!-----------------------------------------------------------------
!
!  This file is (or was) part of SPLASH, a visualisation tool
!  for Smoothed Particle Hydrodynamics written by Daniel Price:
!
!  http://users.monash.edu.au/~dprice/splash
!
!  SPLASH comes with ABSOLUTELY NO WARRANTY.
!  This is free software; and you are welcome to redistribute
!  it under the terms of the GNU General Public License
!  (see LICENSE file for details) and the provision that
!  this notice remains intact. If you modify this file, please
!  note section 2a) of the GPLv2 states that:
!
!  a) You must cause the modified files to carry prominent notices
!     stating that you changed the files and the date of any change.
!
!  Copyright (C) 2005-2009 Daniel Price. All rights reserved.
!  Contact: daniel.price@sci.monash.edu.au
!
!-----------------------------------------------------------------

!-------------------------------------------------------------------------
! this subroutine reads from the data file(s)
! change this to change the format of data input
!
! THIS VERSION IS FOR STEVE FOULKES' ASCII DATA FORMAT
!
! the data is stored in the global array dat
!
! >> this subroutine must return values for the following: <<
!
! ncolumns    : number of data columns
! ndim, ndimV : number of spatial, velocity dimensions
! nstepsread  : number of steps read from this file
!
! dat(maxplot,maxpart,maxstep) : main data array
!
! npartoftype(1:6,maxstep) : number of particles of each type in each timestep
! ntot(maxstep)       : total number of particles in each timestep
!
! time(maxstep)       : time at each step
! gamma(maxstep)      : gamma at each step
!
! most of these values are stored in global arrays
! in the module 'particle_data'
!-------------------------------------------------------------------------

subroutine read_data(rootname,indexstart,ipos,nstepsread)
 use particle_data, only:dat,npartoftype,time,gamma,maxpart,maxcol,maxstep
 use params
 use settings_data, only:ndim,ndimV,ncolumns,ncalc,required,ipartialread,xorigin
 use mem_allocation, only:alloc
 use system_utils, only:lenvironment
 use labels, only:ih
 implicit none
 integer, intent(in) :: indexstart,ipos
 integer, intent(out) :: nstepsread
 character(len=*), intent(in) :: rootname
 integer :: i,j,ierr,nerr,iunit,ncolstep
 integer :: nprint,npart_max,nstep_max,icol
 integer :: nmodel,nstar,ncolread
 logical :: iexist
 real :: tread,hmax,dtmin,tdg,hfac
 real, dimension(3) :: xptmass,yptmass,vxptmass,vyptmass
 character(len=len(rootname)+4) :: dumpfile

 nstepsread = 0
 nstep_max = 0
 npart_max = maxpart
 iunit = 15  ! logical unit number for input

 dumpfile = trim(rootname)
 !
 !--check if first data file exists
 !
 inquire(file=dumpfile,exist=iexist)
 if (.not.iexist) then
    print "(a)",' *** error: '//trim(dumpfile)//': file not found ***'
    return
 endif
 !
 !--fix number of spatial dimensions (0 means no particle coords)
 !
 ndim = 3
 ndimV = 3
 nstar = 2

 j = indexstart
 nstepsread = 0
 print "(a)",' Steve Foulkes/Carol Haswell/James Murray ascii data format'
 write(*,"(26('>'),1x,a,1x,26('<'))") trim(dumpfile)

 !
 !--open the file and read the number of particles
 !
 open(unit=iunit,iostat=ierr,file=dumpfile,status='old',form='formatted')
 if (ierr /= 0) then
    print "(a)",'*** ERROR OPENING '//trim(dumpfile)//' ***'
    return
 endif
!
!--read header line, set time
!
 read(iunit,*,iostat=ierr) nmodel,nprint,hmax,tread,dtmin,tdg
 if (ierr /= 0) print "(a)",' WARNING: error(s) reading first header line'
 print "(a,1pe10.3,a,i10,a,i10)",' time = ',tread,' npart =',nprint,' model number = ',nmodel
 print "(3(a,1pe10.4))",' hmax = ',hmax,' dtmin = ',dtmin,' tdg = ',tdg
!
!--determine how many columns we are going to read
!
 if (lenvironment('FSPLASH_READALL')) then
    ncolstep = 26
    print "(a)",' reading all columns'
 else
    ncolstep = 15
    print "(a,i2)",' reading only to column 15 (setenv FSPLASH_READALL ''yes'' to read all)'
 endif
!
!--(re)allocate memory
!
 nstep_max = max(maxstep,nstep_max,indexstart,1)
 if (.not.allocated(dat) .or. (nprint > maxpart) .or. (ncolstep+ncalc) > maxcol) then
    npart_max = max(npart_max,nprint+nstar,maxpart)
    !--allow extra room if reallocating
    if (allocated(dat)) npart_max = max(npart_max,INT(1.1*(nprint+nstar)),maxpart)
    call alloc(npart_max,nstep_max,max(ncolstep+ncalc,maxcol))
 endif
!
!--set the necessary parameters
!
 ncolumns = ncolstep
 nstepsread = nstepsread + 1
 npartoftype(:,j) = 0
 npartoftype(1,j) = nprint
 npartoftype(2,j) = nstar
 time(j) = tread
 gamma(j) = 5./3.
!
!--now read the timestep data in the dumpfile
!
 nerr = 0
!
!--only read required columns
!
 ncolread = 0
 do i=1,ncolstep
    if (required(i)) ncolread = i
 enddo
 if (ncolread /= ncolstep) then
    ipartialread = .true.
    print*,' reading only up to column ',ncolread
 endif

 do i=1,nprint
    read(iunit,*,iostat=ierr) (dat(i,icol,j),icol = 1,ncolread)
    if (ierr /= 0) nerr = nerr + 1
 enddo
 if (nerr > 0) print *,' ERRORS reading particle data on ',nerr,' lines'
!
!--read point mass information
!
 read(iunit,*,iostat=ierr) xptmass(1),yptmass(1),xptmass(2),yptmass(2),hfac
!--point mass velocities not read, though would put them here if they were
 vxptmass(1) = 0.
 vyptmass(1) = 0.
 vxptmass(2) = 0.
 vyptmass(2) = 0.
 if (ierr /= 0) print *,' ERROR reading primary and secondary positions'

 close(iunit)

!--set labels to get ih for setting smoothing length of stars
 call set_labels

!--copy star particle properties into main data array
 do i=nprint+1,nprint+nstar
    dat(i,1,j) = xptmass(i-nprint)
    dat(i,2,j) = yptmass(i-nprint)
    dat(i,3,j) = 0.
    dat(i,4,j) = vxptmass(i-nprint)
    dat(i,5,j) = vyptmass(i-nprint)
    dat(i,6,j) = 0.
    dat(i,7:ncolstep,j) = 0.
    if (ih > 0) dat(i,ih,j) = epsilon(0.) ! small but non-zero smoothing length
 enddo
 print "(' primary     (x,y) = (',1pe10.2,',',1pe10.2,')')",xptmass(1),yptmass(1)
 print "(' secondary   (x,y) = (',1pe10.2,',',1pe10.2,')')",xptmass(2),yptmass(2)
 print "(a)",' setting origin to primary position... '
 xorigin(1) = xptmass(1)
 xorigin(2) = yptmass(1)
 xorigin(3) = 0.


 return
end subroutine read_data

!!-------------------------------------------------------------------
!! set labels for each column of data
!!
!! read these from a file called 'columns' in the current directory
!! then take sensible guesses as to which quantities are which
!! from the column labels
!!
!!-------------------------------------------------------------------

subroutine set_labels
 use labels, only:label,labeltype,ix,irho,ipmass,ih,ivx,iamvec,labelvec,make_vector_label
 use params
 use settings_data, only:ntypes,ndim,ndimV,UseTypeInRenderings
 use geometry, only:labelcoord
 implicit none
 integer :: i,ifx

 do i=1,ndim
    ix(i) = i
 enddo
 ivx = ndim+1
 ipmass = ivx+ndimV
 ifx = ipmass+1
 irho = ifx+ndimV
 label(irho+1) = 'du/dt'
 label(irho+2) = 'C_{s}'
 label(irho+3) = 'alpha'
 ih = irho+4
 label(irho+5) = 'kpc'
 label(irho+6) = 'schb'
 label(irho+7) = 'dtp'
 label(irho+8) = 'sigma'
 label(irho+9) = 'pdr2'
 label(irho+10) = 'av_sep'
 label(irho+11) = 'radius'
 label(irho+12) = 'viscosity flag'
 label(irho+13) = 'neighbour number'
 label(irho+14) = 'iwas'
 label(irho+15) = 'll'
 if (irho > 0) label(irho) = 'density'
 if (ih > 0) label(ih) = 'smoothing length'
 if (ipmass > 0) label(ipmass) = 'particle mass'
 call make_vector_label('v',ivx,ndimV,iamvec,labelvec,label,labelcoord(:,1))
 call make_vector_label('f',ifx,ndimV,iamvec,labelvec,label,labelcoord(:,1))
 !
 !--set labels for each particle type
 !
 ntypes = 2
 labeltype(1) = 'gas'
 labeltype(2) = 'star'
 UseTypeInRenderings(1) = .true.
 UseTypeInRenderings(2) = .false.

end subroutine set_labels
