# karma - A maubot plugin to track the karma of users.
# Copyright (C) 2018 Tulir Asokan
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.
from typing import List, Tuple, Optional, Type
from time import time

from sqlalchemy import Column, String, Integer, BigInteger, Text, Table, select, and_
from sqlalchemy.sql.base import ImmutableColumnCollection
from sqlalchemy.engine.base import Engine, Connection
from sqlalchemy.ext.declarative import declarative_base

from mautrix.types import Event, UserID, EventID, RoomID


class KarmaCache:
    __tablename__ = "karma_cache"
    db: Engine = None
    t: Table = None
    c: ImmutableColumnCollection = None
    Karma: Type['Karma'] = None

    user_id: UserID = Column(String(255), primary_key=True)
    karma: int = Column(Integer)

    @classmethod
    def get_karma(cls, user_id: UserID) -> Optional[int]:
        rows = cls.db.execute(select([cls.c.karma]).where(cls.c.user_id == user_id))
        try:
            row = next(rows)
            return row[0]
        except StopIteration:
            return None

    @classmethod
    def _set_karma(cls, user_id: UserID, karma: int, conn: Connection) -> None:
        conn.execute(cls.t.delete().where(cls.c.user_id == user_id))
        conn.execute(cls.t.insert().values(user_id=user_id, karma=karma))

    @classmethod
    def set_karma(cls, user_id: UserID, karma: int, conn: Optional[Connection] = None) -> None:
        if conn:
            cls._set_karma(user_id, karma, conn)
        else:
            with cls.db.begin() as conn:
                cls._set_karma(user_id, karma, conn)

    @classmethod
    def get_high(cls, limit: int = 10) -> List[Tuple[UserID, int]]:
        return list(cls.db.execute(cls.t.select().order_by(cls.c.karma.desc()).limit(limit)))

    @classmethod
    def get_low(cls, limit: int = 10) -> List[Tuple[UserID, int]]:
        return list(cls.db.execute(cls.t.select().order_by(cls.c.karma.asc()).limit(limit)))

    @classmethod
    def find_index_from_top(cls, user_id: UserID) -> int:
        i = 0
        for (found,) in cls.db.execute(select([cls.c.user_id]).order_by(cls.c.karma.desc())):
            i += 1
            if found == user_id:
                return i
        return -1

    @classmethod
    def recalculate(cls, user_id: UserID) -> None:
        with cls.db.begin() as txn:
            cls.set_karma(user_id, sum(entry.value for entry in cls.Karma.all(user_id)), txn)

    @classmethod
    def update(cls, user_id: UserID, value_diff: int, conn: Optional[Connection],
               ignore_if_not_exist: bool = False) -> None:
        if not conn:
            conn = cls.db
        existing = conn.execute(select([cls.c.karma]).where(cls.c.user_id == user_id))
        try:
            karma = next(existing)[0] + value_diff
            conn.execute(cls.t.update().where(cls.c.user_id == user_id).values(karma=karma))
        except StopIteration:
            if ignore_if_not_exist:
                return
            conn.execute(cls.t.insert().values(user_id=user_id, karma=value_diff))


class Karma:
    __tablename__ = "karma"
    db: Engine = None
    t: Table = None
    c: ImmutableColumnCollection = None
    KarmaCache: Type[KarmaCache] = None

    given_to: UserID = Column(String(255), primary_key=True)
    given_by: UserID = Column(String(255), primary_key=True)
    given_in: RoomID = Column(String(255), primary_key=True)
    given_for: EventID = Column(String(255), primary_key=True)

    given_from: EventID = Column(String(255))
    given_at: int = Column(BigInteger)
    value: int = Column(Integer)
    content: str = Column(Text)

    @classmethod
    def all(cls, user_id: UserID) -> List['Karma']:
        return [cls(given_to=given_to, given_by=given_by, given_in=given_in, given_for=given_for,
                    given_from=given_from, given_at=given_at, value=value, content=content)
                for given_to, given_by, given_in, given_for, given_from, given_at, value, content
                in cls.db.execute(cls.t.select().where(cls.c.given_to == user_id))]

    @classmethod
    def get(cls, given_to: UserID, given_by: UserID, given_in: RoomID, given_for: Event
            ) -> Optional['Karma']:
        rows = cls.db.execute(cls.t.select().where(and_(
            cls.c.given_to == given_to, cls.c.given_by == given_by,
            cls.c.given_in == given_in, cls.c.given_for == given_for)))
        try:
            (given_to, given_by, given_in, given_for,
             given_from, given_at, value, content) = next(rows)
        except StopIteration:
            return None
        return cls(given_to=given_to, given_by=given_by, given_in=given_in, given_for=given_for,
                   given_from=given_from, given_at=given_at, value=value, content=content)

    def delete(self) -> None:
        with self.db.begin() as txn:
            txn.execute(self.t.delete().where(and_(
                self.c.given_to == self.given_to, self.c.given_by == self.given_by,
                self.c.given_in == self.given_in, self.c.given_for == self.given_for)))
            self.KarmaCache.update(self.given_to, self.value, txn, ignore_if_not_exist=True)

    def insert(self) -> None:
        self.given_at = int(time() * 1000)
        with self.db.begin() as txn:
            txn.execute(self.t.insert().values(given_to=self.given_to, given_by=self.given_by,
                                               given_in=self.given_in, given_for=self.given_for,
                                               given_from=self.given_from, value=self.value,
                                               given_at=self.given_at, content=self.content))
            self.KarmaCache.update(self.given_to, self.value, txn)

    def update(self, new_value: int) -> None:
        self.given_at = int(time() * 1000)
        value_diff = new_value - self.value
        self.value = new_value
        with self.db.begin() as txn:
            txn.execute(self.t.update().where(and_(
                self.c.given_to == self.given_to, self.c.given_by == self.given_by,
                self.c.given_in == self.given_in, self.c.given_for == self.given_for
            )).values(given_from=self.given_from, value=self.value, given_at=self.given_at))
            self.KarmaCache.update(self.given_to, value_diff, txn)


class Version:
    __tablename__ = "version"
    db: Engine = None
    t: Table = None
    c: ImmutableColumnCollection = None

    version: int = Column(Integer, primary_key=True)


def make_tables(engine: Engine) -> Tuple[Type[KarmaCache], Type[Karma], Type[Version]]:
    base = declarative_base()

    class KarmaCacheImpl(KarmaCache, base):
        __table__: Table

    class KarmaImpl(Karma, base):
        __table__: Table

    class VersionImpl(Version, base):
        __table__: Table

    base.metadata.bind = engine
    for table in KarmaCacheImpl, KarmaImpl, VersionImpl:
        table.db = engine
        table.t = table.__table__
        table.c = table.__table__.c
        table.Karma = KarmaImpl
        table.KarmaCache = KarmaCacheImpl

    # TODO replace with alembic
    base.metadata.create_all()

    return KarmaCacheImpl, KarmaImpl, VersionImpl