;###############################
;###   LayerState Switcher   ###
;###############################
;version 3.2
;Matthew D. Jordan - http://scenic-shop.com
; 
;This is a  command transparently saves the current layerstate. Subsequent invocations
;switch between the saved state and the current state.  You can go back and forth until
;your eyes pop out.
;
;command: LSS
;	  - on first run, it will save a layerstate and exit the command
;	  - option: Previous - (default option), switches you to the saved layerstate, and saves the
;                        current layerstate.
;	  -	option: Update   - saves the current layerstate for future retrieval.
;	  -	option: Clear    - delete the auto-generated layerstates that this script creates.
;	  - option: eXit     - duh.

(defun c:lss( / *error* )

	;in case of chemical attack...
	(defun *error* (msg)
	(or (wcmatch (strcase msg) "*BREAK,*CANCEL*,*EXIT*")
        (princ (strcat "\n** Error: " msg " **")))
		(princ)
	)
	
	;is this the first time using this utility?  If so, save a new layerstate...
	(if (not (layerstate-has "layerstate_switcher_temp_1"))
			(progn
				(layerstate-save "layerstate_switcher_temp_1" 255 nil)
				(prompt "\nLayerstate switcher initialized...")
				(princ)
				(quit)
			)
	)

	;purge extra layerstates
	(if (layerstate-has "layerstate_switcher_temp_2")
			(layerstate-delete "layerstate_switcher_temp_2")
	)

	(initget "Previous Update Clear eXit")
		(or	(setq answer (getkword "\nEnter an Layerstate Switch option [Previous/Update/Clear all/eXit] <Previous> : "))
			(setq answer "Previous")
		) ;or
		(cond
			((= answer "Previous")
				(progn 
					(layerstate-save   "layerstate_switcher_temp_2" 255 nil)
					(layerstate-restore "layerstate_switcher_temp_1" nil)
					(layerstate-delete "layerstate_switcher_temp_1")
					(layerstate-rename "layerstate_switcher_temp_2" "layerstate_switcher_temp_1")
					(prompt "\nLayerstate restored...")
				)
			)

			((= answer "Update")
				(progn
					(layerstate-delete "layerstate_switcher_temp_1")
					(layerstate-save   "layerstate_switcher_temp_1" 255 nil)
					(prompt "\nLayerstate updated...")
				)
			)
		
			((= answer "Clear")
				(progn
					(layerstate-delete "layerstate_switcher_temp_1")
					(prompt "\nTemporary layerstates cleared...")
				)
			)
		
			((= answer "eXit"))
		) ;cond
		(princ)
	)