impl.bash

#!/usr/bin/env bash

set -e

function lhs() {
  echo "$1" | awk '{ print $1 }'
}

function rhs() {
  echo "$1" | awk '{ print $2 }'
}

function translate() {
  case "$1" in
    A|X) echo "rock" ;;
    B|Y) echo "paper" ;;
    C|Z) echo "scissors" ;;
    *) return 1 ;;
  esac
}

function translate_instruction() {
  case "$1" in
    X) echo lose;;
    Y) echo draw;;
    Z) echo win;;
    *) return 1;;
  esac
}

function pick_points() {
  case "$1" in
    paper) echo 2 ;;
    scissors) echo 3 ;;
    rock) echo 1 ;;
    *) return 1 ;;
  esac
}

function score_points() {
  case "$1" in
    win) echo 6 ;;
    draw) echo 3 ;;
    loss) echo 0 ;;
    *) return 1 ;;
  esac
}

function play() {
  local oponent="$1"
  local player="$2"

  declare -A win=(
    [scissors]="rock"
    [rock]="paper"
    [paper]="scissors"
  )

  if [ -z "$oponent" ] || [ -z "$player" ] || [ -z "${win[$oponent]}" ] || [ -z "${win[$player]}" ]; then
    return 1
  fi

  test "$oponent" = "$player" && { echo "draw"; return; }
  test "${win[$oponent]}" = "$player" && { echo "win"; return; }

  echo "loss"
}

function needed_hand() {
  local outcome="$1"
  local oponent="$2"

  test "$outcome" = "draw" && { echo "$oponent"; return; }
  if [ "$outcome" = "win" ]; then
    declare -A win=(
      [scissors]="rock"
      [rock]="paper"
      [paper]="scissors"
    )
    echo "${win[$oponent]}"; return
  else
    declare -A loss=(
      [rock]="scissors"
      [paper]="rock"
      [scissors]="paper"
    )
    echo "${loss[$oponent]}"; return
  fi

  return 1
}

function solution_pt1() {
  local line="$1"
  oponent=$(translate "$(lhs "$line")")
  player=$(translate "$(rhs "$line")")
  result=$(play "$oponent" "$player")

  points_for_result=$(score_points "$result")
  points_for_pick=$(pick_points "$player")

  total=$((points_for_pick + points_for_result))
  echo "$total"
}

function solution_pt2() {
  local line="$1"
  oponent=$(translate "$(lhs "$line")")
  outcome=$(translate_instruction "$(rhs "$line")")
  player=$(needed_hand "$outcome" "$oponent")
  result=$(play "$oponent" "$player")

  # echo "$oponent (o) $player (p) vs $outcome (out) -> $player = $result"
  points_for_result=$(score_points "$result")
  points_for_pick=$(pick_points "$player")

  total=$((points_for_pick + points_for_result))
  echo "$total"
}

function loop() {
  local solution="$1"
  local input_file="${2:="test_input.txt"}"

  if [ ! -f "$input_file" ]; then
    echo "input file doesn't exist" >&2
    return 1
  fi

  score=0
  while IFS=$'$\n' read -r line; do
    if [ "$solution" = "pt1" ]; then
      total=$(solution_pt1 "$line")
    elif [ "$solution" = "pt2" ]; then
      total=$(solution_pt2 "$line")
    else
      echo "wrong solution picked" >&2; return 1
    fi
    score=$((score + total))
  done < "$input_file"
  echo "$score"
}