#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
SPARUL adaptor
See <htaccess> for the .htaccess recipe
"""
import sys
from urlparse import urlparse
import httplib
import os

env = os.environ
filename = env['QUERY_STRING'] #assume 'QUERY_STRING' exists via CGI/1.1
METHOD = env['REQUEST_METHOD']

if METHOD == 'HEAD' or METHOD == 'GET':
    print "MS-Author-Via: SPARQL"
    #We basically let apache do the content negotiation. See <htaccess>
    if filename.endswith(".n3"):
        print 'Content-Type: text/rdf+n3'
    elif filename.endswith(".rdf"):
        print 'Content-Type: application/rdf+xml'
    if METHOD == 'HEAD':
        print
        sys.exit()

    F = open(filename)
    print
    print F.read()
    F.close()
    sys.exit()
        
REDIRECT_TO = "http://dig.csail.mit.edu/2007/wiki/tabulator"
REDIRECT_TO_RSS = "http://dig.csail.mit.edu/2007/wiki/tabulator"
REDIRECT_TO_RSS_ON = True #optional

#Two approahces for SPARUL redirection
# 1. 302 - This makes more sense but I don't have time to investigate into
#          browser POST redirection at the momment.
# 2. Proxy - with the Content-Location: header. (current implementation, 
#            see the following code)

NETLOC, PATH = 1, 2
machine, location = urlparse(REDIRECT_TO)[NETLOC:(PATH+1)]
data = sys.stdin.read()
if "<http://purl.org/rss/1.0/item>" in data: #heuristics
    machine, location = urlparse(REDIRECT_TO_RSS)[NETLOC:(PATH+1)]
headers = {"Content-type" : 'application/sparql-query'}
try:
    headers['X-Meta'] = os.environ['HTTP_X_META']
except KeyError:
    pass

conn = httplib.HTTPConnection(machine)
conn.request("POST", location, data, headers)
response = conn.getresponse()
response_data = response.read()


print "Status: %s %s" % (response.status, response.reason)
print "Content-Type: " + response.getheader("Content-type")
print "Content-Location: " + REDIRECT_TO
print "MS-Author-Via: SPARQL"
print response_data

conn.close()