import * as plugins from './plugins.js';
import { SmartdataCollection } from './classes.collection.js';
import { SmartdataDb } from './classes.db.js';

/**
 * Per-SmartdataDb collection cache.
 *
 * Historically this class keyed its cache by class name alone, which meant
 * the first SmartdataDb to request a collection of a given class name
 * "won" — every subsequent call from a different SmartdataDb instance
 * received the cached collection bound to the first db. That silently
 * broke multi-tenant SaaS apps (one db per tenant), tests instantiating
 * multiple SmartdataDbs in sequence, and any in-process db cluster switch.
 *
 * The cache is now keyed by `(SmartdataDb instance, className)` using a
 * WeakMap of db → Map<className, SmartdataCollection>. Entries are GC'd
 * with their parent db automatically.
 */
export class CollectionFactory {
  private perDbCollections: WeakMap<SmartdataDb, Map<string, SmartdataCollection<any>>> = new WeakMap();

  public getCollection = (nameArg: string, dbArg: SmartdataDb): SmartdataCollection<any> => {
    if (!(dbArg instanceof SmartdataDb)) {
      // Preserve the historical behavior of returning undefined-ish for
      // non-db args. All in-repo callers already guard on instanceof
      // before using the result (see classes.collection.ts).
      return undefined as unknown as SmartdataCollection<any>;
    }
    let dbMap = this.perDbCollections.get(dbArg);
    if (!dbMap) {
      dbMap = new Map();
      this.perDbCollections.set(dbArg, dbMap);
    }
    let coll = dbMap.get(nameArg);
    if (!coll) {
      coll = new SmartdataCollection(nameArg, dbArg);
      dbMap.set(nameArg, coll);
    }
    return coll;
  };

  /**
   * @deprecated Internal back-compat shim. The previous field was a public
   * Record<className, SmartdataCollection> but was not part of the
   * documented public API. WeakMap is not iterable, so this getter returns
   * an empty object — anyone actually relying on the old shape would get
   * clean nothing rather than wrong-db data. Will be removed in 8.0.
   */
  public get collections(): { [key: string]: SmartdataCollection<any> } {
    return {};
  }
}