#!/usr/bin/env bash
unset PATH
readonly PATH
source ./utils/main.sh

coord_to_index() {
  local width="$1" x="$2" y="$3"
  printf '%d' "$((y * width + x))"
}

index_to_coord() {
  local width="$1" index="$2"
  printf '%d %d\n' "$((index % width))" "$((index / width))"
}

p1() {
  local input="$1" width=0 height=0
  local line arr=() x y dir='u'
  local -A visited

  while read -r line; do
    ((height++))
    [[ "$width" ]] && width="${#line}"
    while IFS= read -rd '' -n 1 char; do
      [[ "$char" == $'\n' ]] && continue
      arr+=("$char")
    done <<<"$line"
  done <<<"$input"

  local i
  for i in "${!arr[@]}"; do
    [[ "${arr[i]}" == '^' ]] && {
      read -r x y <<<"$(index_to_coord "$width" "$i")"
      arr[i]="."
      visited=(["$x $y"]=1)
      break
    }
  done

  while :; do
    case "$dir" in
      u)
        ((y - 1 < 0)) && break
        [[ "${arr["$(coord_to_index "$width" "$x" "$((y - 1))")"]}" == '#' ]] && dir='r' && continue
        ((y--))
        ;;
      r)
        ((x + 1 >= width)) && break
        [[ "${arr["$(coord_to_index "$width" "$((x + 1))" "$y")"]}" == '#' ]] && dir='d' && continue
        ((x++))
        ;;
      d)
        ((y + 1 >= height)) && break
        [[ "${arr["$(coord_to_index "$width" "$x" "$((y + 1))")"]}" == '#' ]] && dir='l' && continue
        ((y++))
        ;;
      l)
        ((x - 1 < 0)) && break
        [[ "${arr["$(coord_to_index "$width" "$((x - 1))" "$y")"]}" == '#' ]] && dir='u' && continue
        ((x--))
        ;;
      *) : ;;
    esac
    visited+=(["$x $y"]=1)
  done

  printf '%s' "${#visited[@]}"
}

main "$@"