module advent_of_code.tasks.day_2.Star1

open System.IO

let stream = new StreamReader("tasks/day-2/input.txt")

let convertToString (i: int64) = i |> string

let isInvalid (id: string) =
    let individualCount = id.Length / 2
    let firstHalf, secondHalf = id[0..individualCount - 1], id[individualCount..]
    if firstHalf = secondHalf then id |> int64 else 0

let rec getInvalid (lines: string list) =
    let line, tail = lines.Head, lines.Tail
    let els = line.Split("-")
    let low, high = els[0] |> int64, els[1] |> int64
    let invalids = [low .. high] |> List.map convertToString |> List.map isInvalid

    List.sum invalids + if tail.IsEmpty then 0 |> int64 else getInvalid tail

let main =
    let lines = stream.ReadLine().Split(",") |> Array.toList
    getInvalid lines