/*

     File: LinkTextFieldCell.m 

 Abstract: Custom NSTextFieldCell to handle tracking and drawing links. 

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 */

#import "LinkTextFieldCell.h"

@implementation LinkTextFieldCell

- (id)copyWithZone:(NSZone *)zone {

    LinkTextFieldCell *result = [super copyWithZone:zone];

    result->_linkClickedHandler = [_linkClickedHandler copy];

    return result;

}

// Our cell wants to work like a button, and wants to keep tracking until the mouse is released up

+ (BOOL)prefersTrackingUntilMouseUp {

    return YES;

}

// Text cells in NSTableView's normally don't "track the mouse", since they don't resond to clicks. 

// Wait! What about editing? Well, that is done via the NSFieldEditor which handles the clicks/selection/etc.

//

- (NSUInteger)hitTestForEvent:(NSEvent *)event inRect:(NSRect)cellFrame ofView:(NSView *)controlView {

    NSUInteger hitTestResult = [super hitTestForEvent:event inRect:cellFrame ofView:controlView];

    // If we hit on content (ie: text, and not whitespace), then we go ahead and say we want to track

    if ((hitTestResult & NSCellHitContentArea) != 0) {

        hitTestResult |= NSCellHitTrackableArea;

    }

    return hitTestResult;

}

- (void)_setAttributedStringTextColor:(NSColor *)color {

    NSMutableAttributedString *attrValue = [[self attributedStringValue] mutableCopy];

    NSRange range = NSMakeRange(0, [attrValue length]);

    [attrValue addAttribute:NSForegroundColorAttributeName value:color range:range];

    [self setAttributedStringValue:attrValue];

}

// Factor link click handling into own method - used by tracking and accessibility

- (void)_handleLinkClick {

    NSAttributedString *attrValue = [self attributedStringValue];

    NSURL *link = [attrValue attribute:NSLinkAttributeName atIndex:0 effectiveRange:NULL];

    if (link != nil && _linkClickedHandler != nil) {

    // We do have a link -- open it!

    _linkClickedHandler(link, self);

    }

}

// Override tracking to handle the link click -- while we are tracking we change the link

// text color to something different to let the user have some feedback that they are

// clicking on something.

//

// Ideally we want to override stopTracking:at:inView:mouseIsUp:, but we also need to know

// the cellFrame to find out if the user clicked on the content or not.

//

- (BOOL)trackMouse:(NSEvent *)theEvent inRect:(NSRect)cellFrame ofView:(NSView *)controlView untilMouseUp:(BOOL)flag {

    BOOL result = YES;

    // Did we click on the text? We will use the hit testing routine to see if we hit content -- for text cells, that means the text.

    NSUInteger hitTestResult = [self hitTestForEvent:theEvent inRect:cellFrame ofView:controlView];

    if ((hitTestResult & NSCellHitContentArea) != 0) {

        // Give the user some feedback by changing the text color

        [self _setAttributedStringTextColor:[NSColor redColor]];

        // Do the tracking until mouse up

        result = [super trackMouse:theEvent inRect:cellFrame ofView:controlView untilMouseUp:flag];

        // Now we grab the latest event, in case the user moved the mouse in the normal

        // tracking loop, and hit test again

        theEvent = [NSApp currentEvent];

        hitTestResult = [self hitTestForEvent:theEvent inRect:cellFrame ofView:controlView];

        if ((hitTestResult & NSCellHitContentArea) != 0) {

            [self _handleLinkClick];

        }

    }

    return result;

}

// Here's a nice trick -- we want to flip the text color to not be blue when the row is

// selected (ie: has a dark background style)

//

- (void)setBackgroundStyle:(NSBackgroundStyle)style {

    [super setBackgroundStyle:style];

    if (style == NSBackgroundStyleDark) {

        [self _setAttributedStringTextColor:[NSColor whiteColor]];

    }

}

#pragma mark - Accessibility support

// Add an AXPress action to list of actions we support, when asked to perform, handle the link click.

- (NSArray *)accessibilityActionNames {

    return [[super accessibilityActionNames] arrayByAddingObject:NSAccessibilityPressAction];

}

- (void)accessibilityPerformAction:(NSString *)action {

    if ([action isEqualToString:NSAccessibilityPressAction]) {

        [self _handleLinkClick];

    } else {

        [super accessibilityPerformAction:action];

    }

}

@end