### $Id$
### $URL$

from sfa.util.faults import *
from sfa.util.method import Method
from sfa.util.parameter import Parameter, Mixed
from sfa.trust.auth import Auth
from sfa.util.record import GeniRecord
from sfa.server.registry import Registries
from sfa.util.prefixTree import prefixTree

class list(Method):
    """
    List the records in an authority. 

    @param cred credential string specifying the rights of the caller
    @param hrn human readable name of authority to list
    @return list of record dictionaries         
    """

    interfaces = ['registry']
    
    accepts = [
        Parameter(str, "Credential string"),
        Parameter(str, "Human readable name (hrn)")
        ]

    returns = [GeniRecord]
    
    def call(self, cred, hrn):
        
        self.api.auth.check(cred, 'list')
        records = []

        # load all know registry names into a prefix tree and attempt to find
        # the longest matching prefix  
        registries = Registries(self.api)
        hrns = registries.keys()
        tree = prefixTree()
        tree.load(hrns)
        registry_hrn = tree.best_match(hrn)

        #if there was no match then this record belongs to an unknow registry
        if not registry_hrn:
            raise MissingAuthority(hrn)
        
        # if the best match (longest matching hrn) is not the local registry,
        # forward the request
        if registry_hrn != self.api.hrn:
            credential = self.api.getCredential()
            try:
                record_list = registries[registry_hrn].list(credential, hrn)
                records = [record.as_dict() for record in record_list]
                if records:
                    return records
            except:
                pass

        # if we still havnt found the record yet, try the local registry
        if not self.api.auth.hierarchy.auth_exists(hrn):
            raise MissingAuthority(hrn)
        
        table = self.api.auth.get_auth_table(hrn)
        records = table.list()
          
        return records