/*

     File: TrackLocationViewController.m

 Abstract: Attempts to track the user location with a specific level of accuracy. A "distance filter" indicates the smallest change in location that triggers an update from the location manager to its delegate. Presents a SetupViewController instance so the user can configure the desired accuracy and distance filter. Uses a LocationDetailViewController instance to drill down into details for a given location measurement.

  Version: 2.2

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 */

#import "TrackLocationViewController.h"

#import "LocationDetailViewController.h"

#import "CLLocation (Strings).h"

@implementation TrackLocationViewController

@synthesize startButton;

@synthesize descriptionLabel;

@synthesize locationManager;

@synthesize locationMeasurements;

@synthesize tableView;

@synthesize stateString;

- (void)viewDidLoad {

    self.locationMeasurements = [NSMutableArray array];

}

/*

 * The view hierarchy for this controller has been torn down. This usually happens in response to low memory notifications.

 * All IBOutlets should be released by setting their property to nil in order to free up as much memory as possible. 

 * This is also a good place to release other variables that can be recreated when needed.

 */

- (void)viewDidUnload {

    self.startButton = nil;

    self.descriptionLabel = nil;

    self.stateString = nil;

    self.tableView = nil;

    // For the readonly properties, they must be released and set to nil directly.

    [setupViewController release];

    setupViewController = nil;

    [dateFormatter release];

    dateFormatter = nil;

}

- (void)dealloc {

    [stateString release];

    [descriptionLabel release];

    [dateFormatter release];

    [locationManager release];

    [startButton release];

    [setupViewController release];

    [locationMeasurements release];

    [tableView release];

    [locationDetailViewController release];

    [super dealloc];

}

/*

 * The lazy "getter" for the readonly property.

 */

- (SetupViewController *)setupViewController {

    if (setupViewController == nil) {

        setupViewController = [[SetupViewController alloc] initWithNibName:@"TrackLocationSetupView" bundle:nil];

        setupViewController.delegate = self;

    }

    return setupViewController;

}

/*

 * The lazy "getter" for the readonly property.

 */

- (LocationDetailViewController *)locationDetailViewController {

    if (locationDetailViewController == nil) {

        locationDetailViewController = [[LocationDetailViewController alloc] initWithStyle:UITableViewStyleGrouped];

    }

    return locationDetailViewController;

}

/*

 * The lazy "getter" for the readonly property.

 */

- (NSDateFormatter *)dateFormatter {

    if (dateFormatter == nil) {

        dateFormatter = [[NSDateFormatter alloc] init];

        [dateFormatter setDateStyle:NSDateFormatterMediumStyle];

        [dateFormatter setTimeStyle:NSDateFormatterLongStyle];

    }

    return dateFormatter;

}

- (IBAction)start:(id)sender {

    [self.navigationController presentModalViewController:self.setupViewController animated:YES];

}

/* 

 * The reset method allows the user to repeatedly test the location functionality. In addition to discarding all of

 * the location measurements from the previous "run", it animates a transition in the user interface between the table

 * which displays location data and the start button and description label presented at launch.

 */

- (void)reset {

    [self.locationMeasurements removeAllObjects];

    [UIView beginAnimations:@"Reset" context:nil];

    [UIView setAnimationDuration:0.6];

    startButton.alpha = 1.0;

    descriptionLabel.alpha = 1.0;

    tableView.alpha = 0.0;

    [self.navigationItem setLeftBarButtonItem:nil animated:YES];;

    [UIView commitAnimations];

}

#pragma mark Location Manager Interactions

/*

 * This method is invoked when the user hits "Done" in the setup view controller. The options chosen by the user are

 * passed in as a dictionary. The keys for this dictionary are declared in SetupViewController.h.

 */

- (void)setupViewController:(SetupViewController *)controller didFinishSetupWithInfo:(NSDictionary *)setupInfo {

    startButton.alpha = 0.0;

    descriptionLabel.alpha = 0.0;

    tableView.alpha = 1.0;

    // Create the manager object 

    self.locationManager = [[[CLLocationManager alloc] init] autorelease];

    locationManager.delegate = self;

    // This is the most important property to set for the manager. It ultimately determines how the manager will

    // attempt to acquire location and thus, the amount of power that will be consumed.

    locationManager.desiredAccuracy = [[setupInfo objectForKey:kSetupInfoKeyAccuracy] doubleValue];

    // When "tracking" the user, the distance filter can be used to control the frequency with which location measurements

    // are delivered by the manager. If the change in distance is less than the filter, a location will not be delivered.

    locationManager.distanceFilter = [[setupInfo objectForKey:kSetupInfoKeyDistanceFilter] doubleValue];

    // Once configured, the location manager must be "started".

    [locationManager startUpdatingLocation];

    self.stateString = NSLocalizedString(@"Tracking", @"Tracking");

    [self.tableView reloadData];

    UIBarButtonItem *resetItem = [[[UIBarButtonItem alloc] initWithTitle:NSLocalizedString(@"Reset", @"Reset") style:UIBarButtonItemStyleBordered target:self action:@selector(reset)] autorelease];

    [self.navigationItem setLeftBarButtonItem:resetItem animated:YES];;

}

/*

 * We want to get and store a location measurement that meets the desired accuracy. For this example, we are

 *      going to use horizontal accuracy as the deciding factor. In other cases, you may wish to use vertical

 *      accuracy, or both together.

 */

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation {

    // test that the horizontal accuracy does not indicate an invalid measurement

    if (newLocation.horizontalAccuracy < 0) return;

    // test the age of the location measurement to determine if the measurement is cached

    // in most cases you will not want to rely on cached measurements

    NSTimeInterval locationAge = -[newLocation.timestamp timeIntervalSinceNow];

    if (locationAge > 5.0) return;

    // store all of the measurements, just so we can see what kind of data we might receive

    [locationMeasurements addObject:newLocation];

    // update the display with the new location data

    [self.tableView reloadData];    

}

- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error {

    // The location "unknown" error simply means the manager is currently unable to get the location.

    if ([error code] != kCLErrorLocationUnknown) {

        [self stopUpdatingLocation:NSLocalizedString(@"Error", @"Error")];

    }

}

- (void)stopUpdatingLocation:(NSString *)state {

    self.stateString = state;

    [self.tableView reloadData];

    [locationManager stopUpdatingLocation];

    locationManager.delegate = nil;

}

#pragma mark Table View DataSource/Delegate

// The table view has two sections. The first has 1 row which displays status information. The second has a row for each valid location object received from the location manager. 

- (NSInteger)numberOfSectionsInTableView:(UITableView *)table {

    return (self.locationMeasurements.count > 0) ? 2 : 1;

}

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section {

    switch (section) {

        case 0: {

            return NSLocalizedString(@"Status", @"Status");

        } break;

        default: {

            return NSLocalizedString(@"All Measurements", @"All Measurements");

        } break;

    }

}

- (NSInteger)tableView:(UITableView *)table numberOfRowsInSection:(NSInteger)section {

    switch (section) {

        case 0: {

            return 1;

        } break;

        default: {

            return locationMeasurements.count;

        } break;

    }

}

- (UITableViewCell *)tableView:(UITableView *)table cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    switch (indexPath.section) {

        case 0: {

            // The cell for the status row uses the cell style "UITableViewCellStyleValue1", which has a label on the left side of the cell with left-aligned and black text; on the right side is a label that has smaller blue text and is right-aligned. An activity indicator has been added to the cell and is animated while the location manager is updating. The cell's text label displays the current state of the manager.

            static NSString * const kStatusCellID = @"StatusCellID";

            static NSInteger const kStatusCellActivityIndicatorTag = 2;

            UIActivityIndicatorView *activityIndicator = nil;

            UITableViewCell *cell = [table dequeueReusableCellWithIdentifier:kStatusCellID];

            if (cell == nil) {

                cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:kStatusCellID] autorelease];

                cell.selectionStyle = UITableViewCellSelectionStyleNone;

                activityIndicator = [[[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray] autorelease];

                CGRect frame = activityIndicator.frame;

                frame.origin = CGPointMake(290, 12);

                activityIndicator.frame = frame;

                activityIndicator.autoresizingMask = UIViewAutoresizingFlexibleLeftMargin;

                activityIndicator.tag = kStatusCellActivityIndicatorTag;

                [cell.contentView addSubview:activityIndicator];

            } else {

                activityIndicator = (UIActivityIndicatorView *)[cell.contentView viewWithTag:kStatusCellActivityIndicatorTag];

            }

            cell.textLabel.text = stateString;

            if ([stateString isEqualToString:NSLocalizedString(@"Tracking", @"Tracking")]) {

                if (activityIndicator.isAnimating == NO) [activityIndicator startAnimating];

            } else {

                if (activityIndicator.isAnimating) [activityIndicator stopAnimating];

            }

            return cell;

        } break;

        default: {

            // The cells for the location rows use the cell style "UITableViewCellStyleSubtitle", which has a left-aligned label across the top and a left-aligned label below it in smaller gray text. The text label shows the coordinates for the location and the detail text label shows its timestamp.

            static NSString * const kOtherMeasurementsCellID = @"OtherMeasurementsCellID";

            UITableViewCell *cell = [table dequeueReusableCellWithIdentifier:kOtherMeasurementsCellID];

            if (cell == nil) {

                cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:kOtherMeasurementsCellID] autorelease];

                cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;

            }

            CLLocation *location = [locationMeasurements objectAtIndex:indexPath.row];

            cell.textLabel.text = location.localizedCoordinateString;

            cell.detailTextLabel.text = [self.dateFormatter stringFromDate:location.timestamp];

            return cell;

        } break;

    }

}

// Delegate method invoked before the user selects a row. In this sample, we use it to prevent selection in the 

// first section of the table view.

- (NSIndexPath *)tableView:(UITableView *)tableView willSelectRowAtIndexPath:(NSIndexPath *)indexPath {

    return (indexPath.section == 0) ? nil : indexPath;

}

// Delegate method invoked after the user selects a row. Selecting a row containing a location object

// will navigate to a new view controller displaying details about that location.

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

    [self.tableView deselectRowAtIndexPath:indexPath animated:YES];

    CLLocation *location = [locationMeasurements objectAtIndex:indexPath.row];

    self.locationDetailViewController.location = location;

    [self.navigationController pushViewController:locationDetailViewController animated:YES];

}

@end