import * as plugins from './levelcache.plugins.js';
import { LevelCache } from './levelcache.classes.levelcache.js';
import { AbstractCache } from './levelcache.abstract.classes.cache.js';
import { CacheEntry } from './levelcache.classes.cacheentry.js';

export class CacheRouter {
  public levelCacheRef: LevelCache;
  public cacheKeyMap = new plugins.lik.FastMap<AbstractCache>();

  constructor(levelCacheRef: LevelCache) {
    this.levelCacheRef = levelCacheRef;
  }

  /**
   * gets the relevant cache to perform a store action on
   */
  async getCacheForStoreAction(keyArg: string, cacheEntry: CacheEntry): Promise<AbstractCache> {
    let returnCache: AbstractCache;
    const mbToBytesMultiplier = 1000 * 1000;
    const maxMemoryBytes = this.levelCacheRef.options.maxMemoryStorageInMB * mbToBytesMultiplier;
    const maxDiskBytes = this.levelCacheRef.options.maxDiskStorageInMB * mbToBytesMultiplier;
    const maxS3Bytes = this.levelCacheRef.options.maxS3StorageInMB * mbToBytesMultiplier;

    switch (true) {
      case cacheEntry.contents.byteLength <= maxMemoryBytes &&
        this.levelCacheRef.cacheMemoryManager.status === 'active':
        returnCache = this.levelCacheRef.cacheMemoryManager;
        break;
      case this.levelCacheRef.cacheDiskManager.status === 'active' &&
        cacheEntry.contents.byteLength > maxMemoryBytes &&
        cacheEntry.contents.byteLength <= maxDiskBytes &&
        this.levelCacheRef.cacheDiskManager.status === 'active':
        returnCache = this.levelCacheRef.cacheDiskManager;
        break;
      case cacheEntry.contents.byteLength > maxDiskBytes &&
        cacheEntry.contents.byteLength < maxS3Bytes &&
        this.levelCacheRef.cacheS3Manager.status === 'active':
        returnCache = this.levelCacheRef.cacheS3Manager;
        break;
      default:
        returnCache = null;
    }
    this.cacheKeyMap.addToMap(keyArg, returnCache);
    return returnCache;
  }

  /**
   * gets the relevant cache to perform a retrieval action on
   */
  async getCacheForRetrieveAction(keyArg: string): Promise<AbstractCache> {
    const done = plugins.smartpromise.defer<AbstractCache>();
    const returnCache = this.cacheKeyMap.getByKey(keyArg);
    if (!returnCache && this.levelCacheRef.options.persistentCache) {
      const checkCache = (cacheArg: AbstractCache) => {
        const resultPromise = cacheArg.checkKeyPresence(keyArg);
        resultPromise.then((hasKeyArg) => {
          if (hasKeyArg) {
            done.resolve(cacheArg);
          }
        });
        return resultPromise;
      };
      Promise.all([
        checkCache(this.levelCacheRef.cacheMemoryManager),
        checkCache(this.levelCacheRef.cacheDiskManager),
        checkCache(this.levelCacheRef.cacheMemoryManager),
      ]).then(() => {
        done.resolve(returnCache);
      });
    } else {
      done.resolve(returnCache);
    }
    return done.promise;
  }
}