import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Scanner;

/** An implementation of the AddressBook interface that uses
 *  an array list to store the data.
 */
public class ArrayListAddressBook implements AddressBook {
    private ArrayList<Item> items = new ArrayList<Item>();
    private String source;
    private boolean modified;

	public void load(String sourceName)
    {
		source = sourceName;
        try
        {
			Scanner in = new Scanner(new File(source));
            items = new ArrayList<Item>();
			while (in.hasNextLine())
				items.add(new Item(in.nextLine(), in.nextLine(), in.nextLine()));
        }
		catch (IOException ex)
		{
			ex.printStackTrace();
			source = null;
            items = new ArrayList<Item>();
		}
	}

	public String get(String name, String key)
	{
        for (Item it : items)
		{
			if (name.equals(it.getName()) && key.equals(it.getKey()))
				return it.getValue();
		}
		return null;
	}


	public String put(String name, String key, String value)
	{
		modified = true;
        for (Item it : items)
        {
			if (name.equals(it.getName()) && key.equals(it.getKey()))
			{
				String oldValue = it.getValue();
				it.setValue(value);
				return oldValue;
            }
		}
		items.add(new Item(name, key, value));
		return null;
	}

	public void save() 
	{
		if (!modified) return;
		try 
		{
			PrintWriter out = new PrintWriter(source);
			for (Item it : items)
			{
                out.println(it.getName());
                out.println(it.getKey());
                out.println(it.getValue());
			}
			out.close();
			modified = false;
		}
		catch (Exception ex) 
		{
		  ex.printStackTrace();
		}
	}
}