/*
 * Help Access Library 
 * A Library to access the contents of Windows Help files.
 *
 * Copyright (C) 1995-2000 Bernd Herd, http://www.herdsoft.com
 *                                                                  
 * 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.              
 *                                                                  
 * 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., 675 Mass Ave, Cambridge, MA 02139, USA.        
 */
/* ENUMCON.C ------------------------------------------
 * @doc
 * @module ENUMCON.C |
 * Code to enumerate all Context.Strings in a Help-File
 *
 * Help Access Library Project.
 *
 *-----------------------------------------------------*/

#include <windows.h>
#include <windowsx.h>
#include <time.h>
#include <stdio.h>
#include <string.h>
#include "hlpacces.h"


BOOL LOCAL nEnumerateContext(NPIFSFILE ifsfile, CONTEXTENUMPROC fnContextEnumProc, LPARAM lParam);
BOOL LOCAL nEnumeratePage(NPIFSFILE ifsfile, int PageCount, int CurrentLevel, int PageSize, int CurrPage, CONTEXTENUMPROC fnContextEnumProc, LPARAM lParam);

/* @func BOOL | HlpEnumContext |
 *
 * Enumerates all the Context-Id-Hash-Values defined in a Help-File
 * By reading thru all of the CONTEXT internal File.
 *
 * @rdesc TRUE if enumeration has been performed successfully.
 */
BOOL FAR PASCAL DLLEXP HlpEnumContext(
                HIFS ifs,                        // @parm Handle to a opened File-System opened by <f IFSOpen>
                CONTEXTENUMPROC fnContextEnumProc, // @parm <t CONTEXTENUMPROC> Application-Defined Callback-Procedure to be called for every context-Id found in the help file
                LPARAM lParam)                   // @parm Aplication-defined parameter to be transfered to the Callback-function
{ BOOL      Success=FALSE;
  NPIFSFILE ifsfile = IFSOpenFile(ifs, "|CONTEXT");
  if (ifsfile)
  {
    Success = nEnumerateContext(ifsfile, fnContextEnumProc, lParam);

    IFSCloseFile(ifsfile);
  }
  return Success;
}


/* nEnumerateContext
 *
 * Does the buch of Work to do enumeration
 */
BOOL LOCAL nEnumerateContext(NPIFSFILE ifsfile, CONTEXTENUMPROC fnContextEnumProc, LPARAM lParam)
{ BOOL            Success;

  BTREEHEADER     BTreeHdr;
  DWORD           dwSize;
  UINT            PageCount;


  //--------- Read Title B-Tree header ------------------
  IFSReadFile(ifsfile, &BTreeHdr, sizeof(BTreeHdr));
  dwSize = IFSSeekFile(ifsfile, 0L, 2);

  PageCount = (UINT) (dwSize/leword(BTreeHdr.PageSize));

//  printf("# PageCount:%u NLevels: %u NSplits: %u PageSize: %u Total Entries:%ld\n\n", PageCount, BTreeHdr.NLevels, BTreeHdr.NSplits, BTreeHdr.PageSize, BTreeHdr.TotalBtreeEntries);

  Success = nEnumeratePage(ifsfile, PageCount, leword(BTreeHdr.NLevels)-1, leword(BTreeHdr.PageSize), leword(BTreeHdr.RootPage), fnContextEnumProc, lParam);

  return Success;
}

#pragma pack(1)
typedef struct
        { LEWORD  PageNo;
          LEDWORD HashValue;
        } PACKED BTREEINDEXENTRY;
#pragma pack()


BOOL LOCAL nEnumeratePage(NPIFSFILE ifsfile, int PageCount, int CurrentLevel, int PageSize, int CurrPage, CONTEXTENUMPROC fnContextEnumProc, LPARAM lParam)
{ BOOL                  Success    = FALSE;
  DWORD                 loc        = sizeof(BTREEHEADER) + PageSize * (DWORD) CurrPage;
  NPSTR                 page       = (NPSTR) LocalAlloc(LPTR, PageSize);
  LEDWORD FAR *         next;
  BTREENODEHEADER       NodeHeader;
  BTREEINDEXENTRY NEAR *CurrIndexEntry;
  int                   i;

  if (page)
  {
     //----------- Read Page ----------------------------------------
     IFSSeekFile(ifsfile, loc, 0);
     if (PageSize == IFSReadFile(ifsfile, page, PageSize))
     { memcpy(&NodeHeader, page, sizeof(NodeHeader));

       //--------- Are we in a Node or in a leaf? -------------------
       if (CurrentLevel > 0)
       {
         //-- We're in a node, search for next sub-node or leaf --
         for (i=0                  , Success = TRUE, CurrIndexEntry = (BTREEINDEXENTRY NEAR *) (page+sizeof(BTREEINDEXHEADER));
              i<leword(NodeHeader.NEntries)+1 && Success;
              ++i                  ,++CurrIndexEntry)
            //------- We're currently in a node, so recurse down... ----
            Success &= nEnumeratePage(ifsfile, PageCount, CurrentLevel-1, PageSize, leword(CurrIndexEntry->PageNo), fnContextEnumProc, lParam);
       }

       else

       //--------- Enumerate Page contents --------------------------
       for (Success=TRUE, next=(LEDWORD FAR *)(page+sizeof(BTREENODEHEADER)), i=0;
            Success                                        &&i<leword(NodeHeader.NEntries);
                          next+=2                          , i++)
         Success=fnContextEnumProc(ledword(next[0]), ledword(next[1]), lParam);
     }

     //----------- Free Page data except Header ---------------------
     LocalFree((HLOCAL) page);
  }

  return Success;
}