/*

     File: APLRootViewController.m

 Abstract: The table view controller responsible for displaying the list of events, supporting additional functionality:

 * Addition of new new events;

 * Deletion of existing events using UITableView's tableView:commitEditingStyle:forRowAtIndexPath: method.

  Version: 2.0

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 */

#import "APLRootViewController.h"

#import "APLEvent.h"

#import "APLEventDetailViewController.h"

@interface APLRootViewController ()

@property (nonatomic, weak) IBOutlet UIBarButtonItem *addButton;

@property (nonatomic) NSMutableArray *eventsArray;

@property (nonatomic) CLLocationManager *locationManager;

@end

@implementation APLRootViewController

#pragma mark - View lifecycle

- (void)viewDidLoad

{   

    [super viewDidLoad];

    self.navigationItem.leftBarButtonItem = self.editButtonItem;

    // Start the location manager.

    [[self locationManager] startUpdatingLocation];

    /*

     Fetch existing events.

     Create a fetch request, add a sort descriptor, then execute the fetch.

     */

    NSFetchRequest *request = [[NSFetchRequest alloc] init];

    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Event" inManagedObjectContext:self.managedObjectContext];

    [request setEntity:entity];

    // Order the events by creation date, most recent first.

    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"creationDate" ascending:NO];

    [request setSortDescriptors:@[sortDescriptor]];

    // Execute the fetch -- create a mutable copy of the result.

    NSError *error = nil;

    NSMutableArray *mutableFetchResults = [[self.managedObjectContext executeFetchRequest:request error:&error] mutableCopy];

    if (mutableFetchResults == nil) {

        // Handle the error.

    }

    // Set self's events array to the mutable array, then clean up.

    [self setEventsArray:mutableFetchResults];

}

- (void)viewWillAppear:(BOOL)animated

{

    [super viewWillAppear:animated];

    [self.tableView reloadData];

}

#pragma mark - Table view data source methods

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView

{

    // There is only one section.

    return 1;

}

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

{

    // As many rows as there are obects in the events array.

    return [self.eventsArray count];

}

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

{

    // A date formatter for the creation date.

    static NSDateFormatter *dateFormatter = nil;

    if (dateFormatter == nil) {

        dateFormatter = [[NSDateFormatter alloc] init];

        [dateFormatter setTimeStyle:NSDateFormatterMediumStyle];

        [dateFormatter setDateStyle:NSDateFormatterShortStyle];

    }

    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    // Get the event corresponding to the current index path and configure the table view cell.

    APLEvent *event = (APLEvent *)(self.eventsArray)[indexPath.row];

    cell.textLabel.text = [dateFormatter stringFromDate:[event creationDate]];

    cell.imageView.image = event.thumbnail;

    return cell;

}

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender

{

    NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];

    APLEvent *event = (self.eventsArray)[indexPath.row];

    APLEventDetailViewController *inspector = (APLEventDetailViewController *)[segue destinationViewController];

    inspector.event = event;

}

/**

 Handle deletion of an event.

 */

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath

{

    if (editingStyle == UITableViewCellEditingStyleDelete) {

        // Delete the managed object at the given index path.

        NSManagedObject *eventToDelete = (self.eventsArray)[indexPath.row];

        [self.managedObjectContext deleteObject:eventToDelete];

        // Update the array and table view.

        [self.eventsArray removeObjectAtIndex:indexPath.row];

        [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:YES];

        // Commit the change.

        NSError *error = nil;

        if (![self.managedObjectContext save:&error]) {

            // Replace this implementation with code to handle the error appropriately.

            // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.

            NSLog(@"Unresolved error %@, %@", error, [error userInfo]);

            abort();

        }

    }   

}

#pragma mark - Add an event

/**

 Add an event.

 */

- (IBAction)addEvent:(id)sender

{

    // If it's not possible to get a location, then return.

    CLLocation *location = [self.locationManager location];

    if (!location) {

#ifdef DEBUG

        NSLog(@"Getting a random location");

        CLLocationDegrees latitude = random() * 360.0 / INT32_MAX - 180.0;

        CLLocationDegrees longitude = random() * 360.0 / INT32_MAX - 180.0;

        location = [[CLLocation alloc] initWithLatitude:latitude longitude:longitude];

#else

        NSLog(@"Didn't get a location");

        return;

#endif

    }

    /*

     Create a new instance of the Event entity.

     */

    APLEvent *event = (APLEvent *)[NSEntityDescription insertNewObjectForEntityForName:@"Event" inManagedObjectContext:self.managedObjectContext];

    // Configure the new event with information from the location.

    CLLocationCoordinate2D coordinate = [location coordinate];

    [event setLatitude:@(coordinate.latitude)];

    [event setLongitude:@(coordinate.longitude)];

    // Should be timestamp, but this will be constant for simulator.

    // [event setCreationDate:[location timestamp]];

    [event setCreationDate:[NSDate date]];

    // Commit the change.

    NSError *error;

    if (![self.managedObjectContext save:&error]) {

        // Replace this implementation with code to handle the error appropriately.

        // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.

        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);

        abort();

    }

    /*

     Because this is a new event, and events are displayed with most recent events at the top of the list,

     add the new event to the beginning of the events array; then redisplay the table view.

     */

    [self.eventsArray insertObject:event atIndex:0];

    [self.tableView reloadData];

    [self.tableView scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:0] atScrollPosition:UITableViewScrollPositionTop animated:YES];

}

#pragma mark - Location manager

/**

 Return a location manager -- create one if necessary.

 */

- (CLLocationManager *)locationManager

{

    if (_locationManager != nil) {

        return _locationManager;

    }

    _locationManager = [[CLLocationManager alloc] init];

    [_locationManager setDesiredAccuracy:kCLLocationAccuracyNearestTenMeters];

    [_locationManager setDelegate:self];

    return _locationManager;

}

/**

 Conditionally enable the Add button:

 If the location manager is generating updates, then enable the button;

 If the location manager is failing, then disable the button.

 */

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

{

    self.addButton.enabled = YES;

}

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

{

#ifdef DEBUG

    NSLog(@"Location manager failed");

#else

    self.addButton.enabled = NO;

#endif

}

@end