import codecs


class CodecsSearcher:
    '''
    Base CodecsSearcher
    '''
    def __init__(self):
        self._registry = {}

    def __call__(self, encoding):
        """
        leaves the same behavior for `codecs.lookup(encoding)`
        """
        return self.lookup(encoding)

    def lookup(self, encoding):
        return self._registry.get(encoding, None)

    def get_available_codec_names(self):
        return self._registry.keys()


class MyCodecsSearcher(CodecsSearcher):
    '''
    Simple implementation of CodecsSearcher
    '''
    def __init__(self):
        super(MyCodecsSearcher, self).__init__()
        self._registry = {'foobar': codecs.lookup('utf-8')}

Searcher = MyCodecsSearcher()
codecs.register(Searcher)

assert isinstance(Searcher, CodecsSearcher) is True
assert isinstance(codecs.lookup('foobar'), codecs.CodecInfo) is True
assert ('foobar' in Searcher.get_available_codec_names()) is True


class MyLazyCodecsSearcher(CodecsSearcher):
    '''
    More powerful implementation with lazy imports of codecs
    '''
    def __init__(self):
        super(MyLazyCodecsSearcher, self).__init__()
        self._registry = {
            'lazy': self._lazy_fabric,
            'lazy_broken': self._lazy_broken_fabric
        }

    def lookup(self, encoding):
        codecs_fabric = self._registry.get(encoding, None)
        if codecs_fabric:
            return codecs_fabric()
        raise LookupError

    def _lazy_fabric(self):
        from encodings import utf_8
        return utf_8.getregentry()

    def _lazy_broken_fabric(self):
        try:
            from encodings import utf_9
        except ImportError:
            raise LookupError
        else:
            return utf_9.getregentry()


LazySearcher = MyLazyCodecsSearcher()
codecs.register(LazySearcher)

assert isinstance(LazySearcher, CodecsSearcher) is True
assert isinstance(codecs.lookup('lazy'), codecs.CodecInfo) is True
assert ('lazy' in LazySearcher.get_available_codec_names()) is True

try:
    codecs.lookup('lazy_broken')
except Exception as e:
    assert isinstance(e, LookupError) is True