/**implements Map using a hashtable
 */
import java.util.Set;

import maps.Map.Entry;


public class HashTableMap<K extends Hashable<K>,V> implements Map<K,V> {
	private NodeSet<HashEntry<K,V>>[] a;
	private int capacity;
	private int size;
	
	
	
	
	public class HashEntry<K extends Hashable<K>,V> implements Entry<K,V>{
		/**Compares the specified object with this entry for equality*/
		K key;
		V value;
		
		/**default Constructor*/
		public HashEntry(){
			key=null;
			value=null;
		}
		
		/**Constructor*/
		public HashEntry(K k, V v){
			key=k;
			value=v;
		}
		
		/**make two entries  if they contain the same key and value*/
		public boolean equals(Object o){
			if(o==null)return false;
			else {
				if(getClass()!=o.getClass()) return false;
			    else return ((((Entry) o).getKey().equals(key))&&(((Entry) o).getValue().equals(key)));
			}
				
		}
		
		/**Returns the key corresponding to 
		 * this entry*/
		public K getKey(){return key;}
		
		/**Returns the value corresponding to this entry*/
		public V getValue(){return value;}
		
		/**Returns the hash code value for this map entry
		 * note hash code and hash function are compined
		 */
		public int hashCode(){
			return key.hashCode(capacity);
		}
		
		/**Replaces the value corresponding to this entry with the specified value*/
		public V setValue(V v){
			V oldVal=value;
			value=v;
			return oldVal;
		}
		
		/**Returns string representation of entry*/
		public String toString(){
			return "[" + key + "," + value + "]";
		}
		
		
	}
	
	
	
	/**Creates a new hash table with given size
	 * empty set at each index*/
	public HashTableMap(int n){
		capacity=n;
		size=0;
		a= (NodeSet<HashEntry<K,V>>[]) new  NodeSet[capacity]; //compiler may warn, but ok
		for(int i=0;i<capacity;i++){
			a[i]=new NodeSet<HashEntry<K,V>>();
		}
	}
	

	/**return the number of entries in the map*/
	public int size(){return size;}
	
	/**returns true if this map contains no key-value mappings*/
	public boolean isEmpty(){return size==0;} 
	
	/** Returns the value to which the specific key is mapped, or null  */
	public V get(K key){
		HashEntry<K,V> entry=new HashEntry<K,V>(key,null);
		int position=entry.hashCode();
		V newVal=null;
		for(HashEntry<K,V> entry2:a[position])
			if(entry2.getKey().equals(entry.getKey())) newVal=entry2.getValue();
		return newVal;
		
		}
		
	
	/** associates the specific value with the specified key in this map, return old value 
	 * or null if already an entry 
	 * with this key*/
	public V put(K key, V value){
		HashEntry<K,V> entry=new HashEntry<K,V>(key,value);
		int position=entry.hashCode();
		System.out.println("want to place entry at position " + position);
		V newVal=null;
		if(a[position].isEmpty()) {a[position].add(entry);size++;}
		else{
			for(HashEntry<K,V> entry2:a[position]){
			   if(entry2.getKey().equals(entry.getKey())) {
				   newVal=entry2.getValue();entry2.setValue(value);System.out.println("clash!");}
			}
		    if(newVal==null) {a[position].add(entry);size++;}
		}
		return newVal;
	}
	
	/**Removes the mapping for a key from this map if present*/
	public V remove(K key){
		HashEntry<K,V> entry=new HashEntry<K,V>(key,null);
		int position=entry.hashCode();
		HashEntry<K,V> entry3=null;
		V newVal=null;
		for(HashEntry<K,V> entry2:a[position])
			if(entry2.getKey().equals(entry.getKey())) {entry3=entry2;newVal=entry2.getValue();}
		if(entry3!=null) {a[position].remove(entry3);size--;}
	    return newVal;
	}
	
	/**return a set containing all the keys stored in map*/
	public Set<K> keys(){
		Set<K> mySet=(Set<K>) new NodeSet<K>();
		for(int i=0;i<capacity;i++)
			for(HashEntry<K,V> entry2:a[i]) mySet.add(entry2.getKey());
		return mySet;
	}
	
	/**return a set containing all the values associated with the values stored*/
	public Set<V> values(){
		Set<V> mySet=(Set<V>) new NodeSet<V>();
		for(int i=0;i<capacity;i++)
			for(HashEntry<K,V> entry2:a[i]) mySet.add(entry2.getValue());
		return mySet;
	}
	
	/**return a set containing all the key-value entries*/
	public Set<Map.Entry<K,V>> entries(){
		Set<Entry<K, V>> mySet = (Set<Entry<K, V>>) new NodeSet<Entry<K,V>>();
		for(int i=0;i<capacity;i++)
			for(HashEntry<K,V> entry2:a[i]) mySet.add(entry2);
		return mySet;
		
	
	}
	
	/** Return string representing the entries contained in the map*/
	public String toString(){
		Set<Entry<K,V>> mySet = (Set<Entry<K, V>>) this.entries();
		String s="";
		for(Entry<K,V> entry: mySet) s=s+entry+ ",";
		return s;
	}
	
	
    /**Return string representing the entries of map with one row per index 
     * of array - for debugging
     */
	public String outputString(){
		String s="";
		for(int i=0;i<capacity;i++){
		 for(HashEntry<K,V> entry2:a[i]) s=s+entry2+",";
		 s=s+"\n";
		}
		return s;
	}
}