class LRUCache {
  constructor() {
    this.max = 1000;
    this.map = new Map();
  }

  get(key) {
    const value = this.map.get(key);
    if (value === undefined) {
      return undefined;
    } else {
      // Remove the key from the map and add it to the end
      this.map.delete(key);
      this.map.set(key, value);
      return value;
    }
  }

  delete(key) {
    return this.map.delete(key);
  }

  set(key, value) {
    const deleted = this.delete(key);

    if (!deleted && value !== undefined) {
      // If cache is full, delete the least recently used item
      if (this.map.size >= this.max) {
        const firstKey = this.map.keys().next().value;
        this.delete(firstKey);
      }

      this.map.set(key, value);
    }

    return this;
  }
}

module.exports = LRUCache;