DoubleTap.swift

import Foundation

private let tapInterval = 0.2

enum DoubleTap {
    case nope
    case firstDown(Date)
    case firstUp(Date)
    case secondDown(Date)
    case doubleTapped
    
    mutating func down() {
        switch self {
        case .nope:
            print("nope down")
            self = .firstDown(Date.init())
        case .firstDown:
            print("ERROR, First Down Down")
            self = .nope
        case .firstUp(let upAt):
            print("first up down")
            if upAt.timeIntervalSinceNow > -tapInterval {
                self = .secondDown(Date.init())
            } else {
                self = .firstDown(Date.init())
            }
        case .secondDown:
            print("ERROR, Second Down Down")
            self = .nope
        case .doubleTapped:
            print("DOUBLE TAPPED DOWN???")
            self = .firstDown(Date.init())
        }
    }
    
    mutating func up() {
        switch self {
        case .nope:
            print("ERROR NOPE UP")
        case .firstDown(let downAt):
            print("first down up")
            if downAt.timeIntervalSinceNow > -tapInterval {
                self = .firstUp(Date.init())
            } else {
                self = .nope
            }
        case .firstUp:
            print("ERROR, First Up Up")
            self = .nope
        case .secondDown(let downAt):
            print("second down up")
            if downAt.timeIntervalSinceNow > -tapInterval {
                self = .doubleTapped
            } else {
                self = .nope
            }
        case .doubleTapped:
            print("DOUBLE TAPPED UP ERR")
            self = .nope
        }
        
    }
    
    init() {
        self = .nope
    }
    
    mutating func reset() {
        self = .nope
    }
    
    func doubleTapped() -> Bool {
        switch self {
        case .doubleTapped:
            return true
        default:
            return false
        }
    }
    
}