# -*- coding: UTF-8 -*-
from functools import wraps
from django.core import serializers
from django.core.serializers.json import DjangoJSONEncoder
from django.db.models.query import QuerySet
from django.http import HttpResponse
from django.utils import simplejson

class AjaxException(Exception):
    message = u'Ajax error'


ajax_error_response = {'status': 'error', 'message': ''}
ajax_success_response = {'status': 'ok'}


def ajax_json_response(require_params=[], method=None):
    def decorator(func):
        @wraps(func)
        def inner_ajax(request, *args, **kwargs):
            if request.is_ajax():
                if method:
                    if request.method != method:
                        ajax_error_response['message'] = 'Ajax Error. Only %s' % method
                        return HttpResponse(simplejson.dumps(ajax_error_response))
                if require_params:
                    if not hasattr(request, 'params'):
                        setattr(request, 'params', dict())
                    for param in require_params:
                        request_param = request.GET.get(param) or request.POST.get(param)
                        if not request_param:
                            ajax_error_response['message'] = u'Ajax error. Missing %s param' % param
                            return HttpResponse(simplejson.dumps(ajax_error_response))
                        request.params[param] = request_param
                try:
                    response = func(request, *args, **kwargs)
                except AjaxException, e:
                    ajax_error_response['message'] = e.message
                    return HttpResponse(simplejson.dumps(ajax_error_response))
                assert isinstance(response, dict), 'ajax decorated view must to return the dict'
                for key, data in response.iteritems():
                    if isinstance(data, QuerySet):
                        response[key] = serializers.serialize('json', data)
                    elif hasattr(data, '_meta'):
                        response[key] = serializers.serialize('json', [data])[1:-1]
                response.update(ajax_success_response)
                return HttpResponse(simplejson.dumps(ajax_success_response, cls=DjangoJSONEncoder), mimetype='application/json')
            else:
                ajax_error_response['message'] = u'Ajax error. XMLHttpRequest not found'
                return HttpResponse(simplejson.dumps(ajax_error_response))
        return inner_ajax
    return decorator