When will Santa be at my house?

SantaArrivalCalculator.swift

extension Location {
    func closestLocationOnPath(start: Location, end: Location) -> (location: Location, t: Double, distance: Double) {
        let pathVector = (latitude: end.latitude - start.latitude, longitude: end.longitude - start.longitude)
        var t = (self.latitude * pathVector.latitude - start.latitude * pathVector.latitude + self.longitude * pathVector.longitude - start.longitude * pathVector.longitude) / (pow(pathVector.latitude,2) + pow(pathVector.longitude,2))
        t = min(max(t, 0), 1)
        let closestLocation = Location(latitude: start.latitude + t * pathVector.latitude, longitude: start.longitude + t * pathVector.longitude)
        return (location: closestLocation, t: t, distance: distance(to: closestLocation))
    }
    
    func distance(to other: Location) -> Double {
        return sqrt(pow(other.latitude-self.latitude,2) + pow(other.longitude-self.longitude,2))
    }
}

extension Date {
    static func scaled(between first: Date, and second: Date, scale: Double) -> Date {
        precondition(scale <= 1 && scale >= 0, "Scale must be in [0,1].")
        let difference = second.timeIntervalSinceReferenceDate - first.timeIntervalSinceReferenceDate
        return first.addingTimeInterval(difference * scale)
    }
}

func getArrivalTime(at location: Location, with stops: List<Stop>) -> Date {
    guard stops.count > 1 else {
        return stops.first?.time ?? Date()
    }
    
    var minimumDistance = Double.infinity
    var closestTime = Date()
    for index in 0..<(stops.count-1) {
        let startStop = stops[index], endStop = stops[index+1]
        guard let startLocation = startStop.location, let endLocation = endStop.location else {
            continue
        }
        let (_, t, distance) = location.closestLocationOnPath(start: startLocation, end: endLocation)
        if distance < minimumDistance {
            minimumDistance = distance
            closestTime = Date.scaled(between: startStop.time, and: endStop.time, scale: t)
            print(index)
            print(minimumDistance)
            print(closestTime)
        }
    }
    return closestTime
}

getArrivalTime(at: .sanFrancisco, with: santa.route)