module advent_of_code.tasks.day_1.Star2

open System.IO

let stream = new StreamReader("tasks/day-1/input.txt")

let diff (line: string) =
    let direction = if line.StartsWith("R") then 1 else -1
    let count = (line.[1..] |> int)
    // if (direction = -1) then
        // printfn $"Turning left: {line} produces {count}"
    direction * count
    
let solve (line: string) (start: int) =
    let change = diff line
    let changeMod100 = change % 100
    let newPos = start + changeMod100
    // printfn $"Line {line} produces change of {change} turns {changeMod100} moving from {start} to {newPos}"
    let zeroesFound = (abs change / 100) + (if start <> 0 && (newPos <= 0 || newPos >= 100) then 1 else 0)
    (newPos % 100 + (if newPos < 0 then 100 else 0), zeroesFound)

let rec main start zeroes =
    let line = stream.ReadLine()
    let newPos, newZeroes = solve line start
    if stream.EndOfStream then
        (newPos, zeroes + newZeroes)
    else
        main newPos (zeroes + newZeroes)