/*

     File: SearchQuery.m 

 Abstract: Data model for a photo search query.

  Version: 1.7 

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 */

#import "SearchQuery.h"

NSString *SearchQueryChildrenDidChangeNotification = @"SearchQueryChildrenDidChangeNotification";

@implementation SearchQuery

@synthesize _searchURL;

- (id)initWithSearchPredicate:(NSPredicate *)searchPredicate title:(NSString *)title scopeURL:(NSURL *)url {

    self = [super init];

    if (self != nil) {

        _title = [title retain];

        _query = [[NSMetadataQuery alloc] init];

        _searchURL = [url retain];

        // We want the items in the query to automatically be sorted by the file system name;

        // this way, we don't have to do any special sorting

        [_query setSortDescriptors:[NSArray arrayWithObject:[[[NSSortDescriptor alloc] initWithKey:(id)kMDItemFSName ascending:YES] autorelease]]];

        [_query setPredicate:searchPredicate];

        // Use KVO to watch the results of the query

        [_query addObserver:self forKeyPath:@"results" options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld context:nil];

        [_query setDelegate:self];

        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(queryNote:) name:nil object:_query];

        // define the scope/where the search will take placce

        [_query setSearchScopes:(url != nil) ? [NSArray arrayWithObject:url] : nil];

        [_query startQuery];

    }

    return self;    

}

- (void)dealloc {

    [[NSNotificationCenter defaultCenter] removeObserver:self];    

    [_query removeObserver:self forKeyPath:@"results"];

    [_query release];

    [_title release];

    [_searchURL release];

    [_children release];

    [super dealloc];

}

- (void)sendChildrenDidChangeNote {

    [[NSNotificationCenter defaultCenter] postNotificationName:SearchQueryChildrenDidChangeNotification object:self];

}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {

    // Delegate the KVO notification by sending a children changed note.

    // We could check the keyPath, but there is no need, since we only observe one value.

    //

    [_children release];

    _children = [[_query results] retain];

    [self sendChildrenDidChangeNote];

}

#pragma NSMetadataQuery Delegate

- (id)metadataQuery:(NSMetadataQuery *)query replacementObjectForResultObject:(NSMetadataItem *)result {

    // We keep our own search item for the result in order to maintian state (image, thumbnail, title, etc)

    return [[[SearchItem alloc] initWithItem:result] autorelease];

}

- (void)queryNote:(NSNotification *)note {

    // The NSMetadataQuery will send back a note when updates are happening.

    // By looking at the [note name], we can tell what is happening

    //

    if ([[note name] isEqualToString:NSMetadataQueryDidFinishGatheringNotification]) {

        // At this point, the query will be done. You may recieve an update later on.

        if ([_children count] == 0) {

            [_children release];

            SearchItem *emptyItem = [[[SearchItem alloc] initWithItem:nil] autorelease];

            [emptyItem setTitle:NSLocalizedString(@"No results", @"Text to display when there are no results")];

            _children = [[NSArray alloc] initWithObjects:emptyItem, nil];

            [self sendChildrenDidChangeNote];

        }        

    }

}

#pragma mark -

- (NSString *)title {

    return _title;

}

- (NSArray *)children {

    return _children;

}

@end