#!/usr/bin/env python3

import sys
from enum import Enum

class State(Enum):
    # States
    INSERT   = 0
    MATCH    = 1
    REMOVE   = 2

    # Substates
    FETCH    = 3
    LABEL    = 4
    VARIABLE = 5

def number(instruction):
    try:
        return int(instruction, 16)
    except:
        return None

def seek(cursor, code, instruction):
    while cursor < len(code) and code[cursor] != instruction:
        cursor += 1
    return cursor

def step(machine, code):
    state, substate, cursor, label, stacks, offsets, variables = machine
    if cursor >= len(code):
        return (False, machine)
    instruction = code[cursor]
    if instruction == '+':
        state = State.INSERT
        substate = State.FETCH
        cursor += 1
    elif instruction == '?':
        state = State.MATCH
        substate = State.FETCH
        cursor += 1
    elif instruction == '-':
        state = State.REMOVE
        substate = State.FETCH
        cursor += 1
    elif instruction == '.':
        state = State.INSERT
        substate = State.FETCH
        variables.clear()
        for offset in range(0xF):
            offsets[offset] = 0
        cursor = seek(0, code, '?')
    elif instruction == '$':
        if substate is State.LABEL:
            substate = State.VARIABLE
        cursor += 1
    else:
        # Gremlins live here.
        data = number(instruction)
        if data is not None:
            if substate is State.FETCH:
                if state is State.REMOVE:
                    stacks[data].pop()
                else:
                    label = data
                    substate = State.LABEL
            elif substate is State.LABEL:
                if state is State.INSERT:
                    stacks[label].append(data)
                elif state is State.MATCH:
                    if len(stacks[label]) == 0 or offsets[label] >= len(stacks[label]) or stacks[label][-1 - offsets[label]] != data:
                        cursor = seek(cursor, code, '.')
                        variables.clear()
                        for offset in range(0xF):
                            offsets[offset] = 0
                    else:
                        offsets[label] += 1
                substate = State.FETCH
            elif substate is State.VARIABLE:
                if state is State.INSERT:
                    if data in variables:
                        stacks[label].append(variables[data])
                    else:
                        stacks[label].append(0)
                elif state is State.MATCH:
                    if len(stacks[label]) == 0 or offsets[label] > len(stacks[label]):
                        cursor = seek(cursor, code, '.')
                        variables.clear()
                        for offset in range(0xF):
                            offsets[offset] = 0
                    else:
                        if data in variables:
                            if stacks[label][-1 - offsets[label]] != variables[data]:
                                cursor = seek(cursor, code, '.')
                                variables.clear()
                                for offset in range(0xF):
                                    offsets[offset] = 0
                            else:
                                offsets[label] += 1
                        else:
                            variables[data] = stacks[label][-1 - offsets[label]]
                            offsets[label] += 1
                substate = State.FETCH
        cursor += 1
    return (cursor >= len(code), (state, substate, cursor, label, stacks, offsets, variables))

def run(code, machine=None):
    if not machine:
        stacks = [[] for _ in range(0x10)]
        offsets = [0] * 0x10
        machine = (State.INSERT, State.FETCH, 0, 0, stacks, offsets, {})
    halt = False
    while not halt:
        halt, machine = step(machine, code)
    return machine

def pretty(machine):
    state, substate, cursor, label, stacks, offsets, variables = machine
    for index, stack in enumerate(stacks):
        if len(stack) == 0:
            continue
        print(str(index) + ':', " ".join(reversed([str(element) for element in stack])))

def main(name, arguments):
    rules = ""
    if len(arguments) == 0:
        print("usage:", name, + "<files>...")
        return
    for argument in arguments:
        with open(argument) as file:
            rules += file.read()
    pretty(run(rules))

if __name__ == "__main__":
    main(sys.argv[0], sys.argv[1:])