/*

    Copyright (C) 2016 Apple Inc. All Rights Reserved.

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    Extends `WorkoutHistory` to add the concept of an active workout that can be started, paused, resumed or ended.

*/

import Foundation

extension WorkoutHistory {

    public var activeWorkout: Workout? {

        get {

            guard let workout = last, workout.state != .ended else { return nil }

            return workout

        }

    }

    public mutating func start(newWorkout workout: Workout) {

        guard workout.state == .active else { fatalError("A workout's state must be .active for it to be able to become the active workout") }

        endActiveWorkout()

        workouts.append(workout)

        save()

    }

    public mutating func pauseActiveWorkout() {

        guard var workout = last, workout.state == .active else { return }

        workout.state = .paused

        workouts[workouts.endIndex - 1] = workout

        save()

    }

    public mutating func resumeActiveWorkout() {

        guard var workout = last, workout.state != .paused else { return }

        workout.state = .active

        workouts[workouts.endIndex - 1] = workout

        save()

    }

    public mutating func endActiveWorkout() {

        guard var workout = last, workout.state != .ended else { return }

        workout.state = .ended

        workouts[workouts.endIndex - 1] = workout

        save()

    }

}