VB and crystal reports

Hi,

I'm very very new to VB and need someone to please explain this code.
Thanks


'Const Record_number = 5000+
Public cn As Connection
Public mySystem
Public ConnectString, login, myDataBase
Public cntString, fName, secFname, seqFname, myBuf, logfname, reccnt
Public printername


'Public Function GetConfigSys(inParm)
'    On Error GoTo getErr
'    fni = "c:\services\general.cnf"
'    Open fni For Input As #1
'    Line Input #1, buf
'    While (Not EOF(1)) And (Left(buf, Len(inParm)) <> inParm)
'        Line Input #1, buf
'    Wend
'    If EOF(1) Then
'        GetConfigSys = "-1"
'        Else
'        GetConfigSys = Mid(buf, Len(inParm) + 1, 999)
'    End If
'    Close #1
'    Exit Function
'getErr:
'        GetConfigSys = "-1"
'End Function
Private Sub Main()
   
    myBuf = LoadFile(Command())
    constr = GetPartFromReq(myBuf, "constring" & vbTab, vbCrLf)
    seqFname = GetPartFromReq(myBuf, "lastseqfn" & vbTab, vbCrLf)
    logfname = GetPartFromReq(myBuf, "logfile" & vbTab, vbCrLf)
    stRep = GetPartFromReq(myBuf, "repname" & vbTab, vbCrLf)
    Dest = GetPartFromReq(myBuf, "Printer" & vbTab, vbCrLf)
    printername = GetPartFromReq(myBuf, "Printername" & vbTab, vbCrLf)
   
    Open logfname For Append As #2
    Print #2, Format(Now(), "dd/mm/yyyy hh:mm:ss") + UCase(stRep) + " report : Started "
    Print #2, "Destination " + Dest
    On Error GoTo errLogin
    cntr = cntr + 1
    Set cn = New Connection
    cn.CursorLocation = adUseClient
    'ConnectString = LoadFile("c:\services\SARIE\" & "repuser.sec")
    ConnectString = GetPartFromReq(myBuf, "constring" & vbTab, vbCrLf)
    'Record_number = LoadFile("c:\services\SARIE\" & "LastSeq.Seq")
    Record_number = LoadFile(seqFname)
    cn.Open ConnectString
    login = True
   
    Dim rr As Recordset
    Set rr = New Recordset
    tsql = "select business_date ,path_03 ,path_04  from config where company_code = '0000000000' "
    rr.Open tsql, cn, adOpenForwardOnly, adLockReadOnly
    repSave = rr.Fields(1).Value
    repPath = rr.Fields(2).Value
    sDATE = rr.Fields(0).Value
    'commented and changed by shaik ismail to change the date format to yyyymmdd
    'sDate = Right(sDate, 2) & Mid(sDate, 5, 2) & Left(sDate, 4)
    If UCase(stRep) = "TRANSARI" Then
       sDATE = Right(sDATE, 2) & Mid(sDATE, 5, 2) & Left(sDATE, 4)
    End If
       
    rr.Close
    'stRep = "TRANSARI"
'-----------------------------------
    scr = LoadFile(repPath & stRep & ".QUR")
    scs = LoadFile(repPath & stRep & ".QUS")
    scr = Replace(scr, "[Date]", sDATE)
    scr = Replace(scr, "[Record_Number]", Record_number)
    scs = Replace(scs, "[Date]", sDATE)
    scs = Replace(scs, "[Record_Number]", Record_number)
    'rr.Open Replace(scr, "SELECT", "SELECT RECORD_NUMBER , "), cn, adOpenForwardOnly, adLockReadOnly
    rr.Open scs, cn, adOpenForwardOnly, adLockReadOnly
   
    If rr.RecordCount <= 0 Then
        rr.Close
        Print #2, stRep + " No Entry / No Report"
        Print #2, Format(Now(), "dd/mm/yyyy hh:mm:ss") + UCase(stRep); " report : Ended successfully."
        Print #2, "################################################"
        Close #2
        MsgBox "No Entry / No Report "
        Exit Sub
    End If
    rr.MoveLast
    last_rec = rr.Fields(0).Value
   
    Open seqFname For Output As #1
    Print #1, Format(last_rec, "000000")
    Close #1
   
    Print #2, "Records to be printed : " + Str(rr.RecordCount)
    Print #2, "Last printed sequence : " + Str(last_rec)
       
    rr.Close
'---------------------------------------
    'Dest = LoadFile("c:\services\SARIE\DEST.cnf")
    GenReport repPath & stRep, Dest, scr, repSave & stRep
    If Not IsNull(Trim(printername)) And printername <> "-1" Then
       Print #2, "Printer name : " + printername
    Else
       Print #2, "Printer name : Default printer"
    End If
       
    Print #2, Format(Now(), "dd/mm/yyyy hh:mm:ss") + UCase(stRep); " report : Ended successfully."
    Print #2, "################################################"
    Close #2
    MsgBox "Report Has been generated "
    Unload frmSARI
    Exit Sub
errLogin:
    Print #2, stRep + " report cannot be generated due to the below reason"
    Print #2, "Error" + Err.Description
    Print #2, " Contact the administrator ... "
    Print #2, Format(Now(), "dd/mm/yyyy hh:mm:ss") + UCase(stRep); " report : Ended with errors."
    Print #2, "################################################"
    Close #2
    MsgBox " Contact the administrator ... "
End Sub


Public Sub GenReport(inRep, inDest, inFormula, sSave)  '

On Error GoTo genErr
    'repdir = "d:\b2b\rpt\def\"
    'repDown = "d:\b2b\rpt\Reports" & inRep
    dst = crptToWindow
    Select Case inDest
        Case "File"
            dst = crptToFile
            frmMain.repGen.PrintFileType = crptRTF
            frmMain.repGen.PrintFileName = sSave & ".rtf"
        Case "Printer"
            dst = crptToPrinter
        Case "Window"
            dst = crptToWindow
    End Select

frmSARI.repGen.Connect = ConnectString
frmSARI.repGen.ReportFileName = inRep & ".rpt"
frmSARI.repGen.SQLQuery = inFormula
frmSARI.repGen.Destination = dst

If Not IsNull(Trim(printername)) And printername <> "-1" Then
   frmSARI.repGen.printername = printername
End If
frmSARI.repGen.Action = 1

Exit Sub
genErr:
MsgBox "[" & Err.Number & "]" & Err.Description
End Sub

Public Function LoadFile(FilePath)
    Const ForReading = 1, ForWriting = 2, ForAppending = 8
    Set objFileSys = CreateObject("Scripting.FileSystemObject")
    Set fs = objFileSys.GetFile(FilePath)
    Set filestream = objFileSys.OpenTextFile(FilePath, ForReading)
    LoadFile = filestream.read(fs.Size)
    filestream.Close
    Set filestream = Nothing
    Set fs = Nothing
    Set objFileSys = Nothing
End Function

Function GetPartFromReq(sDocument, sToken, eToken)
        Dim pos1, pos2
        Dim result
        result = ""
         
         
        pos1 = InStr(sDocument, sToken)
        pos2 = InStr(pos1 + 1, sDocument, eToken)
       
        If pos1 = 0 Or pos2 = 0 Then
            GetPartFromReq = -1
            Exit Function
        End If
        If pos1 > 0 Then
            If Len(eToken) <> 0 Then
                result = Mid(sDocument, pos1 + Len(sToken), pos2 - (pos1 + Len(sToken)))
            Else
                result = Mid(sDocument, pos1 + Len(sToken))
            End If
        End If
      GetPartFromReq = result
End Function