//
//  XWCoolAnimator+XWPageFlip.m
//  XWTransitionDemo
//
//  Created by wazrx on 16/6/13.
//  Copyright © 2016年 wazrx. All rights reserved.
//

#import "XWCoolAnimator+XWPageFlip.h"
#import "UIView+Snapshot.h"
#import <objc/runtime.h>

static NSString *const kPageFlipTempViewKey = @"kPageFlipTempViewKey";

@implementation XWCoolAnimator (XWPageFlip)

- (void)xw_setPageFlipToAnimation:(id<UIViewControllerContextTransitioning>)transitionContext {
    UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    UIView *tempView = [UIView new];
    tempView.contentImage = fromVC.view.snapshotImage;
    tempView.frame = fromVC.view.frame;
    UIView *containerView = [transitionContext containerView];
    [containerView addSubview:toVC.view];
    [containerView addSubview:tempView];
    fromVC.view.hidden = YES;
    [containerView insertSubview:toVC.view atIndex:0];
    [self _xw_setAnchorPoint:CGPointMake(0, 0.5) forView:tempView];
    CATransform3D transfrom3d = CATransform3DIdentity;
    transfrom3d.m34 = -0.002;
    containerView.layer.sublayerTransform = transfrom3d;
    CAGradientLayer *fromGradient = [CAGradientLayer layer];
    fromGradient.frame = fromVC.view.bounds;
    fromGradient.colors = @[(id)[UIColor blackColor].CGColor,
                            (id)[UIColor blackColor].CGColor];
    fromGradient.startPoint = CGPointMake(0.0, 0.5);
    fromGradient.endPoint = CGPointMake(0.8, 0.5);
    UIView *fromShadow = [[UIView alloc]initWithFrame:fromVC.view.bounds];
    fromShadow.backgroundColor = [UIColor clearColor];
    [fromShadow.layer insertSublayer:fromGradient atIndex:1];
    fromShadow.alpha = 0.0;
    [tempView addSubview:fromShadow];
    CAGradientLayer *toGradient = [CAGradientLayer layer];
    toGradient.frame = fromVC.view.bounds;
    toGradient.colors = @[(id)[UIColor blackColor].CGColor,
                          (id)[UIColor blackColor].CGColor];
    toGradient.startPoint = CGPointMake(0.0, 0.5);
    toGradient.endPoint = CGPointMake(0.8, 0.5);
    UIView *toShadow = [[UIView alloc]initWithFrame:fromVC.view.bounds];
    toShadow.backgroundColor = [UIColor clearColor];
    [toShadow.layer insertSublayer:toGradient atIndex:1];
    toShadow.alpha = 1.0;
    [toVC.view addSubview:toShadow];
    objc_setAssociatedObject(self, &kPageFlipTempViewKey, tempView, OBJC_ASSOCIATION_ASSIGN);
    [UIView animateWithDuration:self.toDuration animations:^{
        tempView.layer.transform = CATransform3DMakeRotation(-M_PI_2, 0, 1, 0);
        fromShadow.alpha = 1.0;
        toShadow.alpha = 0.0;
    } completion:^(BOOL finished) {
        [transitionContext completeTransition:![transitionContext transitionWasCancelled]];
        if ([transitionContext transitionWasCancelled]) {
            [tempView removeFromSuperview];
            fromVC.view.hidden = NO;
        }
    }];

}

- (void)xw_setPageFlipBackAnimation:(id<UIViewControllerContextTransitioning>)transitionContext {
    UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    UIView *containerView = [transitionContext containerView];
    UIView *tempView = objc_getAssociatedObject(self, &kPageFlipTempViewKey);
    [containerView addSubview:toVC.view];
    [UIView animateWithDuration:self.backDuration animations:^{
        tempView.layer.transform = CATransform3DIdentity;
        fromVC.view.subviews.lastObject.alpha = 1.0;
        tempView.subviews.lastObject.alpha = 0.0;
    } completion:^(BOOL finished) {
        if ([transitionContext transitionWasCancelled]) {
            [transitionContext completeTransition:NO];
        }else{
            [transitionContext completeTransition:YES];
            [tempView removeFromSuperview];
            toVC.view.hidden = NO;
        }
    }];
}

- (void)_xw_setAnchorPoint:(CGPoint)point forView:(UIView *)view{
    view.frame = CGRectOffset(view.frame, (point.x - view.layer.anchorPoint.x) * view.frame.size.width, (point.y - view.layer.anchorPoint.y) * view.frame.size.height);
    view.layer.anchorPoint = point;
}
@end