PRO dustem_fit_ext_example,model=model $
                               ,ext_file=ext_file $
                               ,Nitermax=Nitermax $

                               ,fits_save=fits_save $

                               ,wait=wait $
                               ,noobj=noobj $
                               ,help=help $
                               ,verbose=verbose

;+
; NAME:
;    dustem_fit_ext_example  
;
; PURPOSE:
; This routine is an example of how to fit an observational extinction SED
; (StokesI only) with DustEM and DustEMWrap.
;  
; See the DustEMWrap User Guide for more information.
;
; CATEGORY:
;    DustEMWrap, Distributed, High-Level, User Example
;
; CALLING SEQUENCE:

;    dustem_fit_ext_example[,model=][ext_file=][,Nitermax=][,fits_save=][,/help,/wait,/verbose,/noobj]

;
; INPUTS:
;    None
;
; OPTIONAL INPUT PARAMETERS:
;    None
;
; OUTPUTS:
;    None
;
; OPTIONAL OUTPUT PARAMETERS:
;    Plots, results structure in binary FITS table format
;
; ACCEPTED KEY-WORDS:

;    model = specifies the interstellar dust mixture used by
;            DustEM. See userguide or dustem_test_model_exists.pro
;            for more details about available models in current release.

;    ext_file = string naming the path to text file in .xcat format that
;          describes the observational extinction SED. If not set, the file
;          'Data/EXAMPLE_OBSDATA/Mathis90Fitz99_DISM_NH20.xcat' is used.  
;    Nitermax = maximum number of fit iterations. Default is 5.

;    fits_save = if set, save the fit results in a binary

;               FITS file. The code then restore this file and plots
;               the results using the saved results information.
;    help      = if set, print this help
;    wait      = if set, wait this many seconds between each step of
;                the code (for illustration purposes)
;    verbose      = if set, subroutines will run in verbose mode
;    noobj     = if set, runs with no object graphics
;
; COMMON BLOCKS:
;    None
;
; SIDE EFFECTS:
;    None
;
; RESTRICTIONS:
;    The DustEM fortran code must be installed
;    The DustEMWrap IDL code must be installed
;
; PROCEDURES AND SUBROUTINES USED:
;    
;
; EXAMPLES
;    dustem_fit_ext_example

;    dustem_fit_ext_example,Nitermax=1,fits_save='/tmp/mysavefile.fits'

;    dustem_fit_ext_example,model='DBP90'
;
; MODIFICATION HISTORY:
;    Written by AH Oct 2022
;    Evolution details on the DustEMWrap gitlab.
;    See http://dustemwrap.irap.omp.eu/ for FAQ and help.  
;-


IF keyword_set(help) THEN BEGIN
  doc_library,'dustem_fit_ext_example'
  goto,the_end
END

IF keyword_set(model) THEN BEGIN
  use_model=strupcase(model)
ENDIF ELSE BEGIN
  use_model='J13'    
ENDELSE

exists=dustem_test_model_exists(use_model)
if exists ne 1 then $
   message,'Unknown dust model'

use_polarization=0.   ;default is no polarization in models
use_window=2       ; default graphics window number to use for plotting the results
use_verbose=0
if keyword_set(verbose) then use_verbose=1
use_Nitermax=5        ; maximum number of iterations for the fit
IF keyword_set(Nitermax) THEN use_Nitermax=Nitermax

dustem_define_la_common

;=== Set the (model-dependent) parameters that you want to fit
;=== Refer to the DustEM and DustEMWrap userguides for an explanation
;    of the different grain types

;=== Set the (model-dependent) parameters that you want to fit (pd),
;=== their initial values (iv)
;=== and whether they are bounded (ulimed,llimed,llims,ulims).
;=== Fixed parameters (fpd) and their values (fiv) are also set here.
;=== Refer to the DustEM and DustEMWrap User guides for an explanation
;=== of the physical meaning of dust model and plug-in parameters, and
;=== how to specify them.

;=== Example is provided for J13
;=== If you choose a different dust model, you will need to adjust the
;=== parameter information accordingly. 

pd = [ $
     '(*!dustem_params).grains(0).mdust_o_mh'$   ;CM20 -- power law size distribution
     ,'(*!dustem_params).grains(1).mdust_o_mh'$  ;CM20 -- logN size distribution
     ,'(*!dustem_params).grains(2).mdust_o_mh' $ ;aPyM5
     ,'(*!dustem_params).grains(3).mdust_o_mh' ] ;aOlM5

iv =   [2.9e-3, 6.7e-4, 2.1e-3, 2.8e-3]   ; starting guess for the fit    

Npar=n_elements(pd)
ulimed=replicate(0,Npar)
llimed=replicate(1,Npar)
llims=replicate(1.e-15,Npar)

;=== Fixed parameters
fpd=[]
;==initial parameter values for fixed parameters
fiv=[]
        

if keyword_set(wait) then begin
   message,'Finished setting dust model and plug-in parameters: '+use_model,/info
   wait,wait
end

;== INITIALISE DUSTEM
dustem_init,model=use_model,polarization=use_polarization
!dustem_nocatch=1
!dustem_verbose=use_verbose
IF keyword_set(noobj) THEN !dustem_noobj=1
!EXCEPT=2 ; for debugging

;=== READ EXTINCTION DATA THAT WE WANT TO FIT
dir=!dustem_wrap_soft_dir+'/Data/EXAMPLE_OBSDATA/'
file=dir+'Mathis90Fitz99_DISM_NH20.xcat' 
IF keyword_set(ext_file) THEN file=ext_file
ext=read_xcat(file,/silent)

;=== HERE WE SET THE DATA SO THAT THE COMPUTE_ FUNCTIONS BELOW HAVE
;=== THE NECESSARY FIELDS AND INFORMATION

dustem_set_data,m_fit=m_fit,m_show=m_show,x_fit=ext,x_show=ext 

;== SET INITIAL VALUES AND LIMITS OF THE PARAMETERS FOR THE FIT 
;== AND ACTIVATE ANY PLUGINS 
dustem_init_params,use_model,pd,iv,fpd=fpd,fiv=fiv,ulimed=ulimed,llimed=llimed,ulims=ulims,llims=llims,polarization=use_polarization

if keyword_set(wait) then begin
   message,'Finished initializing DustEMWrap, including plugins and fixed parameters',/info
   wait,wait
end


;== INFORMATION TO RUN THE FIT
tol=1.e-10 

;=== INFORMATION TO MAKE THE PLOTS
;=== _x/_extinction means extinction plots, _m/_emissions means emission plots
xr_x=[0.01,30]
yr_x=[1.00E-10,10]
tit='Dust Optical Depth'
;ytit=textoidl('I_\nu (MJy/sr) for N_H=10^{20} H/cm^2')
;xtit=textoidl('\lambda (\mum)')

;===  RUN THE FIT
t1=systime(0,/sec)
res=dustem_mpfit_data(tol=tol,Nitermax=use_Nitermax,gtol=gtol $
                      ,/xlog,/ylog,xr_x=xr_x,yr_x=yr_x,xtit=xtit,ytit=ytit,title=tit $
                      ,legend_xpos=legend_xpos,legend_ypos=legend_ypos $
                      ,errors=errors,chi2=chi2,rchi2=rchi2,show_plot=show_plot)
t2=systime(0,/sec)

if keyword_set(wait) then begin
   message,'Finished running DustEMWrap, using Niters: '+strtrim(string(use_Nitermax),2),/info
   message,'Time taken [sec]: '+sigfig(t2-t1,2,/sci),/info
   wait,wait
end

IF keyword_set(fits_save) THEN BEGIN
   message,'Writing out results structure: '+fits_save,/info
   dustem_write_fits_table,filename=fits_save,help=help

;=== At this point, you could erase all dustem system variables, or exit idl... all the
;=== information needed to recover the results and remake the plots has been saved in the FITS table

  ;; Moved the following to dustem_fitsio_example
  ;; dustem_read_fits_table,filename=fits_save,dustem_st=dustem_st
  ;; ;==== plot result taken from the saved fits table
  ;; res=*(*!dustem_fit).CURRENT_PARAM_VALUES
  ;; IF !dustem_noobj THEN BEGIN
  ;;    dustemwrap_plot_noobj,res,st=dustem_st,xr=xr,/xstyle,yr=yr,/ysty,/ylog,/xlog,title=tit+' (From Saved FITS file)'
  ;; ENDIF ELSE BEGIN
  ;;   dustemwrap_plot,res,st=dustem_st,xr=xr,/xstyle,yr=yr,/ysty,/ylog,/xlog,title=tit+' (From Saved FITS file)'
  ;; ENDELSE

  IF keyword_set(wait) THEN BEGIN

     message,'Saved the results as FITS in the file: '+fits_save,/info

     wait,wait
  ENDIF
ENDIF

the_end:

message,'Finished dustem_fit_ext_example',/info

END