# Standard library imports
import re

# PyQt imports

# Third party imports
from sqlalchemy import (
    delete,
    func,
    select,
    update,
)
from sqlalchemy.orm import aliased
from sqlalchemy.orm.session import Session
from sqlalchemy.sql.elements import BinaryExpression, ColumnElement
from classes import ApplicationError, PlaylistRowDTO

# App imports
from classes import PlaylistDTO, TrackDTO
import helpers
from log import log
from models import (
    db,
    NoteColours,
    Playdates,
    PlaylistRows,
    Playlists,
    Settings,
    Tracks,
)


# Notecolour functions
def get_colour(text: str, foreground: bool = False) -> str:
    """
    Parse text and return background (foreground if foreground==True)
    colour string if matched, else None
    """

    if not text:
        return ""

    match = False

    with db.Session() as session:
        for rec in NoteColours.get_all(session):
            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):
                    match = True
            else:
                if rec.is_casesensitive:
                    if rec.substring in text:
                        match = True
                else:
                    if rec.substring.lower() in text.lower():
                        match = True

            if match:
                if foreground:
                    return rec.foreground or ""
                else:
                    return rec.colour
        return ""


# Track functions
def add_track_to_header(playlistrow_id: int, track_id: int) -> None:
    """
    Add a track to this (header) row
    """

    with db.Session() as session:
        session.execute(
            update(PlaylistRows)
            .where(PlaylistRows.id == playlistrow_id)
            .values(track_id=track_id)
        )
        session.commit()


def create_track(path: str) -> TrackDTO:
    """
    Create a track db entry from a track path and return the DTO
    """

    metadata = helpers.get_all_track_metadata(path)
    with db.Session() as session:
        try:
            track = Tracks(
                session=session,
                path=str(metadata["path"]),
                title=str(metadata["title"]),
                artist=str(metadata["artist"]),
                duration=int(metadata["duration"]),
                start_gap=int(metadata["start_gap"]),
                fade_at=int(metadata["fade_at"]),
                silence_at=int(metadata["silence_at"]),
                bitrate=int(metadata["bitrate"]),
            )

            track_id = track.id
            session.commit()
        except Exception:
            raise ApplicationError("Can't create Track")

    new_track = track_by_id(track_id)
    if not new_track:
        raise ApplicationError("Unable to create new track")

    return new_track


def get_all_tracks() -> list[TrackDTO]:
    """Return a list of all tracks"""

    return _tracks_where(Tracks.id > 0)


def track_by_id(track_id: int) -> TrackDTO | None:
    """
    Return track with specified id
    """

    # Alias PlaydatesTable for subquery
    LatestPlaydate = aliased(Playdates)

    # Subquery: latest playdate for each track
    latest_playdate_subq = (
        select(
            LatestPlaydate.track_id,
            func.max(LatestPlaydate.lastplayed).label("lastplayed"),
        )
        .group_by(LatestPlaydate.track_id)
        .subquery()
    )

    stmt = (
        select(
            Tracks.id.label("track_id"),
            Tracks.artist,
            Tracks.bitrate,
            Tracks.duration,
            Tracks.fade_at,
            Tracks.intro,
            Tracks.path,
            Tracks.silence_at,
            Tracks.start_gap,
            Tracks.title,
            latest_playdate_subq.c.lastplayed,
        )
        .outerjoin(latest_playdate_subq, Tracks.id == latest_playdate_subq.c.track_id)
        .where(Tracks.id == track_id)
    )

    with db.Session() as session:
        record = session.execute(stmt).one_or_none()
        if not record:
            return None

        dto = TrackDTO(
            artist=record.artist,
            bitrate=record.bitrate,
            duration=record.duration,
            fade_at=record.fade_at,
            intro=record.intro,
            lastplayed=record.lastplayed,
            path=record.path,
            silence_at=record.silence_at,
            start_gap=record.start_gap,
            title=record.title,
            track_id=record.track_id,
        )

    return dto


def _tracks_where(where: BinaryExpression | ColumnElement[bool]) -> list[TrackDTO]:
    """
    Return tracks selected by where
    """

    # Alias PlaydatesTable for subquery
    LatestPlaydate = aliased(Playdates)

    # Subquery: latest playdate for each track
    latest_playdate_subq = (
        select(
            LatestPlaydate.track_id,
            func.max(LatestPlaydate.lastplayed).label("lastplayed"),
        )
        .group_by(LatestPlaydate.track_id)
        .subquery()
    )

    stmt = (
        select(
            Tracks.id.label("track_id"),
            Tracks.artist,
            Tracks.bitrate,
            Tracks.duration,
            Tracks.fade_at,
            Tracks.intro,
            Tracks.path,
            Tracks.silence_at,
            Tracks.start_gap,
            Tracks.title,
            latest_playdate_subq.c.lastplayed,
        )
        .outerjoin(latest_playdate_subq, Tracks.id == latest_playdate_subq.c.track_id)
        .where(where)
    )

    results: list[TrackDTO] = []

    with db.Session() as session:
        records = session.execute(stmt).all()
        for record in records:
            dto = TrackDTO(
                artist=record.artist,
                bitrate=record.bitrate,
                duration=record.duration,
                fade_at=record.fade_at,
                intro=record.intro,
                lastplayed=record.lastplayed,
                path=record.path,
                silence_at=record.silence_at,
                start_gap=record.start_gap,
                title=record.title,
                track_id=record.track_id,
            )
            results.append(dto)

    return results


def tracks_like_artist(filter_str: str) -> list[TrackDTO]:
    """
    Return tracks where artist is like filter
    """

    return _tracks_where(Tracks.artist.ilike(f"%{filter_str}%"))


def tracks_like_title(filter_str: str) -> list[TrackDTO]:
    """
    Return tracks where title is like filter
    """

    return _tracks_where(Tracks.title.ilike(f"%{filter_str}%"))


# Playlist functions
def _move_rows(
    session: Session, playlist_id: int, starting_row: int, move_by: int
) -> None:
    """
    Move rows from starting_row by move_by. If move_by is +ve, move rows
    down; if -ve, move them up.
    """

    log.debug(f"(_move_rows_down({playlist_id=}, {starting_row=}, {move_by=}")

    session.execute(
        update(PlaylistRows)
        .where(
            (PlaylistRows.playlist_id == playlist_id),
            (PlaylistRows.row_number >= starting_row),
        )
        .values(row_number=PlaylistRows.row_number + move_by)
    )
    session.commit()


def move_rows_to_playlist(
    from_rows: list[int], from_playlist_id: int, to_row: int, to_playlist_id: int
) -> None:
    """
    Move rows between playlists.
    """

    with db.Session() as session:
        # Prepare desination playlist
        # Find last used row
        last_row = session.execute(
            select(func.max(PlaylistRows.row_number)).where(
                PlaylistRows.playlist_id == to_playlist_id
            )
        ).scalar_one()
        if last_row is None:
            last_row = -1
        # Make room in destination
        if to_row <= last_row:
            _move_rows(session, to_playlist_id, to_row, len(from_rows))
        # Move rows
        row_offset = to_row - min(from_rows)
        stmt = (
            update(PlaylistRows)
            .where(
                PlaylistRows.playlist_id == from_playlist_id,
                PlaylistRows.row_number.in_(from_rows)
            )
            .values(
                playlist_id=to_playlist_id,
                row_number=PlaylistRows.row_number + row_offset
            )
        )
        session.execute(stmt)
        # Remove gaps in source
        _move_rows(session=session,
                   playlist_id=from_playlist_id,
                   starting_row=max(from_rows) + 1,
                   move_by=(len(from_rows) * -1)
                   )
        # Commit changes
        session.commit()
        # Sanity check
    _check_playlist_integrity(session, get_playlist_rows(from_playlist_id), fix=False)
    _check_playlist_integrity(session, get_playlist_rows(to_playlist_id), fix=False)


def move_rows_within_playlist(playlist_id: int, from_rows: list[int], to_row: int) -> None:
    """
    Move rows within a playlist.
    """

    log.debug(f"move_rows_within_playlist({playlist_id=}, {from_rows=}, {to_row=})")

    playlistrows_dto = get_playlist_rows(playlist_id)
    new_order: dict[int, int | None] = dict.fromkeys(range(len(playlistrows_dto)))

    # Populate new_order with moved rows
    next_row = to_row
    # We need to keep, where possible, the rows after to_row unmoved
    if to_row + len(from_rows) > len(playlistrows_dto):
        next_row = max(to_row - len(from_rows) + 1, 0)
    for from_row in from_rows:
        new_order[next_row] = from_row
        next_row += 1

    # Move remaining rows
    remaining_rows = set(new_order.keys()) - set(from_rows)
    next_row = 0
    for row in remaining_rows:
        while new_order[next_row] is not None:
            next_row += 1
        new_order[next_row] = row
        next_row += 1

    # Sanity check
    if None in new_order:
        raise ApplicationError(f"None remains after move: {new_order=}")

    # Update database
    # Build a list of dicts of (id: value, row_number: value}
    update_list = []
    for new_row_number, old_row_number in new_order.items():
        plrid = [a.playlistrow_id for a in playlistrows_dto if a.row_number == old_row_number][0]
        update_list.append(dict(id=plrid, row_number=new_row_number))

    # Update rows
    with db.Session() as session:
        session.execute(update(PlaylistRows), update_list)
        session.commit()

        # Sanity check
        _check_playlist_integrity(session, get_playlist_rows(playlist_id), fix=False)


def create_playlist(name: str, template_id: int) -> PlaylistDTO:
    """
    Create playlist and return DTO.
    """

    with db.Session() as session:
        try:
            playlist = Playlists(session, name, template_id)
            playlist_id = playlist.id
            session.commit()
        except Exception:
            raise ApplicationError("Can't create Playlist")

    new_playlist = playlist_by_id(playlist_id)
    if not new_playlist:
        raise ApplicationError("Can't retrieve new Playlist")

    return new_playlist


def get_playlist_row(playlistrow_id: int) -> PlaylistRowDTO | None:
    """
    Return specific row DTO
    """

    # Alias PlaydatesTable for subquery
    LatestPlaydate = aliased(Playdates)

    # Subquery: latest playdate for each track
    latest_playdate_subq = (
        select(
            LatestPlaydate.track_id,
            func.max(LatestPlaydate.lastplayed).label("lastplayed"),
        )
        .group_by(LatestPlaydate.track_id)
        .subquery()
    )

    stmt = (
        select(
            PlaylistRows.id.label("playlistrow_id"),
            PlaylistRows.row_number,
            PlaylistRows.note,
            PlaylistRows.played,
            PlaylistRows.playlist_id,
            Tracks.id.label("track_id"),
            Tracks.artist,
            Tracks.bitrate,
            Tracks.duration,
            Tracks.fade_at,
            Tracks.intro,
            Tracks.path,
            Tracks.silence_at,
            Tracks.start_gap,
            Tracks.title,
            latest_playdate_subq.c.lastplayed,
        )
        .outerjoin(Tracks, PlaylistRows.track_id == Tracks.id)
        .outerjoin(latest_playdate_subq, Tracks.id == latest_playdate_subq.c.track_id)
        .where(PlaylistRows.id == playlistrow_id)
        .order_by(PlaylistRows.row_number)
    )

    with db.Session() as session:
        record = session.execute(stmt).one_or_none()
        if not record:
            return None

        # Handle cases where track_id is None (no track associated)
        if record.track_id is None:
            dto = PlaylistRowDTO(
                artist="",
                bitrate=0,
                duration=0,
                fade_at=0,
                intro=None,
                lastplayed=None,
                note=record.note,
                path="",
                played=record.played,
                playlist_id=record.playlist_id,
                playlistrow_id=record.playlistrow_id,
                row_number=record.row_number,
                silence_at=0,
                start_gap=0,
                title="",
                track_id=-1,
            )
        else:
            dto = PlaylistRowDTO(
                artist=record.artist,
                bitrate=record.bitrate,
                duration=record.duration,
                fade_at=record.fade_at,
                intro=record.intro,
                lastplayed=record.lastplayed,
                note=record.note,
                path=record.path,
                played=record.played,
                playlist_id=record.playlist_id,
                playlistrow_id=record.playlistrow_id,
                row_number=record.row_number,
                silence_at=record.silence_at,
                start_gap=record.start_gap,
                title=record.title,
                track_id=record.track_id,
            )

    return dto


def _check_playlist_integrity(
    session: Session, playlist_rows: list[PlaylistRowDTO], fix: bool = False
) -> None:
    """
    Ensure the row numbers are contiguous. Fix and log if fix==True,
    else raise ApplicationError.
    """

    for idx, plr in enumerate(playlist_rows):
        if plr.row_number == idx:
            continue

        msg = f"_check_playlist_integrity: incorrect row number ({plr.playlistrow_id=}, {idx=})"
        if fix:
            log.debug(msg)
            plr.row_number = idx
            session.commit()
        else:
            raise ApplicationError(msg)


def get_playlist_rows(playlist_id: int) -> list[PlaylistRowDTO]:
    # Alias PlaydatesTable for subquery
    LatestPlaydate = aliased(Playdates)

    # Subquery: latest playdate for each track
    latest_playdate_subq = (
        select(
            LatestPlaydate.track_id,
            func.max(LatestPlaydate.lastplayed).label("lastplayed"),
        )
        .group_by(LatestPlaydate.track_id)
        .subquery()
    )

    stmt = (
        select(
            PlaylistRows.id.label("playlistrow_id"),
            PlaylistRows.row_number,
            PlaylistRows.note,
            PlaylistRows.played,
            PlaylistRows.playlist_id,
            Tracks.id.label("track_id"),
            Tracks.artist,
            Tracks.bitrate,
            Tracks.duration,
            Tracks.fade_at,
            Tracks.intro,
            Tracks.path,
            Tracks.silence_at,
            Tracks.start_gap,
            Tracks.title,
            latest_playdate_subq.c.lastplayed,
        )
        .outerjoin(Tracks, PlaylistRows.track_id == Tracks.id)
        .outerjoin(latest_playdate_subq, Tracks.id == latest_playdate_subq.c.track_id)
        .where(PlaylistRows.playlist_id == playlist_id)
        .order_by(PlaylistRows.row_number)
    )

    with db.Session() as session:
        results = session.execute(stmt).all()
        # Sanity check
        # TODO: would be good to be confident at removing this
        _check_playlist_integrity(session=session, playlist_rows=results, fix=False)

        dto_list = []
        for row in results:
            # Handle cases where track_id is None (no track associated)
            if row.track_id is None:
                dto = PlaylistRowDTO(
                    artist="",
                    bitrate=0,
                    duration=0,
                    fade_at=0,
                    intro=None,
                    lastplayed=None,
                    note=row.note,
                    path="",
                    played=row.played,
                    playlist_id=row.playlist_id,
                    playlistrow_id=row.playlistrow_id,
                    row_number=row.row_number,
                    silence_at=0,
                    start_gap=0,
                    title="",
                    track_id=-1,
                    # Additional fields like row_fg, row_bg, etc., use default None values
                )
            else:
                dto = PlaylistRowDTO(
                    artist=row.artist,
                    bitrate=row.bitrate,
                    duration=row.duration,
                    fade_at=row.fade_at,
                    intro=row.intro,
                    lastplayed=row.lastplayed,
                    note=row.note,
                    path=row.path,
                    played=row.played,
                    playlist_id=row.playlist_id,
                    playlistrow_id=row.playlistrow_id,
                    row_number=row.row_number,
                    silence_at=row.silence_at,
                    start_gap=row.start_gap,
                    title=row.title,
                    track_id=row.track_id,
                    # Additional fields like row_fg, row_bg, etc., use default None values
                )
            dto_list.append(dto)

    return dto_list


def insert_row(
    playlist_id: int, row_number: int, track_id: int | None, note: str
) -> PlaylistRowDTO:
    """
    Insert a new row into playlist and return new row DTO
    """

    with db.Session() as session:
        # Sanity check
        _check_playlist_integrity(session, get_playlist_rows(playlist_id), fix=False)

        # Make space for new row
        _move_rows(
            session=session, playlist_id=playlist_id, starting_row=row_number, move_by=1
        )

        playlist_row = PlaylistRows.insert_row(
            session=session,
            playlist_id=playlist_id,
            new_row_number=row_number,
            note=note,
            track_id=track_id,
        )
        session.commit()
        playlist_row_id = playlist_row.id

        # Sanity check
        _check_playlist_integrity(session, get_playlist_rows(playlist_id), fix=False)

    new_playlist_row = get_playlist_row(playlistrow_id=playlist_row_id)
    if not new_playlist_row:
        raise ApplicationError("Can't retrieve new playlist row")

    return new_playlist_row


def remove_rows(playlist_id: int, row_numbers: list[int]) -> None:
    """
    Remove rows from playlist

    Delete from highest row back so that not yet deleted row numbers don't change.
    """

    log.debug(f"remove_rows({playlist_id=}, {row_numbers=}")

    with db.Session() as session:
        for row_number in sorted(row_numbers, reverse=True):
            session.execute(
                delete(PlaylistRows).where(
                    PlaylistRows.playlist_id == playlist_id,
                    PlaylistRows.row_number == row_number,
                )
            )
        # Fixup row number to remove gaps
        _check_playlist_integrity(session, playlist_id, fix=True)

        session.commit()


def playlist_by_id(playlist_id: int) -> PlaylistDTO | None:
    """
    Return playlist with specified id
    """

    stmt = select(
        Playlists.id.label("playlist_id"),
        Playlists.name,
        Playlists.favourite,
        Playlists.is_template,
        Playlists.open,
    ).where(Playlists.id == playlist_id)

    with db.Session() as session:
        record = session.execute(stmt).one_or_none()
        if not record:
            return None

        dto = PlaylistDTO(
            name=record.name,
            playlist_id=record.playlist_id,
            favourite=record.favourite,
            is_template=record.is_template,
            open=record.open,
        )

    return dto


# Misc
def get_setting(name: str) -> int | None:
    """
    Get int setting
    """

    with db.Session() as session:
        record = session.execute(
            select(Settings).where(Settings.name == name)
        ).one_or_none()
        if not record:
            return None

    return record.f_int


def set_setting(name: str, value: int) -> None:
    """
    Add int setting
    """

    with db.Session() as session:
        record = session.execute(
            select(Settings).where(Settings.name == name)
        ).one_or_none()
        if not record:
            record = Settings(session=session, name=name)
            if not record:
                raise ApplicationError("Can't create Settings record")
        record.f_int = value
        session.commit()