#!/usr/bin/env bash

FILE=$1
ITER=99

REG_A=$(grep 'Register A:' "$FILE" | cut -f2 -d: )
REG_B=$(grep 'Register B:' "$FILE" | cut -f2 -d: )
REG_C=$(grep 'Register C:' "$FILE" | cut -f2 -d: )
read -r -a INPUT <<< "$(grep 'Program:' "$FILE" | cut -f2 -d: | tr ',' ' ' )"
INPUT_LEN=${#INPUT[@]}

printf "Registers A: %s B: %s C: %s\n" "$REG_A" "$REG_B" "$REG_C" >&2
printf "Input : " >&2
printf "%s " "${INPUT[@]}" >&2
printf "\n" >&2

adv () { # OPCODE 0
  printf "OPCODE : 0 OP: adv OPERAND: %s\n" "$1" >&2
  OPERAND=$( get_combo "$1" )
  REG_A=$(( REG_A / (2 ** OPERAND) ))
}
bxl () { # OPCODE 1
  printf "OPCODE : 1 OP: bxl OPERAND: %s\n" "$1" >&2
  OPERAND=$1
  REG_B=$(( REG_B ^ OPERAND ))
}
bst () { # OPCODE 2
  printf "OPCODE : 2 OP: bst OPERAND: %s\n" "$1" >&2
  OPERAND=$( get_combo "$1" )
  REG_B=$(( OPERAND % 8 ))
}
jnz () { # OPCODE 3
  printf "OPCODE : 3 OP: jnz OPERAND: %s\n" "$1" >&2
  OPERAND=$1
  if [[ $REG_A -eq 0 ]]
  then
    return 0
  else
    POINTER=$OPERAND
  fi
}
bxc () { # OPCODE 4
  printf "OPCODE : 4 OP: bxc OPERAND: %s\n" "$1" >&2
  # OPERAND=$1 # Deprecated for legacy reasons
  REG_B=$(( REG_B ^ REG_C ))
}
out () { # OPCODE 5
  printf "OPCODE : 5 OP: out OPERAND: %s\n" "$1" >&2
  OPERAND=$( get_combo "$1" )
  printf "%s\n" "$(( OPERAND % 8 ))"
}
bdv () { # OPCODE 6
  printf "OPCODE : 6 OP: bdv OPERAND: %s\n" "$1" >&2
  OPERAND=$( get_combo "$1" )
  REG_B=$(( REG_A / (2 ** OPERAND) ))
}
cdv () { # OPCODE 7
  printf "OPCODE : 7 OP: cdv OPERAND: %s\n" "$1" >&2
  OPERAND=$( get_combo "$1" )
  REG_C=$(( REG_A / (2 ** OPERAND) ))
}

get_combo () {
  # Interpret operand value
  if [[ $OPERAND -eq 0 ]]
  then
    printf "$1"
  elif [[ $OPERAND -eq 1 ]]
  then
    printf "$1"
  elif [[ $OPERAND -eq 2 ]]
  then
    printf "$1"
  elif [[ $OPERAND -eq 3 ]]
  then
    printf "$1"
  elif [[ $OPERAND -eq 4 ]]
  then
    printf "%s" "$REG_A"
  elif [[ $OPERAND -eq 5 ]]
  then
    printf "%s" "$REG_B"
  elif [[ $OPERAND -eq 6 ]]
  then
    printf "%s" "$REG_C"
  elif [[ $OPERAND -eq 7 ]]
  then
    printf "Reserved operand. Exiting.\n" >&2
    exit 1
  fi
}

check_quine () {
  for (( i=0; i<INPUT_LEN; i++ ))
  do
    if [[ ${INPUT[$i]} != "${OUTPUT[$i]}" ]]
    then
      return 1
    fi
  done
}

while ! check_quine
do
  read -r -a OUTPUT <<<"$(
    POINTER=0
    while [[ $POINTER -lt $INPUT_LEN ]]
    do
      OPCODE=${INPUT[$POINTER]}
      OPERAND=${INPUT[$POINTER+1]}
      if [[ $OPCODE -eq 0 ]]
      then
        adv "$OPERAND"
        (( POINTER+=2 ))
      elif [[ $OPCODE -eq 1 ]]
      then
        bxl "$OPERAND"
        (( POINTER+=2 ))
      elif [[ $OPCODE -eq 2 ]]
      then
        bst "$OPERAND"
        (( POINTER+=2 ))
      elif [[ $OPCODE -eq 3 ]]
      then
        # jnz itself moves the pointer
        jnz "$OPERAND"
      elif [[ $OPCODE -eq 4 ]]
      then
        bxc "$OPERAND"
        (( POINTER+=2 ))
      elif [[ $OPCODE -eq 5 ]]
      then
        out "$OPERAND"
        (( POINTER+=2 ))
      elif [[ $OPCODE -eq 6 ]]
      then
        bdv "$OPERAND"
        (( POINTER+=2 ))
      elif [[ $OPCODE -eq 7 ]]
      then
        cdv "$OPERAND"
        (( POINTER+=2 ))
      fi
      printf "Registers A : %s B: %s C : %s\n" "$REG_A" "$REG_B" "$REG_C" >&2
      printf "Pointer : %s\n" "$POINTER" >&2
      (( ITER-- ))
      if [[ $ITER -eq 0 ]] ; then break ;fi
    done | paste -s -d "," 
  )"
done