// Copyright © 2017-2020 Trust Wallet.

//

// This file is part of Trust. The full Trust copyright notice, including

// terms governing use, modification, and redistribution, is contained in the

// file LICENSE at the root of the source code distribution tree.

#include <jni.h>

#include <string.h>

static JavaVM* cachedJVM;

extern "C" {

uint32_t random32();

void random_buffer(uint8_t *buf, size_t len);

}

JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *jvm, void *reserved) {

cachedJVM = jvm;

return JNI_VERSION_1_2;

}

uint32_t random32() {

uint32_t result;

random_buffer((uint8_t*) &result, sizeof(uint32_t));

return result;

}

void random_buffer(uint8_t *buf, size_t len) {

JNIEnv *env;

cachedJVM->AttachCurrentThread(&env, NULL);

// SecureRandom random = new SecureRandom();

jclass secureRandomClass = env->FindClass("java/security/SecureRandom");

jmethodID constructor = env->GetMethodID(secureRandomClass, "<init>", "()V");

jobject random = env->NewObject(secureRandomClass, constructor);

//byte array[] = new byte[len];

jbyteArray array = env->NewByteArray(len);

//random.nextBytes(bytes);

jmethodID nextBytes = env->GetMethodID(secureRandomClass, "nextBytes", "([B)V");

env->CallVoidMethod(random, nextBytes, array);

jbyte* bytes = env->GetByteArrayElements(array, nullptr);

memcpy(buf, bytes, len);

env->ReleaseByteArrayElements(array, bytes, JNI_ABORT);

env->DeleteLocalRef(array);

env->DeleteLocalRef(random);

env->DeleteLocalRef(secureRandomClass);

}