from os.path import exists
from importlib.machinery import SourceFileLoader
from django.apps import apps
from collections import OrderedDict
from django.db.models import OuterRef, Subquery

import transfer.models as legacy_models

# from pprint import pprint as print


def transfer_objects(data_type):
    models_list = {}

    for app in apps.get_app_configs():
        if exists(f"{app.path}/transfer.py"):
            card_module = SourceFileLoader("transfer", f"{app.path}/transfer.py").load_module()
            if not hasattr(card_module, "card") or len(card_module.card) < 1:
                continue

            for model, card in card_module.card.items():
                if "data_type" in card and data_type == card["data_type"]:
                    card['app_label'] = app.label
                    models_list[model] = card

    if len(models_list) < 1:
        print(f"Models with data type {data_type} not found in structure")
        exit(1)

    models_list = sort_by_dependencies(models_list)

    legacy_objects = OrderedDict()

    for model, card in models_list.items():
        legacy_objects[model] = get_model_data(model, card)


def sort_by_dependencies(data):
    """Сортировка моделей по зависимостям"""

    """Сначала мы сортируем модели по зависимостям в обратном порядке, используя сортировку вставкой"""
    result = []
    for model, card in data.items():
        if "dependencies" in card and isinstance(card['dependencies'], tuple):
            for model_dependency in result:
                if model_dependency in card['dependencies']:
                    result.insert(result.index(model_dependency), model)
                    break

        else:
            result.append(model)

    """Затем мы создаём сортированный словарь из реверса получившегося результата"""

    result = OrderedDict(
        [(model, data[model]) for model in reversed(result)]
    )

    return result


def get_model_data(model, card):
    # print(f"=================================================\r\n"
    #       f"MODEL: {model}\r\n"
    #       f"=================================================")

    card_fields = card['fields']
    relations = card_fields['relations'] if 'relations' in card_fields else None

    if relations:
        del(card_fields['relations'])

    if len(card_fields) > 1:
        print("You must set one table to transfer")
        return

    legacy_table = list(card_fields.keys())[0]
    fields = list(card_fields.values())[0]

    try:
        legacy_model = apps.get_model(app_label="transfer", model_name=legacy_table)
    except LookupError as e:
        print(f"ERROR: legacy model {model} can not be loaded: {e}")
        return

    legacy_fields = []

    for legacy_field in fields.values():
        if isinstance(legacy_field, str):
            legacy_fields.append(legacy_field)

        elif isinstance(legacy_field, tuple):
            if isinstance(legacy_field[0], tuple):
                """Группа полей"""
                for legacy_field_group in legacy_field:
                    legacy_fields.append(legacy_field_group[1])
            else:
                """Одиночное поле"""
                legacy_fields.append(legacy_field[1])

    #TODO: убрать после совместимости
    if model != "City":
        return

    queryset = legacy_model.objects.only(*legacy_fields)

    """Проверяем наличие внешних связей"""
    if relations:
        queryset = get_relation_data(relations, queryset, fields)

    return get_transfer_data(model, card, queryset)


def get_relation_data(relations, queryset, fields):

    # related_legacy_models = [x.related_model._meta.model.__name__ for x in legacy_model._meta.related_objects]

    """Получаем названия внешних зависимостей"""
    for relation_table, relation_data in relations.items():
        """Если объекты связаны через ForeignKey, то ничего не надо делать - все аннотации уже подключены"""

        if isinstance(relation_data['key'], tuple):
            """Вытаскиваем relation по id"""
            try:
                child_legacy_model = apps.get_model(app_label="transfer", model_name=relation_table)
            except LookupError as e:
                raise LookupError(f"ERROR: legacy model {relation_table} can not be loaded: {e}")

            child_table_queryset = child_legacy_model.objects.filter(
                city_id=OuterRef('pk')
            ).only(*relation_data['fields'].values())

            queryset = queryset.annotate(**{
                f"{relation_table.lower()}":
                Subquery(child_table_queryset)
            })

    return queryset


def get_transfer_data(model, card, queryset):
    from pprint import pprint as print

    try:
        app_model = apps.get_model(app_label=card['app_label'], model_name=model)
    except LookupError as e:
        print(f"ERROR: model {model} from {card['app_label']} can not be loaded: {e}")
        return

    if "fields" not in card or not isinstance(card['fields'], dict) or len(card['fields']) != 1:
        raise ValueError("You must set correct fields to transfer")

    for app_field, legacy_field_data in card['fields'].items():
        print(app_field)
        print(legacy_field_data)

        print("*************************************************************************")
    # print(app_model)
    # print("*************************************************************************")
    # print(queryset)
    return queryset