import json
import os.path

# this is for django objects only
#from django.core import serializers
from django.http                import HttpResponse, HttpResponseForbidden

#from manifold.manifoldquery import ManifoldQuery
from manifold.core.query        import Query
from manifold.core.result_value import ResultValue
from manifold.manifoldapi       import ManifoldAPI
from manifold.manifoldresult    import ManifoldException
from manifold.util.log          import Log
from myslice.configengine       import ConfigEngine

debug=False
#debug=True

# pretend the server only returns - empty lists to 'get' requests - this is to mimick 
# misconfigurations or expired credentials or similar corner case situations
debug_empty=False
#debug_empty=True

# this view is what the javascript talks to when it sends a query
# see also
# myslice/urls.py
# as well as 
# static/js/manifold.js
def proxy (request,format):
    """the view associated with /manifold/proxy/ 
with the query passed using POST"""
    
    # expecting a POST
    if request.method != 'POST':
        print "manifoldproxy.api: unexpected method %s -- exiting"%request.method
        return 
    # we only support json for now
    # if needed in the future we should probably cater for
    # format_in : how is the query encoded in POST
    # format_out: how to serve the results
    if format != 'json':
        print "manifoldproxy.proxy: unexpected format %s -- exiting"%format
        return
    try:
        # translate incoming POST request into a query object
        if debug: print 'manifoldproxy.proxy: request.POST',request.POST
        manifold_query = Query()
        #manifold_query = ManifoldQuery()
        manifold_query.fill_from_POST(request.POST)
        # retrieve session for request

        # We allow some requests to use the ADMIN user account
        if (manifold_query.get_from() == 'local:user' and manifold_query.get_action() == 'create') \
                or (manifold_query.get_from() == 'local:platform' and manifold_query.get_action() == 'get'):
            admin_user, admin_password = ConfigEngine().manifold_admin_user_password()
            manifold_api_session_auth = {'AuthMethod': 'password', 'Username': admin_user, 'AuthString': admin_password}
        else:
            print request.session['manifold']
            manifold_api_session_auth = request.session['manifold']['auth']

        if debug_empty and manifold_query.action.lower()=='get':
            json_answer=json.dumps({'code':0,'value':[]})
            print "By-passing : debug_empty & 'get' request : returning a fake empty list"
            return HttpResponse (json_answer, mimetype="application/json")
                
        # actually forward
        manifold_api= ManifoldAPI(auth=manifold_api_session_auth)
        if debug: print '===> manifoldproxy.proxy: sending to backend', manifold_query
        # for the benefit of the python code, manifoldAPI raises an exception if something is wrong
        # however in this case we want to propagate the complete manifold result to the js world

        result = manifold_api.forward(manifold_query.to_dict())

        # XXX TEMP HACK
        if 'description' in result and result['description'] \
                and isinstance(result['description'], (tuple, list, set, frozenset)):
            result [ 'description' ] = [ ResultValue.to_html (x) for x in result['description'] ]

        json_answer=json.dumps(result)

        return HttpResponse (json_answer, mimetype="application/json")

    except Exception,e:
        print "** PROXY ERROR **",e
        import traceback
        traceback.print_exc()

#################### 
# see CSRF_FAILURE_VIEW in settings.py
# the purpose of redefining this was to display the failure reason somehow
# this however turns out disappointing/not very informative
failure_answer=[ "csrf_failure" ]
def csrf_failure(request, reason=""):
    print "CSRF failure with reason '%s'"%reason
    return HttpResponseForbidden (json.dumps (failure_answer), mimetype="application/json")