from __future__ import annotations

import dataclasses
from dataclasses import dataclass
from datetime import datetime
import logging
from typing import Dict, Generic, Optional, TypeVar

from ..models import MediaCollection, MediaElement


T = TypeVar("T")


class ExtractionError(Exception):
    pass


@dataclass
class ExtractedDataLight:
    object_uri: str
    extractor_name: str
    object_key: str

    def create_media(self) -> MediaElement:
        return MediaElement(
            uri = self.object_uri,
            extractor_name = self.extractor_name,
            extractor_key = self.object_key,
        )

    def create_collection(self) -> MediaCollection:
        return MediaCollection(
            uri = self.object_uri,
            extractor_name = self.extractor_name,
            extractor_key = self.object_key
        )


@dataclass
class ExtractedData(ExtractedDataLight, Generic[T]):
    data: T = dataclasses.field(default=None, repr=False, compare=False)
    cache: Dict = dataclasses.field(default=None, repr=False, compare=False)

    @property
    def has_data(self) -> bool:
        return self.data is not None

    def load_media(self) -> MediaElement:
        return MediaElement.get(extractor_name=self.extractor_name, extractor_key=self.object_key)

    def load_collection(self) -> MediaCollection:
        return MediaCollection.get(extractor_name=self.extractor_name, extractor_key=self.object_key)


@dataclass
class AuthorExtractedData(ExtractedDataLight):
    author_name: str

    @property
    def is_valid(self):
        return len(list(v for _, v in self.__dict__.items() if v is None)) <= 0


E = TypeVar("E", MediaElement, MediaCollection)

class GeneralExtractor(Generic[E, T]):

    name: str

    def __init__(self, name: str):
        self.name = name

    # abstract (for media & collection base classes)

    @staticmethod
    def check_uri(uri: str) -> Optional[E]:
        raise NotImplementedError()

    def _create_object(self, data: ExtractedData[T]) -> E:
        raise NotImplementedError()

    def _load_object(self, data: ExtractedData[T]) -> E:
        raise NotImplementedError()

    # abstract (for specific extractor classes)

    #def uri_suitable(self, uri: str) -> bool:
    #    raise NotImplementedError()

    def can_extract_offline(self, uri: str, cache: Dict = None) -> bool:
        return False

    def _cache_expired(self, date: datetime) -> bool:
        return False

    def _extract_offline_only(self, uri: str, cache: Dict = None) -> ExtractedData[T]:
        raise NotImplementedError()

    def _extract_online(self, uri: str, cache: Dict = None) -> ExtractedData[T]:
        raise NotImplementedError()

    def _update_object_raw(self, object: E, data: T):
        raise NotImplementedError()

    def _update_hook(self, object: E, data: ExtractedData[T]):
        return None

    # defined

    def _extract_offline(self, uri: str, cache: Dict = None) -> ExtractedData[T]:
        return self._extract_offline_only(uri, cache) if self.can_extract_offline(uri, cache) else self._extract_online(uri, cache)

    def _extract_required(self, data: ExtractedData[T]) -> ExtractedData[T]:
        if data.has_data:
            return data
        return self._extract_online(data.object_uri, data.cache)

    def _update_object(self, object: E, data: ExtractedData[T]) -> E:
        object.extractor_cache = data.cache
        object.uri = data.object_uri
        object.add_uris((data.object_uri,))
        self._update_object_raw(object, data.data)
        self._update_hook(object, data)
        return object

    def update_object(self, object: E, check_cache_expired: bool = True) -> E:
        if object.extractor_cache_date and check_cache_expired and not self._cache_expired(object.extractor_cache_date):
            return object
        data = self._extract_online(object.uri, object.extractor_cache)
        logging.debug(f"Updating info for media: {data!r}")
        return self._update_object(object, data)

    def store_object(self, data: ExtractedData[T]) -> E:
        object = self._load_object(data)
        if object:
            logging.debug(f"Found object already in database: {data!r}")
            return object
        data = self._extract_required(data)
        logging.debug(f"Store info for object: {data!r}")
        object = self._create_object(data)
        return self._update_object(object, data)

    def extract_and_store(self, uri: str) -> E:
        object = self.check_uri(uri)
        if object is not None:
            return object
        return self.store_object(self._extract_offline(uri))