module m_fields_to_plot


!   type fieldheaders
!      character(len=8) fieldname
!      integer          layer
!      integer          ix
!      integer          iy
!      integer          ia
!      integer          ib
!      integer          ic
!      integer          length
!   end type fieldheaders

   type fields
      character(len=8) fextract
      integer          laya
      integer          layb
      logical          option
   end type fields


contains
subroutine fields_to_plot(sphere,rotate,normal,fld,nfld,hfile,kdm)
   use mod_hycomfile_io
   implicit none
   integer, parameter  :: iversion=4
   logical, intent(out) :: sphere
   logical, intent(out) :: rotate
   logical, intent(out) :: normal
   type(fields), intent(out) :: fld(1000)
   integer, intent(out) :: nfld
   integer, intent(in)  :: kdm
   type(hycomfile) :: hfile

   integer ndim,i,ivers,lay1,lay2
   character(len=8) char8
   character(len=80) extrfile
   logical option,ex
   
   if (trim(hfile%ftype)=='restart') then
      extrfile='extract.restart'
   else if (trim(hfile%ftype)=='nersc_daily') then
      extrfile='extract.daily'
   else if (trim(hfile%ftype)=='nersc_weekly') then
      extrfile='extract.weekly'
   else
      print *,'Unknown filetype '//trim(hfile%ftype)
      call exit(1)
   end if



   inquire(exist=ex,file=trim(extrfile)) 
   if (.not.ex) then
      print *,'Can not find extract file '//trim(extrfile)
      stop '(fields_to_plot)'
   end if


   open(21,file=trim(extrfile),status='old')
   read(21,*) ivers  
   if (ivers /= iversion) then
      close(21)
      print *,'Version of extract file should be:',iversion
      print *,'From 1 to 2 just add a F or T in column 3,5,7 of line 3'
      print *,'This makes it possible to plot solution on a sphere,'
      print *,'to calculate and plot rotated velocities, and to switch of'
      print *,'the index velocities. Use the line:'
      print *,'2 T T T     # 2-D, sphere, rotate, index velocities'
      print *
      print *,'From version 3 to 4, field names are b characters long, '
      print *,'starting on first column'
      stop 'wrong version of extract file'
   endif
   read(21,*) ! ignored

   read(21,'(t1,i1,t3,l1,t5,l1,t7,l1)')ndim,sphere,rotate,normal       
   print '(3(a,l1))','For velocities are set:  sphere=',sphere,',  rotate=',rotate,',  normal=',normal
   read(21,*)i         ! not used here
   read(21,*) lay1,lay2 ! not used here

   print *,'The following variables (and corresponding layers) will be printed:'
   nfld=0
   do i=1,1000
      !read(21,'(a8,t9,i2,t12,i2,t15,l1)',end=888) char8,lay1,lay2,option  
      read(21,*,end=888) char8,lay1,lay2,option  
      if (option) then
         if (lay2>kdm) then
            print *,'Variable '//trim(char8)//' has lay2 > ',kdm
         end if
         nfld=nfld+1
         fld(nfld)%fextract=adjustl(char8)
         fld(nfld)%laya=lay1
         fld(nfld)%layb=lay2
         fld(nfld)%option=option
         print '(a5,i2,i2)',fld(nfld)%fextract,fld(nfld)%laya,fld(nfld)%layb
      endif
   enddo
 888 close(21)

end subroutine fields_to_plot
end module m_fields_to_plot