package DataStructures.HashMap.Hashing;

public class HashMap {
    private int hsize;
    private LinkedList[] buckets;

    public HashMap(int hsize) {
        buckets = new LinkedList[hsize];
        for (int i = 0; i < hsize; i++) {
            buckets[i] = new LinkedList();
            // Java requires explicit initialisaton of each object
        }
        this.hsize = hsize;
    }

    public int hashing(int key) {
        int hash = key % hsize;
        if (hash < 0)
            hash += hsize;
        return hash;
    }

    public void insertHash(int key) {
        int hash = hashing(key);
        buckets[hash].insert(key);
    }


    public void deleteHash(int key) {
        int hash = hashing(key);

        buckets[hash].delete(key);
    }

    public void displayHashtable() {
        for (int i = 0; i < hsize; i++) {
            System.out.printf("Bucket %d :", i);
            System.out.println(buckets[i].display());
        }
    }
    
    public static class LinkedList {
    	private Node first;
    	
    	public LinkedList() {
    		first = null;
    	}
    	
    	public void insert(int key){
    		if(isEmpty()) {
    			first = new Node(key);
    			return;
    		}
    		
    		Node temp = findEnd(first);
    		temp.setNext(new Node(key));
    	}
    	
    	private Node findEnd(Node n) {
    		if(n.getNext() == null) {
    			return n;
    		} else {
    			return findEnd(n.getNext());
    		}
    	}
    	
    	public Node findKey(int key) {
    		if(!isEmpty()) {
    			return findKey(first, key);
    		} else {
    			System.out.println("List is empty");
    			return null;
    		}
    		
    	}
    	
    	private Node findKey(Node n, int key) {
    		if(n.getKey() == key) {
    			return n;
    		} else if(n.getNext() == null) {
    			System.out.println("Key not found");
    			return null;
    		} else {
    			return findKey(n.getNext(),key);
    		}
    	}
    	
    	public void delete(int key) {
    		if(!isEmpty()) {
    			if(first.getKey() == key) {
    				first = null;
    			} else {
    				delete(first,key);
    			}
    		} else {
    			System.out.println("List is empty");
    		}
    	}
    	
    	private void delete(Node n, int key) {
    		if(n.getNext().getKey() == key) {
    			if(n.getNext().getNext() == null) {
    				n.setNext(null);
    			} else {
    				n.setNext(n.getNext().getNext());
    			}
    		}
    	}
    	
    	public String display() {
    		return display(first);
    	}
    	
    	private String display(Node n) {
    		if(n == null) {
    			return "null";
    		} else {
    			return n.getKey() + "->" + display(n.getNext());
    		}
    	}
    	
    	public boolean isEmpty() {
    		return first == null;
    	}
    }
    
    public static class Node {
    	private Node next;
    	private int key;
    	
    	public Node(int key) {
    		next = null;
    		this.key = key;
    	}
    	
    	public Node getNext() {
    		return next;
    	}
    	
    	public int getKey() {
    		return key;
    	}
    	
    	public void setNext(Node next) {
    		this.next = next;
    	}
    }
}