"""Parse (absolute and relative) URLs.

See RFC 1808: "Relative Uniform Resource Locators", by R. Fielding,

UC Irvine, June 1995.

"""

__all__ = ["urlparse", "urlunparse", "urljoin", "urldefrag",

           "urlsplit", "urlunsplit"]

# A classification of schemes ('' means apply by default)

uses_relative = ['ftp', 'http', 'gopher', 'nntp', 'imap',

                 'wais', 'file', 'https', 'shttp', 'mms',

                 'prospero', 'rtsp', 'rtspu', '', 'sftp']

uses_netloc = ['ftp', 'http', 'gopher', 'nntp', 'telnet',

               'imap', 'wais', 'file', 'mms', 'https', 'shttp',

               'snews', 'prospero', 'rtsp', 'rtspu', 'rsync', '',

               'svn', 'svn+ssh', 'sftp']

non_hierarchical = ['gopher', 'hdl', 'mailto', 'news',

                    'telnet', 'wais', 'imap', 'snews', 'sip', 'sips']

uses_params = ['ftp', 'hdl', 'prospero', 'http', 'imap',

               'https', 'shttp', 'rtsp', 'rtspu', 'sip', 'sips',

               'mms', '', 'sftp']

uses_query = ['http', 'wais', 'imap', 'https', 'shttp', 'mms',

              'gopher', 'rtsp', 'rtspu', 'sip', 'sips', '']

uses_fragment = ['ftp', 'hdl', 'http', 'gopher', 'news',

                 'nntp', 'wais', 'https', 'shttp', 'snews',

                 'file', 'prospero', '']

# Characters valid in scheme names

scheme_chars = ('abcdefghijklmnopqrstuvwxyz'

                'ABCDEFGHIJKLMNOPQRSTUVWXYZ'

                '0123456789'

                '+-.')

MAX_CACHE_SIZE = 20

_parse_cache = {}

def clear_cache():

    """Clear the parse cache."""

    global _parse_cache

    _parse_cache = {}

class BaseResult(tuple):

    """Base class for the parsed result objects.

    This provides the attributes shared by the two derived result

    objects as read-only properties.  The derived classes are

    responsible for checking the right number of arguments were

    supplied to the constructor.

    """

    __slots__ = ()

    # Attributes that access the basic components of the URL:

    @property

    def scheme(self):

        return self[0]

    @property

    def netloc(self):

        return self[1]

    @property

    def path(self):

        return self[2]

    @property

    def query(self):

        return self[-2]

    @property

    def fragment(self):

        return self[-1]

    # Additional attributes that provide access to parsed-out portions

    # of the netloc:

    @property

    def username(self):

        netloc = self.netloc

        if "@" in netloc:

            userinfo = netloc.split("@", 1)[0]

            if ":" in userinfo:

                userinfo = userinfo.split(":", 1)[0]

            return userinfo

        return None

    @property

    def password(self):

        netloc = self.netloc

        if "@" in netloc:

            userinfo = netloc.split("@", 1)[0]

            if ":" in userinfo:

                return userinfo.split(":", 1)[1]

        return None

    @property

    def hostname(self):

        netloc = self.netloc

        if "@" in netloc:

            netloc = netloc.split("@", 1)[1]

        if ":" in netloc:

            netloc = netloc.split(":", 1)[0]

        return netloc.lower() or None

    @property

    def port(self):

        netloc = self.netloc

        if "@" in netloc:

            netloc = netloc.split("@", 1)[1]

        if ":" in netloc:

            port = netloc.split(":", 1)[1]

            return int(port, 10)

        return None

class SplitResult(BaseResult):

    __slots__ = ()

    def __new__(cls, scheme, netloc, path, query, fragment):

        return BaseResult.__new__(

            cls, (scheme, netloc, path, query, fragment))

    def geturl(self):

        return urlunsplit(self)

class ParseResult(BaseResult):

    __slots__ = ()

    def __new__(cls, scheme, netloc, path, params, query, fragment):

        return BaseResult.__new__(

            cls, (scheme, netloc, path, params, query, fragment))

    @property

    def params(self):

        return self[3]

    def geturl(self):

        return urlunparse(self)

def urlparse(url, scheme='', allow_fragments=True):

    """Parse a URL into 6 components:

    <scheme>://<netloc>/<path>;<params>?<query>#<fragment>

    Return a 6-tuple: (scheme, netloc, path, params, query, fragment).

    Note that we don't break the components up in smaller bits

    (e.g. netloc is a single string) and we don't expand % escapes."""

    tuple = urlsplit(url, scheme, allow_fragments)

    scheme, netloc, url, query, fragment = tuple

    if scheme in uses_params and ';' in url:

        url, params = _splitparams(url)

    else:

        params = ''

    return ParseResult(scheme, netloc, url, params, query, fragment)

def _splitparams(url):

    if '/'  in url:

        i = url.find(';', url.rfind('/'))

        if i < 0:

            return url, ''

    else:

        i = url.find(';')

    return url[:i], url[i+1:]

def _splitnetloc(url, start=0):

    delim = len(url)   # position of end of domain part of url, default is end

    for c in '/?#':    # look for delimiters; the order is NOT important

        wdelim = url.find(c, start)        # find first of this delim

        if wdelim >= 0:                    # if found

            delim = min(delim, wdelim)     # use earliest delim position

    return url[start:delim], url[delim:]   # return (domain, rest)

def urlsplit(url, scheme='', allow_fragments=True):

    """Parse a URL into 5 components:

    <scheme>://<netloc>/<path>?<query>#<fragment>

    Return a 5-tuple: (scheme, netloc, path, query, fragment).

    Note that we don't break the components up in smaller bits

    (e.g. netloc is a single string) and we don't expand % escapes."""

    allow_fragments = bool(allow_fragments)

    key = url, scheme, allow_fragments, type(url), type(scheme)

    cached = _parse_cache.get(key, None)

    if cached:

        return cached

    if len(_parse_cache) >= MAX_CACHE_SIZE: # avoid runaway growth

        clear_cache()

    netloc = query = fragment = ''

    i = url.find(':')

    if i > 0:

        if url[:i] == 'http': # optimize the common case

            scheme = url[:i].lower()

            url = url[i+1:]

            if url[:2] == '//':

                netloc, url = _splitnetloc(url, 2)

            if allow_fragments and '#' in url:

                url, fragment = url.split('#', 1)

            if '?' in url:

                url, query = url.split('?', 1)

            v = SplitResult(scheme, netloc, url, query, fragment)

            _parse_cache[key] = v

            return v

        for c in url[:i]:

            if c not in scheme_chars:

                break

        else:

            scheme, url = url[:i].lower(), url[i+1:]

    if scheme in uses_netloc and url[:2] == '//':

        netloc, url = _splitnetloc(url, 2)

    if allow_fragments and scheme in uses_fragment and '#' in url:

        url, fragment = url.split('#', 1)

    if scheme in uses_query and '?' in url:

        url, query = url.split('?', 1)

    v = SplitResult(scheme, netloc, url, query, fragment)

    _parse_cache[key] = v

    return v

def urlunparse((scheme, netloc, url, params, query, fragment)):

    """Put a parsed URL back together again.  This may result in a

    slightly different, but equivalent URL, if the URL that was parsed

    originally had redundant delimiters, e.g. a ? with an empty query

    (the draft states that these are equivalent)."""

    if params:

        url = "%s;%s" % (url, params)

    return urlunsplit((scheme, netloc, url, query, fragment))

def urlunsplit((scheme, netloc, url, query, fragment)):

    if netloc or (scheme and scheme in uses_netloc and url[:2] != '//'):

        if url and url[:1] != '/': url = '/' + url

        url = '//' + (netloc or '') + url

    if scheme:

        url = scheme + ':' + url

    if query:

        url = url + '?' + query

    if fragment:

        url = url + '#' + fragment

    return url

def urljoin(base, url, allow_fragments=True):

    """Join a base URL and a possibly relative URL to form an absolute

    interpretation of the latter."""

    if not base:

        return url

    if not url:

        return base

    bscheme, bnetloc, bpath, bparams, bquery, bfragment = \

            urlparse(base, '', allow_fragments)

    scheme, netloc, path, params, query, fragment = \

            urlparse(url, bscheme, allow_fragments)

    if scheme != bscheme or scheme not in uses_relative:

        return url

    if scheme in uses_netloc:

        if netloc:

            return urlunparse((scheme, netloc, path,

                               params, query, fragment))

        netloc = bnetloc

    if path[:1] == '/':

        return urlunparse((scheme, netloc, path,

                           params, query, fragment))

    if not (path or params or query):

        return urlunparse((scheme, netloc, bpath,

                           bparams, bquery, fragment))

    segments = bpath.split('/')[:-1] + path.split('/')

    # XXX The stuff below is bogus in various ways...

    if segments[-1] == '.':

        segments[-1] = ''

    while '.' in segments:

        segments.remove('.')

    while 1:

        i = 1

        n = len(segments) - 1

        while i < n:

            if (segments[i] == '..'

                and segments[i-1] not in ('', '..')):

                del segments[i-1:i+1]

                break

            i = i+1

        else:

            break

    if segments == ['', '..']:

        segments[-1] = ''

    elif len(segments) >= 2 and segments[-1] == '..':

        segments[-2:] = ['']

    return urlunparse((scheme, netloc, '/'.join(segments),

                       params, query, fragment))

def urldefrag(url):

    """Removes any existing fragment from URL.

    Returns a tuple of the defragmented URL and the fragment.  If

    the URL contained no fragments, the second element is the

    empty string.

    """

    if '#' in url:

        s, n, p, a, q, frag = urlparse(url)

        defrag = urlunparse((s, n, p, a, q, ''))

        return defrag, frag

    else:

        return url, ''

test_input = """

      http://a/b/c/d

      g:h        = <URL:g:h>

      http:g     = <URL:http://a/b/c/g>

      http:      = <URL:http://a/b/c/d>

      g          = <URL:http://a/b/c/g>

      ./g        = <URL:http://a/b/c/g>

      g/         = <URL:http://a/b/c/g/>

      /g         = <URL:http://a/g>

      //g        = <URL:http://g>

      ?y         = <URL:http://a/b/c/d?y>

      g?y        = <URL:http://a/b/c/g?y>

      g?y/./x    = <URL:http://a/b/c/g?y/./x>

      .          = <URL:http://a/b/c/>

      ./         = <URL:http://a/b/c/>

      ..         = <URL:http://a/b/>

      ../        = <URL:http://a/b/>

      ../g       = <URL:http://a/b/g>

      ../..      = <URL:http://a/>

      ../../g    = <URL:http://a/g>

      ../../../g = <URL:http://a/../g>

      ./../g     = <URL:http://a/b/g>

      ./g/.      = <URL:http://a/b/c/g/>

      /./g       = <URL:http://a/./g>

      g/./h      = <URL:http://a/b/c/g/h>

      g/../h     = <URL:http://a/b/c/h>

      http:g     = <URL:http://a/b/c/g>

      http:      = <URL:http://a/b/c/d>

      http:?y         = <URL:http://a/b/c/d?y>

      http:g?y        = <URL:http://a/b/c/g?y>

      http:g?y/./x    = <URL:http://a/b/c/g?y/./x>

"""

def test():

    import sys

    base = ''

    if sys.argv[1:]:

        fn = sys.argv[1]

        if fn == '-':

            fp = sys.stdin

        else:

            fp = open(fn)

    else:

        try:

            from cStringIO import StringIO

        except ImportError:

            from StringIO import StringIO

        fp = StringIO(test_input)

    while 1:

        line = fp.readline()

        if not line: break

        words = line.split()

        if not words:

            continue

        url = words[0]

        parts = urlparse(url)

        print '%-10s : %s' % (url, parts)

        abs = urljoin(base, url)

        if not base:

            base = abs

        wrapped = '<URL:%s>' % abs

        print '%-10s = %s' % (url, wrapped)

        if len(words) == 3 and words[1] == '=':

            if wrapped != words[2]:

                print 'EXPECTED', words[2], '!!!!!!!!!!'

if __name__ == '__main__':

    test()