pro naif, forcedef = forcedef, rw = rw, kernelFile=kernelFile

;+
; NAME:
;  naif
; PURPOSE: (one line)
;   prepare tnaif library and collect some constants into a system variable
; DESCRIPTION:
;   see /usr/local/icy/doc/html/req/icy.html for ICY info
;
; CATEGORY:
;  Astronomy
; CALLING SEQUENCE:
;  naif
; INPUTS:
;  none
; OPTIONAL INPUT PARAMETERS:
;  forcedef - define !naif even if it is defined
;  rw - allow !naif to be read-write
;  kernelFile - the kernels to load.  This can take two different
;    forms,  either a single string which is the 
;    full path name of one kernel file (tls or bsp for
;    example), or a metakernel file with the 
;    names of the kernels to load.  If this optional
;    argument is not defined, the file ; 
;    "kernels.txt" is used. 
;    This file is located in /User/naif/kernels.txt.  
;    Note: under OSX, the cpsice_furnsh function expects the master 
;       kernel file to have lines delimited
;	by line feeds instead of carriage returns.
;
; KEYWORD INPUT PARAMETERS:
;  none
; KEYWORD OUTPUT PARAMETERS:
;  none
; OUTPUTS:
;  None.
; COMMON BLOCKS:
;  None.
; SIDE EFFECTS:
;  Defines the system variable !eph using defsysv
; RESTRICTIONS:
; PROCEDURE:
; MODIFICATION HISTORY:
;  Written 2004 May, by Leslie Young, SwRI
;  Modified 2004 Dec 7, by Cathy Olkin, SwRI
;		1. Moved "help, 'icy',/dlm" to be after package is loaded to remove error message.
;		2. Added a kernel file
;		3. Call cspice_furnsh on the kernel file
;		4. Made a standard kernels.txt file and added an optional argument to override the
;			standard kernel file.
;	To do: 1.  Add to !naif, either the string passed to cspice_furnsh or the contents of the file
; 		   loaded by cspice_furnsh.  I should be able to use the output from cspice_kdata to do this,
;		   but I am not sure how to do this right now.
;-

on_error, 2

; Don't add it if it already exists.
DEFSYSV, '!naif', EXISTS = i
IF i EQ 1 and not keyword_set(forcedef) THEN return

print, cspice_tkvrsn( 'TOOLKIT' )
help, 'icy',/dlm

IF keyword_set(kernelFile) THEN cspice_furnsh, kernelFile
IF not keyword_set(kernelFile) THEN cspice_furnsh, '/usr/local/rsi/idl/lib/layoung/naif/kernels.txt'

; Count the number of loaded kernel files. 
cspice_ktotal, 'ALL', count
print, 'The number of loaded kernel files = ', count
   
; Loop over the count, outputting file information as we loop.
; The loop tells us all files loaded via cspice_furnsh, their
; type, and how they were loaded.
;
  for i = 0, (count-1)  do begin
   
     cspice_kdata, i, 'ALL', file, type, source, handle, found
   
     if ( found ) then begin
            print, 'Index : ' + string(i)
            print, 'File  : ' + file
            print, 'Type  : ' + type
            print, 'Source: ' + source
            print
         endif else begin
            print, 'No kernel found with index: ' + string(i)
         endelse
   
      endfor

ro = 1 ; read-only
if keyword_set(rw) then ro=0
;defsysv, '!naif', $
;  { $
;    tls : tls, $
;    spk : spk $
;  }, ro

;message, $
;  'NAIF variable (!naif) has been added', /inf

print, "target # -98 is New Horizons"

end