/*

     File: RootViewController.m

 Abstract:  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: 1.1

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 */

#import "RootViewController.h"

#import "LocationsAppDelegate.h"

#import "Event.h"

@implementation RootViewController

@synthesize eventsArray, managedObjectContext, addButton, locationManager;

#pragma mark -

#pragma mark View lifecycle

- (void)viewDidLoad {

    [super viewDidLoad];

    // Set the title.

    self.title = @"Locations";

    // Configure the add and edit buttons.

    self.navigationItem.leftBarButtonItem = self.editButtonItem;

    addButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(addEvent)];

    addButton.enabled = NO;

    self.navigationItem.rightBarButtonItem = addButton;

    // Start the location manager.

    [[self locationManager] startUpdatingLocation];

    /*

     Fetch existing events.

     Create a fetch request; find the Event entity and assign it to the request; add a sort descriptor; then execute the fetch.

     */

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

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

    [request setEntity:entity];

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

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

    NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];

    [request setSortDescriptors:sortDescriptors];

    [sortDescriptor release];

    [sortDescriptors release];

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

    NSError *error = nil;

    NSMutableArray *mutableFetchResults = [[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];

    [mutableFetchResults release];

    [request release];

}

- (void)viewDidUnload {

    // Release any properties that are loaded in viewDidLoad or can be recreated lazily.

    self.eventsArray = nil;

    self.locationManager = nil;

    self.addButton = nil;

}

#pragma mark -

#pragma mark Table view data source methods

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

    // Only one section.

    return 1;

}

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

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

    return [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:NSDateFormatterMediumStyle];

    }

    static NSNumberFormatter *numberFormatter = nil;

    if (numberFormatter == nil) {

        numberFormatter = [[NSNumberFormatter alloc] init];

        [numberFormatter setNumberStyle:NSNumberFormatterDecimalStyle];

        [numberFormatter setMaximumFractionDigits:3];

    }

    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    if (cell == nil) {

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

        UITableViewCellStyleSubtitle;

    }

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

    Event *event = (Event *)[eventsArray objectAtIndex:indexPath.row];

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

    NSString *string = [NSString stringWithFormat:@"%@, %@",

                        [numberFormatter stringFromNumber:[event latitude]],

                        [numberFormatter stringFromNumber:[event longitude]]];

    cell.detailTextLabel.text = string;

    return cell;

}

/**

 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 = [eventsArray objectAtIndex:indexPath.row];

        [managedObjectContext deleteObject:eventToDelete];

        // Update the array and table view.

        [eventsArray removeObjectAtIndex:indexPath.row];

        [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:YES];

        // Commit the change.

        NSError *error;

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

            // Handle the error.

        }

    }   

}

#pragma mark -

#pragma mark Add an event

/**

 Add an event.

 */

- (void)addEvent {

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

    CLLocation *location = [locationManager location];

    if (!location) {

        return;

    }

    /*

     Create a new instance of the Event entity.

     */

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

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

    CLLocationCoordinate2D coordinate = [location coordinate];

    [event setLatitude:[NSNumber numberWithDouble:coordinate.latitude]];

    [event setLongitude:[NSNumber numberWithDouble:coordinate.longitude]];

    // Should be the location's timestamp, but this will be constant for simulator.

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

    [event setCreationDate:[NSDate date]];

    // Commit the change.

    NSError *error;

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

        // Handle the error.

    }

    /*

     Since 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.

     */

    [eventsArray insertObject:event atIndex:0];

    NSIndexPath *indexPath = [NSIndexPath indexPathForRow:0 inSection:0];

    [self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];

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

}

#pragma mark -

#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 {

    addButton.enabled = YES;

}

- (void)locationManager:(CLLocationManager *)manager

       didFailWithError:(NSError *)error {

    addButton.enabled = NO;

}

#pragma mark -

#pragma mark Memory management

- (void)dealloc {

    [managedObjectContext release];

    [eventsArray release];

    [locationManager release];

    [addButton release];

    [super dealloc];

}

@end