/*

    File:       PhotoCell.m

    Contains:   A table view cell to display a photo.

    Written by: DTS

    Copyright:  Copyright (c) 2010 Apple Inc. All Rights Reserved.

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                The Apple Software is provided by Apple on an "AS IS" basis. 

                APPLE MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING

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*/

#import "PhotoCell.h"

#import "Photo.h"

@implementation PhotoCell

- (id)initWithReuseIdentifier:(NSString *)reuseIdentifier

{

    self = [super initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:reuseIdentifier];

    if (self != nil) {

        // Observe a bunch of our own properties so that the UI adjusts to any changes.

        [self addObserver:self forKeyPath:@"photo.displayName"    options:0 context:&self->_photo];

        [self addObserver:self forKeyPath:@"photo.date"           options:0 context:&self->_dateFormatter];

        [self addObserver:self forKeyPath:@"photo.thumbnailImage" options:0 context:&self->_photo];

        [self addObserver:self forKeyPath:@"dateFormatter"        options:0 context:&self->_dateFormatter];

    }

    return self;

}

- (void)dealloc

{

    // Remove our observers.

    [self removeObserver:self forKeyPath:@"photo.displayName"];

    [self removeObserver:self forKeyPath:@"photo.date"];

    [self removeObserver:self forKeyPath:@"photo.thumbnailImage"];

    [self removeObserver:self forKeyPath:@"dateFormatter"];

    // Clean up our memory.

    [self->_photo release];

    [self->_dateFormatter release];

    [super dealloc];

}

// Because we self-observe dateFormatter in order to update after a locale change, 

// we only want to fire KVO notifications if the date formatter actually changes (which 

// is infrequent in day-to-day operations.  So we override the setter and handle the 

// KVO notifications ourself.

@synthesize dateFormatter = _dateFormatter;

+ (BOOL)automaticallyNotifiesObserversOfDateFormatter

{

    return NO;

}

- (void)setDateFormatter:(NSDateFormatter *)newValue

{

    if (newValue != self->_dateFormatter) {

        [self willChangeValueForKey:@"dateFormatter"];

        [self->_dateFormatter release];

        self->_dateFormatter = [newValue retain];

        [self  didChangeValueForKey:@"dateFormatter"];

    }

}

@synthesize photo         = _photo;

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

    // Called when various properties of the photo change; updates the cell accordingly.

{

    if (context == &self->_photo) {

        assert(object == self);

        if ([keyPath isEqual:@"photo.displayName"]) {

            if (self.photo == nil) {

                self.textLabel.text   = nil;

            } else {

                self.textLabel.text   = self.photo.displayName;

            }

            // iOS 3 has a bug where, if you set the text of a cell's label to something longer 

            // than the existing text, it doesn't expand the label to accommodate the longer 

            // text.  The end result is that the text gets needlessly truncated.  We fix 

            // this by triggering a re-layout whenever we change the text.

            [self setNeedsLayout];

        } else if ([keyPath isEqual:@"photo.thumbnailImage"]) {

            if (self.photo == nil) {

                self.imageView.image  = nil;

            } else {

                self.imageView.image  = self.photo.thumbnailImage;

            }

        } else {

            assert(NO);

        }

    } else if (context == &self->_dateFormatter) {

        NSString *  dateText;

        assert(object == self);

        assert([keyPath isEqual:@"photo.date"] || [keyPath isEqual:@"dateFormatter"]);

        dateText = nil;

        if (self.photo != nil) {

            if (self.dateFormatter == nil) {

                // If there's no date formatter, just use the date's description.  This is 

                // somewhat lame, and you wouldn't want to run this code path in general.

                dateText = [self.photo.date description];

            } else {

                dateText = [self.dateFormatter stringFromDate:self.photo.date];

            }

        }

        self.detailTextLabel.text = dateText;

        [self setNeedsLayout];      // see comment above

    } else if (NO) {   // Disabled because the super class does nothing useful with it.

        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];

    }

}

@end