package Examples;

import java.util.logging.Logger;

import Sequenic.T3.SuiteUtils.Inference.Comment;

/**
 * A class implementing unbalanced binary search tree.  Note that all
 * "matching" is based on the compareTo method. 
 *
 * <p>Adapted from original code by Mark Weiss.
 *
 * <p>Is this class correct....?
 *
 * @author Mark Allen Weiss
 *
 */

// ******************PUBLIC OPERATIONS*********************
// void insert( x )   --> Insert x
// void remove( x )   --> Remove x
// Comparable find( x )   --> Return item that matches x
// Comparable findMin( )  --> Return smallest item
// Comparable findMax( )  --> Return largest item
// boolean isEmpty( ) --> Return true if empty; else false
// void makeEmpty( )  --> Remove all items
public class BinarySearchTree {
	
	private final static Comment comment = new Comment(Logger.getLogger(BinarySearchTree.class.getName())) ; 

    /**
     * Construct the tree.
     */
    public BinarySearchTree() {
        root = null;
    }

    /**
     * Insert x into the tree; duplicates are ignored.
     * @param x the item to insert.
     */
    public void insert(Comparable x) {
    	if (x==null) throw new IllegalArgumentException();
    	comment.with("inputs ok").end();
        root = insert(x, root);
    }

    /**
     * Remove from the tree. Nothing is done if x is not found.
     * @param x the item to remove.
     */
    public void remove(Comparable x) {
    	if (x==null) throw new IllegalArgumentException();
    	comment.with("inputs ok").end();
    	//System.out.println("**>> remove " + x) ;
        root = remove(x, root);
    }


    /**
     * Find the smallest item in the tree.
     * @return smallest item or null if empty.
     */
    public Comparable findMin() {
        return elementAt(findMin(root));
    }


    /**
     * Find the largest item in the tree.
     * @return the largest item of null if empty.
     */
    public Comparable findMax() {
        return elementAt(findMax(root));
    }

    
    /**
     * Find an item in the tree.
     * @param x the item to search for.
     * @return the matching item or null if not found.
     */
    public Comparable find(Comparable x) {
    	if (x==null) throw new IllegalArgumentException();
    	comment.with("inputs ok").end();
        return elementAt(find(x, root));
    }

    /**
     * Make the tree logically empty.
     */
    public void makeEmpty() {
        root = null;
    }

    
    /**
     * Test if the tree is logically empty.
     * @return true if empty, false otherwise.
     */
    public boolean isEmpty() {
        return root == null;
    }


    /**
     * Internal method to get element field.
     * @param t the node.
     * @return the element field or null if t is null.
     */
    private Comparable elementAt(BinaryNode t) {
    	comment.with("dead end").If(t==null) ;
        return t == null ? null : t.element;
    }

    /**
     * Internal method to insert into a subtree.
     * @param x the item to insert.
     * @param t the node that roots the tree.
     * @return the new root.
     */
    private BinaryNode insert(Comparable x, BinaryNode t) {
        /* 1*/ if (t == null) /* 2*/ {
            t = new BinaryNode(x, null, null);
        /* 3*/ } else if (x.compareTo(t.element) < 0) /* 4*/ {
            t.left = insert(x, t.left);
        /* 5*/ } else if (x.compareTo(t.element) > 0) /* 6*/ {
            t.right = insert(x, t.right);
        /* 7*/ } else { comment.with("Duplicate; do nothing").end() ; /* 8*/ }
		/* 9*/ return t;
    }


    /**
     * Internal method to remove from a subtree.
     * @param x the item to remove.
     * @param t the node that roots the tree.
     * @return the new root.
     */
    private BinaryNode remove(Comparable x, BinaryNode t) {
        if (t == null) {
        	comment.with("Item not found; do nothing").end() ;
            return t;   

        }
        if (x.compareTo(t.element) < 0) {
            t.left = remove(x, t.left);
        } else if (x.compareTo(t.element) > 0) {
            t.right = remove(x, t.right);
        } else if (t.left != null 
        		&& t.right != null) // Two children
        {
        	comment.with("Two children").end() ;
            t.element = findMin(t.right).element;
            t.right = remove(t.element, t.right);
        } else {
        	comment.with("Has only one child").end() ;
        	comment.with("No right child").If(t.left != null) ;
            t = (t.left != null) 
            		? t.left 
            		: t.right;
        }
        return t;
    }

    /**
     * Internal method to find the smallest item in a subtree.
     * @param t the node that roots the tree.
     * @return node containing the smallest item.
     */
    private BinaryNode findMin(BinaryNode t) {
        if (t == null) {
        	comment.with("No minimum").end() ;
            return null;
        } else if (t.left == null) {
            return t;
        }
        return findMin(t.left);
    }

    /**
     * Internal method to find the largest item in a subtree.
     * @param t the node that roots the tree.
     * @return node containing the largest item.
     */
    private BinaryNode findMax(BinaryNode t) {
        if (t != null) {
            while (t.right != null) {
                t = t.right;
            }
        }
        comment.with("No maximum").If(t == null) ;
        return t;
    }

    /**
     * Internal method to find an item in a subtree.
     * @param x is item to search for.
     * @param t the node that roots the tree.
     * @return node containing the matched item.
     */
    private BinaryNode find(Comparable x, BinaryNode t) {
        if (t == null) {
            return null;
        }
        if (x.compareTo(t.element) < 0) {
            return find(x, t.left);
        } else if (x.compareTo(t.element) > 0) {
            return find(x, t.right);
        } else {
            return t;// Match
        }
    }

    /** The tree root. */
    private BinaryNode root;
    
    
}