//  TPrefs.cp - Preference Object  

// 

// Apple Macintosh Developer Technical Support

// Written by:  Vinnie Moscaritolo

//

//  Copyright (work in progress)  Apple Computer, Inc All rights reserved.

//

// You may incorporate this sample code into your applications without

// restriction, though the sample code has been provided "AS IS" and the

// responsibility for its operation is 100% yours.  However, what you are

// not permitted to do is to redistribute the source as "DSC Sample Code"

// after having made changes. If you're going to re-distribute the source,

// we require that you make it clear in the source that the code was

// descended from Apple Sample Code, but that you've made changes.

// 

#include <PLStringFuncs.h>

#include <string.h>

#include <Files.h>

#include "TPrefs.h"

#include "TMacException.h"

// ---------------------------------------------------------------------------

    TPrefs::TPrefs() //   

// ---------------------------------------------------------------------------

//  

{

    fCollection = NewCollection();

    ThrowMacErrIfNil(fCollection, nilHandleErr);    

 }

// ---------------------------------------------------------------------------

    TPrefs::~TPrefs() //   

// ---------------------------------------------------------------------------

//  

{ 

    DisposeCollection (fCollection);

}

// ---------------------------------------------------------------------------

OSErr TPrefs::Set(  FourCharCode    tag, 

                    SInt32          id,

                    SInt32          itemSize,

                    void *          itemData)

// ---------------------------------------------------------------------------

//  

{ 

    return AddCollectionItem(fCollection, tag, id, itemSize, itemData);

}

// ---------------------------------------------------------------------------

OSErr TPrefs::Get(  FourCharCode    tag, 

                    SInt32          id,

                    SInt32*         itemSize,

                    void *          itemData)

// ---------------------------------------------------------------------------

//  

{ 

    return GetCollectionItem(fCollection, tag, id, itemSize, itemData);

}

// ---------------------------------------------------------------------------

OSErr TPrefs::Read() //   

// ---------------------------------------------------------------------------

//  

{ 

    FSSpec  fss;

    OSErr   err;

    err = this->GetPrefSpec(&fss);

    if(!err)

    {

        short   fileRefNum;

        Size    eof;

        SInt32  ByteCount;

        SInt32  size;

        FSpOpenDF (&fss,fsRdPerm,&fileRefNum);

        GetEOF (fileRefNum, &eof);

        size = sizeof (SInt32);

        err = FSRead (fileRefNum ,&size, &ByteCount);

        if(!err)

        {

            if(ByteCount + sizeof (SInt32) <= eof)  

            {

                Handle buffer = NewHandle (ByteCount);

                if (!buffer) err = MemError ( );

                HLockHi (buffer);

                size = ByteCount;

                err = FSRead (fileRefNum ,&size, *buffer);

                if(!err)

                {

                    err = UnflattenCollectionFromHdl ( fCollection, buffer);

                }

                HUnlock (buffer);

            }

            else 

                err = eofErr;

        }

        FSClose (fileRefNum);

    }

    return err;

}

// ---------------------------------------------------------------------------

OSErr TPrefs::CreatePrefFile(FSSpec *fss)   

// ---------------------------------------------------------------------------

//  

{ 

    return ( FSpCreate (fss, '????' ,kPrefsFileType,smSystemScript) );

}

// ---------------------------------------------------------------------------

OSErr TPrefs::GetPrefSpec(FSSpec *fss)   

// ---------------------------------------------------------------------------

//  

{ 

    FSSpec      prefsFSS;

// find the pref folder

    ThrowIfMacErr( FindFolder(kOnSystemDisk, kPreferencesFolderType, kCreateFolder, &prefsFSS.vRefNum, &prefsFSS.parID ));

    // make a file spec for the prefs file 

    FSMakeFSSpec(prefsFSS.vRefNum, prefsFSS.parID , "\ppref file", fss);

// needs to be written to general case.

    return (-1);

}

// ---------------------------------------------------------------------------

void TPrefs::Write() //   

// ---------------------------------------------------------------------------

//  

{ 

    FSSpec  fss;

    OSErr   err;

    short   fileRefNum;

    if(fCollection )

    {

        err = this->GetPrefSpec(&fss);

        if( err == fnfErr   )

        {

            err = this->CreatePrefFile(&fss);

        }

        if(!err)

        {

            Handle flattened = NewHandle(0);

            SInt32 size;

            SInt32 ByteCount;

            ThrowIfMacErr( FSpOpenDF (&fss,fsWrPerm,&fileRefNum));

            err = FlattenCollectionToHdl(fCollection, flattened);

            ByteCount = GetHandleSize(flattened);

            size = sizeof (SInt32);

            FSWrite (fileRefNum, &size ,&ByteCount);

            size = ByteCount;

            FSWrite (fileRefNum, &size ,*flattened);

            DisposeHandle(flattened);

            FSClose (fileRefNum);

            FlushVol (nil, fss.vRefNum);

        }

    }

}