import traceback, sys

from HTTPServlet import HTTPServlet


class RPCServlet(HTTPServlet):

    def call(self, methodName, *args, **keywords):
        """Call custom method.

        Subclasses may override this class for custom handling of methods.

        """
        if methodName in self.exposedMethods():
            return getattr(self, methodName)(*args, **keywords)
        else:
            raise NotImplementedError, methodName

    def exposedMethods(self):
        """Get exposed methods.

        Subclasses should return a list of methods that will be exposed
        through XML-RPC.

        """
        return ['exposedMethods']

    def resultForException(self, e, trans):
        """Get text for exception.

        Given an unhandled exception, returns the string that should be
        sent back in the RPC response as controlled by the
        RPCExceptionReturn setting.

        """
        # report exception back to server
        setting = trans.application().setting('RPCExceptionReturn')
        assert setting in ('occurred', 'exception', 'traceback'), \
            'setting = %r' % setting
        if setting == 'occurred':
            result = 'unhandled exception'
        elif setting == 'exception':
            result = str(e)
        elif setting == 'traceback':
            result = ''.join(traceback.format_exception(*sys.exc_info()))
        return result

    def sendOK(self, contentType, contents, trans, contentEncoding=None):
        """Send a 200 OK response with the given contents."""
        response = trans.response()
        response.setStatus(200, 'OK')
        response.setHeader('Content-type', contentType)
        response.setHeader('Content-length', str(len(contents)))
        if contentEncoding:
            response.setHeader('Content-encoding', contentEncoding)
        response.write(contents)

    def handleException(self, transaction):
        """Handle exception.

        If ReportRPCExceptionsInWebKit is set to True, then flush the response
        (because we don't want the standard HTML traceback to be appended to
        the response) and then handle the exception in the standard WebKit way.
        This means logging it to the console, storing it in the error log,
        sending error email, etc. depending on the settings.

        """
        setting = transaction.application().setting('ReportRPCExceptionsInWebKit')
        if setting:
            transaction.response().flush()
            transaction.application().handleExceptionInTransaction(
                sys.exc_info(), transaction)

    def transaction(self):
        # most uses of RPC will not need this
        return self._transaction

    def awake(self, transaction):
        HTTPServlet.awake(self, transaction)
        self._transaction = transaction

    def sleep(self, transaction):
        self._transaction = None
        HTTPServlet.sleep(self, transaction)