/**
 * Date: 		Feb 02, 06
 * Course: 		cs601
 * Class name: 	LinkedListDictionary.java
 * Purpose: 	implements the Dictionary interface
 */
package dict;

public class LinkedListDictionary implements Dictionary{
	
	public ListItem head;
	
	public LinkedListDictionary () {
		head = null;
	}
	
	public void map(String key, Object o) {
		
		if (key == "" || o == "") {
			System.out.println("Null cannot be added!!!");
			System.exit(0);
		}
		
		Object a = key+":"+o;
		
		ListItem l = new ListItem(a);
		//if the list is empty
		if (head==null)
		{
			head = l;
		}
		else  // add to end
		{
			ListItem walker = head;
			while (walker.next!= null)
			{
				walker=walker.next;
			}
			walker.next = l;
		}
	}
	 public Object unlink (String key) {
		 ListItem walker = head;
		 
		 String buffer = "";
		 String [] splits;
		 
		 String a = (String)walker.data;
		 splits = a.split(":");
		 
		 //if there's only one object in the list
		 if (splits[0].compareTo(key) == 0){
			 head = head.next;
			 return walker.data;
		 }
		 //to remove the second object
		 if (walker.next != null) {
			 String b = (String)walker.next.data;
			 String [] splitss = b.split(":");
			 
			 if (splitss[0].compareTo(key) == 0) {
				 Object rval = walker.next.data;
				 walker.next = walker.next.next;
				 return rval;
			 }
		 }
		 //loop through the rest of the list
		 while (walker.next.next!= null && !(splits[0].compareTo(key) == 0)) {
			 walker = walker.next;
			 
			 a = (String)walker.next.data;
			 splits = a.split(":");
		 } 
		 
		 if (splits[0].compareTo(key) == 0){
			 
			 Object rval = walker.next.data;
			 walker.next = walker.next.next;
			 return rval;
		 }
		 
		 if (buffer == "") {
			 return "null " + null;
		 }
		 else 
			 return "buffer " + buffer;
	 }
	 public Object find (String key) {
		 ListItem walker = head;
		 String buffer = "";
		 
		 while (walker!= null) {
			 String [] splits;
			 
			 String a = (String)walker.data;
			 splits = a.split(":");
			 
			 if (splits[0].compareTo(key) == 0){
				 buffer += walker.data + " ";
			 }
			 walker = walker.next;
		 }
		 if (buffer == "") {
			 return null;
		 }
		 else 
			 return buffer;
	 }
	 
	 public String toString () {
		ListItem walker = head;
		String buffer = "";
		
		buffer += "[";
		while (walker!= null){
			buffer += walker.data;
			if (walker.next != null)
				buffer += ",";
			walker=walker.next;
		}
		buffer += "]";	 
		 return buffer;
	 }
	 /*
	public static void main(String args[]){
		
		LinkedListDictionary list = new LinkedListDictionary();
		list.map("aaa","ABC");
		list.map("bbb","DEF");
		list.map("ccc","GHI");
		list.map("ddd","JKL");
		System.out.println("find " + list.find("w") );
		System.out.println("find " + list.find("aaa") );
		System.out.println("unlink " + list.unlink("ccs") );
		System.out.println(list);
	}*/
}