import structure.*;

public class InfiniteQuestions
{
    public static void play(ReadStream human, BinaryTree database)
    // pre: database is non-null
    // post: the game is finished, and if we lost, we expanded the database
    {
	if (!database.left().isEmpty())
	{ // further choices; must ask a question to distinguish them
	    System.out.println(database.value());
	    if (human.readLine().equals("yes"))
	    {
		play(human,database.left());
	    } else {
		play(human,database.right());
	    }
	} else { // must be a statement node
	    System.out.println("Is it "+database.value()+"?");
	    if (human.readLine().equals("yes"))
	    {
		System.out.println("I guessed it!");
	    } else {
		System.out.println("Darn.  What were you thinking of?");
		// learn!
		BinaryTree newObject = new BinaryTree(human.readLine());
		BinaryTree oldObject = new BinaryTree(database.value());
		database.setLeft(newObject);
		database.setRight(oldObject);
		System.out.println("What question would distinguish "+
				   newObject.value()+" from "+
				   oldObject.value()+"?");
		database.setValue(human.readLine());
	    }
	}
    }

    public static void main(String args[])
    {
	ReadStream human = new ReadStream();
	// construct a simple database -- knows only about a computer
	BinaryTree database = new BinaryTree("a computer");

	System.out.println("Do you want to play a game?");
	while (human.readLine().equals("yes"))
	{
	    System.out.println("Think of something...I'll guess it");
	    play(human,database);
	    System.out.println("Do you want to play again?");
	}
	System.out.println("Have a good day!");
    }
}

/*
Do you want to play a game?
yes
Think of something...I'll guess it
Is it a computer?
no
Darn.  What were you thinking of?
a car
What question would distinguish a car from a computer?
Does it have a horn?
Do you want to play again?
yes
Think of something...I'll guess it
Does it have a horn?
yes
Is it a car?
no
Darn.  What were you thinking of?
a unicorn
What question would distinguish a unicorn from a car?
Is it magical?
Do you want to play again?
yes
Think of something...I'll guess it
Does it have a horn?
yes
Is it magical?
no
Is it a car?
yes
I guessed it!
Do you want to play again?
no
Have a good day!
*/