class LinkedListNode {
    constructor(key, value) {
        this.key = key;
        this.value = value;
        this.next = null;
    };
};

class LinkedList {
    constructor() {
        this.map = new Map();
        this.head = null;
        this.tail = null;
    };

    getElement(id) {
        const element = this.map.get(id);
        if (!element) return;

        return element.value;
    }

    hasElement(id) {
        return this.map.has(id);
    }
  
    isEmpty() {
        return this.head === null;
    }
  
    addItem(key, value) {  
        const temp = new LinkedListNode(key, value);
  
        if (!this.head) {
            this.head = temp;
            this.tail = temp;
        } else {
            this.tail.next = temp;
            this.tail = temp;
        };
  
        this.map.set(key, temp);
    }
  
    each(cb) {
        if (this.isEmpty()) return;
    
        let current = this.head;
        while (current) {
            cb(current.key, current.value);
            
            current = current.next;
        };
    }

    clearEach(cb) {
        if (this.isEmpty()) return;
    
        let current = this.head;
        while (current) {
            cb(current.key, current.value);
            
            current = current.next;
        };

        this.head = null;
        this.tail = null;
      
        this.map.clear();
    }
};

module.exports = LinkedList;