/*

     File: SearchItem.m 

 Abstract: Data model for a search result item.

  Version: 1.7 

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 be used to endorse or promote products derived from the Apple Software 

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 expressly stated in this notice, no other rights or licenses, express or 

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

 MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION 

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 */

#import "SearchItem.h"

NSString *SearchItemDidChangeNotification = @"SearchItemDidChangeNotification";

@implementation SearchItem

- (id)initWithItem:(NSMetadataItem *)item {

    self = [super init];

    if (self)

        _item = [item retain];

    return self;

}

- (void)dealloc {

    [_url release];

    [_title release];

    [_thumbnailImage release];

    [_item release];

    [super dealloc];

}

- (NSMetadataItem *)metadataItem {

    return _item;

}

- (NSString *)title {

    if (_title == nil) {

        // First access -- dynamically get the title and cache it.

        _title = [(NSString *)[_item valueForAttribute:(NSString *)kMDItemDisplayName] retain];

    }

    return _title;

}

- (void)setTitle:(NSString *)title {

    if (![_title isEqualToString:title]) {

        [_title release];

        _title = [title copy];

    }

}

- (NSDate *)modifiedDate {

    return (NSDate *)[_item valueForAttribute:(NSString *)kMDItemContentModificationDate];

}

- (NSString *)cameraModel {

    return (NSString *)[_item valueForAttribute:(NSString *)kMDItemAcquisitionModel];

}

- (NSURL *)filePathURL {

    if (_url == nil) {

        NSString *path = [_item valueForAttribute:(NSString *)kMDItemPath];

        if (path != nil) {

            _url = [[NSURL fileURLWithPath:path] retain];

        }

    }

    return [[_url retain] autorelease];

}

+ (NSSize)getImageSizeFromImageSource:(CGImageSourceRef)imageSource {

    CGImageRef imageRef = CGImageSourceCreateImageAtIndex(imageSource, 0, NULL);

    NSSize result;

    if (imageRef != NULL) {

        result.width = CGImageGetWidth(imageRef);

        result.height = CGImageGetHeight(imageRef);

        CGImageRelease(imageRef);

    } else {

        result = NSZeroSize;

    }

    return result;

}

+ (NSImage *)makeThumbnailImageFromImageSource:(CGImageSourceRef)imageSource {

    NSImage *result;

    // This code needs to be threadsafe, as it will be called from the background thread.

    // The easiest way to ensure you only use stack variables is to make it a class method.

    NSNumber *maxPixelSize = [NSNumber numberWithInteger:32];

    NSDictionary *imageOptions = [NSDictionary dictionaryWithObjectsAndKeys:

                                    (id)kCFBooleanTrue,(id)kCGImageSourceCreateThumbnailFromImageIfAbsent,

                                    maxPixelSize, (id)kCGImageSourceThumbnailMaxPixelSize,

                                    kCFBooleanTrue, (id)kCGImageSourceCreateThumbnailWithTransform,

                                  nil];

    CGImageRef imageRef = CGImageSourceCreateThumbnailAtIndex(imageSource, 0, (CFDictionaryRef)imageOptions);

    if (imageRef != NULL) {

        CGRect rect;

        rect.origin.x = 0;

        rect.origin.y = 0;

        rect.size.width = CGImageGetWidth(imageRef);

        rect.size.height = CGImageGetHeight(imageRef);

        result = [[[NSImage alloc] init] autorelease];

        [result setFlipped:YES];

        [result setSize:NSMakeSize(rect.size.width, rect.size.height)];

        [result lockFocus];

        CGContextDrawImage((CGContextRef)[[NSGraphicsContext currentContext] graphicsPort], rect, imageRef);

        [result unlockFocus];

        CFRelease(imageRef);

    } else {

        result = nil;

    }

    return result;

}

/* Use a background thread for computing the image thumbnails. This logic is rather complex,

    but should be easy to follow. The general procedure is to use a shared queue to place

    the SearchItems onto for thumbnail computation. 

*/

#define HAS_DATA 1

#define NO_DATA  0

// The computeThumbnailClientQueue protectes the computeThumbnailClientQueue

static NSConditionLock *computeThumbnailConditionLock = nil;

static NSMutableArray *computeThumbnailClientQueue = nil;

+ (void)subthreadComputePreviewThumbnailImages {

    BOOL shouldExit = NO;

    while (!shouldExit) {

        NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

        NSImage *image = nil;

        BOOL aquiredLock = [computeThumbnailConditionLock lockWhenCondition:HAS_DATA beforeDate:[NSDate dateWithTimeIntervalSinceNow:5.0]];

        if (aquiredLock && ([computeThumbnailClientQueue count] > 0)) {

            // Remove the item from the queue. Retain it to ensure it stays alive while we use it in the thread.

            SearchItem *item = [[computeThumbnailClientQueue objectAtIndex:0] retain];

            // Grab the URL while holding the lock, since the _url is cached and shared

            NSURL *urlForImage = [item filePathURL];

            [computeThumbnailClientQueue removeObjectAtIndex:0];

            // Unlock the lock so the main thread can put more things on the stack

            BOOL hasMoreData = [computeThumbnailClientQueue count] > 0;

            [computeThumbnailConditionLock unlockWithCondition:hasMoreData ? HAS_DATA : NO_DATA];

            // Now, we can do our slow operations, like loading the image

            CGImageSourceRef imageSource = CGImageSourceCreateWithURL((CFURLRef)urlForImage, nil);

            if (imageSource) {

                // Grab the width/height

                NSSize imageSize = [[self class] getImageSizeFromImageSource:imageSource];

                // Signal the main thread

                [item performSelectorOnMainThread:@selector(mainThreadComputeImageSizeFinished:)

                                       withObject:[NSValue valueWithSize:imageSize]

                                    waitUntilDone:NO];

                // Now, compute the thumbnail

                image = [[self class] makeThumbnailImageFromImageSource:imageSource];

                [item performSelectorOnMainThread:@selector(mainThreadComputePreviewThumbnailFinished:) withObject:image waitUntilDone:NO];

                CFRelease(imageSource);

            }

            // Now, we are done with the item.

            [item release];

        } else {

            // It is possible that something was placed on the queue; check if we are done while holding the lock.

            [computeThumbnailConditionLock lock];

            shouldExit = [computeThumbnailClientQueue count] == 0;

            if (shouldExit) {

                [computeThumbnailClientQueue release];

                computeThumbnailClientQueue = nil;

            }

            [computeThumbnailConditionLock unlock];

        }

        [pool release];

    }

}

- (void)computeThumbnailImageInBackgroundThread {

    if (computeThumbnailConditionLock == nil) {

        computeThumbnailConditionLock = [[NSConditionLock alloc] initWithCondition:NO_DATA];

    }

    // See if we need to startup the thread. The computeThumbnailClientQueue being nil is the signal to start the thread..

    // Acquire the lock first.

    [computeThumbnailConditionLock lock];

    if (computeThumbnailClientQueue == nil) {

        computeThumbnailClientQueue = [[NSMutableArray alloc] init];

        [NSThread detachNewThreadSelector:@selector(subthreadComputePreviewThumbnailImages) toTarget:[self class] withObject:nil];

    }

    if ([computeThumbnailClientQueue indexOfObjectIdenticalTo:self] == NSNotFound) {

        [computeThumbnailClientQueue addObject:self];

    }

    BOOL hasMoreData = [computeThumbnailClientQueue count] > 0;

    // Now, unlock, which will signal the background thread to start working

    [computeThumbnailConditionLock unlockWithCondition:hasMoreData ? HAS_DATA : NO_DATA];

}

- (NSImage *)thumbnailImage {

    if (!(_state & ItemStateThumbnailLoaded)) {

        if (_thumbnailImage == nil && (_state & ItemStateThumbnailLoading) == 0) {

            _state |= ItemStateThumbnailLoading;

            [self computeThumbnailImageInBackgroundThread];

        }

    }

    return _thumbnailImage;

}

- (void)mainThreadComputePreviewThumbnailFinished:(NSImage *)thumbnail {

    _state &= ~ItemStateThumbnailLoading;

    _state |= ItemStateThumbnailLoaded;

    if (_thumbnailImage != thumbnail) {

        [_thumbnailImage release];

        _thumbnailImage = [thumbnail retain];

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

    }

}

- (void)mainThreadComputeImageSizeFinished:(NSValue *)imageSizeValue {

    _imageSize = [imageSizeValue sizeValue];

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

}

- (NSSize)imageSize {

    return _imageSize;

}

@end