package bhylu.bikelab

class HireCounter(val capacity: Int) {
    init { require(capacity >= 0) }
    var hired = 0
        private set
    val free: Int get() = capacity - hired
    fun hire(amount: Int): Boolean {
        if (amount <= 0 || amount > free) return false
        hired += amount
        return true
    }
}

data class HireRow(val id: String, val station: String, val minutes: Int)

fun stationTotals(rows: List<HireRow>): Map<String, Long> {
    require(rows.size <= 1000)
    val seen = mutableSetOf<String>()
    val totals = mutableMapOf<String, Long>()
    for (row in rows) {
        require(row.id.isNotBlank() && row.station.isNotBlank() && row.minutes in 1..240)
        require(seen.add(row.id)) { "Duplicate hire id" }
        totals[row.station] = (totals[row.station] ?: 0L) + row.minutes.toLong()
    }
    return totals.toSortedMap()
}