// Copyright (C) 2010  Internet Systems Consortium, Inc. ("ISC")
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
// PERFORMANCE OF THIS SOFTWARE.


#ifndef _RBTREE_H
#define _RBTREE_H 1

#include <dns/name.h>
#include <dns/rrset.h>
#include <dns/rrsetlist.h>
#include <boost/shared_ptr.hpp>
#include <boost/utility.hpp>

using namespace isc::dns;
namespace isc {
namespace datasrc {

/// \brief rbtree color define
enum RBTreeColor {BLACK = 1, RED};
class RBTree;

/// \brief \c RBNode class represent one domain name in the domain space

/// It has two roles, the first one is as one node in the \c RBTree the second one
/// is store the data related to DNS. As for the first role, it has left, right, parent and color memebers
/// which used to keey the balance of the \c RBTree. As for the second role, 
//  it stores the rrsets belongs to the domain name and a rbtree which includes all the subdomains of this node
/// the name stored in the node is relative related to its parent node. 
/// One special kind of node is non-terminal node
/// which has subdomains with rrset but it self doesn't has any rrset
///
/// \b Note: \c RBNode should create or destroied only by \c RBTree so constructor and destructor function aren't exposed


class RBNode : public boost::noncopyable{
    public:
        /// only /c RBTree can create and destroy \c RBNode
        friend class RBTree;
        typedef boost::shared_ptr<RRsetList> RRsetListPtr;

        /// \name Test functions
        ///
        //@{
        /// \brief return whether current domain name has ns records
        bool isDelegate() const { return is_delegate_;}

        /// \brief return whether current domain name is non-terminal
        /// A non-terminal domain has no rrsets but at least one its descendant
        /// domain has rrset
        bool isNonterminal() const { return is_nonterminal_;}

        /// \brief return the name of current node, it's relative to its parents
        //
        /// \todo Is it meaningful to return the absolute of the node?
        const Name &getName() const {return name_;}

        // \brief return next node whose name is bigger than current node
        RBNode* successor();
        //@}


        /// \name modify function
        //@{

        /// \brief add the rrset to the node
        /// \Note: there is no check whether the node already has the rrset or not
        /// and no check about whether the name of the rrset is same with the node or not
        /// All of above is rely on interface user
        int addRRset(RRsetPtr rrset);
        //@}

    private:
        /// \name Constructors and destructor
        //@{
        /// \param nullnode The null point for \c RBNode isnot use \c NULL, but use one specified
        /// default node singled as null node, this is intended to keep the code more unify
        RBNode(const Name& name, RRsetListPtr rrsets = RRsetListPtr(), RBNode* nullnode = NULL);

        /// the class isn't left to be inherted
        ~RBNode(); 
        //@}
        

        /// \brief copy the DNS related date to another node except the sub domain tree
        void cloneDNSData(RBNode& node);
        /// \brief when copy the DNS data from one node to another, except the rrsets, name etc, 
        /// also needs to maintain the down and up relationship, which includes set the down point of current
        /// node and up point of sub domain tree 
        void setDownTree(RBTree* down);

        /// data to maintain the rbtree balance
        RBNode*  parent_;
        RBNode*  left_;
        RBNode*  right_;
        int       color_;

        /// data to carry dns info
        Name      name_;
        RRsetListPtr rrsets_;
        RBTree*  down_;
        bool      is_delegate_;
        bool      is_nonterminal_;
};

/// \brief \c RBTree class represent all the domains with same suffix, so it can be used to store
/// the domains in one zone
///
/// \c RBTree is a generic red black tree, and contains all the node with same suffix, since each
/// name may have sub domain names so \c RBTree is a recursive data struct or tree in tree
/// So for one zone, severl RBTrees are involved. But from outside, the sub tree is
/// opaque for end user. 
class RBTree : public boost::noncopyable{
    friend class RBNode;
    public:
        /// \brief The return value for find method
        ///    - EXACTMATCH: return the node in the tree exactly same with the target
        ///    - FINDREFERRAL: return the node which is the ancestor of the target containing ns record
        ///    - NOTFOUND: other conditions except EXACTMATCH & FINDREFERRAL
        enum FindResult{EXACTMATCH, FINDREFERRAL, NOTFOUND};

        /// \name Constructor and Destructor
        //@{
        RBTree();
        /// \b Note: RBTree is not intended to be inherited so the destructor isnot virtual
        ~RBTree();
        //@}

        /// \name Inquery methods
        //@{
        /// \brief find the node with the name 
        /// \param name Target to be found
        /// \param node Point to the node when the return vaule is \c not NOTFOUND, if
        /// if the return value is NOTFOUND, the value of node is \c unknown
        FindResult find(const Name& name, RBNode** node)const;

        /// \brief Get all the node count in the tree
        int getNodeCount() const;
        //@}

        /// \name Debug function
        //@{
        /// \brief print the node in the trees
        /// \todo is it better to return one string instead of print to the stdout?
        void printTree(int depth = 0)const;
        //@}

        /// \name Modify function
        //@{
        /// \brief insert the domain name into the tree
        /// \param name The name want to be inserted into the tree
        /// \param inserted_node If no node with the name in the tree, 
        /// new \c RBNode will be created, otherwise nothing will be done
        /// anyway the pointer point to the node with the name will be assign to inserted_node
        /// \return return 0 means no node exists in the tree with the name before insert
        /// return 1 means already has the node with the given name
        //
        /// If want to add rrset into one node, but not sure whether the node already exist
        /// Instead of call \c find, call \c insert and then call the RBNode interface to 
        /// add rrset into the node is a better way
        int insert(const Name& name, RBNode** inserted_node);

        /// \brief erase the node with the domain name
        /// \return If no node with the name, return one otherwise return zero
        int erase(const Name& name);
        //@}

    private:
        /// \name RBTree balance function
        //@{
        void deleteRebalance(RBNode* node);
        void insertRebalance(RBNode* node);
        RBNode* rightRotate(RBNode* p);
        RBNode* leftRotate(RBNode* p);
        //@}

        /// \name Helper function
        //@{
        /// All the public function has related recursive helper function
        void eraseNode(RBNode* node);
        FindResult findHelper(const Name& name, RBTree** tree, RBNode** node)const;
        int getNodeCountHelper(const RBNode* node) const;
        void printTreeHelper(RBNode* node, int depth)const;
        //@}


        RBNode*  root_;
        RBNode*  NULLNODE;
        RBNode*  up_;
        /// the node count of current tree except the sub domain trees
        unsigned int node_count_; 
};
}
}


#endif