#
# SfaAPI authentication 
#
import sys

from sfa.trust.certificate import Keypair, Certificate
from sfa.trust.credential import Credential
from sfa.trust.trustedroots import TrustedRoots
from sfa.util.faults import *
from sfa.trust.hierarchy import Hierarchy
from sfa.util.config import *
from sfa.util.xrn import get_authority
from sfa.trust.sfaticket import SfaTicket

from sfa.util.sfalogging import logger

class Auth:
    """
    Credential based authentication
    """

    def __init__(self, peer_cert = None, config = None ):
        self.peer_cert = peer_cert
        self.hierarchy = Hierarchy()
        if not config:
            self.config = Config()
        self.load_trusted_certs()

    def load_trusted_certs(self):
        self.trusted_cert_list = TrustedRoots(self.config.get_trustedroots_dir()).get_list()
        self.trusted_cert_file_list = TrustedRoots(self.config.get_trustedroots_dir()).get_file_list()

        
        
    def checkCredentials(self, creds, operation, hrn = None):
        valid = []
        if not isinstance(creds, list):
            creds = [creds]
        logger.debug("Auth.checkCredentials with %d creds"%len(creds))
        for cred in creds:
            try:
                self.check(cred, operation, hrn)
                valid.append(cred)
            except:
                cred_obj=Credential(string=cred)
                logger.debug("failed to validate credential - dump=%s"%cred_obj.dump_string(dump_parents=True))
                error = sys.exc_info()[:2]
                continue
            
        if not len(valid):
            raise InsufficientRights('Access denied: %s -- %s' % (error[0],error[1]))
        
        return valid
        
        
    def check(self, cred, operation, hrn = None):
        """
        Check the credential against the peer cert (callerGID included 
        in the credential matches the caller that is connected to the 
        HTTPS connection, check if the credential was signed by a 
        trusted cert and check if the credential is allowed to perform 
        the specified operation.    
        """
        self.client_cred = Credential(string = cred)
        self.client_gid = self.client_cred.get_gid_caller()
        self.object_gid = self.client_cred.get_gid_object()
        
        # make sure the client_gid is not blank
        if not self.client_gid:
            raise MissingCallerGID(self.client_cred.get_subject())
       
        # validate the client cert if it exists
        if self.peer_cert:
            self.verifyPeerCert(self.peer_cert, self.client_gid)                   

        # make sure the client is allowed to perform the operation
        if operation:
            if not self.client_cred.can_perform(operation):
                raise InsufficientRights(operation)

        if self.trusted_cert_list:
            self.client_cred.verify(self.trusted_cert_file_list, self.config.SFA_CREDENTIAL_SCHEMA)
        else:
           raise MissingTrustedRoots(self.config.get_trustedroots_dir())
       
        # Make sure the credential's target matches the specified hrn. 
        # This check does not apply to trusted peers 
        trusted_peers = [gid.get_hrn() for gid in self.trusted_cert_list]
        if hrn and self.client_gid.get_hrn() not in trusted_peers:
            target_hrn = self.object_gid.get_hrn()
            if not hrn == target_hrn:
                raise PermissionError("Target hrn: %s doesn't match specified hrn: %s " % \
                                       (target_hrn, hrn) )       
        return True

    def check_ticket(self, ticket):
        """
        Check if the tickt was signed by a trusted cert
        """
        if self.trusted_cert_list:
            client_ticket = SfaTicket(string=ticket)
            client_ticket.verify_chain(self.trusted_cert_list)
        else:
           raise MissingTrustedRoots(self.config.get_trustedroots_dir())

        return True 

    def verifyPeerCert(self, cert, gid):
        # make sure the client_gid matches client's certificate
        if not cert.is_pubkey(gid.get_pubkey()):
            raise ConnectionKeyGIDMismatch(gid.get_subject()+":"+cert.get_subject())            

    def verifyGidRequestHash(self, gid, hash, arglist):
        key = gid.get_pubkey()
        if not key.verify_string(str(arglist), hash):
            raise BadRequestHash(hash)

    def verifyCredRequestHash(self, cred, hash, arglist):
        gid = cred.get_gid_caller()
        self.verifyGidRequestHash(gid, hash, arglist)

    def validateGid(self, gid):
        if self.trusted_cert_list:
            gid.verify_chain(self.trusted_cert_list)

    def validateCred(self, cred):
        if self.trusted_cert_list:
            cred.verify(self.trusted_cert_file_list)

    def authenticateGid(self, gidStr, argList, requestHash=None):
        gid = GID(string = gidStr)
        self.validateGid(gid)
        # request_hash is optional
        if requestHash:
            self.verifyGidRequestHash(gid, requestHash, argList)
        return gid

    def authenticateCred(self, credStr, argList, requestHash=None):
        cred = Credential(string = credStr)
        self.validateCred(cred)
        # request hash is optional
        if requestHash:
            self.verifyCredRequestHash(cred, requestHash, argList)
        return cred

    def authenticateCert(self, certStr, requestHash):
        cert = Certificate(string=certStr)
        self.validateCert(self, cert)   

    def gidNoop(self, gidStr, value, requestHash):
        self.authenticateGid(gidStr, [gidStr, value], requestHash)
        return value

    def credNoop(self, credStr, value, requestHash):
        self.authenticateCred(credStr, [credStr, value], requestHash)
        return value

    def verify_cred_is_me(self, credential):
        is_me = False 
        cred = Credential(string=credential)
        caller_gid = cred.get_gid_caller()
        caller_hrn = caller_gid.get_hrn()
        if caller_hrn != self.config.SFA_INTERFACE_HRN:
            raise SfaPermissionDenied(self.config.SFA_INTEFACE_HRN)

        return   
        
    def get_auth_info(self, auth_hrn):
        """
        Given an authority name, return the information for that authority.
        This is basically a stub that calls the hierarchy module.
        
        @param auth_hrn human readable name of authority  
        """

        return self.hierarchy.get_auth_info(auth_hrn)


    def veriry_auth_belongs_to_me(self, name):
        """
        Verify that an authority belongs to our hierarchy. 
        This is basically left up to the implementation of the hierarchy
        module. If the specified name does not belong, ane exception is 
        thrown indicating the caller should contact someone else.

        @param auth_name human readable name of authority
        """

        # get auth info will throw an exception if the authority doesnt exist
        self.get_auth_info(name)


    def verify_object_belongs_to_me(self, name):
        """
        Verify that an object belongs to our hierarchy. By extension,
        this implies that the authority that owns the object belongs
        to our hierarchy. If it does not an exception is thrown.
    
        @param name human readable name of object        
        """
        auth_name = self.get_authority(name)
        if not auth_name:
            auth_name = name 
        if name == self.config.SFA_INTERFACE_HRN:
            return
        self.verify_auth_belongs_to_me(auth_name) 
             
    def verify_auth_belongs_to_me(self, name):
        # get auth info will throw an exception if the authority doesnt exist
        self.get_auth_info(name) 


    def verify_object_permission(self, name):
        """
        Verify that the object gid that was specified in the credential
        allows permission to the object 'name'. This is done by a simple
        prefix test. For example, an object_gid for plc.arizona would 
        match the objects plc.arizona.slice1 and plc.arizona.
    
        @param name human readable name to test  
        """
        object_hrn = self.object_gid.get_hrn()
        if object_hrn == name:
            return
        if name.startswith(object_hrn + "."):
            return
        #if name.startswith(get_authority(name)):
            #return
    
        raise PermissionError(name)

    def determine_user_rights(self, caller_hrn, record):
        """
        Given a user credential and a record, determine what set of rights the
        user should have to that record.
        
        This is intended to replace determine_rights() and
        verify_cancreate_credential()
        """

        rl = Rights()
        type = record['type']


        if type=="slice":
            researchers = record.get("researcher", [])
            pis = record.get("PI", [])
            if (caller_hrn in researchers + pis):
                rl.add("refresh")
                rl.add("embed")
                rl.add("bind")
                rl.add("control")
                rl.add("info")

        elif type == "authority":
            pis = record.get("PI", [])
            operators = record.get("operator", [])
            if (caller_hrn == self.config.SFA_INTERFACE_HRN):
                rl.add("authority")
                rl.add("sa")
                rl.add("ma")
            if (caller_hrn in pis):
                rl.add("authority")
                rl.add("sa")
            if (caller_hrn in operators):
                rl.add("authority")
                rl.add("ma")

        elif type == "user":
            rl.add("refresh")
            rl.add("resolve")
            rl.add("info")

        elif type == "node":
            rl.add("operator")

        return rl

    def verify_cancreate_credential(self, src_cred, record):
        """
        Verify that a user can retrive a particular type of credential.
        For slices, the user must be on the researcher list. For SA and
        MA the user must be on the pi and operator lists respectively
        """

        type = record.get_type()
        cred_object_hrn = src_cred.get_gid_object().get_hrn()
        if cred_object_hrn in [self.config.SFA_REGISTRY_ROOT_AUTH]:
            return
        if type=="slice":
            researchers = record.get("researcher", [])
            if not (cred_object_hrn in researchers):
                raise PermissionError(cred_object_hrn + " is not in researcher list for " + record.get_name())
        elif type == "sa":
            pis = record.get("pi", [])
            if not (cred_object_hrn in pis):
                raise PermissionError(cred_object_hrn + " is not in pi list for " + record.get_name())
        elif type == "ma":
            operators = record.get("operator", [])
            if not (cred_object_hrn in operators):
                raise PermissionError(cred_object_hrn + " is not in operator list for " + record.get_name())

    def get_authority(self, hrn):
        return get_authority(hrn)

    def filter_creds_by_caller(self, creds, caller_hrn_list):
        """
        Returns a list of creds who's gid caller matches the 
        specified caller hrn
        """
        if not isinstance(creds, list):
            creds = [creds]
        creds = []
        if not isinistance(caller_hrn_list, list):
            caller_hrn_list = [caller_hrn_list]
        for cred in creds:
            try:
                tmp_cred = Credential(string=cred)
                if tmp_cred.get_gid_caller().get_hrn() in [caller_hrn_list]:
                    creds.append(cred)
            except: pass
        return creds