//
//  FloatingButton.swift
//  DreamCloud
//
//  Created by Marian Fotev on 17/06/2018.
//  Copyright © 2018 Marian Fotev. All rights reserved.
//

import UIKit
import RxSwift
import RxCocoa

class FloatingButton: UIButton {

    let bag = DisposeBag()

    func attach(to scrollView: UIScrollView) {
        let topConstraint = NSLayoutConstraint(item: self,
                                               attribute: NSLayoutAttribute.top,
                                               relatedBy: NSLayoutRelation.equal,
                                               toItem: self.superview,
                                               attribute: NSLayoutAttribute.top,
                                               multiplier: 1,
                                               constant: 20)


        let fr = self.convert(CGPoint.zero, from:scrollView)





        superview?.addConstraints([topConstraint])

        layer.shadowColor = UIColor.darkGray.cgColor
        layer.cornerRadius = 8
        layer.shadowOpacity = 0.7
        layer.shadowOffset = CGSize.zero
        layer.shadowRadius = 10

        scrollView.rx
            .contentOffset
            .asObservable()
            .bind { offset in

                if abs(fr.y + scrollView.frame.height - self.frame.height / 2 - 10) > offset.y {
                    topConstraint.constant = fr.y + scrollView.frame.height - self.frame.height / 2 + offset.y - 10
                    UIView.animate(withDuration: 0.25, delay: 0.05, options: .curveEaseInOut, animations: {
                        self.layer.shadowRadius = 10
                        self.layer.shadowOpacity = 0.7
                        self.transform = CGAffineTransform(scaleX: 1.05, y: 1.05)
                        self.layoutIfNeeded()

                    })

                } else {
                    UIView.animate(withDuration: 0.25, delay: 0.05, options: .curveEaseInOut, animations: {
                        topConstraint.constant = 20
                        self.layer.shadowRadius = 5
                        self.layer.shadowOpacity = 1
                        self.transform = CGAffineTransform(scaleX: 1, y: 1)
                        self.layoutIfNeeded()
                    })
                }

        }.disposed(by: bag)
    }

}