import UIKit

public extension UIView {

    func addHeightConstraint(_ height: CGFloat) {
        addConstraint(NSLayoutConstraint(item: self,
                                         attribute: .height,
                                         relatedBy: .equal,
                                         toItem: nil,
                                         attribute: .notAnAttribute,
                                         multiplier: 1.0,
                                         constant: height))
    }

    func addHeightWidthRatio( _ ratio: CGFloat) {
        addConstraint(NSLayoutConstraint(item: self,
                                         attribute: .height,
                                         relatedBy: .equal,
                                         toItem: self,
                                         attribute: .width,
                                         multiplier: ratio, constant: 0))
    }

    func addWidthConstraint(_ height: CGFloat) {
        addConstraint(NSLayoutConstraint(item: self,
                                         attribute: .width,
                                         relatedBy: .equal,
                                         toItem: nil,
                                         attribute: .notAnAttribute,
                                         multiplier: 1.0,
                                         constant: height))
    }

    func centerXAxisToSuperView() {
        guard let superview = superview else { return }
        superview.addConstraint(NSLayoutConstraint(item: self,
                                                   attribute: .centerX,
                                                   relatedBy: .equal,
                                                   toItem: superview,
                                                   attribute: .centerX,
                                                   multiplier: 1,
                                                   constant: 0))
    }

    func centerYAxisToSuperView() {
        guard let superview = superview else { return }
        superview.addConstraint(NSLayoutConstraint(item: self,
                                                   attribute: .centerY,
                                                   relatedBy: .equal,
                                                   toItem: superview,
                                                   attribute: .centerY,
                                                   multiplier: 1,
                                                   constant: 0))
    }

    func centerToSuperView() {
        centerXAxisToSuperView()
        centerYAxisToSuperView()
    }

    func stickEdgesToSuperView(edges: [NSLayoutAttribute] = [.leading, .trailing, .top, .bottom], spaces: [CGFloat] = [0.0, 0.0, 0.0, 0.0]) {
        guard let superview = superview, edges.count == spaces.count else { return }
        for (index, edge) in edges.enumerated() {
            switch edge {
            case .top, .leading:
                superview.addConstraint(NSLayoutConstraint(item: self,
                                                           attribute: edge,
                                                           relatedBy: .equal,
                                                           toItem: superview,
                                                           attribute: edge,
                                                           multiplier: 1.0,
                                                           constant: spaces[index]))
            case .bottom, .trailing:
                superview.addConstraint(NSLayoutConstraint(item: superview,
                                                           attribute: edge,
                                                           relatedBy: .equal,
                                                           toItem: self,
                                                           attribute: edge,
                                                           multiplier: 1.0,
                                                           constant: spaces[index]))
            default:
                break
            }
        }
    }

    func stickToTopView(topView: UIView, _ space: CGFloat) {
        guard let superview = superview else { return }
        superview.addConstraint(NSLayoutConstraint(
            item: self,
            attribute: .top,
            relatedBy: .equal,
            toItem: topView,
            attribute: topView == superview ? .top : .bottom,
            multiplier: 1.0,
            constant: space))
    }

    func stickToBottomView(bottomView: UIView, _ space: CGFloat) {
        guard let superview = superview else { return }
        superview.addConstraint(NSLayoutConstraint(
            item: bottomView,
            attribute: bottomView == superview ? .bottom : .top,
            relatedBy: .equal,
            toItem: self,
            attribute: .bottom,
            multiplier: 1.0,
            constant: space))
    }

    func stickToLeftView(leftView: UIView, _ space: CGFloat) {
        guard let superview = superview else { return }
        superview.addConstraint(NSLayoutConstraint(
            item: self,
            attribute: .leading,
            relatedBy: .equal,
            toItem: leftView,
            attribute: leftView == superview ? .leading : .trailing,
            multiplier: 1.0,
            constant: space))
    }

    func stickToRightView(rightView: UIView, _ space: CGFloat) {
        guard let superview = superview else { return }
        superview.addConstraint(NSLayoutConstraint(
            item: rightView,
            attribute: rightView == superview ? .trailing : .leading,
            relatedBy: .equal,
            toItem: self,
            attribute: .trailing,
            multiplier: 1.0,
            constant: space))
    }
}