from collections.abc import Iterator
from typing import Optional

from folkugat_web.dal.sql import Connection, get_connection
from folkugat_web.model import playlists as model

from ._conversion import row_to_playlist_entry


def _filter_clause(
    entry_id: Optional[int] = None,
    set_id: Optional[int] = None,
    session_id: Optional[int] = None,
) -> tuple[str, dict]:
    filter_clauses = []
    query_data = {}

    if entry_id is not None:
        filter_clauses.append("id = :id")
        query_data["id"] = entry_id
    if set_id is not None:
        filter_clauses.append("set_id = :set_id")
        query_data["set_id"] = set_id
    if session_id is not None:
        filter_clauses.append("session_id = :session_id")
        query_data["session_id"] = session_id

    return " AND ".join(filter_clauses), query_data


def get_playlist_entries(
    entry_id: Optional[int] = None,
    set_id: Optional[int] = None,
    session_id: Optional[int] = None,
    con: Optional[Connection] = None,
) -> Iterator[model.PlaylistEntry]:
    filter_clause, data = _filter_clause(entry_id=entry_id, set_id=set_id, session_id=session_id)
    query = f"""
      SELECT
        id, session_id, set_id, tema_id
      FROM playlists
      WHERE {filter_clause}
    """
    with get_connection(con) as con:
        cur = con.cursor()
        cur.execute(query, data)
        return map(row_to_playlist_entry, cur.fetchall())