package basic.datastructure.map;

import basic.datastructure.list.ArrayList;

public class HashMap<K,V> extends AbstractMap<K,V> {

int size = 0;

private ArrayList<Node> hashMap;

private final int DEFAULT_SIZE = 16;

private final double LOAD_FACTOR = 0.75;

public HashMap(){

this.hashMap = new ArrayList<>(DEFAULT_SIZE);

for(int i = 0 ; i < hashMap.getCapacity(); i++){

hashMap.add(new Node(null,null));

}

}

@Override

public void put(K key, V value) {

checkNullKey(key);

int hash = hash(key);

Node node = hashMap.get(hash);

while(node.next!=null){

node = node.getNext();

if(node.getKey().equals(key)){

node.setValue(value);

return;

}

}

node.setNext(new Node(key,value));

size++;

}

@Override

public boolean containsKey(K key) {

checkNullKey(key);

int hash = hash(key);

Node node = hashMap.get(hash).getNext();

while(node != null){

if(node.getKey().equals(key)){

return true;

}

node = node.getNext();

}

return false;

}

@Override

public V get(K key) {

checkNullKey(key);

int hash = hash(key);

Node node = hashMap.get(hash).getNext();

while(node!=null){

if(node.getKey().equals(key)){

return node.getValue();

}

node = node.getNext();

}

return null;

}

@Override

public V remove(K key) {

checkNullKey(key);

int hash = hash(key);

Node pre = hashMap.get(hash);

Node node = pre.next;

while(node != null){

if(node.key.equals(key)){

pre.setNext(node.getNext());

size--;

return node.value;

}

pre = node;

node = node.getNext();

}

return null;

}

@Override

public void clear() {

hashMap = new ArrayList<>(DEFAULT_SIZE);

for(int i = 0 ; i < hashMap.getCapacity();i++){

hashMap.add(new Node(null,null));

}

size = 0;

}

@Override

public int size() {

return this.size;

}

@Override

public boolean isEmpty() {

return size==0;

}

private int hash(K key){

return Math.abs(key.hashCode()) % hashMap.getCapacity();

}

private class Node implements Map.Entry<K,V>{

private K key;

private V value;

private Node next;

Node(K key, V value){

this.key = key;

this.value = value;

this.next = null;

}

public Node getNext() { return this.next;}

public void setNext(Node next) { this.next = next;}

@Override

public K getKey() {

return this.key;

}

@Override

public V getValue() {

return this.value;

}

@Override

public V setValue(V value) {

this.value = value;

return this.value;

}

}

}