MODULE get_GCMInput
!
! Make sure files are open appropriate for current run time and read what is needed as 
! inputs to TIME3D and edynamo. 
!
  USE shr_kind_mod,   only : r8 => shr_kind_r8            ! 8-byte reals
  USE namelist,       only: nfiles,input_ncfiles,output_ncfiles
  USE fileInput,      only: nFilesIO,inNCFiles,outNCFiles,secPerFile,secRunBeg,secRunEnd
  
  IMPLICIT NONE
  SAVE
  PUBLIC
 
  INTEGER :: iFileOpen      ! Sequential number of which input file is currently open
 
  CHARACTER(LEN=1024), ALLOCATABLE :: inNCFiles(:)
  CHARACTER(LEN=1024), ALLOCATABLE :: outNCFiles(:)

CONTAINS
!-----------------------------------------------------------------------
SUBROUTINE get_InGCMFile(iTimeStep,timeStepSec,runTimeSec)
!
!  Given the current run time, time step, and last time of current open file (if a file is currently open),
!  check if this is the first time step and, if so, open the first file.  If not first time step and if 
!  last time of current file being read is prior to the current run time, open the next file if this is
!  not the last input file. If this is the second time of the current file, close the previous file.  
!  Otherwise, pass back current file netCDF id
!
  USE netcdf

  IMPLICIT NONE
  SAVE

  INTEGER, INTENT(IN) :: iTimeStep       ! Current time step in run 
  INTEGER, INTENT(IN) :: timeStepSec     ! Size of time step in seconds 
  INTEGER, INTENT(IN) :: runTimeSec      ! Current run time in seconds
!
! Local
!
  INTEGER :: ncGCMID1
  INTEGER :: secFileEnd

  IF (iTimeStep == 1) THEN

    istat = nf90_open(inNCFiles(1),NF90_NOWRITE,ncGCMID1)
    istat = nf90_open(inNCFiles(2),NF90_NOWRITE,ncGCMID2)
    !
    ! Get number of times and first time of second open file:
    !
    iStat = NF90_INQ_DIMID(ncGCMID2,'time',idUnlim)
    iStat = NF90_INQUIRE_DIMENSION(ncGCMID2,idUnlim,varName,nTime)
    iStat = NF90_INQ_VARID(ncGCMID2,'time',timeID)
    iStat = NF90_GET_VAR(ncGCMID2,timeID,fracDaysBeg,(/1/),(/nTime/))        
    file2FirstTime = fracDaysBeg(1) * 386400
    file2LastTime = fracDaysBeg(nTime) * 386400

    iFileOpen = 2

  ENDIF
!
! If time of run is after first time of second open file, close first file and change first 
! file id to second file id
!
  IF (runTimeSec >= file2FirstTime) THEN

    istat = nf90_close(ncGCMID1)
    ncGCMID1 = ncGCMID2
    !
    !  If this is not the last input file, open the next input file as second file
    !
    IF iFileOpen < nFilesIO THEN 

      istat = nf90_open(inNCFiles(iFileOpen+1),NF90_NOWRITE,ncGCMID2)
      !
      ! Get number of times and first time of new second open file:
      !
      iStat = NF90_INQ_DIMID(ncGCMID2,'time',idUnlim)
      iStat = NF90_INQUIRE_DIMENSION(ncGCMID2,idUnlim,varName,nTime)
      iStat = NF90_INQ_VARID(ncGCMID2,'time',timeID)
      iStat = NF90_GET_VAR(ncGCMID2,timeID,fracDaysBeg,(/1/),(/nTime/))        
      file2FirstTime = fracDaysBeg(1) * 386400
      file2LastTime = fracDaysBeg(nTime) * 386400

      iFileOpen = iFileOpen + 1 

    ENDIF

  ENDIF

END SUBROUTINE get_InGCMFile

!-----------------------------------------------------------------------
SUBROUTINE get_GCMData()

!
!  Need to read data for first two input files if this is the first time step. For
!  for following time steps, check if new second file opened and, if so, read data.
!