""" Composer for HTTP responses

This module contains a composer, which can compose responses to
HTTP requests from a client.
"""

import re
import time

from config import config
from message import Response
from resource import Resource, FileExistError, FileAccessError
import weblogging as logging

class ResponseComposer:
    """Class that composes a HTTP response to a HTTP request"""

    def __init__(self, timeout):
        """Initialize the ResponseComposer
        
        Args:
            timeout (int): connection timeout
        """
        self.timeout = timeout
    
    def compose_response(self, request):
        """Compose a response to a request
        
        Args:
            request (webhttp.Request): request from client

        Returns:
            webhttp.Response: response to request

        """
        response = Response()

        if re.search(r'\/\.\.?(\/|$)', request.uri):
            response.code = 403
            response.set_header('Connection', 'close')
            response.body = 'Don\'t even think about it.'
            response.set_content_length()
            return response

        return self.serve(request.uri, request=request)

    def serve(self, uri, code=200, etag=None, request=None, error_page=False):
        response = Response()
        try:
            resource = Resource(uri)
            req = request
            if req != None and (
                    resource.etag_match(req.get_header('If-None-Match')) or \
                    not resource.etag_match(req.get_header('If-Match') or '*')):
                response.code = 304
            else:
                response.code = code
                response.body = resource.get_content()
            response.set_header('ETag', resource.generate_etag())
            response.set_header('Connection', 'close')
            response.set_header('Content-Type', resource.get_content_type())
            response.set_content_length()
        except FileExistError:
            if not error_page:
                return self.serve(config('error404'), code=404, error_page=True)
            else:
                response.code = code
                response.set_header('Connection', 'close')
                response.body = 'Error %d' % code
                response.set_content_length()
        except FileAccessError:
            return self.serve(config('error403'), code=403, error_page=True)

        return response

    def make_date_string(self):
        """Make string of date and time
        
        Returns:
            str: formatted string of date and time
        """
        return time.strftime("%a, %d %b %Y %H:%M:%S", time.localtime())