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# This file is part of beets.
# Copyright 2012, Adrian Sampson.
# 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.

"""Uses user-specified rewriting rules to canonicalize names for path
import re
import logging
from collections import defaultdict

from beets.plugins import BeetsPlugin
from beets import ui
from beets import library

log = logging.getLogger('beets')

def rewriter(field, rules):
    """Create a template field function that rewrites the given field
    with the given rewriting rules. ``rules`` must be a list of
    (pattern, replacement) pairs.
    def fieldfunc(item):
        value = getattr(item, field)
        for pattern, replacement in rules:
            if pattern.match(value.lower()):
                # Rewrite activated.
                return replacement
        # Not activated; return original value.
        return value
    return fieldfunc

class RewritePlugin(BeetsPlugin):
    template_fields = {}

    def configure(self, config):
        cls = type(self)

        # Gather all the rewrite rules for each field.
        rules = defaultdict(list)
        if not config.has_section('rewrite'):
        for key, value in config.items('rewrite', True):
                fieldname, pattern = key.split(None, 1)
            except ValueError:
                raise ui.UserError("invalid rewrite specification")
            if fieldname not in library.ITEM_KEYS:
                raise ui.UserError("invalid field name (%s) in rewriter" %
            log.debug(u'adding template field %s' % key)
            pattern = re.compile(pattern.lower())
            rules[fieldname].append((pattern, value))
            if fieldname == 'artist':
                # Special case for the artist field: apply the same
                # rewrite for "albumartist" as well.
                rules['albumartist'].append((pattern, value))

        # Replace each template field with the new rewriter function.
        for fieldname, fieldrules in rules.iteritems():
            cls.template_fields[fieldname] = rewriter(fieldname, fieldrules)