// HardLinkShlExt.cpp : Implementation of CHardLinkShlExt

#include "stdafx.h"
#include "resource.h"
#include "HardLink.h"
#include "HardLinkShlExt.h"

/////////////////////////////////////////////////////////////////////////////
// CHardLinkShlExt IShellExtInit methods

STDMETHODIMP CHardLinkShlExt::Initialize (
    LPCITEMIDLIST pidlFolder, LPDATAOBJECT pDO, HKEY hProgID )
{
    AFX_MANAGE_STATE(AfxGetStaticModuleState());

COleDataObject dataobj;
HGLOBAL        hglobal;
HDROP          hdrop;
TCHAR          szRoot[MAX_PATH];
TCHAR          szFileSystemName[256];
TCHAR          szFile[MAX_PATH];
UINT           uFile, uNumFiles;

    m_bitmap.LoadBitmap ( IDB_LINKBITMAP );

    dataobj.Attach ( pDO, FALSE );      // FALSE = don't release IDataObject interface when destroyed

    // Get the name of the directory where the files were dropped.
    if ( !SHGetPathFromIDList ( pidlFolder, m_szFolderDroppedIn ) )
        return E_FAIL;

    // Get the root of the target folder, and see if it's on an NTFS volume.
    lstrcpy ( szRoot, m_szFolderDroppedIn );
    PathStripToRoot ( szRoot );

    if ( !GetVolumeInformation ( szRoot, NULL, 0, NULL, NULL, NULL, 
                                 szFileSystemName, 256 ) )
        {
        // Couldn't determine file system type.
        return E_FAIL;
        }

#ifndef NOT_ON_WIN2K
    if ( 0 != lstrcmpi ( szFileSystemName, _T("ntfs") ))
        {
        // The file system isn't NTFS, so it doesn't support hard links.
        return E_FAIL;
        }
#endif

    // Make sure the target dir ends in a backslash, to make later processing easier.
    PathAddBackslash ( m_szFolderDroppedIn );

    // Get a list of all the objects that were dropped.
    hglobal = dataobj.GetGlobalData ( CF_HDROP );

    if ( NULL == hglobal )
        return E_INVALIDARG;

    hdrop = (HDROP) GlobalLock ( hglobal );

    if ( NULL == hdrop )
        {
        GlobalFree ( hglobal );
        return E_INVALIDARG;
        }

    // Determine how many files were dropped.
    uNumFiles = DragQueryFile ( hdrop, 0xFFFFFFFF, NULL, 0 );

    // Check each dropped item.  If there are any directories present,
    // we have to bail out, since a directory can't be linked to.
    // We also have to check that the dropped items reside on the same
    // volume as the directory where they were dropped - hard links can only
    // be made on the same volume.
    for ( uFile = 0; uFile < uNumFiles; uFile++ )
        {
        if ( DragQueryFile ( hdrop, uFile, szFile, MAX_PATH ) )
            {
            if ( PathIsDirectory ( szFile ))
                {
                // We found a directory!  Bail out.
                m_lsDroppedFiles.RemoveAll();
                break;
                }

            if ( !PathIsSameRoot ( szFile, m_szFolderDroppedIn ) )
                {
                // Dropped files came from a different volume - bail out.
                m_lsDroppedFiles.RemoveAll();
                break;
                }

            // Add the file to our list of dropped files.
            m_lsDroppedFiles.AddTail ( szFile );
            }
        }   // end for

    GlobalUnlock ( hglobal );
    GlobalFree ( hglobal );

    return ( m_lsDroppedFiles.GetCount() > 0 ) ? S_OK : E_FAIL;
}


/////////////////////////////////////////////////////////////////////////////
// CHardLinkShlExt IContextMenu methods

STDMETHODIMP CHardLinkShlExt::QueryContextMenu (
    HMENU hmenu, UINT uMenuIndex, UINT uidFirstCmd,
    UINT uidLastCmd, UINT uFlags )
{
    AFX_MANAGE_STATE(AfxGetStaticModuleState());

    // If the flags include CMF_DEFAULTONLY then we shouldn't do anything.
    if ( uFlags & CMF_DEFAULTONLY )
        return MAKE_HRESULT ( SEVERITY_SUCCESS, FACILITY_NULL, 0 );

    // Add the hard link menu item.
    InsertMenu ( hmenu, uMenuIndex, MF_STRING | MF_BYPOSITION, uidFirstCmd,
                 _T("Create &Hard Link(s) Here") );

    if ( NULL != m_bitmap.GetSafeHandle() )
        SetMenuItemBitmaps ( hmenu, uMenuIndex, MF_BYPOSITION, m_bitmap, NULL );

    // Return 1 to tell the shell that we added 1 top-level menu item.
    return MAKE_HRESULT ( SEVERITY_SUCCESS, FACILITY_NULL, 1 );
}

STDMETHODIMP CHardLinkShlExt::InvokeCommand ( LPCMINVOKECOMMANDINFO pInfo )
{
    AFX_MANAGE_STATE(AfxGetStaticModuleState());

TCHAR    szNewFilename[MAX_PATH+32];   // +32 in case a path overruns MAX_PATH (we'll handle this case and error out)
CString  sSrcFile;
TCHAR    szSrcFileTitle[MAX_PATH];
CString  sMessage;
UINT     uLinkNum;
POSITION pos;

    // Double-check that we're getting called for our own menu item - lpVerb
    // must be 0.
    if ( 0 != pInfo->lpVerb )
        return E_INVALIDARG;

    // Start enumerating the files we're going to make links for.
    pos = m_lsDroppedFiles.GetHeadPosition();

    // Sanity check - the list must not be empty.
    ASSERT ( NULL != pos );

    while ( NULL != pos )
        {
        // Get the next source filename.
        sSrcFile = m_lsDroppedFiles.GetNext ( pos );

        // Remove the path - this reduces "C:\xyz\foo\stuff.exe" to "stuff.exe"
        lstrcpy ( szSrcFileTitle, sSrcFile );
        PathStripPath ( szSrcFileTitle );

        // Make the filename for the hard link - we'll first try 
        // "Hard link to stuff.exe"
        wsprintf ( szNewFilename, _T("%sHard link to %s"), m_szFolderDroppedIn,
                   szSrcFileTitle );

        // Check if that filename already exists.  If so, we'll try
        // "Hard link (2) to stuff.exe", incrementing the number up to an
        // arbitrary limit of 99.
        for ( uLinkNum = 2;
              PathFileExists ( szNewFilename ) && uLinkNum < 100; 
              uLinkNum++ )
            {
            // Try another filename for the link.
            wsprintf ( szNewFilename, _T("%sHard link (%u) to %s"),
                       m_szFolderDroppedIn, uLinkNum, szSrcFileTitle );

            // If the resulting filename is longer than MAX_PATH, show an 
            // error message.
            if ( lstrlen ( szNewFilename ) >= MAX_PATH )
                {
                sMessage.Format ( _T("Failed to make a link to %s. The resulting filename would be too long.\n\nDo you want to continue making links?"),
                                  (LPCTSTR) sSrcFile );

                if ( IDNO == MessageBox ( pInfo->hwnd, sMessage, _T("Create Hard Links"),
                                          MB_ICONQUESTION | MB_YESNO ) )
                    break;
                else
                    continue;
                }
            }

        // If we hit our limit of 100 links, tell the user what's up.
        if ( 100 == uLinkNum )
            {
            sMessage.Format ( _T("Failed to make a link to %s. Reached limit of 100 links in a single directory.\n\nDo you want to continue making links?"),
                              (LPCTSTR) sSrcFile );

            if ( IDNO == MessageBox ( pInfo->hwnd, sMessage, _T("Create Hard Links"),
                                      MB_ICONQUESTION | MB_YESNO ) )
                break;
            else
                continue;
            }

        // Make the link!
#ifdef NOT_ON_WIN2K
        MessageBox(pInfo->hwnd, szNewFilename, "The new link would be:", MB_OK);
#else
        if ( !CreateHardLink ( szNewFilename, sSrcFile, NULL ) )
            {
            LPVOID pvMsgBuf = NULL;
            DWORD  dwLastErr = GetLastError();
            int    nChoice;

            FormatMessage ( FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | 
                              FORMAT_MESSAGE_IGNORE_INSERTS,
                            NULL, dwLastErr,
                            MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
                            (LPTSTR) &pvMsgBuf, 0, NULL );

            sMessage.Format ( _T("Failed to make a link to %s.\n\nError 0x%08lX - %s\nDo you want to continue making links?"),
                              (LPCTSTR) sSrcFile, dwLastErr,
                              pvMsgBuf ? pvMsgBuf : _T("(No description available)") );

            nChoice = MessageBox ( pInfo->hwnd, sMessage, _T("Create Hard Links"),
                                   MB_ICONQUESTION | MB_YESNO );

            if ( NULL != pvMsgBuf )
                LocalFree ( pvMsgBuf );

            if ( IDNO == nChoice )
                break;
            }
#endif
        }   // end while

    return S_OK;
}