:param unicode_: unicode to encode

    :rtype: str

    :returns: str object

    """

    if isinstance(unicode_, str):

        return unicode_

    try:

        return unicode_.encode(to_encoding)

    except UnicodeEncodeError:

        pass

    try:

        import chardet

        encoding = chardet.detect(unicode_)['encoding']

        print encoding

        if encoding is None:

            raise UnicodeEncodeError()

        return unicode_.encode(encoding)

    except (ImportError, UnicodeEncodeError):

        return unicode_.encode(to_encoding, 'replace')

    return safe_str

def engine_from_config(configuration, prefix='sqlalchemy.', **kwargs):

    """

    Custom engine_from_config functions that makes sure we use NullPool for

    file based sqlite databases. This prevents errors on sqlite. This only 

    applies to sqlalchemy versions < 0.7.0

    """

    import sqlalchemy

    from sqlalchemy import engine_from_config as efc

    import logging

    if int(sqlalchemy.__version__.split('.')[1]) < 7:

        # This solution should work for sqlalchemy < 0.7.0, and should use

        # proxy=TimerProxy() for execution time profiling

        from sqlalchemy.pool import NullPool

        url = configuration[prefix + 'url']

        if url.startswith('sqlite'):

            kwargs.update({'poolclass': NullPool})

        return efc(configuration, prefix, **kwargs)

    else:

        import time

        from sqlalchemy import event

        from sqlalchemy.engine import Engine

        log = logging.getLogger('sqlalchemy.engine')

        BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE = xrange(30, 38)

        engine = efc(configuration, prefix, **kwargs)

        def color_sql(sql):

            COLOR_SEQ = "\033[1;%dm"

            COLOR_SQL = YELLOW

            normal = '\x1b[0m'

            return ''.join([COLOR_SEQ % COLOR_SQL, sql, normal])

        if configuration['debug']:

            #attach events only for debug configuration

            def before_cursor_execute(conn, cursor, statement,

                                    parameters, context, executemany):

                context._query_start_time = time.time()

                log.info(color_sql(">>>>> STARTING QUERY >>>>>"))

            def after_cursor_execute(conn, cursor, statement,

                                    parameters, context, executemany):

                total = time.time() - context._query_start_time

                log.info(color_sql("<<<<< TOTAL TIME: %f <<<<<" % total))

            event.listen(engine, "before_cursor_execute",

                         before_cursor_execute)

            event.listen(engine, "after_cursor_execute",

                         after_cursor_execute)

    return engine

def age(curdate):

    """

    turns a datetime into an age string.

    :param curdate: datetime object

    :rtype: unicode

    :returns: unicode words describing age

    """

    from datetime import datetime

    from webhelpers.date import time_ago_in_words

    _ = lambda s:s

    if not curdate:

        return ''

    agescales = [(_(u"year"), 3600 * 24 * 365),

                 (_(u"month"), 3600 * 24 * 30),

                 (_(u"day"), 3600 * 24),

                 (_(u"hour"), 3600),

                 (_(u"minute"), 60),

                 (_(u"second"), 1), ]

    age = datetime.now() - curdate

    age_seconds = (age.days * agescales[2][1]) + age.seconds

    pos = 1

    for scale in agescales:

        if scale[1] <= age_seconds:

            if pos == 6:pos = 5

            return '%s %s' % (time_ago_in_words(curdate,

                                                agescales[pos][0]), _('ago'))

        pos += 1

    return _(u'just now')

def uri_filter(uri):

    """

    Removes user:password from given url string

    :param uri:

    :rtype: unicode

    :returns: filtered list of strings  

    """

    if not uri:

        return ''

    proto = ''

    for pat in ('https://', 'http://'):

        if uri.startswith(pat):

            uri = uri[len(pat):]

            proto = pat

            break

    # remove passwords and username

    uri = uri[uri.find('@') + 1:]

    # get the port

    cred_pos = uri.find(':')

    if cred_pos == -1:

        host, port = uri, None

    else:

        host, port = uri[:cred_pos], uri[cred_pos + 1:]

    return filter(None, [proto, host, port])

def credentials_filter(uri):

    """

    Returns a url with removed credentials

    :param uri:

    """

    uri = uri_filter(uri)

    #check if we have port

    if len(uri) > 2 and uri[2]:

        uri[2] = ':' + uri[2]

    return ''.join(uri)

def get_changeset_safe(repo, rev):

    """

    Safe version of get_changeset if this changeset doesn't exists for a 

    repo it returns a Dummy one instead

    :param repo:

    :param rev:

    """

    from vcs.backends.base import BaseRepository

    from vcs.exceptions import RepositoryError

    if not isinstance(repo, BaseRepository):

        raise Exception('You must pass an Repository '

                        'object as first argument got %s', type(repo))

    try:

        cs = repo.get_changeset(rev)

    except RepositoryError:

        from rhodecode.lib.utils import EmptyChangeset

        cs = EmptyChangeset(requested_revision=rev)

    return cs

    """

    Returns tuple of (number, id) from repository containing this package

    or None if repository could not be found.

    """

    try:

        from vcs import get_repo

        from vcs.utils.helpers import get_scm

        from vcs.exceptions import RepositoryError, VCSError

        repopath = os.path.join(os.path.dirname(__file__), '..', '..')

        scm = get_scm(repopath)[0]

        repo = get_repo(path=repopath, alias=scm)

        tip = repo.get_changeset()

        return (tip.revision, tip.short_id)

    except (ImportError, RepositoryError, VCSError), err:

        print ("Cannot retrieve rhodecode's revision. Original error "

               "was: %s" % err)

        return None