### $Id$
### $URL$
import re
from sfa.util.faults import *
URN_PREFIX = "urn:publicid:IDN"

def get_leaf(hrn):
    parts = hrn.split(".")
    return ".".join(parts[-1:])

def get_authority(xrn):
    hrn, type = urn_to_hrn(xrn)
    if type and type == 'authority':
        return hrn
    
    parts = hrn.split(".")
    return ".".join(parts[:-1])

def hrn_to_pl_slicename(hrn):
    parts = hrn.split(".")
    return parts[-2] + "_" + parts[-1]

# assuming hrn is the hrn of an authority, return the plc authority name
def hrn_to_pl_authname(hrn):
    parts = hrn.split(".")
    return parts[-1]

# assuming hrn is the hrn of an authority, return the plc login_base
def hrn_to_pl_login_base(hrn):
    return hrn_to_pl_authname(hrn)

def hostname_to_hrn(auth_hrn, login_base, hostname):
    """
    Convert hrn to plantelab name.
    """
    sfa_hostname = ".".join([auth_hrn, login_base, hostname.split(".")[0]])
    return sfa_hostname

def slicename_to_hrn(auth_hrn, slicename):
    """
    Convert hrn to planetlab name.
    """
    parts = slicename.split("_")
    slice_hrn = ".".join([auth_hrn, parts[0]]) + "." + "_".join(parts[1:])

    return slice_hrn

def email_to_hrn(auth_hrn, email):
    parts = email.split("@")
    username = parts[0]
    username = username.replace(".", "_").replace("+", "_") 
    person_hrn = ".".join([auth_hrn, username])
    
    return person_hrn 

def urn_to_hrn(urn):
    """
    convert a urn to hrn
    return a tuple (hrn, type)
    Warning: urn_to_hrn() replces some special characters that 
    are not replaced in hrn_to_urn(). Due to this, 
    urn_to_hrn() -> hrn_to_urn() may not return the original urn
    """

    # if this is already a hrn dont do anything
    if not urn or not urn.startswith(URN_PREFIX):
        return urn, None

    name = urn[len(URN_PREFIX):]
    hrn_parts = name.split("+")
    type = hrn_parts.pop(2)
    
         
    # Remove the authority name (e.g. '.sa')
    if type == 'authority':
        hrn_parts = hrn_parts[:-1]

    # convert hrn_parts (list) into hrn (str) by doing the following    
    # dont allow special characters (except ':') in the site login base
    # remove blank elements
    # replace ':' with '.'
    # join list elements using '.'
    only_alphanum = re.compile('[^a-zA-Z0-9:]+')
    valid_chars = lambda x: only_alphanum.sub('', x).replace(':', '.')
    hrn = '.'.join([valid_chars(part) for part in hrn_parts if part]) 
    
    return str(hrn), str(type) 
    
    
def hrn_to_urn(hrn, type=None):
    """
    convert an hrn and type to a urn string
    """
    # if  this is already a urn dont do anything 
    if not hrn or hrn.startswith(URN_PREFIX):
        return hrn

    authority = get_authority(hrn)
    name = get_leaf(hrn)
     
    if type == 'authority':
        authority = hrn
        name = 'sa'   
    
    if authority.startswith("plc"):
        if type == None:
            urn = "+".join(['',authority.replace('.',':'),name])
        else:
            urn = "+".join(['',authority.replace('.',':'),type,name])

    else:
        urn = "+".join(['',authority,type,name])
        
    return URN_PREFIX + urn