#import "RNElapsedRealtime.h"
#include <sys/sysctl.h>

@implementation RNElapsedRealtime
RCT_EXPORT_MODULE(RNElapsedRealtime);

/**
 * Return a relative time in seconds that can't be tampered with by the user
 */
RCT_EXPORT_METHOD(getElapsedRealtime: (RCTPromiseResolveBlock)resolve rejecter:(RCTPromiseRejectBlock)reject)
{
    resolve([NSString stringWithFormat:@"%ld", [self uptime]]);
}

/**
 * Get the system up time in seconds
 *
 * Method originally from here:
 * http://stackoverflow.com/questions/12488481/getting-ios-system-uptime-that-doesnt-pause-when-asleep
 */
- (time_t)uptime
{
    struct timeval boottime;
    int mib[2] = {CTL_KERN, KERN_BOOTTIME};
    size_t size = sizeof(boottime);
    time_t now;
    time_t uptime = -1;
    
    (void) time(&now);
    
    if (sysctl(mib, 2, &boottime, &size, NULL, 0) != -1 && boottime.tv_sec != 0) {
        uptime = now - (boottime.tv_sec);
    }
    
    return uptime;
}
@end