// deck.gl-community
// SPDX-License-Identifier: MIT
// Copyright (c) vis.gl contributors

export class Cache<K, V> {
  private readonly _keys = new Map<K, {value: V; version: number}>();

  /**
   * @param key The key of the cache
   * @returns {*} The value of the cache as set by the `set` method.
   */
  get(key: K): V | undefined {
    return this._keys.get(key)?.value;
  }

  /**
   * @param key The key of the cache
   * @param createValue A callback to create the value of the cache if it is needed.
   * @param version The version of the cache. If the version is smaller than the current version, the cache will not be updated.
   */
  set(key: K, createValue: (...args: unknown[]) => V, version: number): void {
    const cached = this._keys.get(key);

    const keyUpdated = cached === undefined || version > cached.version;
    if (!keyUpdated) {
      return;
    }

    this._keys.set(key, {version, value: createValue()});
  }
}