//
//  FluidTimingCurve.swift
//  Sheet
//
//  Created by Guilherme Rambo on 05/08/19.
//  Copyright © 2019 Peixe Urbano. All rights reserved.
//

import UIKit

public final class FluidTimingCurve: NSObject, UITimingCurveProvider {

    public let initialVelocity: CGVector
    let mass: CGFloat
    let stiffness: CGFloat
    let damping: CGFloat

    public init(velocity: CGVector, stiffness: CGFloat = 400, damping: CGFloat = 30, mass: CGFloat = 1.0) {
        self.initialVelocity = velocity
        self.stiffness = stiffness
        self.damping = damping
        self.mass = mass

        super.init()
    }

    public func encode(with aCoder: NSCoder) {
        fatalError("Not supported")
    }

    public init?(coder aDecoder: NSCoder) {
        fatalError("Not supported")
    }

    public func copy(with zone: NSZone? = nil) -> Any {
        return FluidTimingCurve(velocity: initialVelocity)
    }

    public var timingCurveType: UITimingCurveType {
        return .composed
    }

    public var cubicTimingParameters: UICubicTimingParameters? {
        return .init(animationCurve: .easeIn)
    }

    public var springTimingParameters: UISpringTimingParameters? {
        return UISpringTimingParameters(mass: mass, stiffness: stiffness, damping: damping, initialVelocity: initialVelocity)
    }

}

public extension UISpringTimingParameters {

    /// A design-friendly way to create a spring timing curve.
    ///
    /// - Parameters:
    ///   - damping: The 'bounciness' of the animation. Value must be between 0 and 1.
    ///   - response: The 'speed' of the animation.
    ///   - initialVelocity: The vector describing the starting motion of the property. Optional, default is `.zero`.
    convenience init(damping: CGFloat, response: CGFloat, initialVelocity: CGVector = .zero) {
        let stiffness = pow(2 * .pi / response, 2)
        let damp = 4 * .pi * damping / response
        self.init(mass: 1, stiffness: stiffness, damping: damp, initialVelocity: initialVelocity)
    }

}