"""Shared database access for Thinker and Expert nodes."""

import logging

log = logging.getLogger("runtime")

DB_HOST = "mariadb-eras"
DB_USER = "root"
DB_PASS = "root"
ALLOWED_DATABASES = ("eras2_production", "plankiste_test")


def run_db_query(query: str, database: str = "eras2_production",
                 host: str = DB_HOST, user: str = DB_USER, password: str = DB_PASS) -> str:
    """Execute a read-only SQL query against MariaDB. Returns tab-separated results."""
    import pymysql
    trimmed = query.strip().upper()
    if not (trimmed.startswith("SELECT") or trimmed.startswith("DESCRIBE") or trimmed.startswith("SHOW")):
        return "Error: Only SELECT/DESCRIBE/SHOW queries allowed"
    if database not in ALLOWED_DATABASES:
        return f"Error: Unknown database '{database}'"
    conn = pymysql.connect(host=host, user=user, password=password,
                           database=database, connect_timeout=5, read_timeout=15)
    try:
        with conn.cursor() as cur:
            cur.execute(query)
            rows = cur.fetchall()
            if not rows:
                return "(no results)"
            cols = [d[0] for d in cur.description]
            lines = ["\t".join(cols)]
            for row in rows:
                lines.append("\t".join(str(v) if v is not None else "" for v in row))
            return "\n".join(lines)
    finally:
        conn.close()