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 rhodecode.lib.vcs.backends.base import BaseRepository

    from rhodecode.lib.vcs.exceptions import RepositoryError

    from rhodecode.lib.vcs.backends.base import EmptyChangeset

    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:

        cs = EmptyChangeset(requested_revision=rev)

    return cs

def datetime_to_time(dt):

    if dt:

        return time.mktime(dt.timetuple())

def time_to_datetime(tm):

    if tm:

        if isinstance(tm, basestring):

            try:

                tm = float(tm)

            except ValueError:

                return

        return datetime.datetime.fromtimestamp(tm)

MENTIONS_REGEX = r'(?:^@|\s@)([a-zA-Z0-9]{1}[a-zA-Z0-9\-\_\.]+)(?:\s{1})'

def extract_mentioned_users(s):

    """

    Returns unique usernames from given string s that have @mention

    :param s: string to get mentions

    """

    usrs = set()

    for username in re.findall(MENTIONS_REGEX, s):

        usrs.add(username)

    return sorted(list(usrs), key=lambda k: k.lower())

class AttributeDict(dict):

    def __getattr__(self, attr):

        return self.get(attr, None)

    __setattr__ = dict.__setitem__

    __delattr__ = dict.__delitem__

def fix_PATH(os_=None):

    """

    Get current active python path, and append it to PATH variable to fix issues

    of subprocess calls and different python versions

    """

    if os_ is None:

        import os

    else:

        os = os_

    cur_path = os.path.split(sys.executable)[0]

    if not os.environ['PATH'].startswith(cur_path):

        os.environ['PATH'] = '%s:%s' % (cur_path, os.environ['PATH'])

def obfuscate_url_pw(engine):

    _url = engine or ''

    from sqlalchemy.engine import url as sa_url

    try:

        _url = sa_url.make_url(engine)

        if _url.password:

            _url.password = 'XXXXX'

    except Exception:

        pass

    return str(_url)

def get_server_url(environ):

    req = webob.Request(environ)

    return req.host_url + req.script_name

def _extract_extras(env=None):

    """

    Extracts the rc extras data from os.environ, and wraps it into named

    AttributeDict object

    """

    if not env:

        env = os.environ

    try:

        rc_extras = json.loads(env['RC_SCM_DATA'])

    except Exception:

        print os.environ

        print >> sys.stderr, traceback.format_exc()

        rc_extras = {}

    try:

        for k in ['username', 'repository', 'locked_by', 'scm', 'make_lock',

                  'action', 'ip']:

            rc_extras[k]

    except KeyError, e:

        raise Exception('Missing key %s in os.environ %s' % (e, rc_extras))

    return AttributeDict(rc_extras)

def _set_extras(extras):

    os.environ['RC_SCM_DATA'] = json.dumps(extras)

def unique_id(hexlen=32):

    alphabet = "23456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghjklmnpqrstuvwxyz"

    return suuid(truncate_to=hexlen, alphabet=alphabet)

def suuid(url=None, truncate_to=22, alphabet=None):

    """

    Generate and return a short URL safe UUID.

    If the url parameter is provided, set the namespace to the provided

    URL and generate a UUID.

    :param url to get the uuid for

    :truncate_to: truncate the basic 22 UUID to shorter version

    The IDs won't be universally unique any longer, but the probability of

    a collision will still be very low.

    """

    # Define our alphabet.

    _ALPHABET = alphabet or "23456789ABCDEFGHJKLMNPQRSTUVWXYZ"

    # If no URL is given, generate a random UUID.

    if url is None:

        unique_id = uuid.uuid4().int

    else:

        unique_id = uuid.uuid3(uuid.NAMESPACE_URL, url).int

    alphabet_length = len(_ALPHABET)

    output = []

    while unique_id > 0:

        digit = unique_id % alphabet_length

        output.append(_ALPHABET[digit])

        unique_id = int(unique_id / alphabet_length)

    return "".join(output)[:truncate_to]

def get_current_rhodecode_user():

    """

    defined, else returns None.

    """

    from pylons import tmpl_context

    if hasattr(tmpl_context, 'rhodecode_user'):

        return tmpl_context.rhodecode_user

    return None