"""Shared SQLite schema inspection for text-evidence expansion."""

import sqlite3


def sqlite_table_exists(conn: sqlite3.Connection, table_name: str) -> bool:
    return (
        conn.execute(
            "SELECT 1 FROM sqlite_master " "WHERE type IN ('table', 'view') AND name = ? LIMIT 1",
            (table_name,),
        ).fetchone()
        is not None
    )


def sqlite_table_columns(conn: sqlite3.Connection, table_name: str) -> set[str]:
    if not sqlite_table_exists(conn, table_name):
        return set()
    rows = conn.execute(f"PRAGMA table_info({table_name})").fetchall()
    return {str(row[1]) for row in rows if len(row) > 1}