# Copyright (c) 2009 Tim Freeman
# 
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
# 
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
#
# (This is the standard MIT License, copied from
# http://www.opensource.org/licenses/mit-license.php on 24 Apr 2007.)
#desc Draw the state of a Turing machine as it executes, so they can
#desc be debugged.
import bits

def draw_tape(tape_length, tape_bits, headpos):
    lineref = [""]
    def addmarker(where):
        if where == headpos:
            lineref[0] += ">"
        elif where == headpos - 1:
            lineref[0] += "<"
        else:
            lineref[0] += " "
    for i in range(tape_length, -1, -1):
        addmarker(i)
        if i == tape_length: bit = " "
        else: bit = str(bits.getbits(tape_bits, i, 1))
        lineref[0] += bit
    addmarker(-1)
    return lineref[0]

def show_octal(stateno):
    return "%03o" % (stateno,)

# bpsn stands for "bits per state number".
def draw_action(action, bpsn, state_to_name):
    action_str = ["w0", "w1", "tr", "dn"][bits.getbits(action, 0, 2)]
    motion = ["l", "r"][bits.getbits(action, 2, 1)]
    next = bits.getbits(action, 3, bpsn)
    return "%2s%1s %s" % (action_str, motion, state_to_name(next))


def draw_line(tape_length, tape_bits, headpos, sn, state, bpsn, short,
              state_to_name):
    tape = draw_tape(tape_length, tape_bits, headpos)
    bpa = bpsn + 3
    def da(which):
        return draw_action(bits.getbits(state, which * bpa, bpa), bpsn,
                           state_to_name)
    zero = bits.getbits(state, 0, bpa)
    one = bits.getbits(state, bpa, bpa)
    end = bits.getbits(state, 2*bpa, bpa)
    if not short:
        tape += " state %s 0>%s 1>%s end>%s" % (state_to_name(sn),
                                                da(0), da(1), da(2))
    return tape

def do_animation(tape_length, tape_bits, headpos, sn, state, bpsn,
                 state_to_name, short):
    print draw_line(tape_length, tape_bits, headpos, sn, state, bpsn,
                 state_to_name = state_to_name, short=short)

def default_animation(tape_length, tape_bits, headpos, sn, state, bpsn,
                 short):
    do_animation(tape_length, tape_bits, headpos, sn, state, bpsn,
                 state_to_name=show_octal, short=short)