;+

;PURPOSE:	To return a data structure for a specific time from a FAST l1 common block.

;USEAGE:	dat=get_fa1_ses(t)

;			The routine assumes the l1 common block is already loaded into IDL.

;KEYWORDS:	/START to return data structure for the first time in l1 common block.

;			/EN to return data structure for the last time in l1 common block.

;			/ADVANCE to return the next data structure in the l1 common block.

;			/RETREAT to return the previous data structure in the l1 common block.

;			INDEX=INDEX to return the INDEXth data structure in the l1 common block.

;			/CALIB does nothing.

;			/TIMES returns array of starting times in l1 common block instead of data structure.

;			UNITS=UNITS allows you to choose the returned data's units.  Default is compressed.

;BUGS:		None that I know of.

;UPDATES:

;-



function get_fa1_ses,t, $

					start=start, $

					en=en, $

					advance=advance, $

					retreat=retreat, $

					index=index, $

					calib=calib, $

					times=times, $

					units=units



common fa_ses_l1,get_ind,all_dat



if keyword_set(times) then return,all_dat.time

ntimes=n_elements(all_dat.time)



time_threshold=.05

if n_elements(index) EQ 0 then begin

	if keyword_set(advance) then begin

		if get_ind EQ ntimes-1 then begin

			print,'Error: End of Data. Cannot Advance.'

			return,{data_name:'', valid:0}

		endif

		index=get_ind+1

	endif

	if keyword_set(retreat) then begin

		if get_ind EQ 0 then begin

			print,'Error: Beginning of Data. Cannot Retreat'

			return,{data_name:'', valid:0}

		endif

		index=get_ind-1

	endif

	if keyword_set(en) AND keyword_set(start) then begin

		print,'Error: Both /EN and /START Keywords Set'

		return,{data_name:'', valid:0}

	endif

	if keyword_set(start) then index=0

	if keyword_set(en) then index=ntimes-1

	if n_elements(index) EQ 0 then begin

		if keyword_set(t) then begin

			t=time_double(t)

			time_tmp=(all_dat.time+all_dat.end_time)/2

			min_tmp=min(time_tmp-t,index_tmp,/absolute)

			min_tmp=abs(min(all_dat.time-t,index_tmp2,/absolute))

			if min_tmp LT time_threshold then index_tmp=index_tmp2

			original_t=t

			index=index_tmp[0]

			if abs(min_tmp) GT 5 then begin

				print,'Warning: All Data Samples Further than 5 Seconds from t'

				original_flag=1

			endif

		endif else begin

			ctime,t,npoints=1

			if NOT keyword_set(t) then begin

				print,'Error @ fa_seb_struct_1l.pro: CTIME Failure!'

				return,{data_name:'', valid:0}

			endif

			time_tmp=(all_dat.time+all_dat.end_time)/2

			min_tmp=min(time_tmp-t,index_tmp,/absolute)

			min_tmp=abs(min(all_dat.time-t,index_tmp2,/absolute))

			if min_tmp LT time_threshold then index_tmp=index_tmp2

			original_t=t

			index=index_tmp[0]

			if abs(min_tmp) GT 5 then begin

				print,'Warning: All Data Samples Further than 5 Seconds from t'

				original_flag=1

			endif

		endelse

	endif

endif

if (index LT 0) OR (index GE ntimes) then begin

	print,'Error: Index Out of Bounds!'

	return,{data_name:'', valid:0}

endif

;t=all_dat.time[index]

get_ind=long(index)



nbins=all_dat.nbins[index]

nenergy=all_dat.nenergy[index]

mode_ind=all_dat.mode_ind[index]



if mode_ind EQ 0 then data=all_dat.data0[0:47,0:15,all_dat.data_ind[index]]

if mode_ind EQ 1 then data=all_dat.data1[0:23,0:15,all_dat.data_ind[index]]

if mode_ind EQ 2 then data=all_dat.data2[0:11,0:15,all_dat.data_ind[index]]

if mode_ind EQ 3 then data=all_dat.data3[0:5,0:15,all_dat.data_ind[index]]



end_time=all_dat.end_time[index]

units_procedure=all_dat.units_procedure

valid=all_dat.valid[index]



gf=shift(all_dat.gf[0:nenergy-1,0:nbins-1,all_dat.gf_ind[index]],0,-all_dat.gf_shift[index])

dtheta=replicate(22.5,nenergy,nbins)

theta=all_dat.theta[0:nenergy-1,0:nbins-1,all_dat.theta_ind[index]]+all_dat.theta_shift[index]

where_gt=where(theta GT all_dat.theta_max[index])

where_lt=where(theta LT all_dat.theta_min[index])

if where_gt[0] NE -1 then theta[where_gt]-=360.

if where_lt[0] Ne -1 then theta[where_lt]+=360.



if keyword_set(original_t) AND (NOT keyword_set(original_flag)) then begin

	if (original_t LT (all_dat.time[index]-time_threshold)) OR $

		(original_t GT (end_time+time_threshold)) then $

		print,'Warning: t Not Between TIME and END_TIME'

endif



datastr={data_name:all_dat.data_name, $

		valid:valid, $

		data_quality:all_dat.data_quality[index], $

		project_name:'FAST', $

		units_name:all_dat.units_name, $

		units_procedure:units_procedure, $

		time:all_dat.time[index], $

		end_time:end_time, $

		integ_t:all_dat.integ_t[index], $

		nbins:nbins, $

		nenergy:nenergy, $

		data:float(data), $

		energy:all_dat.energy[0:nenergy-1,0:nbins-1,all_dat.energy_ind[index]], $

		bins:all_dat.bins[0:nenergy-1,0:nbins-1,all_dat.bins_ind[index]], $

		theta:theta, $

		geom:gf, $

		gf:gf, $

		denergy:all_dat.denergy[0:nenergy-1,0:nbins-1,all_dat.energy_ind[index]], $

		dtheta:dtheta, $

		eff:all_dat.eff[0:nenergy-1,0:nbins-1,all_dat.energy_ind[index]], $

		dead:all_dat.dead, $

		mass:all_dat.mass, $

		geom_factor:all_dat.geom_factor[index], $

		geomfactor:all_dat.geom_factor[index], $

		sc_pot:all_dat.sc_pot[index], $

		charge:all_dat.charge, $

		header_bytes:all_dat.header_bytes[*,index], $

		index:index, $

		spin_phase:all_dat.spin_phase[index], $

		spin_num:all_dat.spin_num[index], $

		spin_ph_hdr:all_dat.spin_ph_hdr[index], $

		sweep_num:all_dat.sweep_num[index], $

		swps_per_set:all_dat.swps_per_set[index] }



if NOT keyword_set(units) then units='Counts'

if valid EQ 1 then call_procedure,units_procedure,datastr,units



return,datastr



end