;+
; Fit E_measure-E_model per maneuver.
;
; time_range. Optional, used because not all data are available.
;-

function rbsp_phasef_read_fit_coef, time_range, probe=probe

    prefix = 'rbsp'+probe+'_'
    fillval = !values.f_nan
    xyz = constant('xyz')

    rbspx = 'rbsp'+probe
    root_dir = join_path([default_local_root(),'rbsp',rbspx,'e_fit'])
    if file_test(root_dir) eq 0 then file_mkdir, root_dir


    ; Load the time of the sections.
    txt_file = join_path([root_dir,prefix+'maneuver_list_for_efit.txt'])
    section_times = rbsp_phasef_read_fit_times(probe=probe, filename=txt_file)
    nsection = n_elements(section_times)*0.5
    if n_elements(time_range) eq 0 then time_range = minmax(section_times)

    ; The file to save data.
    sav_file = join_path([root_dir, prefix+'efit_coef.sav'])
    if file_test(sav_file) eq 0 then begin
        fit_list = list()
        for section_id=0, nsection-1 do begin
            section_time_range = reform(section_times[section_id,*])
            fit_info = dictionary()
            fit_info.time_range = section_time_range
            fit_list.add, fit_info
        endfor
        save, fit_list, filename=sav_file
    endif
    restore, filename=sav_file


;---Loop through the sections to see if update is needed.
    is_updated = 0
    foreach fit_info, fit_list do begin
        section_time_range = fit_info.time_range
        if section_time_range[0] lt time_range[0] then continue
        if section_time_range[1] gt time_range[1] then continue
        if fit_info.haskey('y') and fit_info.haskey('z') then continue


    ;---Load data.
        rbsp_efw_phasef_read_wobble_free_var, section_time_range, probe=probe
        dis = snorm(get_var_data(prefix+'r_mgse', times=times))
        store_data, prefix+'dis', times, dis
        orbit_time_step = total(times[0:1]*[-1,1])
        index = where(dis le 2)
        perigee_times = times[time_to_range(index, time_step=1)]
        store_data, prefix+'perigee_times', 0, perigee_times
        perigee_times = get_var_data(prefix+'perigee_times')
        nfit_section = 10
        index = where(perigee_times[*,0] ge section_time_range[0] and $
            perigee_times[*,1] le section_time_range[1], count)
        if count eq 0 or count lt nfit_section+1 then continue


    ;---Prepare fitting.
        rbsp_read_e_model, section_time_range, probe=probe, datatype='e_model_related'
        b_mgse = get_var_data(prefix+'b_mgse', times=times)
        v_mgse = get_var_data(prefix+'v_mgse')
        vcoro_mgse = get_var_data(prefix+'vcoro_mgse')
        u_mgse = (v_mgse-vcoro_mgse)*1e-3

        ndim = 3
        nrec = n_elements(times)
        xxs = fltarr(ndim,nrec,ndim)
        ; For Ey.
        xxs[0,*,1] =  u_mgse[*,0]*b_mgse[*,1]
        xxs[1,*,1] = -u_mgse[*,0]*b_mgse[*,0]-u_mgse[*,2]*b_mgse[*,2]
        xxs[2,*,1] =  u_mgse[*,2]*b_mgse[*,1]
        ; For Ez.
        xxs[0,*,2] =  u_mgse[*,0]*b_mgse[*,2]
        xxs[1,*,2] =  u_mgse[*,1]*b_mgse[*,0]
        xxs[2,*,2] = -u_mgse[*,0]*b_mgse[*,0]-u_mgse[*,1]*b_mgse[*,1]


        rbsp_efw_phasef_read_e_uvw, section_time_range, probe=probe
        interp_time, prefix+'e_uvw', times
        e_uvw = get_var_data(prefix+'e_uvw')
        e_mgse = cotran(e_uvw, times, 'uvw2mgse', probe=probe)
;        ; Remove eclipse.
;        pad_time = 0.
;        rbsp_read_eclipse_flag, section_time_range, probe=probe
;        flag = get_var_data(prefix+'eclipse_flag', times=uts)
;        index = where(flag eq 1, count)
;        fillval = !values.f_nan
;        if count ne 0 then begin
;            nan_times = uts[time_to_range(index,time_step=1)]
;            nnan_time = n_elements(nan_times)*0.5
;            for ii=0,nnan_time-1 do begin
;                index = lazy_where(times,'[]', nan_times[ii,*]+[-1,1]*pad_time, count=count)
;                if count eq 0 then continue
;                e_mgse[index,*] = fillval
;            endfor
;        endif
        store_data, prefix+'de_mgse', times, e_mgse
        yys = get_var_data(prefix+'de_mgse')
        store_data, prefix+'fit_data', times, xxs, yys



    ;---Do fit.
        ; Find the last several perigees.
        fit_time_ranges = perigee_times[index[count-1-nfit_section:count-1],*]
        nfit_time_range = n_elements(fit_time_ranges)*0.5

        get_data, prefix+'fit_data', times, xxs, yys
        time_index = []
        for jj=0,nfit_time_range-1 do begin
            index = lazy_where(times, '[]', fit_time_ranges[jj,*], count=count)
            if count eq 0 then continue
            time_index = [time_index,index]
        endfor
        xxs = xxs[*,time_index,*]
        yys = yys[time_index,*]
        uts = times[time_index]

        ; Calc fit coefs.
        fit_coef = fltarr(ndim+1,ndim)+fillval
        fit_index = [1,2]
        foreach jj, fit_index do begin
            yy = yys[*,jj]
            xx = xxs[*,*,jj]
            index = where(finite(yy) and finite(snorm(transpose(xx))), count)
            if count lt 10 then continue

            res = regress(xx[*,index],yy[index], sigma=sigma, const=const)
            fit_coef[*,jj] = [res[*],const]

            yfit = reform(xxs[*,*,jj] ## res)+const
            store_data, prefix+'de'+xyz[jj]+'_fit', uts, [[yy],[yfit],[yy-yfit]], $
                limits={colors:sgcolor(['red','green','blue']),labels:['old','fit','new']}
        endforeach

        ; Save fit coefs.
        foreach jj, fit_index do fit_info[xyz[jj]] = reform(fit_coef[*,jj])
        is_updated = 1
    endforeach


    if is_updated then begin
        save, fit_list, filename=sav_file

        log_file = join_path([data_dir, prefix+'maneuver_fit_coef.txt'])
        tab = '    '
        if file_test(log_file) eq 1 then file_delete, log_file
        ftouch, log_file
        foreach fit_info, fit_list do begin
            msg = ''
            msg += strjoin(time_string(fit_info.time_range,tformat='YYYY-MM-DD/hh:mm:ss'),'  ')+tab
            the_y = fit_info.haskey('y')? fit_info['y']: 0
            the_z = fit_info.haskey('z')? fit_info['z']: 0
            msg += strjoin(string(the_y,format='(F13.10)'),'  ')+tab
            msg += strjoin(string(the_z,format='(F13.10)'),'  ')+tab
            lprmsg, msg, log_file
        endforeach
    endif


    good_fit_list = list()
    foreach fit_info, fit_list do begin
        if ~fit_info.haskey('y') then continue
        if ~fit_info.haskey('z') then continue
        good_fit_list.add, fit_info
    endforeach


    return, good_fit_list

end


foreach probe, ['a','b'] do fit_list = rbsp_phasef_read_fit_coef(probe=probe)
stop

time_range = time_double(['2018-01-01','2019-01-01'])
time_range = time_double(['2013-01-01','2019-01-01'])
foreach probe, ['a','b'] do fit_list = rbsp_phasef_read_fit_coef(time_range, probe=probe)


end
