import sys
import xmlrpc.client
import socket
from urllib.parse import urlparse

from sfa.util.sfalogging import logger
from sfa.util.ssl import simple_ssl_context

class PlShell:
    """
    A simple xmlrpc shell to a myplc instance
    This class can receive all PLCAPI calls to the underlying testbed
    For safety this is limited to a set of hard-coded calls
    """

    direct_calls = [
        'AddNode', 'AddPerson', 'AddPersonKey', 'AddPersonToSite',
        'AddPersonToSlice', 'AddRoleToPerson', 'AddSite', 'AddSiteTag', 'AddSlice',
        'AddSliceTag', 'AddSliceToNodes', 'BindObjectToPeer', 'DeleteKey',
        'DeleteNode', 'DeletePerson', 'DeletePersonFromSlice', 'DeleteSite',
        'DeleteSlice', 'DeleteSliceFromNodes', 'DeleteSliceTag', 'GetInitScripts',
        'GetInterfaces', 'GetKeys', 'GetNodeTags', 'GetPeers',
        'GetPersons', 'GetSlices', 'GetSliceTags', 'GetTagTypes',
        'UnBindObjectFromPeer', 'UpdateNode', 'UpdatePerson', 'UpdateSite',
        'UpdateSlice', 'UpdateSliceTag',
        # also used as-is in importer
        'GetSites', 'GetNodes', 'GetSiteTags',
        # Lease management methods
        'GetLeases', 'GetLeaseGranularity', 'DeleteLeases', 'UpdateLeases',
        'AddLeases',
        # HRN management methods
        'SetPersonHrn', 'GetPersonHrn', 'SetSliceHrn', 'GetSliceHrn',
        'SetNodeHrn', 'GetNodeHrn', 'GetSiteHrn', 'SetSiteHrn',
        # Tag slice/person/site created by SFA
        'SetPersonSfaCreated', 'GetPersonSfaCreated', 'SetSliceSfaCreated',
        'GetSliceSfaCreated', 'SetNodeSfaCreated', 'GetNodeSfaCreated',
        'GetSiteSfaCreated', 'SetSiteSfaCreated',
    ]
    # support for other names - this is experimental
    alias_calls = {
        'get_authorities': 'GetSites',
        'get_nodes': 'GetNodes',
    }

    # use the 'capability' auth mechanism for higher performance when the PLC
    # db is local
    def __init__(self, config):
        url = config.SFA_PLC_URL
        # try to figure if the url is local
        hostname = urlparse(url).hostname
        is_local = False
        if hostname == 'localhost':
            is_local = True
        # otherwise compare IP addresses;
        # this might fail for any number of reasons, so let's harden that
        try:
            # xxx todo this seems to result in a DNS request for each incoming request to the AM
            # should be cached or improved
            url_ip = socket.gethostbyname(hostname)
            local_ip = socket.gethostbyname(socket.gethostname())
            if url_ip == local_ip:
                is_local = True
        except:
            pass

        if is_local:
            try:
                # too bad this is not installed properly
                plcapi_path = "/usr/share/plc_api"
                if plcapi_path not in sys.path:
                    sys.path.append(plcapi_path)
                import PLC.Shell
                plc_direct_access = True
            except:
                plc_direct_access = False
        if is_local and plc_direct_access:
            logger.debug('plshell access - capability')
            self.plauth = {
                'AuthMethod': 'capability',
                'Username': str(config.SFA_PLC_USER),
                'AuthString': str(config.SFA_PLC_PASSWORD),
            }
            self.proxy = PLC.Shell.Shell()

        else:
            logger.debug('plshell access - xmlrpc')
            self.plauth = {
                'AuthMethod': 'password',
                'Username':   str(config.SFA_PLC_USER),
                'AuthString': str(config.SFA_PLC_PASSWORD),
            }
            self.proxy = xmlrpc.client.ServerProxy(
                url, verbose=False, allow_none=True,
                context=simple_ssl_context())

    def __getattr__(self, name):
        def func(*args, **kwds):
            actual_name = None
            if name in PlShell.direct_calls:
                actual_name = name
            if name in PlShell.alias_calls:
                actual_name = PlShell.alias_calls[name]
            if not actual_name:
                raise Exception(
                    "Illegal method call %s for PL driver" % (name))
            result = getattr(self.proxy, actual_name)(
                self.plauth, *args, **kwds)
            logger.debug('PlShell %s (%s) returned ... ' % (name, actual_name))
            return result
        return func