#include <ctype.h>
#include <stdlib.h>
#include <stdio.h>

#include <mach/mach_port.h>
#include <mach/mach_interface.h>
#include <mach/mach_init.h>

#include <IOKit/pwr_mgt/IOPMLib.h>
#include <IOKit/IOMessage.h>

#include <jni.h>

struct MySleepContext {
    io_connect_t root_port; // the Root Power Domain IOService;
    jobject callback; // the Java callback
    JNIEnv * env; // the Java environment
};

void MySleepCallBack(void * pointer, io_service_t service, natural_t messageType, void * messageArgument) {
    struct MySleepContext * context = pointer;
    jclass callbackClass = (*context->env)->GetObjectClass(context->env, context->callback);
    jmethodID mid = (*context->env)->GetMethodID(context->env, callbackClass, "allowIdleSleep", "()Z");
    jboolean allow = (*context->env)->CallBooleanMethod(context->env, context->callback, mid);

    switch (messageType) {
        case kIOMessageCanSystemSleep:
            if (allow == JNI_TRUE) {
                IOAllowPowerChange(context->root_port, (long) messageArgument);
            } else {
                IOCancelPowerChange(context->root_port, (long) messageArgument);
            }
            break;
        case kIOMessageSystemWillSleep:
            IOAllowPowerChange(context->root_port, (long) messageArgument);
            break;
        default:
            break;
    }
}

JNIEXPORT void JNICALL KeepAwakeNative_keepAwakeNative (JNIEnv * env, jobject obj, jobject callback) {
    IONotificationPortRef notifyPortRef;
    io_object_t notifierObject;

    struct MySleepContext * context;
    context->callback = callback;
    context->env = env;

    context->root_port = IORegisterForSystemPower(context, &notifyPortRef, MySleepCallBack, &notifierObject);
    CFRunLoopAddSource(CFRunLoopGetCurrent(), IONotificationPortGetRunLoopSource(notifyPortRef), kCFRunLoopCommonModes);

    // blocks
    CFRunLoopRun();
}