#!/usr/bin/python3

import os.path
import re

import sqlalchemy

from datetime import datetime
from typing import List, Optional

from pydub import AudioSegment
from sqlalchemy.ext.associationproxy import association_proxy
from sqlalchemy.ext.declarative import declarative_base, DeclarativeMeta
from sqlalchemy import (
    Boolean,
    Column,
    DateTime,
    Float,
    ForeignKey,
    Integer,
    String,
    func
)
from sqlalchemy.exc import IntegrityError
from sqlalchemy.orm import (
    backref,
    relationship,
    sessionmaker,
    scoped_session, RelationshipProperty
)
from sqlalchemy.orm.collections import attribute_mapped_collection
from sqlalchemy.orm.exc import MultipleResultsFound, NoResultFound

from config import Config
from helpers import (
    fade_point,
    get_audio_segment,
    leading_silence,
    trailing_silence,
)
from log import DEBUG, ERROR

# Create session at the global level as per
# https://docs.sqlalchemy.org/en/13/orm/session_basics.html
# and make objects persistent
# https://docs.sqlalchemy.org/en/14/orm/session_state_management.html

engine = sqlalchemy.create_engine(
    f"{Config.MYSQL_CONNECT}?charset=utf8",
    encoding='utf-8',
    echo=Config.DISPLAY_SQL,
    pool_pre_ping=True)

# Create a Session factory
Session = scoped_session(sessionmaker(bind=engine))
# sm: sessionmaker = sessionmaker(bind=engine)  # , expire_on_commit=False)
# Session = scoped_session(sm)

Base: DeclarativeMeta = declarative_base()
Base.metadata.create_all(engine)


def db_init():
    return


# Database classes
class NoteColours(Base):
    __tablename__ = 'notecolours'

    id: int = Column(Integer, primary_key=True, autoincrement=True)
    substring: str = Column(String(256), index=False)
    colour: str = Column(String(21), index=False)
    enabled: bool = Column(Boolean, default=True, index=True)
    is_regex: bool = Column(Boolean, default=False, index=False)
    is_casesensitive: bool = Column(Boolean, default=False, index=False)
    order: int = Column(Integer, index=True)

    def __init__(
            self, session: Session, substring: str, colour: str,
            enabled: bool = True, is_regex: bool = False,
            is_casesensitive: bool = False, order: int = 0) -> None:
        self.substring = substring
        self.colour = colour
        self.enabled = enabled
        self.is_regex = is_regex
        self.is_casesensitive = is_casesensitive
        self.order = order

        session.add(self)
        session.commit()

    def __repr__(self) -> str:
        return (
            f"<NoteColour(id={self.id}, substring={self.substring}, "
            f"colour={self.colour}>"
        )

    @classmethod
    def get_all(cls, session: Session) -> Optional[List["NoteColours"]]:
        """Return all records"""

        return session.query(cls).all()

    @classmethod
    def get_by_id(cls, session: Session, note_id: int) -> \
            Optional["NoteColours"]:
        """Return record identified by id, or None if not found"""

        return session.query(NoteColours).filter(
            NoteColours.id == note_id).first()

    @staticmethod
    def get_colour(session: Session, text: str) -> Optional[str]:
        """
        Parse text and return colour string if matched, else None
        """

        for rec in (
                session.query(NoteColours)
                        .filter(NoteColours.enabled.is_(True))
                        .order_by(NoteColours.order)
                        .all()
        ):
            if rec.is_regex:
                flags = re.UNICODE
                if not rec.is_casesensitive:
                    flags |= re.IGNORECASE
                p = re.compile(rec.substring, flags)
                if p.match(text):
                    return rec.colour
            else:
                if rec.is_casesensitive:
                    if rec.substring in text:
                        return rec.colour
                else:
                    if rec.substring.lower() in text.lower():
                        return rec.colour

        return None


class Notes(Base):
    __tablename__ = 'notes'

    id: int = Column(Integer, primary_key=True, autoincrement=True)
    playlist_id: int = Column(Integer, ForeignKey('playlists.id'))
    playlist: RelationshipProperty = relationship(
        "Playlists", back_populates="notes", lazy="joined")
    row: int = Column(Integer, nullable=False)
    note: str = Column(String(256), index=False)

    def __init__(
            self, session: Session, playlist_id: int, row: int,
            text: str) -> None:
        """Create note"""

        DEBUG(f"Notes.__init__({playlist_id=}, {row=}, {text=})")
        self.playlist_id = playlist_id
        self.row = row
        self.note = text
        session.add(self)
        session.commit()

    def __repr__(self) -> str:
        return (
            f"<Note(id={self.id}, row={self.row}, note={self.note}>"
        )

    def delete_note(self, session: Session) -> None:
        """Delete note"""

        DEBUG(f"delete_note({self.id=}")

        session.query(Notes).filter_by(id=self.id).delete()
        session.commit()

    def update_note(
            self, session: Session, row: int,
            text: Optional[str] = None) -> None:
        """
        Update note details. If text=None, don't change text.
        """

        DEBUG(f"Notes.update_note({self.id=}, {row=}, {text=})")

        self.row = row
        if text:
            self.note = text
        session.commit()


class Playdates(Base):
    __tablename__ = 'playdates'

    id: int = Column(Integer, primary_key=True, autoincrement=True)
    lastplayed: datetime = Column(DateTime, index=True, default=None)
    track_id: int = Column(Integer, ForeignKey('tracks.id'))
    tracks: RelationshipProperty = relationship(
        "Tracks", back_populates="playdates", lazy="joined")

    def __init__(self, session: Session, track: "Tracks") -> None:
        """Record that track was played"""

        DEBUG(f"add_playdate(track={track})")

        self.lastplayed = datetime.now()
        self.track_id = track.id
        track.update_lastplayed(session)
        session.add(self)
        session.commit()

    @staticmethod
    def last_played(session: Session, track_id: int) -> Optional[datetime]:
        """Return datetime track last played or None"""

        last_played: Optional[Playdates] = session.query(
            Playdates.lastplayed).filter((Playdates.track_id == track_id)
        ).order_by(Playdates.lastplayed.desc()).first()
        if last_played:
            return last_played[0]
        else:
            return None

    @staticmethod
    def remove_track(session: Session, track_id: int) -> None:
        """
        Remove all records of track_id
        """

        session.query(Playdates).filter(
            Playdates.track_id == track_id,
        ).delete()
        session.commit()


class Playlists(Base):
    """
    Manage playlists
    """

    __tablename__ = "playlists"

    id: int = Column(Integer, primary_key=True, autoincrement=True)
    name: str = Column(String(32), nullable=False, unique=True)
    last_used: datetime = Column(DateTime, default=None, nullable=True)
    loaded: bool = Column(Boolean, default=True, nullable=False)
    notes = relationship(
        "Notes", order_by="Notes.row", back_populates="playlist", lazy="joined")

    tracks = association_proxy('playlist_tracks', 'tracks')
    row = association_proxy('playlist_tracks', 'row')

    def __init__(self, session: Session, name: str) -> None:
        self.name = name
        session.add(self)
        session.commit()

    def __repr__(self) -> str:
        return f"<Playlists(id={self.id}, name={self.name}>"

    def add_note(self, session: Session, row: int, text: str) -> Notes:
        """Add note to playlist at passed row"""

        return Notes(session, self.id, row, text)

    def add_track(
            self, session: Session, track: "Tracks",
            row: Optional[int] = None) -> None:
        """
        Add track to playlist at given row.
        If row=None, add to end of playlist
        """

        if not row:
            row = PlaylistTracks.next_free_row(session, self)

        PlaylistTracks(session, self.id, track.id, row)

    def close(self, session: Session) -> None:
        """Record playlist as no longer loaded"""

        self.loaded = False
        session.add(self)
        session.commit()

    @classmethod
    def get_all(cls, session: Session) -> List["Playlists"]:
        """Returns a list of all playlists ordered by last use"""

        return (
            session.query(cls)
                .order_by(cls.last_used.desc())
        ).all()

    @classmethod
    def get_by_id(cls, session: Session, playlist_id: int) -> "Playlists":
        return (session.query(cls).filter(cls.id == playlist_id)).one()

    @classmethod
    def get_closed(cls, session: Session) -> List["Playlists"]:
        """Returns a list of all closed playlists ordered by last use"""

        return (
            session.query(cls)
                .filter(cls.loaded.is_(False))
                .order_by(cls.last_used.desc())
        ).all()

    @classmethod
    def get_open(cls, session: Session) -> List["Playlists"]:
        """
        Return a list of playlists marked "loaded", ordered by loaded date.
        """

        return (
            session.query(cls)
                .filter(cls.loaded.is_(True))
                .order_by(cls.last_used.desc())
        ).all()

    def mark_open(self, session: Session) -> None:
        """Mark playlist as loaded and used now"""

        self.loaded = True
        self.last_used = datetime.now()
        if self not in session:
            session.add(self)
        session.commit()

    def remove_all_tracks(self, session: Session) -> None:
        """
        Remove all tracks from this playlist
        """

        session.query(PlaylistTracks).filter(
            PlaylistTracks.playlist_id == self.id,
        ).delete()
        session.commit()

    def remove_track(self, session: Session, row: int) -> None:
        DEBUG(f"Playlist.remove_track({self.id=}, {row=})")

        session.query(PlaylistTracks).filter(
            PlaylistTracks.playlist_id == self.id,
            PlaylistTracks.row == row
        ).delete()
        session.commit()


class PlaylistTracks(Base):
    __tablename__ = 'playlist_tracks'

    id: int = Column(Integer, primary_key=True, autoincrement=True)
    playlist_id: int = Column(Integer, ForeignKey('playlists.id'),
        primary_key=True)
    track_id: int = Column(Integer, ForeignKey('tracks.id'), primary_key=True)
    row: int = Column(Integer, nullable=False)
    tracks: RelationshipProperty = relationship("Tracks")
    playlist: RelationshipProperty = relationship(
        Playlists,
        backref=backref(
            "playlist_tracks",
            collection_class=attribute_mapped_collection("row"),
            lazy="joined"
        )
    )

    def __init__(
            self, session: Session, playlist_id: int, track_id: int,
            row: int) -> None:
        DEBUG(f"PlaylistTracks.__init__({playlist_id=}, {track_id=}, {row=})")

        self.playlist_id = playlist_id
        self.track_id = track_id
        self.row = row
        session.add(self)
        session.commit()

    @staticmethod
    def move_track(
            session: Session, from_playlist_id: int, row: int,
            to_playlist_id: int) -> None:
        """
        Move track between playlists. This would be more efficient with
        an ORM-enabled UPDATE statement, but this works just fine.
        """
        DEBUG(
            "PlaylistTracks.move_tracks("
            f"{from_playlist_id=}, {row=}, {to_playlist_id=})"
        )

        new_row: int
        max_row: Optional[int] = session.query(
            func.max(PlaylistTracks.row)).filter(
            PlaylistTracks.playlist_id == to_playlist_id).scalar()
        if max_row is None:
            # Destination playlist is empty; use row 0
            new_row = 0
        else:
            # Destination playlist has tracks; add to end
            new_row = max_row + 1
        try:
            record: PlaylistTracks = session.query(PlaylistTracks).filter(
                PlaylistTracks.playlist_id == from_playlist_id,
                PlaylistTracks.row == row).one()
        except NoResultFound:
            ERROR(
                f"No rows matched in query: "
                f"PlaylistTracks.playlist_id == {from_playlist_id}, "
                f"PlaylistTracks.row == {row}"
            )
            return
        record.playlist_id = to_playlist_id
        record.row = new_row
        session.commit()

    @staticmethod
    def next_free_row(session: Session, playlist: Playlists) -> int:
        """Return next free row number"""

        row: int

        last_row: int = session.query(
            func.max(PlaylistTracks.row)
        ).filter_by(playlist_id=playlist.id).first()
        # if there are no rows, the above returns (None, ) which is True
        if last_row and last_row[0] is not None:
            row = last_row[0] + 1
        else:
            row = 0

        return row


class Settings(Base):
    __tablename__ = 'settings'

    id: int = Column(Integer, primary_key=True, autoincrement=True)
    name: str = Column(String(32), nullable=False, unique=True)
    f_datetime: datetime = Column(DateTime, default=None, nullable=True)
    f_int: int = Column(Integer, default=None, nullable=True)
    f_string: str = Column(String(128), default=None, nullable=True)

    @classmethod
    def get_int_settings(cls, session: Session, name: str) -> "Settings":
        """Get setting for an integer or return new setting record"""

        int_setting: Settings

        try:
            int_setting = session.query(cls).filter(
                cls.name == name).one()
        except NoResultFound:
            int_setting = Settings()
            int_setting.name = name
            int_setting.f_int = None
            session.add(int_setting)
            session.commit()
        return int_setting

    def update(self, session: Session, data):
        for key, value in data.items():
            assert hasattr(self, key)
            setattr(self, key, value)
        session.commit()


class Tracks(Base):
    __tablename__ = 'tracks'

    id: int = Column(Integer, primary_key=True, autoincrement=True)
    title: str = Column(String(256), index=True)
    artist: str = Column(String(256), index=True)
    duration: int = Column(Integer, index=True)
    start_gap: int = Column(Integer, index=False)
    fade_at: int = Column(Integer, index=False)
    silence_at: int = Column(Integer, index=False)
    path: str = Column(String(2048), index=False, nullable=False)
    mtime: float = Column(Float, index=True)
    lastplayed: datetime = Column(DateTime, index=True, default=None)
    playlists: RelationshipProperty = relationship("PlaylistTracks",
        back_populates="tracks",
        lazy="joined")
    playdates: RelationshipProperty = relationship("Playdates",
        back_populates="tracks",
        lazy="joined")

    def __init__(self, session: Session, path: str) -> None:
        self.path = path
        session.add(self)
        session.commit()

    def __repr__(self) -> str:
        return (
            f"<Track(id={self.id}, title={self.title}, "
            f"artist={self.artist}, path={self.path}>"
        )

    @staticmethod
    def get_all_paths(session) -> List[str]:
        """Return a list of paths of all tracks"""

        return [a[0] for a in session.query(Tracks.path).all()]

    @classmethod
    def get_all_tracks(cls, session: Session) -> List["Tracks"]:
        """Return a list of all tracks"""

        return session.query(cls).all()

    @classmethod
    def get_or_create(cls, session: Session, path: str) -> "Tracks":
        """
        If a track with path exists, return it;
        else created new track and return it
        """

        DEBUG(f"Tracks.get_or_create({path=})")

        try:
            track = session.query(cls).filter(cls.path == path).one()
        except NoResultFound:
            track = Tracks(session, path)

        return track

    @classmethod
    def get_from_filename(cls, session: Session, filename: str) \
            -> Optional["Tracks"]:
        """
        Return track if one and only one track in database has passed
        filename (ie, basename of path). Return None if zero or more
        than one track matches.
        """

        DEBUG(f"Tracks.get_track_from_filename({filename=})")
        try:
            track = session.query(Tracks).filter(Tracks.path.ilike(
                f'%{os.path.sep}{filename}')).one()
            return track
        except (NoResultFound, MultipleResultsFound):
            return None

    @classmethod
    def get_from_path(cls, session: Session, path: str) -> List["Tracks"]:
        """
        Return track with passee path, or None.
        """

        DEBUG(f"Tracks.get_track_from_path({path=})")

        return session.query(Tracks).filter(Tracks.path == path).first()

    @classmethod
    def get_by_id(cls, session: Session, track_id: int) -> Optional["Tracks"]:
        """Return track or None"""

        try:
            DEBUG(f"Tracks.get_track(track_id={track_id})")
            track = session.query(Tracks).filter(Tracks.id == track_id).one()
            return track
        except NoResultFound:
            ERROR(f"get_track({track_id}): not found")
            return None

    def rescan(self, session: Session) -> None:
        """
        Update audio metadata for passed track.
        """

        audio: AudioSegment = get_audio_segment(self.path)
        self.duration = len(audio)
        self.fade_at = round(fade_point(audio) / 1000,
            Config.MILLISECOND_SIGFIGS) * 1000
        self.mtime = os.path.getmtime(self.path)
        self.silence_at = round(trailing_silence(audio) / 1000,
            Config.MILLISECOND_SIGFIGS) * 1000
        self.start_gap = leading_silence(audio)
        session.add(self)
        session.commit()

    @staticmethod
    def remove_by_path(session: Session, path: str) -> None:
        """Remove track with passed path from database"""

        DEBUG(f"Tracks.remove_path({path=})")

        try:
            session.query(Tracks).filter(Tracks.path == path).delete()
            session.commit()
        except IntegrityError as exception:
            ERROR(f"Can't remove track with {path=} ({exception=})")

    @classmethod
    def search_artists(cls, session: Session, text: str) -> List["Tracks"]:

        return (
            session.query(cls)
                .filter(cls.artist.ilike(f"%{text}%"))
                .order_by(cls.title)
        ).all()

    @classmethod
    def search_titles(cls, session: Session, text: str) -> List["Tracks"]:
        return (
            session.query(cls)
                .filter(cls.title.ilike(f"%{text}%"))
                .order_by(cls.title)
        ).all()

    def update_lastplayed(self, session: Session) -> None:
        self.lastplayed = datetime.now()
        session.add(self)
        session.commit()

    def update_artist(self, session: Session, artist: str) -> None:
        self.artist = artist
        session.add(self)
        session.commit()

    def update_title(self, session: Session, title: str) -> None:
        self.title = title
        session.add(self)
        session.commit()

    def update_path(self, newpath: str) -> None:
        self.path = newpath