/*

 Copyright (C) 2017 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 Lists all songs in a table view. Also allows sorting and grouping via bottom segmented control.

 */

#import "SongsViewController.h"

#import "SongDetailsController.h"

#import "Song.h"

@interface SongsViewController ()

@property (nonatomic, strong) SongDetailsController *detailController;

@property (nonatomic, strong) NSFetchedResultsController *fetchedResultsController;

@property (nonatomic, strong) IBOutlet UISegmentedControl *fetchSectioningControl;

@end

#pragma mark -

@implementation SongsViewController

- (void)viewDidLoad {

    [super viewDidLoad];

    [self fetch];   // Start fetching songs from our data store.

}

- (IBAction)changeFetchSectioning:(id)sender {

    self.fetchedResultsController = nil;

    [self fetch];

}

- (void)fetch {

    NSError *error = nil;

    BOOL success = [self.fetchedResultsController performFetch:&error];

    NSAssert2(success, @"Unhandled error performing fetch at SongsViewController.m, line %d: %@", __LINE__, [error localizedDescription]);

    [self.tableView reloadData];

}

- (NSFetchedResultsController *)fetchedResultsController {

    if (_fetchedResultsController == nil) {

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

        fetchRequest.entity = [NSEntityDescription entityForName:@"Song" inManagedObjectContext:self.managedObjectContext];

        NSArray *sortDescriptors = nil;

        NSString *sectionNameKeyPath = nil;

        if (self.fetchSectioningControl.selectedSegmentIndex == 1) {

            sortDescriptors = @[[[NSSortDescriptor alloc] initWithKey:@"category.name" ascending:YES], [[NSSortDescriptor alloc] initWithKey:@"rank" ascending:YES]];

            sectionNameKeyPath = @"category.name";

        } else {

            sortDescriptors = @[[[NSSortDescriptor alloc] initWithKey:@"rank" ascending:YES]];

        }

        fetchRequest.sortDescriptors = sortDescriptors;

        _fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest

                                                                        managedObjectContext:self.managedObjectContext

                                                                          sectionNameKeyPath:sectionNameKeyPath

                                                                                   cacheName:nil];

    }    

    return _fetchedResultsController;

}    

#pragma mark - UITableViewDataSource

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

    return self.fetchedResultsController.sections.count;

}

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

    id <NSFetchedResultsSectionInfo> sectionInfo = (self.fetchedResultsController.sections)[section];

    return sectionInfo.numberOfObjects;

}

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

    id <NSFetchedResultsSectionInfo> sectionInfo = (self.fetchedResultsController.sections)[section];

    if (self.fetchSectioningControl.selectedSegmentIndex == 0) {

        return [NSString stringWithFormat:NSLocalizedString(@"Top %d songs", @"Top %d songs"), sectionInfo.numberOfObjects];

    } else {

        return [NSString stringWithFormat:NSLocalizedString(@"%@ - %d songs", @"%@ - %d songs"), sectionInfo.name, sectionInfo.numberOfObjects];

    }

}

- (NSArray *)sectionIndexTitlesForTableView:(UITableView *)table {

    // Return list of section titles to display in section index view (e.g. "ABCD...Z#").

    return self.fetchedResultsController.sectionIndexTitles;

}

- (NSInteger)tableView:(UITableView *)table sectionForSectionIndexTitle:(NSString *)title atIndex:(NSInteger)index {

    // Tell table which section corresponds to section title/index (e.g. "B",1)).

    return [self.fetchedResultsController sectionForSectionIndexTitle:title atIndex:index];

}

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

    static NSString *kCellIdentifier = @"SongCell";

    UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:kCellIdentifier forIndexPath:indexPath];

    Song *song = [self.fetchedResultsController objectAtIndexPath:indexPath];

    cell.textLabel.text =

        [NSString stringWithFormat:NSLocalizedString(@"#%d %@", @"#%d %@"), song.rank.integerValue, song.title];

    return cell;

}

#pragma mark - Segue support

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

    if ([segue.identifier isEqualToString:@"showDetail"]) {

        SongDetailsController *detailsController = (SongDetailsController *)segue.destinationViewController;

        NSIndexPath *selectedIndexPath = self.tableView.indexPathForSelectedRow;

        detailsController.song = [self.fetchedResultsController objectAtIndexPath:selectedIndexPath];

    }

}

@end