/*

     File: APLRecentSearchesController.m 

 Abstract: A table view controller to manage and display a list of recent search strings.

 The search strings are stored in user defaults to maintain the list between launches of the application.

 The view controller manages two arrays:

 * recentSearches is the array that corresponds to the full set of recent search strings stored in user defaults.

 * displayedRecentSearches is an array derived from recent searches, filtered by the current search string (if any).

 The recentSearches array is kept synchronized with user defaults, and avoids the need to query user defaults every time the search string is updated.

 The table view displays the contents of the displayedRecentSearches array.

 The view controller has a delegate that it notifies if row in the table view is selected.

 The view controller's size in the popover is set in the storyboard.

  Version: 2.3 

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 */

#import "APLRecentSearchesController.h"

NSString *RecentSearchesKey = @"RecentSearchesKey";

@interface APLRecentSearchesController ()

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

@property (nonatomic) NSArray *recentSearches;

@property (nonatomic) NSArray *displayedRecentSearches;

@property (nonatomic, readwrite) UIActionSheet *confirmSheet;

@end

#pragma mark -

@implementation APLRecentSearchesController

#pragma mark - View lifecycle

- (void)viewDidLoad {

    [super viewDidLoad];

    // Set up the recent searches list, from user defaults or using an empty array.

    NSArray *recents = [[NSUserDefaults standardUserDefaults] objectForKey:RecentSearchesKey];

    if (recents) {

        self.recentSearches = recents;

        self.displayedRecentSearches = recents;

    }

    else {

        self.recentSearches = [NSArray array];

        self.displayedRecentSearches = [NSArray array];

    }

    // Disable the Clear button if there are no recents items.

    if ([self.recentSearches count] == 0) {

        self.clearButtonItem.enabled = NO;

    }    

}

- (void)viewWillAppear:(BOOL)animated {

    // Ensure the complete list of recents is shown on first display.

    [super viewWillAppear:animated];

    self.displayedRecentSearches = self.recentSearches;

}

#pragma mark - Managing the recents list

- (void)addToRecentSearches:(NSString *)searchString {

    // Filter out any strings that shouldn't be in the recents list.

    if ([searchString isEqualToString:@""]) {

        return;

    }

    // Create a mutable copy of recent searches and remove the search string if it's already there (it's added to the top of the list later).

    NSMutableArray *mutableRecents = [self.recentSearches mutableCopy];

    [mutableRecents removeObject:searchString];

    // Add the new string at the top of the list.

    [mutableRecents insertObject:searchString atIndex:0];

    // Update user defaults.

    [[NSUserDefaults standardUserDefaults] setObject:mutableRecents forKey:RecentSearchesKey];

    // Set self's recent searches to the new recents array, and reload the table view.

    self.recentSearches = mutableRecents;

    self.displayedRecentSearches = mutableRecents;

    [self.tableView reloadData];

    // Ensure the clear button is enabled.

    self.clearButtonItem.enabled = YES;

}

- (void)filterResultsUsingString:(NSString *)filterString {

    // If the search string is zero-length, then restore the recent searches, otherwise

    // create a predicate to filter the recent searches using the search string.

    //

    if ([filterString length] == 0) {

        self.displayedRecentSearches = self.recentSearches;

    }

    else {

        NSPredicate *filterPredicate = [NSPredicate predicateWithFormat:@"self BEGINSWITH[cd] %@", filterString];

        NSArray *filteredRecentSearches = [self.recentSearches filteredArrayUsingPredicate:filterPredicate];

        self.displayedRecentSearches = filteredRecentSearches;

    }

    [self.tableView reloadData];

}

- (IBAction)showClearRecentsAlert:(id)sender {

    NSString *cancelButtonTitle = NSLocalizedString(@"Cancel", @"Cancel button title");

    NSString *clearAllRecentsButtonTitle = NSLocalizedString(@"Clear All Recents", @"Clear All Recents button title");

    // If the user taps the Clear Recents button, present an action sheet to confirm.

    self.confirmSheet = [[UIActionSheet alloc] initWithTitle:@"" delegate:self cancelButtonTitle:cancelButtonTitle destructiveButtonTitle:clearAllRecentsButtonTitle otherButtonTitles:nil];

    [self.confirmSheet showInView:self.view];

}

- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex {

    if (buttonIndex == 0) {

        /*

         If the user chose to clear recents, remove the recents entry from user defaults, set the list to an empty array, and redisplay the table view.

         */

        [[NSUserDefaults standardUserDefaults] setObject:nil forKey:RecentSearchesKey];

        self.recentSearches = [NSArray array];

        self.displayedRecentSearches = [NSArray array];

        [self.tableView reloadData];

        self.clearButtonItem.enabled = NO;

    }

    self.confirmSheet = nil;

}

#pragma mark - Table view methods

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

    return [self.displayedRecentSearches count];

}

// Display the strings in displayedRecentSearches.

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

    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    cell.textLabel.text = [self.displayedRecentSearches objectAtIndex:indexPath.row];

    return cell;

}

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

    // Notify the delegate if a row is selected.

    [self.delegate recentSearchesController:self didSelectString:[self.displayedRecentSearches objectAtIndex:indexPath.row]];

}

@end