"""
    WSGI application implementation
"""

# for error reporting
import sys, traceback

# for Request/Response
import http

class Application (object) :
    """
        Our WSGI application, implements the wsgi __call__ interface
    """

    def __init__ (self, handler) :
        """
            Initialize to use the given handler for requests
        """

        self.handler = handler
    
    def handle_request (self, env, start_response) :
        """
            The actual request handling code
        """

        # build Request object
        request = http.Request(env)

        try :
            # request -> response using our handler
            response = self.handler.handle_request(request)

        except http.ResponseError, err :
            # just use the generated response
            response = err.get_response()

        # send response
        assert response, "No response"
        
        # send response status/headers
        start_response(response.get_status(), response.get_headers())

        # send respones data
        yield response.get_data()

    def __call__ (self, env, start_response) :
        """
            Wraps handle_request to trap errors
        """

        try :
            # passthrough request_handler
            for chunk in self.handle_request(env, start_response) :
                yield chunk

        except :
            # execption info
            info = sys.exc_info()

            # try and send 500 ISE to browser, if no headers yet...
            start_response("500 Internal Server Error", [('Content-type', "text/plain; charset=utf8")], info)

            # send traceback
            yield traceback.format_exc()