import java.io.File
import kotlin.text.Regex

fun main() {
    part1()
    part2()
}

fun part1() {
    val input = File("input")
    val numbers: List<Int> =
            input.useLines { it.map { getPairsOfDigits(it) }.map { digitsToInt(it) }.toList() }

    println(numbers.sum())
}

fun part2() {
    val input = File("input")
    val numbers: List<Int> =
            input.useLines {
                it.map { getPairsOfDigitsAndNames(it) }.map { digitsToInt(it) }.toList()
            }
    println(numbers.sum())
}

fun getPairsOfDigits(line: String): Pair<Int?, Int?> {
    return line.fold(Pair<Int?, Int?>(null, null)) { acc, next ->
        try {
            val digit = next.digitToInt()
            if (acc.first == null) {
                Pair(digit, null)
            } else {
                Pair(acc.first, digit)
            }
        } catch (nfe: IllegalArgumentException) {
            acc
        }
    }
}

fun getPairsOfDigitsAndNames(line: String): Pair<Int?, Int?> {
    val matchValues = Regex("one|two|three|four|five|six|seven|eight|nine|0|1|2|3|4|5|6|7|8|9")
    val digits = matchValues.findAll(line)

    val matchToInt = { it: String ->
        when (it) {
            "one" -> 1
            "two" -> 2
            "three" -> 3
            "four" -> 4
            "five" -> 5
            "six" -> 6
            "seven" -> 7
            "eight" -> 8
            "nine" -> 9
            "0" -> 0
            "1" -> 1
            "2" -> 2
            "3" -> 3
            "4" -> 4
            "5" -> 5
            "6" -> 6
            "7" -> 7
            "8" -> 8
            "9" -> 9
            else -> throw IllegalArgumentException("Illegal character: '${it}'")
        }
    }

    val first = matchToInt(digits.first().value)
    val last = matchToInt(digits.last().value)

    println("${line}: ${first}, ${last}")

    return Pair(first, last)
}

fun digitsToInt(digits: Pair<Int?, Int?>): Int {
    return when {
        digits.first == null -> throw Exception("no digit found on a line")
        digits.second == null -> digits.first as Int * 10 + digits.first as Int
        else -> digits.first as Int * 10 + digits.second as Int
    }
}