import sys
import xmlrpclib
import socket
from urlparse import urlparse

from sfa.util.sfalogging import logger

class NitosShell:
    """
    A simple xmlrpc shell to a myplc instance
    This class can receive all NITOS API  calls to the underlying testbed
    For safety this is limited to a set of hard-coded calls
    """
    
    direct_calls = ['getNodes','getChannels','getSlices','getUsers','getReservedNodes',
                    'getReservedChannels','getTestbedInfo'
                    ]


    # use the 'capability' auth mechanism for higher performance when the PLC db is local    
    def __init__ ( self, config ) :
        url = config.SFA_NITOS_URL
#        url = "http://195.251.17.239:8080/RPC2"
        # 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':   config.SFA_PLC_USER,
            #                'AuthString': config.SFA_PLC_PASSWORD,
            #                }
            self.proxy = PLC.Shell.Shell ()

        else:
            logger.debug('nitosshell access - xmlrpc')
            #self.plauth = { 'AuthMethod': 'password',
            #                'Username':   config.SFA_PLC_USER,
            #                'AuthString': config.SFA_PLC_PASSWORD,
            #                }
            self.proxy = xmlrpclib.Server(url, verbose = False, allow_none = True)

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