matcher.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# GuessIt - A library for guessing information from filenames
# Copyright (c) 2013 Nicolas Wack <wackou@gmail.com>
# Copyright (c) 2013 Rémi Alvergnat <toilal.dev@gmail.com>
#
# GuessIt is free software; you can redistribute it and/or modify it under
# the terms of the Lesser GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# GuessIt is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# Lesser GNU General Public License for more details.
#
# You should have received a copy of the Lesser GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

from __future__ import absolute_import, division, print_function, \
    unicode_literals

import logging

from guessit import PY3, u
from guessit.transfo import TransformerException
from guessit.matchtree import MatchTree
from guessit.textutils import normalize_unicode, clean_default
from guessit.guess import Guess
import inspect

log = logging.getLogger(__name__)


class IterativeMatcher(object):
    """An iterative matcher tries to match different patterns that appear
    in the filename.

    The ``filetype`` argument indicates which type of file you want to match.
    If it is undefined, the matcher will try to see whether it can guess
    that the file corresponds to an episode, or otherwise will assume it is
    a movie.

    The recognized ``filetype`` values are:
    ``['subtitle', 'info', 'movie', 'moviesubtitle', 'movieinfo', 'episode',
    'episodesubtitle', 'episodeinfo']``

    ``options`` is a dict of options values to be passed to the transformations used
    by the matcher.

    The IterativeMatcher works mainly in 2 steps:

    First, it splits the filename into a match_tree, which is a tree of groups
    which have a semantic meaning, such as episode number, movie title,
    etc...

    The match_tree created looks like the following::

      0000000000000000000000000000000000000000000000000000000000000000000000000000000000 111
      0000011111111111112222222222222233333333444444444444444455555555666777777778888888 000
      0000000000000000000000000000000001111112011112222333333401123334000011233340000000 000
      __________________(The.Prestige).______.[____.HP.______.{__-___}.St{__-___}.Chaps].___
      xxxxxttttttttttttt               ffffff  vvvv    xxxxxx  ll lll     xx xxx         ccc
      [XCT].Le.Prestige.(The.Prestige).DVDRip.[x264.HP.He-Aac.{Fr-Eng}.St{Fr-Eng}.Chaps].mkv

    The first 3 lines indicates the group index in which a char in the
    filename is located. So for instance, ``x264`` (in the middle) is the group (0, 4, 1), and
    it corresponds to a video codec, denoted by the letter ``v`` in the 4th line.
    (for more info, see guess.matchtree.to_string)

    Second, it tries to merge all this information into a single object
    containing all the found properties, and does some (basic) conflict
    resolution when they arise.
    """
    def __init__(self, filename, options=None, **kwargs):
        options = dict(options or {})
        for k, v in kwargs.items():
            if k not in options or not options[k]:
                options[k] = v  # options dict has priority over keyword arguments
        self._validate_options(options)
        if not PY3 and not isinstance(filename, unicode):
            log.warning('Given filename to matcher is not unicode...')
            filename = filename.decode('utf-8')

        filename = normalize_unicode(filename)
        clean_function = None
        if options and options.get('clean_function'):
            clean_function = options.get('clean_function')
            if not hasattr(clean_function, '__call__'):
                module, function = clean_function.rsplit('.')
                if not module:
                    module = 'guessit.textutils'
                clean_function = getattr(__import__(module), function)
                if not clean_function:
                    log.error('Can\'t find clean function %s. Default will be used.' % options.get('clean_function'))
                    clean_function = clean_default
        else:
            clean_function = clean_default

        self.match_tree = MatchTree(filename, clean_function=clean_function)
        self.options = options
        self._transfo_calls = []

        # sanity check: make sure we don't process a (mostly) empty string
        if clean_function(filename).strip() == '':
            return

        from guessit.plugins import transformers

        try:
            mtree = self.match_tree
            if 'type' in self.options:
                mtree.guess.set('type', self.options['type'], confidence=0.0)

            # Process
            for transformer in transformers.all_transformers():
                disabled = options.get('disabled_transformers')
                if not disabled or not transformer.name in disabled:
                    self._process(transformer, False)

            # Post-process
            for transformer in transformers.all_transformers():
                disabled = options.get('disabled_transformers')
                if not disabled or not transformer.name in disabled:
                    self._process(transformer, True)

            log.debug('Found match tree:\n%s' % u(mtree))
        except TransformerException as e:
            log.debug('An error has occurred in Transformer %s: %s' % (e.transformer, e))

    def _process(self, transformer, post=False):

        if not hasattr(transformer, 'should_process') or transformer.should_process(self.match_tree, self.options):
            if post:
                transformer.post_process(self.match_tree, self.options)
            else:
                transformer.process(self.match_tree, self.options)
                self._transfo_calls.append(transformer)

    @property
    def second_pass_options(self):
        second_pass_options = {}
        for transformer in self._transfo_calls:
            if hasattr(transformer, 'second_pass_options'):
                transformer_second_pass_options = transformer.second_pass_options(self.match_tree, self.options)
                if transformer_second_pass_options:
                    second_pass_options.update(transformer_second_pass_options)

        return second_pass_options

    def _validate_options(self, options):
        valid_filetypes = ('subtitle', 'info', 'video',
                   'movie', 'moviesubtitle', 'movieinfo',
                   'episode', 'episodesubtitle', 'episodeinfo')

        type = options.get('type')
        if type and type not in valid_filetypes:
            raise ValueError("filetype needs to be one of %s" % (valid_filetypes,))

    def matched(self):
        return self.match_tree.matched()


def build_guess(node, name, value=None, confidence=1.0):
    guess = Guess({name: node.clean_value if value is None else value}, confidence=confidence)
    if value is None:
        guess.metadata().span = node.span
    guess.metadata().input = node.value if value is None else value
    return guess


def found_property(node, name, value=None, confidence=1.0, update_guess=True, logger=None):
    # automatically retrieve the log object from the caller frame
    if not logger:
        caller_frame = inspect.stack()[1][0]
        logger = caller_frame.f_locals['self'].log
    guess = build_guess(node, name, value, confidence)
    return found_guess(node, guess, update_guess=update_guess, logger=logger)


def found_guess(node, guess, update_guess=True, logger=None):
    if node.guess:
        if update_guess:
            node.guess.update_highest_confidence(guess)
        else:
            child = node.add_child(guess.metadata().span)
            child.guess = guess
    else:
        node.guess = guess
    log_found_guess(guess, logger)
    return node.guess


def log_found_guess(guess, logger=None):
    for k, v in guess.items():
        (logger or log).debug('Property found: %s=%s (%s) (confidence=%.2f)' %
                              (k, v, guess.raw(k), guess.confidence(k)))


def _get_split_spans(node, span):
    partition_spans = node.get_partition_spans(span)
    for to_remove_span in partition_spans:
        if to_remove_span[0] == span[0] and to_remove_span[1] in [span[1], span[1] + 1]:
            partition_spans.remove(to_remove_span)
            break
    return partition_spans


class GuessFinder(object):
    def __init__(self, guess_func, confidence=None, logger=None, options=None):
        self.guess_func = guess_func
        self.confidence = confidence
        self.logger = logger or log
        self.options = options

    def process_nodes(self, nodes):
        for node in nodes:
            self.process_node(node)

    def process_node(self, node, iterative=True, partial_span=None):
        value = None
        if partial_span:
            value = node.value[partial_span[0]:partial_span[1]]
        else:
            value = node.value
        string = ' %s ' % value  # add sentinels

        if not self.options:
            matcher_result = self.guess_func(string, node)
        else:
            matcher_result = self.guess_func(string, node, self.options)

        if matcher_result:
            if not isinstance(matcher_result, Guess):
                result, span = matcher_result
            else:
                result, span = matcher_result, matcher_result.metadata().span

            if result:
                # readjust span to compensate for sentinels
                span = (span[0] - 1, span[1] - 1)

                # readjust span to compensate for partial_span
                if partial_span:
                    span = (span[0] + partial_span[0], span[1] + partial_span[0])

                partition_spans = None
                if self.options and 'skip_nodes' in self.options:
                    skip_nodes = self.options.get('skip_nodes')
                    for skip_node in skip_nodes:
                        if skip_node.parent.node_idx == node.node_idx[:len(skip_node.parent.node_idx)] and\
                            skip_node.span == span or\
                                skip_node.span == (span[0] + skip_node.offset, span[1] + skip_node.offset):
                            if partition_spans is None:
                                partition_spans = _get_split_spans(node, skip_node.span)
                            else:
                                new_partition_spans = []
                                for partition_span in partition_spans:
                                    tmp_node = MatchTree(value, span=partition_span, parent=node)
                                    tmp_partitions_spans = _get_split_spans(tmp_node, skip_node.span)
                                    new_partition_spans.extend(tmp_partitions_spans)
                                partition_spans.extend(new_partition_spans)

                if not partition_spans:
                    # restore sentinels compensation

                    guess = None
                    if isinstance(result, Guess):
                        guess = result
                    else:
                        guess = Guess(result, confidence=self.confidence, input=string, span=span)

                    if not iterative:
                        found_guess(node, guess, logger=self.logger)
                    else:
                        absolute_span = (span[0] + node.offset, span[1] + node.offset)
                        node.partition(span)
                        if node.is_leaf():
                            found_guess(node, guess, logger=self.logger)
                        else:
                            found_child = None
                            for child in node.children:
                                if child.span == absolute_span:
                                    found_guess(child, guess, logger=self.logger)
                                    found_child = child
                                    break
                            for child in node.children:
                                if not child is found_child:
                                    self.process_node(child)
                else:
                    for partition_span in partition_spans:
                        self.process_node(node, partial_span=partition_span)