#include <jni.h>
#include <stdio.h>
#include "HelloJNI.h"

// Implementation of native method sayHello() of HelloJNI class
JNIEXPORT void JNICALL Java_HelloJNI_sayHello(JNIEnv *env, jobject thisObj) {
   printf("Hello World!\n");
   fflush(stdout);
   return;
}

// Implementation of native method isPrime() of HelloJNI class
JNIEXPORT jboolean JNICALL Java_HelloJNI_isPrime(JNIEnv *env, jobject thisObj, jint num) {
    if (num <= 1) return 0;
    if (num % 2 == 0 && num > 2) return 0;
    for(int i = 3; i < num / 2; i+= 2)
    {
        if (num % i == 0)
            return 0;
    }
    return 1;
}

// Implementation of native method forEachElement() of HelloJNI class
JNIEXPORT void JNICALL Java_HelloJNI_forEachElement(JNIEnv *env, jobject thisObj, jfloatArray array, jfloat val, jstring op) {
    jfloat* flt = (*env)->GetFloatArrayElements(env, array, NULL);
    jint i = 0;
    const char *str = (*env)->GetStringUTFChars(env, op, 0);
    for(i = 0; i < 5; i++) {
        if(!strncmp(str, "add")) {
            flt[i] += val;
        }
        else if(!strncmp(str, "subtract")) {
            flt[i] -= val;
        }
        else if(!strncmp(str, "multiply")) {
            flt[i] *= val;
        }
        else if(!strncmp(str, "divide")) {
            flt[i] /= val;
        }
    }
    (*env)->ReleaseFloatArrayElements(env, array, flt, 0);
    (*env)->ReleaseStringUTFChars(env, op, str);
    return;
}