import { Schema, model, models, Model } from "mongoose";

export interface IStockLock {
  _id: string; // `${businessId}:${branchId}:${productId}`
  owner: string; // random id of the request holding the lock
  lockedUntil: Date; // lease expiry: a crashed request cannot hold the lock forever
}

/**
 * A short lease on one product's stock at one branch, held while a request
 * reads the current balance and writes a movement that depends on it (see
 * withStockLock in src/lib/server/stock.ts). Rows are deleted on release;
 * an expired row is simply taken over by the next request.
 */
const stockLockSchema = new Schema<IStockLock>(
  {
    _id: { type: String, required: true },
    owner: { type: String, required: true },
    lockedUntil: { type: Date, required: true },
  },
  { versionKey: false }
);

export const StockLock =
  (models.StockLock as Model<IStockLock>) || model<IStockLock>("StockLock", stockLockSchema);