//
//  MFScrollingViewController.m
//  MobileFirstFramework
//
//  Created by Pfeil, Scott Robert on 11/21/17.
//  Copyright © 2017 Verizon Wireless. All rights reserved.
//

#import "MFScrollingViewController.h"
#import <MVMCore/MVMCoreDispatchUtility.h>
#import "MFTransparentGIFView.h"
#import <MVMCore/MVMCoreGetterUtility.h>
#import <MVMCore/MVMCoreLoadObject.h>
#import <MVMCore/NSDictionary+MFConvenience.h>
#import "NSLayoutConstraint+MVMCoreUIConvenience.h"
#import <MVMCore/MVMCoreJSONConstants.h>
#import "MVMCoreUIUtility.h"
#import "MVMCoreUIConstants.h"
#import "MVMCoreUISession.h"

@interface MFScrollingViewController ()

// A flag for if the Keyboard Notifications are added.
@property (assign, nonatomic) BOOL keyboardNotificationsAdded;

// Stores the pre-keyboard content inset.
@property (assign, nonatomic) UIEdgeInsets preKeyboardContentInset;

// Boolean for if the keyboard is showing or now.
@property (assign, nonatomic, readwrite) BOOL keyboardIsShowing;

// Boolean for if the scroll indicator has flashed
@property (assign, nonatomic, readwrite) BOOL isScrollIndicatorFlashed;

// Property for reference of hand scroll animation gif
@property (strong, nonatomic) MFTransparentGIFView *gifView;

@property (assign, nonatomic, readwrite) BOOL isPageTypeEnabledForHandScrollAnimation;

@property (assign) __block BOOL isHandScrollAnimationRendered;

@property (nullable, strong, nonatomic) id scrollFlashNotificationObserver;

// To add gif view for scroll animation
- (void)addScrollDownHandAnimation;

@end

@implementation MFScrollingViewController

static CGFloat const HandScrollMargin = 10.f;
static NSTimeInterval const HandScrollAnimationTiming = 7.f;

- (BOOL)isFlashScrollIndicatorAccesible {
    
    return YES;
}

- (void)newDataBuildScreen {
    [super newDataBuildScreen];
    [self updatePageHandScrollAnimationStatus];
    
    if ([self shouldEnableHandScrollAnimation]) {
        [self addScrollDownHandAnimation];
    }
}

- (void)initialLoad {
    [super initialLoad];
    
    // Adds the tap gesture to dismiss the keyboard.
    self.dismissKeyboardTapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(dismissFieldInput:)];
    self.dismissKeyboardTapGesture.enabled = NO;
    
    //This flag is required to offset for footer for tableView
    self.isHandScrollAnimationRendered = NO;
    self.isPageTypeEnabledForHandScrollAnimation = NO;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    
    [self.view addGestureRecognizer:self.dismissKeyboardTapGesture];
    self.scrollView.alwaysBounceVertical = NO;
    self.scrollView.delegate = self;
    
    self.isScrollIndicatorFlashed = NO;
}

- (void)viewDidLayoutSubviews {
    [super viewDidLayoutSubviews];
    
    BOOL automaticInset = NO;
    if (@available(iOS 11.0, *)) {
        automaticInset = self.scrollView.contentInsetAdjustmentBehavior == UIScrollViewContentInsetAdjustmentAutomatic;
    }
    
    // Takes into account the navigation bar.
    if (!automaticInset && (self.edgesForExtendedLayout & UIRectEdgeTop)) {
        
        CGFloat top = 0;
        if (self.navigationController && ![self.navigationController isNavigationBarHidden] && ![self navigationBarTransparent] && (self.navigationController.extendedLayoutIncludesOpaqueBars || !self.navigationController.navigationBar.opaque)) {
            
            // Navigation bar is showing, set the top content inset to its height.
            top = CGRectGetMaxY(self.navigationController.navigationBar.frame);
        } else {
            
            // No navigation bar, account for the status bar if need be
            top = [MVMCoreUIUtility getTopSpaceWithStatusBarForView:self.scrollView];
        }
        
        UIEdgeInsets inset;
        if (self.keyboardIsShowing) {
            inset = self.preKeyboardContentInset;
        } else {
            inset = self.scrollView.contentInset;
        }
        
        if (!fequal(top, inset.top)) {
            inset = UIEdgeInsetsMake(top, inset.left, inset.bottom, inset.right);
            
            if (self.keyboardIsShowing) {
                self.preKeyboardContentInset = inset;
            } else {
                self.scrollView.contentInset = inset;
            }
            
            // Fixes an ios bug where setting the scroll content doesn't redraw the scroll content at offset 0.
            if (self.scrollView.contentOffset.y < 1) {
                [self.scrollView scrollRectToVisible:CGRectMake(0, 0, CGRectGetWidth(self.view.frame), 1) animated:NO];
            }
        }
    }
    
    
    // Update any constraints.
    [self.view setNeedsUpdateConstraints];
    
    [self.view layoutSubviews];
}

- (void)updateViewConstraints {
    [super updateViewConstraints];
    
    // Sets the width of the content to the width of the screen.
    self.contentWidthConstraint.constant = CGRectGetWidth(self.view.bounds) - self.scrollView.contentInset.left - self.scrollView.contentInset.right;
}

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    [self registerForKeyboardNotifications];
    [self registerForScrollFlashWhenLaunch];
}

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    [self unregisterForKeyboardNotifications];
    [self unregisterForScrollFlashWhenLaunch];
}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    
    if (!self.shouldTriggerStartAnimations || DisableAnimations) {
        [self pageAnimationEnded];
    }
}

- (void)viewDidDisappear:(BOOL)animated {
    [super viewDidDisappear:animated];
    
    if (!CGAffineTransformIsIdentity(self.view.transform)) {
        self.view.transform = CGAffineTransformIdentity;
        self.scrollView.contentInset = UIEdgeInsetsMake(0,0,0,0);
    }
}

#pragma mark - keyboard handling

- (void)keyboardWillShow:(nonnull NSNotification *)notification {
    
    // Stores the current scroll insets if the keyboard was hidden.
    if (!self.keyboardIsShowing) {
        self.preKeyboardContentInset = self.scrollView.contentInset;
    }
    self.keyboardIsShowing = YES;
    
    // Enables the tap gesture.
    self.dismissKeyboardTapGesture.enabled = YES;
    
    [MVMCoreUIUtility setScrollViewInsetForKeyboardShow:notification scrollView:self.scrollView viewController:self rectToScrollTo:^CGRect{
        return [self rectToScrollToWhenKeyboardPopsUp];
    }];
}

- (void)keyboardWillBeHidden:(nonnull NSNotification *)notification {
    self.keyboardIsShowing = NO;
    
    // Disables the tap gesture.
    self.dismissKeyboardTapGesture.enabled = NO;
    
    [MVMCoreUIUtility setScrollViewInsetForKeyboardHide:notification scrollView:self.scrollView viewController:self contentInset:self.preKeyboardContentInset];
}

- (CGRect)rectToScrollToWhenKeyboardPopsUp {
    return [self.scrollView convertRect:[self.selectedField frame] fromView:[self.selectedField superview]];
}

- (void)registerForKeyboardNotifications {
    
    if (!self.keyboardNotificationsAdded) {
        self.keyboardNotificationsAdded = YES;
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillBeHidden:) name:UIKeyboardWillHideNotification object:nil];
    }
}

- (void)unregisterForKeyboardNotifications {
    if (self.keyboardNotificationsAdded) {
        self.keyboardNotificationsAdded = NO;
        [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillShowNotification object:nil];
        [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillHideNotification object:nil];
    }
}

#pragma mark - UIScrollViewDelegate Functions

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    [self stopHandScrollAnimation:YES];
}


#pragma mark - Scroll Flash Handling
- (void)registerForScrollFlashWhenLaunch {
    
    if ([self isFlashScrollIndicatorAccesible]) {
        
        __weak MFScrollingViewController *weakSelf = self;
        self.scrollFlashNotificationObserver = [[NSNotificationCenter defaultCenter] addObserverForName:@"PageAnimationEnded" object:nil queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification * _Nonnull note) {
            [weakSelf pageAnimationEnded];
        }];
    }
}

- (void)unregisterForScrollFlashWhenLaunch {
    
    if (self.scrollFlashNotificationObserver) {
        
        [[NSNotificationCenter defaultCenter] removeObserver:self name:@"PageAnimationEnded" object:nil];
        self.scrollFlashNotificationObserver = nil;
    }
}

- (void)pageAnimationEnded {
    
    //Implemented for Single View Appearance for now
    //Can be enabled for every time view appear
    if (self.isScrollIndicatorFlashed == NO) {
        
        __weak MFScrollingViewController *weakSelf = self;
        [MVMCoreDispatchUtility performBlockOnMainThread:^{
            [weakSelf.scrollView flashScrollIndicators];
            weakSelf.isScrollIndicatorFlashed = YES;
        }];
    }
    
    // To Show or Hide Hand Scroll Animation
    if (![self shouldEnableHandScrollAnimation]) {
        return;
    }
    if ([self isHandScrollAnimationRequired])  {
        
        __weak MFScrollingViewController *weakSelf = self;
        [MVMCoreDispatchUtility performBlockOnMainThread: ^{
            [weakSelf startHandScrollAnimation];
        }];
    } else {
        [self stopHandScrollAnimation:NO];
    }
}

#pragma mark - Hand Scroll Animation

// this can be ovveriden by subclass to enable or disable the same. but should check for server flag in subclass implementation
- (BOOL)shouldEnableHandScrollAnimation {
    // depends on server master flag for app
    // to check if the hand scroll animation is enabled for the page
    return self.isPageTypeEnabledForHandScrollAnimation;
}

- (void)updatePageHandScrollAnimationStatus {
    if ([MVMCoreUISession sharedGlobal].enableHandScrollAnimation) {
        self.isPageTypeEnabledForHandScrollAnimation = [self.loadObject.pageJSON boolForKey:KeyHandScrollAnimation];
    }
}

- (void)addScrollDownHandAnimation {
    
    if (!self.gifView) {
        
        MFTransparentGIFView *gifView = [[MFTransparentGIFView alloc] initWithFrame:CGRectZero ImageName:KeyHandScroll StartImmediately:YES Duration:-1 LoopCompletionBlock:nil];
        gifView.translatesAutoresizingMaskIntoConstraints = NO;
        [self.view addSubview:gifView];
        gifView.contentMode = UIViewContentModeScaleAspectFit;
        
        // width is changed to match aspect ratio of asset
        [NSLayoutConstraint constraintPinView:gifView heightConstraint:YES heightConstant:50 widthConstraint:YES widthConstant:25];
        [NSLayoutConstraint constraintPinSubview:gifView pinCenterX:YES pinCenterY:NO];
        [NSLayoutConstraint constraintWithItem:gifView attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:self.scrollView attribute:NSLayoutAttributeBottom multiplier:1.f constant:-30].active = YES;
        
        self.gifView = gifView;
    }
}

- (BOOL)isHandScrollAnimationRequired {
    return (self.scrollView.contentSize.height - self.scrollView.frame.size.height) > HandScrollMargin;
}

- (void)startHandScrollAnimation {
    
    if (self.isHandScrollAnimationRendered) {
        return;
    }
    
    self.isHandScrollAnimationRendered = YES;
    
    self.gifView.alpha = 1.f;
    __weak MFScrollingViewController *weakSelf = self;
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(HandScrollAnimationTiming * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        
        [weakSelf stopHandScrollAnimation:YES];
    });
    
}

- (void)stopHandScrollAnimation:(BOOL)animated {
    
    __weak MFScrollingViewController *weakSelf = self;
    [MVMCoreDispatchUtility performBlockOnMainThread:^{
        if (animated) {
            [UIView animateWithDuration:0.5 animations:^{
                weakSelf.gifView.alpha = 0.f;
            } completion:nil];
        } else {
            weakSelf.gifView.alpha = 0.f;
        }
    }];
}

@end