/**
 * *****************************************************************************
 *  AVLTree.h: a simple implementation of the AVL Tree
 *  Author:      Hung Q. Ngo
 * *****************************************************************************
 */
#ifndef AVLTREE_H_
#define AVLTREE_H_

#include <iostream>
#include <sstream>

template <typename Key, typename Value>
class AVLTree {
public:
    AVLTree() : root(NULL) { }

    void  inorder_print()  { inorder_print(root); std::cout << std::endl; }
    void  preorder_print() { preorder_print(root); std::cout << std::endl; }
    void  postorder_print() { postorder_print(root); std::cout << std::endl; }

    bool  insert(Key, Value);
    bool  remove(Key);
    bool  find(Key key) { return search(root, key) != NULL; }
    const Value& get(Key);
    const Value& minimum();
    const Value& maximum();
    void  clear() { clear(root); }


private:
    // The node is similar to a BSTNode; use parent pointer to simplify codes
    // A tree is simply a pointer to a BSTNode, we will assume that variables of
    // type Key are comparable using <, <=, ==, >=, and >
    // we do not allow default keys and values
    struct AVLNode {
        enum { LEFT_HEAVY = 1, BALANCED = 0, RIGHT_HEAVY = -1};
        int balance;
        Key key;
        Value value;
        AVLNode* left;
        AVLNode* right;
        AVLNode* parent;

        AVLNode(const Key& k, const Value& v)
        : key(k), value(v), parent(NULL), left(NULL), right(NULL),
          balance(BALANCED) {}

        std::string to_string() const {
            std::ostringstream oss;
            oss << key << "(" << balance << ")";
            return oss.str();
        }
    };

    AVLNode* root;
    AVLNode* successor(AVLNode* node);
    AVLNode* predecessor(AVLNode* node);
    AVLNode* search(AVLNode*, Key);

    void rebalance(AVLNode*);
    void right_rotate(AVLNode*&);
    void left_rotate(AVLNode*&);

    void inorder_print(AVLNode*);
    void preorder_print(AVLNode*);
    void postorder_print(AVLNode*);

    void clear(AVLNode*&);
};

#include "AVLTree.cpp" // only done for template classes

#endif