#include "javatech_jni22_JNIDemo.h"

JNIEXPORT void JNICALL
    Java_javatech_jni22_JNIDemo_doStatic (JNIEnv *jenv, jclass cls)
{} // doStatic

JNIEXPORT void JNICALL
    Java_javatech_jni22_JNIDemo_doSomething (JNIEnv *jenv, jobject jo)
{
    // Find the jclass corresponding to the jobject
    jclass cls = jenv->GetObjectClass (jo);

    // Get the static a_static_float field.
    jfieldID fid = jenv->GetStaticFieldID (cls, "a_static_float", "F");
    jfloat a_static_float = jenv->GetStaticFloatField (cls, fid);
    printf ("got a_static_float = %f\n", a_static_float);

    // Find the field ID of the 'my_custom' field
    jfieldID my_custom_fid = jenv->GetFieldID (
	cls, "my_custom", "Ljavatech/jni22/MyCustomObject;"
    );
    if (my_custom_fid == NULL)
	return;
    printf ("got my_custom_fid\n");

    // Get the jobject reference to 'my_custom'
    jobject my_custom_jo = jenv->GetObjectField (jo, my_custom_fid);
    printf ("got my_custom_jo\n");

    // Find the jclass of the my_custom_jo jobject.
    jclass my_custom_cls = jenv->GetObjectClass (my_custom_jo);
    printf ("got my_custom_cls\n");

    // Find the field ID of the 'val' field of MyCustomObject.
    jfieldID val_fid = jenv->GetFieldID (my_custom_cls, "val", "I");
    if (val_fid == NULL) {
	jthrowable jth = jenv->ExceptionOccurred ();
	if (jth) {
	    printf ("    there was an exception\n");
	    jenv->ExceptionDescribe ();
	    jenv->ExceptionClear ();
	    printf ("    described and cleared it\n");
	}
	return;
    }
    printf ("got val_fid\n");

    // Get the 'val' field
    jint val = jenv->GetIntField (my_custom_jo, val_fid);
    printf ("got val = %d\n", val);

    // Manipulate it somehow
    jint multiplier = (jint) a_static_float;
    val *= multiplier;
    printf ("multiplied it by %f\n", a_static_float);

    // Set it back into my_custom_jo
    jenv->SetIntField (my_custom_jo, val_fid, val);
    printf ("put it back into my_custom_jo\n");

    // Get the method ID to call a Java method
    jmethodID mid = jenv->GetMethodID (cls, "callback", "(I)I");
    if (mid == NULL)
	return;
    printf ("got mid\n");

    jint param = 8;
    // Call the Java method
    printf ("calling Java 'callback' method\n");
    jint ret = jenv->CallIntMethod (jo, mid, param);
    // Check for any exception that may have occurred during the Java method
    jthrowable jth = jenv->ExceptionOccurred ();
    if (jth) {
	printf ("    there was an exception\n");
	jenv->ExceptionDescribe ();
	jenv->ExceptionClear ();
	printf ("    did not return from Java 'callback'\n");
    }
    else
	printf ("    return from 'callback' = %d\n", ret);
} // doSomething