~repos /plum

enum Step(n: Int) =
  | READ_MIN_OCCURANCES(Step(0))
  | READ_MAX_OCCURANCES(Step(1))
  | READ_CHAR_TO_COUNT(Step(2))
  | COUNT_OCCURANCES(Step(3))

toNumber(Step) =
  match self
    | READ_MIN_OCCURANCES => 0
    | READ_MAX_OCCURANCES => 1
    | READ_CHAR_TO_COUNT => 2
    | COUNT_OCCURANCES => 3

type PasswordCheckState =
  step: Step
  min_occurances: Int
  max_occurances: Int
  current_occurances: Int
  char_to_counst: Int

initialCheckState() -> PasswordCheckState =
  PasswordCheckState(
    step: READ_MIN_OCCURANCES,
    min_occurances: 0,
    max_occurances: 0,
    current_occurances: 0,
    char_to_count: '\0',
  )

main() -> Unit =
  input = fs.readFile!("./examples/test/demos/aoc2020/2.txt")
  valid_passwords_count = 0
  state = initialCheckState()
  for i in 0..input.len()
    c = input.charAt(i)
    if state.step == READ_MIN_OCCURANCES
      if c == '-'
        state.step = READ_MAX_OCCURANCES
        continue
      state.min_occurances *= 10
      state.min_occurances += (c - '0') as Int
    else if state.step == READ_MAX_OCCURANCES
      if c == ' '
        state.step = READ_CHAR_TO_COUNT
        continue
      state.max_occurances *= 10
      state.max_occurances += (c - '0') as Int
    else if state.step == READ_CHAR_TO_COUNT
      state.char_to_count = c
      # skip `${c}: `, (+1 will be skipped by loop)
      i += 2
      state.step = COUNT_OCCURANCES
      continue
    else if state.step == COUNT_OCCURANCES
      if c == '\n'
        if state.current_occurances >= state.min_occurances && state.current_occurances <= state.max_occurances
          valid_passwords_count += 1
        state = initialCheckState()
        continue
      if c == state.char_to_count
        state.current_occurances += 1
  writeLn(valid_passwords_count)