/*

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

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 Helper functions and methods for working with dates.

 */

import Foundation

func getDate(daysAgo days: Double = 0, hoursAgo hours: Double = 0, minutesAgo minutes: Double = 0, secondsAgo seconds: Double = 0) -> Date {

    let hoursPerDay: Double = 24

    let hoursMeasurement = Measurement(value: (days * hoursPerDay) + hours, unit: UnitDuration.hours)

    let minutesMeasurement = Measurement(value: minutes, unit: UnitDuration.minutes)

    let secondsMeasurement = Measurement(value: seconds, unit: UnitDuration.seconds)

    let totalMeasurement = hoursMeasurement + minutesMeasurement + secondsMeasurement

    let totalTimeInterval = totalMeasurement.converted(to: UnitDuration.seconds).value

    return Date() - totalTimeInterval

}

extension Date {

    func timeAgoString() -> String? {

        let components = Calendar.current.dateComponents([.year, .month, .day, .hour, .minute, .second], from: self, to: Date())

        let formatter = DateComponentsFormatter()

        formatter.unitsStyle = .full

        if components.year != nil, components.year != 0 {

            formatter.allowedUnits = .year

        }

        else if components.month != nil, components.month != 0 {

            formatter.allowedUnits = .month

        }

        else if components.day != nil, components.day != 0 {

            formatter.allowedUnits = .day

        }

        else if components.hour != nil, components.hour != 0 {

            formatter.allowedUnits = .hour

        }

        else if components.minute != nil, components.minute != 0 {

            formatter.allowedUnits = .minute

        }

        else {

            formatter.allowedUnits = .second

        }

        guard let timeString = formatter.string(from: components) else {

            return nil

        }

        return String(format: NSLocalizedString("%@ ago", comment: "Format string for relative time ago"), timeString)

    }

}