# -*- coding: utf-8 -*-
from django.db import models
from django.core.exceptions import FieldError


class LinkedDocsMixin(models.Model):
    """Mixin: добавляет метод для получения списка связанных документов."""
    LINKED_DOCS_MODELS = ('Invoice', 'Faktura', 'Nakladn', 'AktRabot',)

    class Meta:
        abstract = True

    def linked_docs(self):
        if getattr(self, '_cache_linked_docs', None) is None:
            self._cache_linked_docs = {}

            model_name = self.__class__.__name__  # имя модели на инстансе которой вызвали метод linked_docs

            if model_name == 'Invoice':
                invoice_id = self.id

                for doc in self.LINKED_DOCS_MODELS:
                    if doc != 'Invoice':
                        queryset = models.get_model('docs', doc).objects.filter(invoice=invoice_id)

                        if queryset:
                            self._cache_linked_docs[doc] = queryset

            else:
                invoice_id = getattr(self, 'invoice_id', None)

                if invoice_id:
                    for doc in self.LINKED_DOCS_MODELS:
                        doc_model = models.get_model('docs', doc)

                        if doc != 'Invoice':
                            queryset = doc_model.objects.filter(invoice_id=invoice_id)
                            if model_name == doc:
                                queryset = queryset.exclude(id=self.id)
                        else:
                            queryset = doc_model.objects.filter(id=invoice_id)

                        if queryset:
                            self._cache_linked_docs[doc] = queryset

        return self._cache_linked_docs