/*

     File: APLCalibrationCalculator.m

 Abstract: Illustrates how to calibrate the measured power of a beacon.

  Version: 1.1

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 */

#import "APLCalibrationCalculator.h"

#import "APLDefaults.h"

@import CoreLocation;

static const NSTimeInterval ALCalibrationDwell = 20.0f;

NSString *AppErrorDomain = @"com.example.apple-samplecode.AirLocate";

@interface APLCalibrationCalculator()

@property CLLocationManager *locationManager;

@property CLBeaconRegion *region;

@property (getter=isCalibrating) BOOL calibrating;

@property NSMutableArray *rangedBeacons;

@property NSTimer *timer;

@property (strong) APLCalibrationProgressHandler progressHandler;

@property (strong) APLCalibrationCompletionHandler completionHandler;

@property float percentComplete;

@end

@implementation APLCalibrationCalculator

- (id)initWithRegion:(CLBeaconRegion *)region completionHandler:(APLCalibrationCompletionHandler)handler

{

    self = [super init];

    if(self)

    {

        // This location manager will be used to collect RSSI samples from the targeted beacon.

        _locationManager = [[CLLocationManager alloc] init];

        _locationManager.delegate = self;

        _region = region;

        _completionHandler = [handler copy];

        _rangedBeacons = [[NSMutableArray alloc] init];

    }

    return self;

}

- (void)locationManager:(CLLocationManager *)manager didRangeBeacons:(NSArray *)beacons inRegion:(CLBeaconRegion *)region

{

    // CoreLocation will call this delegate method at 1 Hz with updated range information.

    @synchronized(self)

    {

        [_rangedBeacons addObject:beacons];

        if(_progressHandler)

        {

            dispatch_async(dispatch_get_main_queue(), ^{

                // Bump the progress callback back to the UI thread as we'll be updating the UI.

                _percentComplete += 1.0f / ALCalibrationDwell;

                _progressHandler(_percentComplete);

            });

        }

    }

}

- (void)performCalibrationWithProgressHandler:(APLCalibrationProgressHandler)handler

{

    @synchronized(self)

    {

        if(!self.calibrating)

        {

            // Calibration consists of collecting RSSI samples for 20 seconds.

            // Once we have all the samples we will average the mid-80th percentile in timerElapsed:.

            self.calibrating = YES;

            [self.rangedBeacons removeAllObjects];

            self.percentComplete = 0.0f;

            self.progressHandler = [handler copy];

            [self.locationManager startRangingBeaconsInRegion:self.region];

            self.timer = [[NSTimer alloc] initWithFireDate:[NSDate dateWithTimeIntervalSinceNow:ALCalibrationDwell] interval:0 target:self selector:@selector(timerElapsed:) userInfo:nil repeats:NO];

            [[NSRunLoop currentRunLoop] addTimer:self.timer  forMode:NSDefaultRunLoopMode];

        }

        else

        {

            // Send back an error if calibration is already in progress.

            NSString *localizedErrorString = NSLocalizedString(@"Calibration is already in progress", @"Error string");

            NSDictionary *userInfo = @{ NSLocalizedDescriptionKey : localizedErrorString };

            NSError *error = [NSError errorWithDomain:AppErrorDomain code:4 userInfo:userInfo];

            dispatch_async(dispatch_get_main_queue(), ^{

                _completionHandler(0, error);

            });

        }

    }

}

- (void)cancelCalibration

{

    @synchronized(self)

    {

        // Fire the timer early if calibration is being cancelled.

        // timerElapsed: will handle reporting the cancellation.

        if(self.calibrating)

        {

            self.calibrating = NO;

            [self.timer fire];

        }

    }

}

- (void)timerElapsed:(id)sender

{

    @synchronized(self)

    {

        // We can stop ranging at this point as we've either been cancelled or

        // collected all of the RSSI samples we need.

        [_locationManager stopRangingBeaconsInRegion:_region];

        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

            @synchronized(self) {                

                __block NSError *error = nil;

                NSMutableArray *allBeacons = [[NSMutableArray alloc] init];

                NSInteger measuredPower = 0;

                if(!self.calibrating)

                {

                    NSString *localizedErrorString = NSLocalizedString(@"Calibration was cancelled", @"Error string");

                    NSDictionary *userInfo = @{ NSLocalizedDescriptionKey : localizedErrorString };

                    error = [NSError errorWithDomain:AppErrorDomain code:2 userInfo:userInfo];

                }

                else

                {

                    [self.rangedBeacons enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {

                        NSArray *beacons = (NSArray *)obj;

                        if(beacons.count > 1)

                        {

                            NSString *localizedErrorString = NSLocalizedString(@"More than one beacon of the specified type was found", @"Error string");

                            NSDictionary *userInfo = @{ NSLocalizedDescriptionKey : localizedErrorString };

                            error = [NSError errorWithDomain:AppErrorDomain code:1 userInfo:userInfo];

                            *stop = YES;

                        }

                        else

                        {

                            [allBeacons addObjectsFromArray:beacons];

                        }

                    }];

                    if(allBeacons.count <= 0)

                    {

                        NSString *localizedErrorString = NSLocalizedString(@"No beacon of the specified type was found", @"Error string");

                        NSDictionary *userInfo = @{ NSLocalizedDescriptionKey : localizedErrorString };

                        error = [NSError errorWithDomain:AppErrorDomain code:3 userInfo:userInfo];

                    }

                    else

                    {

                        // Measured power is an average of the mid-80th percentile of RSSI samples.

                        NSUInteger outlierPadding = allBeacons.count * 0.1f;                    

                        [allBeacons sortUsingDescriptors:@[[NSSortDescriptor sortDescriptorWithKey:@"rssi" ascending:YES]]];

                        NSArray *sample = [allBeacons subarrayWithRange:NSMakeRange(outlierPadding, allBeacons.count - (outlierPadding * 2))];

                        measuredPower = [[sample valueForKeyPath:@"@avg.rssi"] integerValue];

                    }

                }

                // Bump the completion callback to the UI thread as we'll be updating the UI.

                dispatch_async(dispatch_get_main_queue(), ^{

                    _completionHandler(measuredPower, error);

                });

                self.calibrating = NO;

                [self.rangedBeacons removeAllObjects];

                self.progressHandler = nil;

            }

        });

    }

}

@end