package assignment.week3.taxipark

/*
 * Task #1. Find all the drivers who performed no trips.
 */
fun TaxiPark.findFakeDrivers(): Set<Driver> =
    this.allDrivers
        .filter { driver -> this.trips.none { trip -> trip.driver == driver } }
        .toSet()

/*
 * Task #2. Find all the clients who completed at least the given number of trips.
 */
fun TaxiPark.findFaithfulPassengers(minTrips: Int): Set<Passenger> =
    this.allPassengers
        .filter { passenger -> this.trips.count { trip -> trip.passengers.contains(passenger) } >= minTrips }
        .toSet()

/*
 * Task #3. Find all the passengers, who were taken by a given driver more than once.
 */
fun TaxiPark.findFrequentPassengers(driver: Driver): Set<Passenger> =
    this.allPassengers
        .filter { passenger ->
            this.trips
                .filter { trip -> trip.passengers.contains(passenger) }
                .count { trip -> trip.driver == driver } > 1
        }
        .toSet()

/*
 * Task #4. Find the passengers who had a discount for majority of their trips.
 */
fun TaxiPark.findSmartPassengers(): Set<Passenger> = this.allPassengers
    .filter(fun(passenger: Passenger): Boolean {
        val (discounted, nonDiscounted) = this.trips
            .filter { it.passengers.contains(passenger) }
            .partition { it.discount != null }

        if (nonDiscounted.isEmpty()) {
            return discounted.isNotEmpty()
        }
        return (discounted.size.toDouble()) / nonDiscounted.size > 1.0
    })
    .toSet()

/*
 * Task #5. Find the most frequent trip duration among minute periods 0..9, 10..19, 20..29, and so on.
 * Return any period if many are the most frequent, return `null` if there're no trips.
 */
fun TaxiPark.findTheMostFrequentTripDurationPeriod(): IntRange? {
    val (maxDuration, _) = this.trips
        .map { trip -> trip.duration / 10 }
        .groupBy { it }
        .maxByOrNull { it.value.size } ?: return null

    val startRange = maxDuration * 10
    return startRange.rangeTo(startRange + 9)
}

/*
 * Task #6.
 * Check whether 20% of the drivers contribute 80% of the income.
 */
fun TaxiPark.checkParetoPrinciple(): Boolean {
    if (this.trips.isEmpty()) {
        return false
    }
    val totalIncome = this.trips.sumOf(Trip::cost)

    val top20Percent = this.trips
        .groupBy { it.driver }
        .values
        .map { trips -> trips.sumOf(Trip::cost) }
        .sortedDescending()
        .take((this.allDrivers.size * 0.2).toInt())
        .sum()

    return top20Percent >= totalIncome * 0.8
}