import itertools
import hmac
import time
import zlib
import time

def peek_iter(iterable):
    try:
        first = next(iterable)
    except StopIteration:
        return None

    return itertools.chain([first], iterable)


def split_prefix(key, prefixs):
    for p in prefixs:
        if key.startswith(p):
            plen = len(p)
            return (key[:plen], key[plen:])


def create_decompressor():
    return zlib.decompressobj(16 + zlib.MAX_WBITS)


class HMACCookieMaker:
    def __init__(self, key, name):
        self.key = key
        self.name = name


    def __call__(self, duration, extraId = ''):
        expire = str(long(time.time() + duration))

        if extraId:
            msg = extraId + '-' + expire
        else:
            msg = expire

        hmacdigest = hmac.new(self.key, msg)
        hexdigest = hmacdigest.hexdigest()

        if extraId:
            cookie = '{0}-{1}={2}-{3}'.format(self.name, extraId, expire, hexdigest)
        else:
            cookie = '{0}={1}-{2}'.format(self.name, expire, hexdigest)

        return cookie

        #return cookie + hexdigest


# Adapted from example at
class PerfTimer:
    def __init__(self, perfdict, name):
        self.perfdict = perfdict
        self.name = name

    def __enter__(self):
        self.start = time.clock()
        return self

    def __exit__(self, *args):
        self.end = time.clock()
        if self.perfdict is not None:
            self.perfdict[self.name] = str(self.end - self.start)


# adapted from wsgiref.request_uri, but doesn't include domain name and allows ':' in url
def request_uri(environ, include_query=1):
    """Return the requested path, optionally including the query string"""
    from urllib import quote
    url = quote(environ.get('SCRIPT_NAME', '')+environ.get('PATH_INFO',''),safe='/;=,:')
    if include_query and environ.get('QUERY_STRING'):
        url += '?' + environ['QUERY_STRING']
    return url