load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/shea_util.ncl"

begin

  ; get file and variable name from shell environment
  ; =================================================
  ifile = getenv("opath")+getenv("pfile")
  ofile = getenv("opath")+getenv("qfile")
  ivar  = getenv("ivar")



  ; read variables from file
  ; ========================
  f1 = addfile (ifile, "r")
  var   = f1->$ivar$   
  time  = f1->time
  lat2d = f1->lat
  lon2d = f1->lon
 
;  print("lat2d: min="+min(lat2d)+"   max="+max(lat2d))
;  printVarSummary(var)
;  print(" min="+min(var)+"   max="+max(var))     

  dimvar = dimsizes( var )
  nt     = dimvar(0)
  nlat   = dimvar(1)
  mlon   = dimvar(2)

;********************************************
; Before interpolating make all lon >= 0.0
; The reason is to get around the dateline longitude sign switch
; going from positive [eg 150E] to negative [eg -170]
;********************************************

  lon2d = where(lon2d.ge.0, lon2d, lon2d+360.)

;  LON1D   = ndtooned(lon2d)       ; convert to one dimensional array
;  ii      = ind(LON1D.lt.0.)      ; returns indices where condition is true
;  LON1D(ii) = LON1D(ii) + 360.
;  lon2d   = onedtond( LON1D, dimsizes(lon2d) ) ; converts to multidimesional array

;  print(" min="+min(lat2d)+"   max="+max(lat2d))   ; min=0.89728   max=85.3335
;  print(" min="+min(lon2d)+"   max="+max(lon2d))   ; min=148.64    max=357.433

;********************************************
; interpolate: specify region, set up new lat/lon grid that original data will be regridded to
;********************************************
  NLAT          = 360 ;180
  MLON          = 720

  dlat          = 0.5
  lat           = (ispan ( 0,NLAT-1,1 )*dlat)-90    ; -90 to 89
  lat!0         = "lat"
  lat@units     = "degrees_north"
  lat&lat       = lat

  dlon          = 0.5
  lon           = ispan ( 0,MLON-1,1 )*dlon    ; 0 to 359
  lon!0         = "lon"
  lon@units     = "degrees_east"
  lon&lon       = lon

  varNEW           = new ((/nt,NLAT,MLON/), typeof(var), getFillValue(var))
  varNEW!0         = "time"
  varNEW&time      =  time
  varNEW!1         = "lat"
  varNEW&lat       =  lat
  varNEW!2         = "lon"
  varNEW&lon       =  lon
  varNEW@units     = var@units
  varNEW@long_name = var@long_name

;  printVarSummary(var)
;  printVarSummary(varNEW)

  do t = 0, nt-1
     varNEW(t,:,:) = triple2grid(ndtooned(lon2d), ndtooned(lat2d), ndtooned( var(t,:,:) ) ,lon, lat, False)
  end do

  ;printVarSummary(lat)
  ;printVarSummary(varNEW)

; write modified data into netcdf file
;   ncdf = addfile(ofile,"w")  ; overwrite (w-option), create new (c-option)
   ncdf = addfile(ofile,"c")  ; overwrite (w-option), create new (c-option)                     
   ncdf->time  = time  
   ncdf->lon   = lon  
   ncdf->lat   = lat
   ncdf->$ivar$ = varNEW  
   
end