//
//  AnimatedSwitch.swift
//  lottie-swift
//
//  Created by Brandon Withrow on 2/4/19.
//

import Foundation
import UIKit
/**
 An interactive switch with an 'On' and 'Off' state. When the user taps on the
 switch the state is toggled and the appropriate animation is played.
 
 Both the 'On' and 'Off' have an animation play range associated with their state.
 */
final public class AnimatedSwitch: AnimatedControl {
  
  /// The current state of the switch.
  public var isOn: Bool {
    set {
      updateOnState(isOn: newValue, animated: false)
      accessibilityValue = newValue ? NSLocalizedString("On", comment: "On") : NSLocalizedString("Off", comment: "Off")
    }
    get {
      return _isOn
    }
  }
  
  /// Sets the play range for the given state. When the switch is toggled, the animation range is played.
  public func setProgressForState(fromProgress: AnimationProgressTime,
                                  toProgress: AnimationProgressTime,
                                  forOnState: Bool) {
    if forOnState {
      onStartProgress = fromProgress
      onEndProgress = toProgress
    } else {
      offStartProgress = fromProgress
      offEndProgress = toProgress
    }
    
    updateOnState(isOn: _isOn, animated: false)
  }
  
  public override init(animation: Animation) {
    /// Generate a haptic generator if available.
    #if os(iOS)
    if #available(iOS 10.0, *) {
      self.hapticGenerator = HapticGenerator()
    } else {
      self.hapticGenerator = NullHapticGenerator()
    }
    #else
    self.hapticGenerator = NullHapticGenerator()
    #endif
    super.init(animation: animation)
    self.accessibilityTraits = UIAccessibilityTraitButton
  }
  
  public override init() {
    /// Generate a haptic generator if available.
    #if os(iOS)
    if #available(iOS 10.0, *) {
      self.hapticGenerator = HapticGenerator()
    } else {
      self.hapticGenerator = NullHapticGenerator()
    }
    #else
    self.hapticGenerator = NullHapticGenerator()
    #endif
    super.init()
    self.accessibilityTraits = UIAccessibilityTraitButton
  }
  
  required public init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
  }
  
  fileprivate var onStartProgress: CGFloat = 0
  fileprivate var onEndProgress: CGFloat = 1
  fileprivate var offStartProgress: CGFloat = 1
  fileprivate var offEndProgress: CGFloat = 0
  fileprivate var _isOn: Bool = false
  fileprivate var hapticGenerator: ImpactGenerator
  
  // MARK: Animation State

  func updateOnState(isOn: Bool, animated: Bool) {
    _isOn = isOn
    var startProgress = isOn ? onStartProgress : offStartProgress
    var endProgress = isOn ? onEndProgress : offEndProgress
    let finalProgress = endProgress
    
    let realtimeProgress = animationView.realtimeAnimationProgress
    
    let previousStateStart = isOn ? offStartProgress : onStartProgress
    let previousStateEnd = isOn ? offEndProgress : onEndProgress
    if realtimeProgress.isInRange(min(previousStateStart, previousStateEnd),
                                  max(previousStateStart, previousStateEnd)) {
      /// Animation is currently in the previous time range. Reverse the previous play.
      startProgress = previousStateEnd
      endProgress = previousStateStart
    }
    
    guard animated == true else {
      animationView.currentProgress = finalProgress
      return
    }
    self.hapticGenerator.generateImpact()
    animationView.play(fromProgress: startProgress, toProgress: endProgress, loopMode: LottieLoopMode.playOnce) { (finished) in
      if finished == true {
        self.animationView.currentProgress = finalProgress
      }
    }
  }
  
  public override func endTracking(_ touch: UITouch?, with event: UIEvent?) {
    super.endTracking(touch, with: event)
    updateOnState(isOn: !_isOn, animated: true)
    sendActions(for: .valueChanged)
  }
  
}

protocol ImpactGenerator {
  func generateImpact()
}

class NullHapticGenerator: ImpactGenerator {
  func generateImpact() {
    
  }
}

#if os(iOS)
@available(iOS 10.0, *)
class HapticGenerator: ImpactGenerator {
  func generateImpact() {
    impact.impactOccurred()
  }
  
  fileprivate let impact = UIImpactFeedbackGenerator(style: .light)
}
#endif