# -*- coding: utf-8 -*-
'''
Tricky admin -> xadmin merger.
Alex Moiseenko aka IMDagger.
'''
import logging
import types
from functools import wraps, update_wrapper
from django.http import HttpRequest
from django.contrib.admin import ModelAdmin

class IgnoredAdminModel(Exception):
    pass

def translate(klass, model_obj):
    '''
    Very tricky function to merge Django admin's model descriptors
    into the XAdmin registry, because it doesn't work from the
    box due to the huge difference and some copied xadmin's
    functionality (this one has own incompatible metaclass, incompatible
    methods with same goal as Django's admin does).
    This function tries to fill this gap.
    '''
    if issubclass(klass, ModelAdmin):
        attrs = {}

        slices = reversed((klass,) + klass.__bases__)
        # all bases after ModelAdmin
        is_nested = lambda s: issubclass(s, ModelAdmin) and s != ModelAdmin
        custom_slices = filter(is_nested, slices)
        for admin_slice in custom_slices:
            # copy just only custom methods and fields
            for k, v in admin_slice.__dict__.iteritems():
                if k.startswith('__'):
                    continue
                if isinstance(v, types.FunctionType):
                    def method_for(k, v):
                        @wraps(v)
                        def inner(self, *args, **kwargs):
                            real_handler = getattr(model_obj, k)
                            if args and isinstance(args[0], HttpRequest):
                                # args list already contains request
                                return real_handler(*args, **kwargs)
                            # request should be first argument after self
                            elif 'request' in real_handler.im_func.func_code.co_varnames[:2]:
                                return real_handler(self.request, *args, **kwargs)
                            else:
                                return real_handler(*args, **kwargs)
                        return inner
                    attrs[k] = method_for(k, v)
                elif not isinstance(v, property):
                    attrs[k] = v

        # xadmin doesn't work with func-obj specified columns
        if 'list_display' in attrs:
            str_list = []
            for idx, column in enumerate(attrs['list_display']):
                if callable(column):
                    internal_name = '_list_{name}_{unique}'.format(name=column.__name__, unique=idx)

                    column_handler = staticmethod(column)
                    attrs[internal_name] = column_handler
                    # patch __func__, because column_handler
                    # is a static method object yet
                    update_wrapper(column_handler.__func__, column)

                    str_list.append(internal_name)
                else:
                    str_list.append(column)
            display_type = type(attrs['list_display'])
            attrs['list_display'] = display_type(str_list)

        essential = type('{0}Wrapper'.format(klass.__name__), (object,), attrs)
        return essential
    else:
        raise IgnoredAdminModel('This function doesn\'t support {0} yet'.format(klass))

def sew(admin, to, RegistryError):
    xadmin = to
    for model, admin_obj in admin.site._registry.iteritems():
        try:
            x = xadmin.site.register(model, translate(admin_obj.__class__, admin_obj))
            admin_obj.admin_site = x
        except (RegistryError, IgnoredAdminModel), e:
            logger = logging.getLogger(__name__)
            logger.debug('Admin sewing notice', exc_info=True, extra={'descriptor': e})