; ==============================================================================
;  filename_3b.pro
;
;  Defines function filename_3b which constructs the CIPS Level 3B
;  file name from the following arguments:
;
;     hem       hemisphere ('north' or 'south')                  string
;     year      year (e.g. 2009)                                 integer or string
;     version   CIPS data version # (e.g., '05.20')              string
;     revision  CIPS data revision # (e.g., '04')                string
;
;  Modifications/updates:
;
;  <  Sep 2019    Jerry D. Lumpe       Initial Creation
;  16 Sep 2019    Paul E. Meade        Cleaned Up, Added Comments
;   7 Nov 2019    Jerry D. Lumpe       Added flag_preliminary input and logic 
;  25 Feb 2020    Bill Barrett         Minor changes
;
; ==============================================================================

function filename_3b, hem, year, version, revision, flag_preliminary

  ; Generate the 'season' element of the file name from the hemisphere and year strings.
  ; Trim off the century from the four digit year
  if size(year, /type) eq 7 then y1 = string(year) $
    else y1 = year
  y1=strmid(strtrim(y1,2),2,2)
  season=hem+'_'+y1
  ; The southern hemisphere uses both the begin and end year
  if(hem eq 'south') then begin
    y2 = strtrim(string(fix(y1)+1),2)
    season=season + y2
  endif

  ;  Generate the 'version' and 'revision' elements of the file name:
  ; version should be something like '05.20'
  if(strlen(version) eq 4) then version='0'+version
  ; revision should be something like '01
  if(strlen(revision) eq 1) then revision='0'+revision

  ;  Concatenate the file name elements into the final file name:
  preliminary = flag_preliminary eq 1 ? '_prelim.preliminary' : ''
  file='cips_sci_3b_'+season+'_v'+version+'_r'+revision+ preliminary + '.mp4'

  return,file
end