void *eventHandler, const char *event)
{
	JavaVMAttachArgs attachArgs = { JNI_VERSION_1_6, NULL, NULL };
	jobject jEventHandler = eventHandler;
	JNIEnv *env;
	char buf[128];

	__android_log_write(ANDROID_LOG_ERROR, TAG, "wgOnEvent enter 2");
	jint rs = (*gVm)->AttachCurrentThread(gVm, &env, &attachArgs);

	sprintf(buf, "AttachCurrentThread %i %p", rs, env);
	__android_log_write(ANDROID_LOG_ERROR, TAG, buf);
	assert (rs == JNI_OK);
	jstring jevent = (*env)->NewStringUTF(env, event);
	sprintf(buf, "NewStringUTF %p", jevent);
	__android_log_write(ANDROID_LOG_ERROR, TAG, buf);
	//free(event);
	sprintf(buf, "CallVoidMethod %p %p %p %p", env, jEventHandler, gOnEventMethod, jevent);
	__android_log_write(ANDROID_LOG_ERROR, TAG, buf);
	(*env)->CallVoidMethod(env, jEventHandler, gOnEventMethod, jevent);
	/* sprintf(buf, "CallVoidMethod"); */
	/* __android_log_write(ANDROID_LOG_ERROR, TAG, buf); */
	// TODO free jevent?
	__android_log_write(ANDROID_LOG_ERROR, TAG, "wgOnEvent end");
}