import re

import urllib

from email.Utils import formatdate

from django.utils.encoding import smart_str, force_unicode

from django.utils.functional import allow_lazy

ETAG_MATCH = re.compile(r'(?:W/)?"((?:\\.|[^"])*)"')

def urlquote(url, safe='/'):

    """

    A version of Python's urllib.quote() function that can operate on unicode

    strings. The url is first UTF-8 encoded before quoting. The returned string

    can safely be used as part of an argument to a subsequent iri_to_uri() call

    without double-quoting occurring.

    """

    return force_unicode(urllib.quote(smart_str(url), safe))

urlquote = allow_lazy(urlquote, unicode)

def urlquote_plus(url, safe=''):

    """

    A version of Python's urllib.quote_plus() function that can operate on

    unicode strings. The url is first UTF-8 encoded before quoting. The

    returned string can safely be used as part of an argument to a subsequent

    iri_to_uri() call without double-quoting occurring.

    """

    return force_unicode(urllib.quote_plus(smart_str(url), safe))

urlquote_plus = allow_lazy(urlquote_plus, unicode)

def urlencode(query, doseq=0):

    """

    A version of Python's urllib.urlencode() function that can operate on

    unicode strings. The parameters are first case to UTF-8 encoded strings and

    then encoded as per normal.

    """

    if hasattr(query, 'items'):

        query = query.items()

    return urllib.urlencode(

        [(smart_str(k),

         isinstance(v, (list,tuple)) and [smart_str(i) for i in v] or smart_str(v))

            for k, v in query],

        doseq)

def cookie_date(epoch_seconds=None):

    """

    Formats the time to ensure compatibility with Netscape's cookie standard.

    Accepts a floating point number expressed in seconds since the epoch, in

    UTC - such as that outputted by time.time(). If set to None, defaults to

    the current time.

    Outputs a string in the format 'Wdy, DD-Mon-YYYY HH:MM:SS GMT'.

    """

    rfcdate = formatdate(epoch_seconds)

    return '%s-%s-%s GMT' % (rfcdate[:7], rfcdate[8:11], rfcdate[12:25])

def http_date(epoch_seconds=None):

    """

    Formats the time to match the RFC1123 date format as specified by HTTP

    RFC2616 section 3.3.1.

    Accepts a floating point number expressed in seconds since the epoch, in

    UTC - such as that outputted by time.time(). If set to None, defaults to

    the current time.

    Outputs a string in the format 'Wdy, DD Mon YYYY HH:MM:SS GMT'.

    """

    rfcdate = formatdate(epoch_seconds)

    return '%s GMT' % rfcdate[:25]

# Base 36 functions: useful for generating compact URLs

def base36_to_int(s):

    """

    Convertd a base 36 string to an integer

    """

    return int(s, 36)

def int_to_base36(i):

    """

    Converts an integer to a base36 string

    """

    digits = "0123456789abcdefghijklmnopqrstuvwxyz"

    factor = 0

    # Find starting factor

    while True:

        factor += 1

        if i < 36 ** factor:

            factor -= 1

            break

    base36 = []

    # Construct base36 representation

    while factor >= 0:

        j = 36 ** factor

        base36.append(digits[i / j])

        i = i % j

        factor -= 1

    return ''.join(base36)

def parse_etags(etag_str):

    """

    Parses a string with one or several etags passed in If-None-Match and

    If-Match headers by the rules in RFC 2616. Returns a list of etags

    without surrounding double quotes (") and unescaped from \<CHAR>.

    """

    etags = ETAG_MATCH.findall(etag_str)

    if not etags:

        # etag_str has wrong format, treat it as an opaque string then

        return [etag_str]

    etags = [e.decode('string_escape') for e in etags]

    return etags

def quote_etag(etag):

    """

    Wraps a string in double quotes escaping contents as necesary.

    """

    return '"%s"' % etag.replace('\\', '\\\\').replace('"', '\\"')