/*
 * Copyright (c) 1987, 1988, 1989 Stanford University
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided
 * that the above copyright notice appear in all copies and that both that
 * copyright notice and this permission notice appear in supporting
 * documentation, and that the name of Stanford not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  Stanford makes no representations about
 * the suitability of this software for any purpose.  It is provided "as is"
 * without express or implied warranty.
 *
 * STANFORD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
 * IN NO EVENT SHALL STANFORD BE LIABLE FOR ANY SPECIAL, 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.
 */

/*
 * Interface to ObjectMan (object manager) class.
 */

#ifndef objectman_h
#define objectman_h

#include <InterViews/defs.h>
#include <InterViews/Graphic/persistent.h>

#define INVALIDOFFSET 1
#define NAMESIZE 100

typedef long ObjOffset;

extern char* OBJMAP_POSTFIX;
extern char* OBJSTORE_POSTFIX;

class Cache;
class PFile;
class Ref;
class RefList;

class ObjectMan : public Persistent {
public:
    ObjectMan();
    ObjectMan(
	char* filename, 
	void (*userInitializer)(RefList*) =nil,
	Persistent* (*userCreator)(ClassId) =nil
    );
    ~ObjectMan();

	/* 
	 * The parameter userInitializer must point to a function that creates
	 * primordial root objects needed by your application, and installs
	 * them in the passed RefList.  It will be called only when the
	 * application is run for the FIRST TIME.  Henceforth, such objects
	 * will be read from the persistent object store.
	 *
	 * The parameter userCreator must point to a function that can create
	 * an instance of ANY persistent object used in the application, given
	 * a ClassId.  Typically it will deal explicitly with Classes derived
	 * specifically for this application, and call library-defined
	 * functions for Classes taken from libraries.
	 */
    
    RefList* GetRoot();
    Persistent* Create(ClassId id);
    UID GetUID(Persistent*);
	/* returns a unique UID for the Persistent */
	/* looks in cache first, allocates new UID if not found */
	
    bool Invalidate(Persistent*);
	/* sets the objStore offset associated with the object in the */
	/* objMap to INVALIDOFFSET; useful when deallocating an object */
	/* once and for all */

    bool IsCached(Ref*);
	/* looks in the cache for the referenced object; returns false if */
	/* not found, true otherwise.  Puts the object into Ref as a side */
	/* effect */
    bool Find(Ref*);
	/* put Persistent * into Ref, maybe seeking for and reading */
	/* Persistent */
	/* from disk and return true if all went well */
    bool Retrieve(Ref*);
	/* reads Persistent blindly from disk (no seek) and return true */
	/* if all went well.  Assumes object referred to by *ref is */
	/* NOT in memory.  Used when reading clustered objects, */
	/* for which no offset exists in the objMap since clustered objects */
	/* are written consecutively */

    bool Store(Persistent*);	    /* find new (disk) space for Persistent */
    bool Update(Persistent*);    /* update objMap for Persistent */

    bool ObjectIsDirty(Persistent*);
    void ObjectTouch(Persistent*);
    void ObjectClean(Persistent*);

    virtual ClassId GetClassId();
    virtual bool IsA(ClassId);
protected:
    void (*userInitializer)(RefList*);
    Persistent* (*userCreator)(ClassId id);

    ObjOffset getOffset(UID);
    bool seek(UID uid);	/* moves to proper position in objStore */
    UID nextUID();

    virtual bool read(PFile*);
    virtual bool write(PFile*);
protected:
    UID lastuid;		/* last UID I allocated */
    ObjOffset lastuidOffset;	/* spot where lastuid is written in objStore */
    ObjOffset currentOffset;    /* offset of last Persistent calling Write */

    char filename [NAMESIZE];   /* we'll gag if names get too big */
    Cache* objCache;
    PFile* objMap, *objStore;

    RefList* root;
};

#endif