# Python CAS library

import urllib, urllib2

class PyCAS(object):
    """A class for working with a CAS server."""
    
    def __init__(self, url, renew=False, **kwords):
        self.url = url
        self.renew = renew
        self.paths = {
            'login_path': '/login',
            'logout_path': '/login',
            'validate_path': '/validate',
        }
        self.paths.update(kwords)        
    
    def login_url(self, service):
        """Return the login URL for the given service."""
        base = self.url + self.paths['login_path'] + '?service=' + urllib.quote_plus(service)
        if self.renew:
            base += "&renew=true"
        return base

    def logout_url(self, url=None):
        """Return the logout URL."""
        base = self.url + self.paths['logout_path'] 
        if url:
            base += '?url=' + urllib.quote_plus(url)
        return base

    def validate_url(self, service, ticket):
        """Return the validation URL for the given service. (For CAS 1.0)"""
        base = self.url + self.paths['validate_path'] + '?service=' + urllib.quote_plus(service) + '&ticket=' + urllib.quote_plus(ticket)
        if self.renew:
            base += "&renew=true"
        return base

    def validate_ticket(self, service, ticket):
        """Validate the given ticket against the given service."""
        f = urllib2.urlopen(self.validate_url(service, ticket))
        valid = f.readline()
        valid = valid.strip() == 'yes'
        user = f.readline().strip()
        
        return (valid, user)