import types

from django.http import HttpResponse
from django.utils import simplejson
from django.conf import settings
from django.core.urlresolvers import get_callable
import itertools
import sys
from django.http import Http404
    

def _get_traceback( exc_info=None):
    "Helper function to return the traceback as a string"
    import traceback
    return '\n'.join(traceback.format_exception(*(exc_info or sys.exc_info())))
       

def _copy_x_headers(orig_resp, target_resp):
    if not orig_resp or not hasattr(orig_resp,'items'):
        return

    for key, value in orig_resp.items():
        if key.lower().startswith('x-'):
            target_resp[key] = value
            

def _json_dump(data):
    return HttpResponse(simplejson.dumps(data, ensure_ascii=False),
                        mimetype='application/javascript')

def accept_ajax(view_func):
    def _wrap_view_func(request, *args, **kwargs):
        is_ajax = True
        if hasattr(request, 'is_ajax'):
            if not request.is_ajax():
                is_ajax = False
        else:
            # for backward compatibility with Django pre 1.0
            if not (request.META.has_key('HTTP_ACCEPT') and 'application/javascript' in request.META['HTTP_ACCEPT']):
                is_ajax = False

        origin_resp = None

        #FIXME: require refactoring here
        if not is_ajax:
            # require direct call original function (out of try/except) to proper determine error exception
            # in orinical view
            origin_resp = view_func(request, *args, **kwargs)
            if isinstance(origin_resp, types.DictType) or isinstance(origin_resp, types.ListType):
                return _json_dump(origin_resp)
            else:
                return origin_resp

        response_dict = {}
        response_dict['debug'] = False
        try:
            origin_resp = view_func(request, *args, **kwargs)
            if isinstance(origin_resp, types.DictType) or isinstance(origin_resp, types.ListType):
                if isinstance(origin_resp, types.DictType):
                    if 'status' not in origin_resp:
                        origin_resp['status'] = 200
                return _json_dump(origin_resp)
                    
            if hasattr(origin_resp, 'mimetype') and origin_resp.mimetype == 'application/javascript':
                return origin_resp

            response_dict['status'] = origin_resp.status_code
            response_dict['content'] = origin_resp.content
        except Http404, e:
            raise Http404(e)
        except Exception, e:
            response_dict['status'] = 500
            
            if settings.DEBUG:
                from django.views import debug
                rc = debug.technical_500_response(request, *sys.exc_info())
                response_dict['debug'] = True
                response_dict['debug_msg'] = rc.content
            else:
                from django.core.mail import mail_admins

                exc_info = sys.exc_info()

                subject = 'Error (%s IP): %s' % ((request.META.get('REMOTE_ADDR') in settings.INTERNAL_IPS and 'internal' or 'EXTERNAL'), request.path)
                try:
                    request_repr = repr(request)
                except:
                    request_repr = "Request repr() unavailable"

                message = "%s\n\n%s" % (_get_traceback(exc_info), request_repr)
                mail_admins(subject, message, fail_silently=True)

        resp = HttpResponse(simplejson.dumps(response_dict,ensure_ascii=False), mimetype='application/javascript')
        _copy_x_headers(origin_resp, resp)
        return resp


    return _wrap_view_func




def qs_to_json(qs, map_dict):
    """
      Iterate over qs and do mapping action for each item accoring to map_dict
      example:
         qs is QuerySet for object with fields id, name
         map_dict = {'value': 'id',
                     'label': 'name'}

         resulting dump will contain list of objects with fields value and label
    """
    def _get_value(name, obj):
        attr = getattr(obj, name)
        if callable(attr):
            return unicode(attr())
        return unicode(attr)
    
    
    label_list = [ dict([ (key, _get_value(value, item)) for key, value in map_dict.iteritems() ])
                   for item in qs ]
   
    return simplejson.dumps(label_list)