#!/usr/bin/env bash

adv () { # OPCODE 0
  $DEBUG && printf "OPCODE : 0 OP: adv OPERAND: %s\n" "$1" >&2
  OPERAND=$( get_combo "$1" )
  #REG_A=$(( REG_A / (2 ** OPERAND) ))
  REG_A=$( printf "%s / (2 ^ %s) \n" "$REG_A" "$OPERAND" | bc )
}
bxl () { # OPCODE 1
  $DEBUG && printf "OPCODE : 1 OP: bxl OPERAND: %s\n" "$1" >&2
  OPERAND=$1
  REG_B=$(( REG_B ^ OPERAND ))
}
bst () { # OPCODE 2
  $DEBUG && printf "OPCODE : 2 OP: bst OPERAND: %s\n" "$1" >&2
  OPERAND=$( get_combo "$1" )
  REG_B=$(( OPERAND % 8 ))
}
jnz () { # OPCODE 3
  $DEBUG && 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
  $DEBUG && 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
  $DEBUG && printf "OPCODE : 5 OP: out OPERAND: %s\n" "$1" >&2
  OPERAND=$( get_combo "$1" )
  printf "%s\n" "$(( OPERAND % 8 ))"
}
bdv () { # OPCODE 6
  $DEBUG && printf "OPCODE : 6 OP: bdv OPERAND: %s\n" "$1" >&2
  OPERAND=$( get_combo "$1" )
  #REG_B=$(( REG_A / (2 ** OPERAND) ))
  REG_B=$( printf "%s / (2 ^ %s) \n" "$REG_A" "$OPERAND" | bc )
}
cdv () { # OPCODE 7
  $DEBUG && printf "OPCODE : 7 OP: cdv OPERAND: %s\n" "$1" >&2
  OPERAND=$( get_combo "$1" )
  #REG_C=$(( REG_A / (2 ** OPERAND) ))
  REG_C=$( printf "%s / (2 ^ %s) \n" "$REG_A" "$OPERAND" | bc )
}

# Get combo operand
get_combo () {
  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 if the program is a quine
check_quine () {
  $DEBUG && printf "%s," "${INPUT[@]}"
  $DEBUG && printf "%s," "${OUTPUT[@]}"
  for (( i=0; i<${#INPUT[@]}; i++ ))
  do
    if [[ ${INPUT[$i]} != "${OUTPUT[$i]}" ]]
    then
      return 1
    fi
  done
}

# Check digits
check_tail () {
  $DEBUG && printf "%s," "${INPUT[@]}"
  $DEBUG && printf "%s," "${OUTPUT[@]}"
  for (( i=${#INPUT[@]}; i>=${#INPUT[@]}-$1; i-- ))
  do
    if [[ ${INPUT[$i]} != "${OUTPUT[$i]}" ]]
    then
      return 1
    fi
  done
}

# Interpret opcode
read_opcode () {
  local OPCODE=$1
  local OPERAND=$2
  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
}

execute_machine () {
    POINTER=0
    while [[ $POINTER -lt $INPUT_LEN ]]
    do
      OPCODE=${INPUT[$POINTER]}
      OPERAND=${INPUT[$POINTER+1]}
      read_opcode "$OPCODE" "$OPERAND"
      $DEBUG && printf "Registers A : %s B: %s C : %s\n" "$REG_A" "$REG_B" "$REG_C" >&2
      $DEBUG && printf "Pointer : %s\n" "$POINTER" >&2
      (( MACHINE_ITER-- ))
      if [[ $MACHINE_ITER -eq 0 ]] ; then break ; fi
    done | paste -s -d " " 
}