/*

    Copyright (C) 2017 Apple Inc. All Rights Reserved.

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    AlignmentGuidesView shows how to use NSAlignmentFeedbackFilter to align a box to the edges of its container and the container's center.

                The sample shows how to feed the filter using both a tracking loop (see mouseDown) and a gesture recognizer (see panGestureUpdated). These two methods feed the filter the latest event information, and then call into the appropriate handler for mouse down/dragged/up.

*/

#import "AAPLAlignmentGuidesView.h"

@implementation AAPLAlignmentGuidesView

- (id)initWithCoder:(nonnull NSCoder *)coder {

    self = [super initWithCoder:coder];

    if (self) {

        self.feedbackFilter = [NSAlignmentFeedbackFilter new];

        self.boxFrame = NSMakeRect(180.0, 210.0, 200.0, 200.0);

        self.dragOriginOffset = NSZeroPoint;

        self.drawCenterXAsHoldingItem = NO;

        self.drawCenterYAsHoldingItem = NO;

    }

    return self;

}

// *** Updating the filter using a tracking loop. mouseDown tracks the entire mouse drag, updating the alignment filter with each event.

- (void)mouseDown:(nonnull NSEvent *)theEvent {

    if (self.eventHandlingButton.indexOfSelectedItem != 0) {

        return;

    }

    if (![self handleMouseDown:[self convertPoint:theEvent.locationInWindow fromView:nil]]) {

        return;

    }

    [self.feedbackFilter updateWithEvent:theEvent];

    const NSEventMask mask = [NSAlignmentFeedbackFilter inputEventMask]|NSEventMaskLeftMouseUp;

    [self.window trackEventsMatchingMask:mask timeout:NSEventDurationForever mode:NSEventTrackingRunLoopMode handler:^(NSEvent *event, BOOL *stop) {

        [self.feedbackFilter updateWithEvent:event];

        NSRect fromFrame = self.boxFrame;

        switch (event.type) {

            case NSEventTypeLeftMouseUp:

                [self handleMouseUp];

                (*stop) = YES;

                break;

            case NSEventTypeLeftMouseDragged:

                [self handleMouseDragged:[self convertPoint:event.locationInWindow fromView:nil]];

                break;

            default:

                break;

        }

        self.boxFrame = [self performAlignmentFrom:fromFrame draggedTo:self.boxFrame];

        [self setNeedsDisplay:YES];

    }];

}

// *** Updating the filter using a pan gesture recognizer. panGestureUpdated updates the alignment filter for each movement.

- (BOOL)gestureRecognizerShouldBegin:(NSGestureRecognizer *)recognizer {

    // If we aren't using the gesture recognizer, bail here since mouseDown will handle it.

    if ([self.eventHandlingButton indexOfSelectedItem] != 1) {

        return NO;

    }

    // Return whether or not a draggable object was clicked

    return [self handleMouseDown:[recognizer locationInView:self]];

}

- (IBAction)magnificationChanged:(NSSlider *)slider {

    self.enclosingScrollView.magnification = slider.doubleValue;

}

- (IBAction)panGestureUpdated:(NSPanGestureRecognizer *)recognizer {

    // Store the last frame shown to the user

    NSRect fromFrame = self.boxFrame;

    switch (recognizer.state) {

        case NSGestureRecognizerStateBegan:

            [self.feedbackFilter updateWithPanRecognizer:recognizer];

            break;

        case NSGestureRecognizerStateChanged:

            [self.feedbackFilter updateWithPanRecognizer:recognizer];

            [self handleMouseDragged:[recognizer locationInView:self]];

            break;

        case NSGestureRecognizerStateEnded:

        case NSGestureRecognizerStateCancelled:

            [self handleMouseUp];

            break;

        default:

            break;

    }

    // Now perform alignment

    // It's important to do this for every action so that periodic events can cause alignment to happen (consider case of fast-moving cursor stopping over a guide)

    self.boxFrame = [self performAlignmentFrom:fromFrame draggedTo:self.boxFrame];

    [self setNeedsDisplay:YES];

}

// *** Mouse down/dragged/up handling. On drag update where the item would be without any alignment (its offset), and then call into performAlignment.

// Generic handler for starting drag. Returns whether or not a draggable object was clicked

- (BOOL)handleMouseDown:(NSPoint)location {

    self.dragOriginOffset = NSMakePoint(location.x-self.boxFrame.origin.x, location.y-self.boxFrame.origin.y);

    if (!NSPointInRect(location, self.boxFrame)) {

        return NO;

    }

    // Start a drag

    return YES;

}

// Generic handler for moving a drag

- (void)handleMouseDragged:(NSPoint)location {

    self.boxFrame = NSMakeRect(location.x-self.dragOriginOffset.x, location.y-self.dragOriginOffset.y, self.boxFrame.size.width, self.boxFrame.size.height);

    self.boxFrame = [self constrainRectToBounds:self.boxFrame];

    if (self.useGridButton.state == NSOnState) {

        NSPoint origin;

        origin.x = round(self.boxFrame.origin.x/10.0) * 10.0;

        origin.y = round(self.boxFrame.origin.y/10.0) * 10.0;

        self.boxFrame = NSMakeRect(origin.x, origin.y, self.boxFrame.size.width, self.boxFrame.size.height);

    }

    [self scrollRectToVisible:NSMakeRect(location.x, location.y, 1.0, 1.0)];

}

// Generic handler for stopping a drag

- (void)handleMouseUp { }

- (NSRect)performAlignmentFrom:(NSRect)movedFrom draggedTo:(NSRect)draggedTo {

    NSRect newRect = draggedTo;

    // *** Align the edges of the box to the edges of the container

    NSMutableArray<id<NSAlignmentFeedbackToken>> *preparedAlignments = [NSMutableArray array];

    id<NSAlignmentFeedbackToken> token;

    if ((token = [self.feedbackFilter alignmentFeedbackTokenForHorizontalMovementInView:self previousX:NSMinX(movedFrom) alignedX:0.0 defaultX:NSMinX(draggedTo)])) {

        newRect.origin.x = 0.0;

        [preparedAlignments addObject:token];

    }

    if ((token = [self.feedbackFilter alignmentFeedbackTokenForHorizontalMovementInView:self previousX:NSMaxX(movedFrom) alignedX:self.bounds.size.width defaultX:NSMaxX(draggedTo)])) {

        newRect.origin.x = self.bounds.size.width-newRect.size.width;

        [preparedAlignments addObject:token];

    }

    if ((token = [self.feedbackFilter alignmentFeedbackTokenForVerticalMovementInView:self previousY:NSMinY(movedFrom) alignedY:0.0 defaultY:NSMinY(draggedTo)])) {

        newRect.origin.y = 0.0;

        [preparedAlignments addObject:token];

    }

    if ((token = [self.feedbackFilter alignmentFeedbackTokenForVerticalMovementInView:self previousY:NSMaxY(movedFrom) alignedY:self.bounds.size.height defaultY:NSMaxY(draggedTo)])) {

        newRect.origin.y = self.bounds.size.height-newRect.size.height;

        [preparedAlignments addObject:token];

    }

    // *** Align the centers of the box to the centers of the container

    if ((token = [self.feedbackFilter alignmentFeedbackTokenForHorizontalMovementInView:self previousX:NSMidX(movedFrom) alignedX:NSMidX(self.bounds) defaultX:NSMidX(draggedTo)])) {

        newRect.origin.x = NSMidX(self.bounds)-newRect.size.width/2.0;

        [preparedAlignments addObject:token];

        self.drawCenterXAsHoldingItem = YES;

    }

    else {

        self.drawCenterXAsHoldingItem = NO;

    }

    if ((token = [self.feedbackFilter alignmentFeedbackTokenForVerticalMovementInView:self previousY:NSMidY(movedFrom) alignedY:NSMidY(self.bounds) defaultY:NSMidY(draggedTo)])) {

        newRect.origin.y = NSMidY(self.bounds)-newRect.size.height/2.0;

        [preparedAlignments addObject:token];

        self.drawCenterYAsHoldingItem = YES;

    }

    else {

        self.drawCenterYAsHoldingItem = NO;

    }

    [self.feedbackFilter performFeedback:preparedAlignments performanceTime: NSHapticFeedbackPerformanceTimeDrawCompleted];

    return newRect;

}

// *** Your app can draw however it wants. The box could be a subview, or anything really. Here we're drawing using bezier paths.

- (void)drawRect:(NSRect)dirtyRect {

    [super drawRect:dirtyRect];

    [self drawHorizontalGuide:NSMidY(self.bounds) holdingItem:self.drawCenterYAsHoldingItem];

    [self drawVerticalGuide:NSMidX(self.bounds) holdingItem:self.drawCenterXAsHoldingItem];

    [self drawBox:self.boxFrame drawCenterAlignmentGuides:true];

}

@end