//
//  MRNavigationBarProgressView.m
//  MRNavigationBarProgressView
//
//  Created by Marius Rackwitz on 09.10.13.
//  Copyright (c) 2013 Marius Rackwitz. All rights reserved.
//

#import "MRNavigationBarProgressView.h"
#import <objc/runtime.h>



static NSString *const MR_UINavigationControllerDidShowViewControllerNotification = @"UINavigationControllerDidShowViewControllerNotification";
static NSString *const MR_UINavigationControllerLastVisibleViewController = @"UINavigationControllerLastVisibleViewController";



@interface UINavigationController (NavigationBarProgressView_Private)

@property (nonatomic, weak) MRNavigationBarProgressView *progressView;

@end


@implementation UINavigationController (NavigationBarProgressView_Private)

- (void)setProgressView:(MRNavigationBarProgressView *)progressView {
    objc_setAssociatedObject(self, @selector(progressView), progressView, OBJC_ASSOCIATION_ASSIGN);
}

- (MRNavigationBarProgressView *)progressView {
    return objc_getAssociatedObject(self, @selector(progressView));
}

@end



@interface MRNavigationBarProgressView ()

@property (nonatomic, weak, readwrite) UIView *progressView;
@property (nonatomic, weak, readwrite) UIViewController *viewController;
@property (nonatomic, weak, readwrite) UIView *barView;

@end


@implementation MRNavigationBarProgressView
@dynamic progress;

static NSNumberFormatter *progressNumberFormatter;

+ (void)initialize {
    NSNumberFormatter *numberFormatter = [NSNumberFormatter new];
    numberFormatter.numberStyle = NSNumberFormatterPercentStyle;
    numberFormatter.locale = NSLocale.currentLocale;
    progressNumberFormatter = numberFormatter;
}

+ (instancetype)progressViewForNavigationController:(UINavigationController *)navigationController {
    // Try to get existing bar
    MRNavigationBarProgressView *progressView = navigationController.progressView;
    if (progressView) {
        return progressView;
    }
    
    // Create new bar
    UINavigationBar *navigationBar = navigationController.navigationBar;
    progressView = [MRNavigationBarProgressView new];
    progressView.barView = navigationBar;
    
    progressView.progressTintColor = navigationBar.tintColor
        ? navigationBar.tintColor : UIApplication.sharedApplication.delegate.window.tintColor;
    
    // Store bar and add to view hierachy
    navigationController.progressView = progressView;
    [navigationController.navigationBar addSubview:progressView];
    
    // Observe topItem
    progressView.viewController = navigationController.topViewController;
    [progressView registerObserverForNavigationController:navigationController];
    
    return progressView;
}

- (id)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        [self commonInit];
    }
    return self;
}

- (id)initWithCoder:(NSCoder *)aDecoder {
    self = [super initWithCoder:aDecoder];
    if (self) {
        [self commonInit];
    }
    return self;
}

+ (BOOL)requiresConstraintBasedLayout {
    return YES;
}

- (void)commonInit {
    self.isAccessibilityElement = YES;
    self.accessibilityLabel = NSLocalizedString(@"Determinate Progress", @"Accessibility label for navigation bar progress view");
    self.accessibilityTraits = UIAccessibilityTraitUpdatesFrequently;
    
    self.autoresizingMask = UIViewAutoresizingFlexibleWidth;
    self.opaque = NO;
    
    UIView *progressView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 0, self.bounds.size.height)];
    progressView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleRightMargin;
    progressView.backgroundColor = self.tintColor;
    [self addSubview:progressView];
    self.progressView = progressView;
    
    self.progress = 0;
    
    [self tintColorDidChange];
}

- (void)registerObserverForNavigationController:(UINavigationController *)navigationController {
    [NSNotificationCenter.defaultCenter addObserver:self
                                           selector:@selector(navigationControllerDidShowViewController:)
                                               name:MR_UINavigationControllerDidShowViewControllerNotification
                                             object:navigationController];
}

- (void)unregisterObserverForNavigationController:(UINavigationController *)navigationController {
    [NSNotificationCenter.defaultCenter removeObserver:self];
}

- (void)navigationControllerDidShowViewController:(NSNotification *)notification {
    UINavigationController *navigationController = notification.object;
    UIViewController *lastVisibleVC = notification.userInfo[MR_UINavigationControllerLastVisibleViewController];
    
    // Check if our controller will be still the topViewController or was popped
    if (lastVisibleVC == self.viewController) {
        // Unregister observer
        [self unregisterObserverForNavigationController:navigationController];
        
        // Remove reference
        navigationController.progressView = nil;
        
        // Remove receiver from view hierachy
        [self removeFromSuperview];
    }
}

- (void) dealloc {
    [NSNotificationCenter.defaultCenter removeObserver:self];
}

- (void)setBarView:(UIView *)barView {
    _barView = barView;
    [self layoutSubviews];
}


#pragma mark - Layout

- (void)layoutSubviews {
    [super layoutSubviews];
    
    CGRect barFrame = self.barView.frame;
    const CGFloat progressBarHeight = 2;
    
    CGRect frame = CGRectMake(barFrame.origin.x,
                              0,
                              barFrame.size.width,
                              progressBarHeight);
    
    if ([self.barView isKindOfClass:UINavigationBar.class]) {
        const CGFloat barBorderHeight = 0.5;
        frame.origin.y = barFrame.size.height - progressBarHeight + barBorderHeight;
    }
    
    if (!CGRectEqualToRect(self.frame, frame)) {
        self.frame = frame;
    }
    
    [self layoutProgressView];
}

- (void)layoutProgressView {
    self.progressView.frame = CGRectMake(0, 0, self.frame.size.width * self.progress, self.frame.size.height);
}


#pragma mark - Getter and setter for progress tint color

- (void)setProgressTintColor:(UIColor *)tintColor {
    self.progressView.backgroundColor = tintColor;
}

- (UIColor *)progressTintColor {
    return self.progressView.backgroundColor;
}


#pragma mark - Control progress

- (void)setProgress:(float)progress {
    assert(progress >= 0 && progress <= 1);
    [self _setProgress:progress];
}

- (void)_setProgress:(float)progress {
    _progress = progress;
    [self progressDidChange];
}

- (void)progressDidChange {
    self.progressView.alpha = self.progress >= 1 ? 0 : 1;
    [self layoutProgressView];
    
    self.accessibilityValue = [progressNumberFormatter stringFromNumber:@(self.progress)];
    UIAccessibilityPostNotification(UIAccessibilityScreenChangedNotification, self);
}

- (void)setProgress:(float)progress animated:(BOOL)animated {
    if (animated) {
        if (progress > 0 && progress < 1.0 && self.progressView.alpha <= CGFLOAT_MIN) {
            // progressView was hidden. Make it visible first.
            self.progressView.alpha = 1;
        }
        
        void(^completion)(BOOL) = ^(BOOL finished){
            [UIView animateWithDuration:0.3 delay:0 options:UIViewAnimationOptionCurveEaseOut animations:^{
                self.progressView.alpha = self.progress >= 1 ? 0 : 1;
            } completion:nil];
        };
        
        if (progress > self.progress || self.progress >= 1) {
            // Progress increased: ease out.
            [UIView animateWithDuration:0.3 delay:0 options:UIViewAnimationOptionCurveEaseOut animations:^{
                [self _setProgress:progress];
            } completion:completion];
        } else {
            // Progress decreased: bounce.
            [UIView animateWithDuration:0.3 delay:0 usingSpringWithDamping:0.5 initialSpringVelocity:0 options:0 animations:^{
                [self _setProgress:progress];
            } completion:completion];
        }
    } else {
        self.progress = progress;
    }
}

@end