// Iterators.h
//
// Copyright (c) 2003, Ingo Weinhold (bonefish@cs.tu-berlin.de)
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
// 
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
// You can alternatively use *this file* under the terms of the the MIT
// license included in this package.

#ifndef ITERATORS_H
#define ITERATORS_H

#include <SupportDefs.h>

#include "DirItem.h"

class Block;
class InternalNode;
class VKey;
class LeafNode;
class Node;
class Tree;

// TreePath
class TreePath {
public:
        class Element;

public:
        TreePath(uint32 maxLength);
        ~TreePath();

        status_t InitCheck() const;

        uint32 GetMaxLength() const;
        uint32 GetLength() const;
        const Element *ElementAt(int32 index) const;
        const Element *GetTopElement() const;

        status_t PushElement(uint64 blockNumber, int32 index);
        status_t PopElement();

private:
        uint32  fMaxLength;
        uint32  fLength;
        Element *fElements;
};

// TreePath::Element
class TreePath::Element {
public:
        Element() {}
        ~Element() {}

        status_t SetTo(uint64 blockNumber, int32 index);

        uint64 GetBlockNumber() const;
        int32 GetIndex() const;

private:
        uint64  fBlockNumber;
        uint32  fIndex;
};


// TreeIterator
class TreeIterator {
public:
        TreeIterator(Tree *tree);
        ~TreeIterator();

        status_t SetTo(Tree *tree);
        void Unset();
        status_t InitCheck() const;

        Tree *GetTree() const { return fTree; }

        Node *GetNode() const;
        int32 GetLevel() const;

        status_t GoTo(uint32 direction);

        status_t GoToPreviousLeaf(LeafNode **node = NULL);
        status_t GoToNextLeaf(LeafNode **node = NULL);
        status_t FindRightMostLeaf(const VKey *k, LeafNode **node = NULL);

        status_t Suspend();
        status_t Resume();

public:
        enum {
                FORWARD,
                BACKWARDS,
                UP,
                DOWN,
        };

private:
        status_t _PushCurrentNode(Node *newTopNode = NULL, int32 newIndex = 0);
        status_t _PopTopNode();
        status_t _SearchRightMost(InternalNode *node, const VKey *k, int32 *index);

private:
        Tree            *fTree;
        Node            *fCurrentNode;
        int32           fIndex;
        TreePath        *fPath;
};

// ItemIterator
class ItemIterator {
public:
        ItemIterator(Tree *tree);

        status_t SetTo(Tree *tree);
        status_t InitCheck() const;

        Tree *GetTree() const { return fTreeIterator.GetTree(); }

        status_t GetCurrent(Item *item);
        status_t GoToPrevious(Item *item = NULL);
        status_t GoToNext(Item *item = NULL);
        status_t FindRightMostClose(const VKey *k, Item *item = NULL);
        status_t FindRightMost(const VKey *k, Item *item = NULL);

        status_t Suspend();
        status_t Resume();

private:
        status_t _GetLeafNode(LeafNode **node) const;
        status_t _SearchRightMost(LeafNode *node, const VKey *k,
                                                          int32 *index) const;

private:
        TreeIterator    fTreeIterator;
        int32                   fIndex;
};

// ObjectItemIterator
class ObjectItemIterator {
public:
        ObjectItemIterator(Tree *tree, uint32 dirID, uint32 objectID,
                                           uint64 startOffset = 0);

        status_t SetTo(Tree *tree, uint32 dirID, uint32 objectID,
                                   uint64 startOffset = 0);
        status_t InitCheck() const;

        Tree *GetTree() const { return fItemIterator.GetTree(); }
        uint32 GetDirID() const { return fDirID; }
        uint32 GetObjectID() const { return fObjectID; }
        uint64 GetOffset() const { return fOffset; }

        status_t GetNext(Item *foundItem);
        status_t GetNext(Item *foundItem, uint32 type);
        status_t GetPrevious(Item *foundItem);
        status_t GetPrevious(Item *foundItem, uint32 type);

        status_t Suspend();
        status_t Resume();

private:
        ItemIterator    fItemIterator;
        uint32                  fDirID;
        uint32                  fObjectID;
        uint64                  fOffset;
        bool                    fFindFirst;
        bool                    fDone;
};

// DirEntryIterator
class DirEntryIterator {
public:
        DirEntryIterator(Tree *tree, uint32 dirID, uint32 objectID,
                                         uint64 startOffset = 0, bool fixedHash = false);

        status_t SetTo(Tree *tree, uint32 dirID, uint32 objectID,
                                   uint64 startOffset = 0, bool fixedHash = false);
        status_t InitCheck() const;

        status_t Rewind();

        Tree *GetTree() const { return fItemIterator.GetTree(); }
        uint32 GetDirID() const { return fItemIterator.GetDirID(); }
        uint32 GetObjectID() const { return fItemIterator.GetObjectID(); }
        uint64 GetOffset() const { return fItemIterator.GetOffset(); }

        status_t GetNext(DirItem *foundItem, int32 *entryIndex,
                                         DirEntry **entry = NULL);
        status_t GetPrevious(DirItem *foundItem, int32 *entryIndex,
                                                 DirEntry **entry = NULL);

        status_t Suspend();
        status_t Resume();

private:
        ObjectItemIterator      fItemIterator;
        DirItem                         fDirItem;
        int32                           fIndex;
        bool                            fFixedHash;
        bool                            fDone;
};

// StreamReader
class StreamReader {
public:
        StreamReader(Tree *tree, uint32 dirID, uint32 objectID);

        status_t SetTo(Tree *tree, uint32 dirID, uint32 objectID);
        status_t InitCheck() const;

        Tree *GetTree() const { return fItemIterator.GetTree(); }
        uint32 GetDirID() const { return fItemIterator.GetDirID(); }
        uint32 GetObjectID() const { return fItemIterator.GetObjectID(); }
        uint64 GetOffset() const { return fItemIterator.GetOffset(); }

        off_t StreamSize() const { return fStreamSize; }

        status_t ReadAt(off_t position, void *buffer, size_t bufferSize,
                                        size_t *bytesRead);

        status_t Suspend();
        status_t Resume();

private:
        status_t _GetStreamSize();
        status_t _SeekTo(off_t position);
        status_t _ReadIndirectItem(off_t offset, void *buffer, size_t bufferSize);
        status_t _ReadDirectItem(off_t offset, void *buffer, size_t bufferSize);

private:
        ObjectItemIterator      fItemIterator;
        Item                            fItem;
        off_t                           fStreamSize;
        off_t                           fItemOffset;
        off_t                           fItemSize;
        uint32                          fBlockSize;
};

#endif  // ITERATORS_H