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

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;
    switch (true) {
      case cacheEntry.contents.byteLength <= 500:
        returnCache = this.levelCacheRef.cacheMemoryManager;
        break;
      case this.levelCacheRef.cacheDiskManager.status === 'active' &&
        cacheEntry.contents.byteLength >= 500 &&
        (cacheEntry.contents.byteLength < 10000 ||
          this.levelCacheRef.cacheS3Manager.status === 'inactive'):
        returnCache = this.levelCacheRef.cacheDiskManager;
        break;
      case cacheEntry.contents.byteLength >= 10000 &&
        this.levelCacheRef.cacheS3Manager.status === 'active':
        returnCache = this.levelCacheRef.cacheS3Manager;
        break;
      default:
        returnCache = this.levelCacheRef.cacheMemoryManager;
    }
    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;
  }
}