import { eq } from "drizzle-orm";
import type { Db, Queryable } from "../db/client";
import { companies } from "../db/schema";

/**
 * Runs `fn` in a transaction holding a row lock on the player's company, so
 * changes to one player's money and fleet never interleave (Step 6.14).
 */
export function withPlayerLock<T>(
  db: Db,
  playerId: string,
  fn: (tx: Queryable) => Promise<T>,
): Promise<T> {
  return db.transaction(async (tx) => {
    await tx
      .select({ id: companies.id })
      .from(companies)
      .where(eq(companies.playerId, playerId))
      .for("update");
    return fn(tx);
  });
}