from __future__ import annotations

import dataclasses
from dataclasses import dataclass
from datetime import datetime
import math
import logging
from typing import Callable, Dict, Iterable, List, Optional, Set, Tuple, TypeVar, Union

from pony import orm

db = orm.Database()


####
## Model Extensions
####


@dataclass
class TagRootElement:
    base: Tagable
    children: List[TagTreeElement] = dataclasses.field(default_factory=lambda: [])

    def share_score(self, points: float) -> PreferenceScoreAppender:
        if len(self.children) <= 0:
            return PreferenceScoreAppender()
        single_share = points / len(self.children)
        shares = (child.share_score(single_share) for child in self.children)
        return PreferenceScoreAppender(shares)


@dataclass
class TagTreeElement:
    base: Tag
    children: List[TagTreeElement] = dataclasses.field(default_factory=lambda: [])

    def share_score(self, points: float) -> PreferenceScoreAppender:
        if len(self.children) <= 0:
            return PreferenceScoreAppender(PreferenceScore({self.base: points}))
        children_fraction = len(self.children)
        base_fraction = children_fraction + 1
        single_share = points / (base_fraction + children_fraction)
        base_share = PreferenceScore({self.base: single_share * base_fraction})
        shares = (child.share_score(single_share) for child in self.children)
        return base_share & shares


TagElement = Union[TagRootElement, TagTreeElement]


class Tagable:

    ## abstracted

    @property
    def assigned_tags(self) -> Set[Tag]:
        """
        Tags which are directly assigned to this object by the user or automatic actions.
        """
        raise NotImplementedError("")

    @property
    def inherited_tags(self) -> Set[Tag]:
        """
        Tags, which are inherited by any other means than super/sub-tag relationships.
        This relationship does not declare a distance between this tags and assigned tags.
        """
        return set()

    @property
    def super_tags(self) -> Set[Tag]:
        """
        Tags, which are inherited only by super/sub-tag relationships.
        This relationship does declare a distance between this tags and assigned tags.
        """
        return set()

    ## implemented

    @property
    def direct_tags(self) -> Set[Tag]:
        return self.assigned_tags | self.inherited_tags

    @property
    def __tag_hierachy(self) -> Tuple[TagRootElement, Set[Tag]]:
        root = TagRootElement(
            base=self,
            children=[TagTreeElement(tag) for tag in self.direct_tags],
        )
        stack: List[TagTreeElement] = root.children[:]
        used: Set[Tag] = self.direct_tags
        while len(stack) > 0:
            cur = stack.pop(0)
            for tag in cur.base.super_tags:
                if tag not in used:
                    elem = TagTreeElement(tag)
                    cur.children.append(elem)
                    stack.append(elem)
                    used.add(tag)
        return root, used

    @property
    def tag_hierachy(self) -> TagRootElement:
        return self.__tag_hierachy[0]

    @property
    def all_tags(self) -> Set[Tag]:
        return self.__tag_hierachy[1]


T = TypeVar("T", bound=Tagable)


@dataclass
class PreferenceScore:
    points: Dict[Tag, float] = dataclasses.field(default_factory=lambda: {})

    def __add__(self, other: PreferenceScoreCompatible) -> PreferenceScore:
        return (self & other).calculate()

    def __and__(self, other: PreferenceScoreCompatible) -> PreferenceScoreAppender:
        return PreferenceScoreAppender(self, other)

    def __mul__(self, scalar: float) -> PreferenceScore:
        return PreferenceScore({tag: score * scalar for tag, score in self.points.items()})

    def __neg__(self) -> PreferenceScore:
        return self * -1

    def adapt_score(self, tagable: Tagable, score: float) -> PreferenceScore:
        return (self & tagable.tag_hierachy.share_score(score)).calculate()

    def calculate_score(self, object: Tagable) -> float:
        return math.fsum(self.points[tag] for tag in object.all_tags if tag in self.points)

    def order_by_score(self, objects: Iterable[T]) -> List[T]:
        return sorted(objects, key=lambda o: self.calculate_score(o))


class PreferenceScoreAppender:
    points_list: List[PreferenceScore]

    def __init__(self, *args: PreferenceScoreCompatible):
        self.points_list = []
        for preference in args:
            self.__append(preference)

    def __append(self, preference: PreferenceScoreCompatible):
        if isinstance(preference, PreferenceScore):
            self.points_list.append(preference)
        elif isinstance(preference, PreferenceScoreAppender):
            self.points_list.extend(preference.points_list)
        else:
            for sub_pref in preference:
                self.__append(sub_pref)

    def __and__(self, other: PreferenceScoreCompatible) -> PreferenceScoreAppender:
        return PreferenceScoreAppender(self, other)

    def calculate(self) -> PreferenceScore:
        combined: Dict[Tag, List[float]] = {}
        for preference in self.points_list:
            for tag, score in preference.points.items():
                if tag not in combined:
                    combined[tag] = []
                combined[tag].append(score)
        return PreferenceScore({tag: math.fsum(scores) for tag, scores in combined.items()})


PreferenceScoreCompatibleSimple = Union[PreferenceScore, PreferenceScoreAppender]
PreferenceScoreCompatible = Union[PreferenceScoreCompatibleSimple, Iterable[PreferenceScoreCompatibleSimple]]


def generate_preference_list(
    base: PreferenceScore,
    object_gen: Callable[[], List[MediaElement]],
    score_adapt: float,
    limit: Optional[int] = None
) -> List[MediaElement]:
    res_ids = list[int]()
    tag_map = dict[MediaCollection, Tag]()
    element_list = object_gen()
    for element in element_list:
        for link in element.collection_links:
            if link.collection not in tag_map:
                tag = Tag(title="Automatic")
                tag.use_for_preferences = True
                link.collection.tag_list.add(tag)
                tag_map[link.collection] = tag
    orm.flush()
    while True:
        if len(element_list) <= 0:
            break
        first_element = base.order_by_score(element_list)[0]
        res_ids.append(first_element.id)
        if limit is not None and limit <= len(res_ids):
            break
        first_element.watched = True # simulative
        base = base.adapt_score(first_element, score_adapt)
        element_list = object_gen()
    orm.rollback()
    return [MediaElement[i] for i in res_ids]


@dataclass
class CollectionStats:

    to_watch_count: int
    ignored_count: int # but not watched
    watched_count: int

    to_watch_seconds: int
    ignored_seconds: int # but not watched
    watched_seconds: int

    @property
    def full_count(self) -> int:
        return self.to_watch_count + self.ignored_count + self.watched_count

    @property
    def full_seconds(self) -> int:
        return self.to_watch_seconds + self.ignored_seconds + self.watched_seconds

    @classmethod
    def from_collection(cls, collection: MediaCollection) -> CollectionStats:
        to_watch_count = 0
        ignored_count = 0
        watched_count = 0
        to_watch_seconds = 0
        ignored_seconds = 0
        watched_seconds = 0
        for link in collection.media_links:
            media = link.element
            if media.watched:
                watched_count += 1
                watched_seconds += media.length
            else:
                watched_seconds += media.progress
                if media.ignored:
                    ignored_count += 1
                    ignored_seconds += media.left_length
                else:
                    to_watch_count += 1
                    to_watch_seconds += media.left_length
        return CollectionStats(
            to_watch_count=to_watch_count,
            ignored_count=ignored_count,
            watched_count=watched_count,
            to_watch_seconds=to_watch_seconds,
            ignored_seconds=ignored_seconds,
            watched_seconds=watched_seconds,
        )


####
## Models
####


## Tag & Selection Score's


class Tag(db.Entity, Tagable):

    id: int = orm.PrimaryKey(int, auto=True)

    title: str = orm.Required(str)
    notes: str = orm.Optional(str)

    use_for_preferences: bool = orm.Required(bool, default=True)

    super_tag_list: Iterable[Tag] = orm.Set(lambda: Tag, reverse="sub_tag_list")
    sub_tag_list: Iterable[Tag] = orm.Set(lambda: Tag, reverse="super_tag_list")

    _collection_list: Iterable[MediaCollection] = orm.Set(lambda: MediaCollection)
    _media_list: Iterable[MediaElement] = orm.Set(lambda: MediaElement)

    @property
    def assigned_tags(self) -> Set[Tag]:
        return {self}

    @property
    def super_tags(self) -> Set[Tag]:
        return set(self.super_tag_list)


## Element <-> Collection Linking


class MediaCollectionLink(db.Entity):

    collection: MediaCollection = orm.Required(lambda: MediaCollection)
    element: MediaElement = orm.Required(lambda: MediaElement)
    orm.PrimaryKey(collection, element)
    season: int = orm.Required(int, default=0)
    episode: int = orm.Required(int, default=0)
    orm.composite_index(season, episode)

    @property
    def element_id(self):
        return self.element.id

    @property
    def element_release_date(self):
        return self.element.release_date

    @staticmethod
    def sorted(iterable: Iterable[MediaCollectionLink]) -> List[MediaCollectionLink]:
        return sorted(iterable, key=lambda m: (m.season, m.episode, m.element_release_date, m.element_id))
    natural_order = (season, episode, element_release_date, element_id) # unusuable due to ponyorm, see https://github.com/ponyorm/pony/issues/612


## Media Elements


class MediaElement(db.Entity, Tagable):

    id: int = orm.PrimaryKey(int, auto=True)
    uri: str = orm.Required(str, unique=True)

    title: str = orm.Optional(str)
    notes: str = orm.Optional(str)
    release_date: datetime = orm.Optional(datetime)

    extractor_name: str = orm.Optional(str)
    extractor_key: str = orm.Optional(str)
    orm.composite_index(extractor_name, extractor_key)
    last_updated: datetime = orm.Optional(datetime)

    watched: bool = orm.Required(bool, default=False)
    ignored: bool = orm.Required(bool, default=False)
    progress: int = orm.Required(int, default=0)
    length: int = orm.Optional(int)

    tag_list : Iterable[Tag] = orm.Set(lambda: Tag)
    uris: Iterable[MediaUriMapping] = orm.Set(lambda: MediaUriMapping)
    collection_links: Iterable[MediaCollectionLink] = orm.Set(lambda: MediaCollectionLink)

    @property
    def was_extracted(self) -> bool:
        return self.last_updated is not None

    @property
    def left_length(self) -> int:
        return 0 if self.watched else self.length - self.progress

    @property
    def ignored_recursive(self) -> bool:
        return orm.count(link for link in MediaCollectionLink if link.episode == self and link.collection.ignored == True) > 0

    @property
    def ignored_any(self) -> bool:
        return self.ignored or self.ignored_recursive

    @property
    def skip_over(self) -> bool:
        return self.ignored or self.watched

    @property
    def can_considered(self) -> bool:
        if self.skip_over:
            return False
        for link in self.collection_links:
            if link.collection.watch_in_order and self != link.collection.next_episode.element:
                return False
        return True

    @property
    def assigned_tags(self) -> Set[Tag]:
        return set(self.tag_list)

    @property
    def inherited_tags(self) -> Set[Tag]:
        result = set()
        for link in self.collection_links:
            result |= link.collection.direct_tags
        return result

    def merge_to(self, other: MediaElement):
        if self.watched:
            other.watched = True
        if self.ignored:
            other.ignored = True
        if self.progress >= 0 and other.progress <= 0:
            other.progress = self.progress
        for uri_map in self.uris:
            uri_map.element = other
        for link in self.collection_links:
            if not MediaCollectionLink.get(collection=link.collection, element=other):
                link.element = other
        self.delete() # will also delete still existing uri mappings and collection links
        orm.flush()

    def add_uris(self, uri_list: Iterable[str]):
        for uri in set(uri_list):
            mapping: MediaUriMapping = MediaUriMapping.get(uri=uri)
            if not mapping:
                logging.debug(f"Add URI mapping {uri!r} to media {self.id!r}")
                MediaUriMapping(
                    uri=uri,
                    element=self,
                )
                continue
            if mapping.element != self:
                raise Exception(f"URI duplicated for two different media's: {uri}") # TODO may replace with merge call
        orm.flush()

    def before_insert(self):
        self.before_update()

    def before_update(self):
        self.add_uris((self.uri,))

    @property
    def info_link(self):
        return f"/media/{self.id}"


class MediaUriMapping(db.Entity):

    id: int = orm.PrimaryKey(int, auto=True)
    uri: str = orm.Required(str, unique=True)
    element: MediaElement = orm.Required(MediaElement)


## Media Collections


class MediaCollection(db.Entity, Tagable):

    id: int = orm.PrimaryKey(int, auto=True)
    uri: str = orm.Required(str, unique=True)

    title: str = orm.Optional(str)
    notes: str = orm.Optional(str)
    release_date: datetime = orm.Optional(datetime)

    extractor_name: str = orm.Optional(str)
    extractor_key: str = orm.Optional(str)
    orm.composite_index(extractor_name, extractor_key)
    last_updated: datetime = orm.Optional(datetime)

    keep_updated: bool = orm.Required(bool, default=False)
    watch_in_order_auto: bool = orm.Required(bool, default=True)

    ignored: bool = orm.Required(bool, default=False)
    watch_in_order: bool = orm.Required(bool, default=True)

    tag_list: Iterable[Tag] = orm.Set(lambda: Tag)
    uris: Iterable[CollectionUriMapping] = orm.Set(lambda: CollectionUriMapping)
    media_links: Iterable[MediaCollectionLink] = orm.Set(MediaCollectionLink)

    @property
    def was_extracted(self) -> bool:
        return self.last_updated is not None

    @property
    def next_episode(self) -> Optional[MediaCollectionLink]:
        #return orm \
        #    .select(link for link in self.media_links if not link.element.watched) \
        #    .order_by(*MediaCollectionLink.natural_order) \
        #    .first()
        episodes = MediaCollectionLink.sorted(orm.select(link for link in self.media_links if not link.element.watched and not link.element.ignored))
        return episodes[0] if len(episodes) > 0 else None

    @property
    def completed(self) -> bool:
        return self.next_episode is None

    @property
    def assigned_tags(self) -> Set[Tag]:
        return set(self.tag_list)

    @property
    def stats(self) -> CollectionStats:
        return CollectionStats.from_collection(self)

    def add_episode(self, media: MediaElement, season: int = 0, episode: int = 0) -> MediaCollectionLink:
        link: MediaCollectionLink = MediaCollectionLink.get(collection=self, element=media)
        if link is None:
            link = MediaCollectionLink(collection=self, element=media)
        link.season, link.episode = season, episode
        orm.flush()
        return link

    def add_uris(self, uri_list: Iterable[str]):
        for uri in set(uri_list):
            mapping: CollectionUriMapping = CollectionUriMapping.get(uri=uri)
            if not mapping:
                logging.debug(f"Add URI mapping {uri!r} to collection {self.id!r}")
                CollectionUriMapping(
                    uri=uri,
                    element=self,
                )
                continue
            if mapping.element != self:
                raise Exception(f"URI duplicated for two different collections's: {uri}") # TODO may replace with merge call
        orm.flush()

    def before_insert(self):
        self.before_update()

    def before_update(self):
        self.add_uris((self.uri,))

    @property
    def info_link(self):
        return f"/collection/{self.id}"


class CollectionUriMapping(db.Entity):

    id: int = orm.PrimaryKey(int, auto=True)
    uri: str = orm.Required(str, unique=True)
    element: MediaCollection = orm.Required(MediaCollection)