;;; Functions modeling a standard text adventure world.
;;; Location is modeled as containment, movement is modeled via passage nodes
;;; that hold properties and descriptions for a given exit.
;;; Global properties are held in the player object YOU, which also acts as
;;; the default avatar object.

(module world (adventure create-object move-object add-alias set-hidden toggle-fixed set-enter-message set-destination get-container print-room-description)
  (import scheme)
  (import chicken.base)
  (import chicken.file)
  (import srfi-1)
  (import matchable)
  (import fmt)
  (import ansi-escape-sequences)
  (import util)
  (import database)
  (import io)


  ;; The canonical name of a given cardinal direction
  ;; and it's aliases.
  (define +cardinal-sets+
    '((north n)
      (northeast ne north-east)
      (east e)
      (southeast se south-east)
      (south s)
      (southwest sw south-west)
      (west w)
      (northwest nw north-west)
      (up u)
      (down d)))

  ;; The mirror direction for a given direction.
  (define +cardinal-opposites+
    '((north . south)
      (northeast . southwest)
      (east . west)
      (southeast . northwest)
      (south . north)
      (southwest . northeast)
      (west . east)
      (northwest . southeast)
      (up . down)
      (down . up)))

  ;; Main game loop exit condition.
  (define *exit-adventure* #f)

  (define-syntax get-set-define
    (er-macro-transformer
     (lambda (exp rename compare)
       (let ((flag (car exp)))
	 (begin
	   `(define (,(string->symbol (string-append (symbol->string flag) "-get")) object value)
	      (database-get object ,flag value))
	   `(define (,(string->symbol (string-append (symbol->string flag) "-set")) object value)
	      (database-set object ,flag value)))))))

  (get-set-define test-value)

  ;; Set the name of an object.
  (define (set-name object name)
    (database-set object 'name name))

  ;; Set the description of an object.
  (define (set-description object description)
    (database-set object 'description description))

  ;; Get the name of an object.
  (define (get-name object)
    (database-get object 'name (symbol->string object)))

  ;; Get the description of an object.
  (define (get-description object)
    (database-get object 'description "You see the swirling void of creation."))
  
  (define (get-container object)
    (database-get object 'container #f))

  (define (get-contents object)
    (database-get object 'contents '()))

  (define (set-destination object destination)
    (database-set object 'destination destination))

  (define (get-destination object)
    (database-get object 'destination #f))

  (define (set-enter-message object msg)
    (database-set object 'enter-message msg))

  (define (get-enter-message object)
    (database-get object 'enter-message #f))

  (define (get-aliases object)
    (database-get object 'aliases '()))

  (define (set-aliases object alias-list)
    (database-set object 'aliases alias-list))

  (define (add-alias object alias)
    (let ((aliases (get-aliases object)))
      (if (not (member alias aliases))
	  (set-aliases object (cons alias aliases)))))

  (define (remove-alias object alias)
    (let ((aliases (get-aliases object)))
      (if (member alias aliases)
	  (set-aliases object (remove (curry eq? alias) aliases)))))

  (define (set-hidden object value)
    (database-set object 'hidden value))
  
  (define (get-hidden object)
    (database-get object 'hidden #f))

  (define (set-fixed object value)
    (database-set object 'fixed value))

  (define (get-fixed object value)
    (database-get object 'fixed #f))

  (define (get-put-message object)
    (database-get object 'put-message "You put the ~a into the ~a."))

  ;; Is development mode enabled?

  (define (devmode-enabled?)
    (database-get 'you 'devmode #f))

  (define (toggle-devmode)
    (toggle-flag 'you 'devmode))

  ;; Is an object fixed in place (e.g. cannot be picked up?)

  (define (fixed? object)
    (database-get object 'fixed #f))

  (define (toggle-fixed object)
    (toggle-flag object 'fixed))

  ;; Match a tag against a list of objects, checking for its tag and its aliases.

  (define (match-object tag objects)
    (let loop ((objects objects))
      (if (null? objects)
	  #f
	  (let ((taglist (cons (car objects) (get-aliases (car objects)))))
	    (if (member tag taglist)
		(car objects)
		(loop (cdr objects)))))))

  (define (create-object tag name description)
    (set-name tag name)
    (set-description tag description))

  (define (move-object object container)
    (let ((prev-container (get-container object)))
      (database-set object 'container container)
      (let ((contents (get-contents container)))
	(if (not (member object contents))
	    (begin
	      (database-set container 'contents (cons object contents))
	      (database-set prev-container 'contents (remove (curry eq? object) (get-contents prev-container))))))))

  ;; Determine the objects visible to a source object, zork-style
  (define (visible-objects source)
    (let ((result (get-container source)))
      (if (and result (object-exists? result))
	  (cons (get-container source) (get-contents (get-container source)))
	  (error "Tried to determine visible objects for object without a container."))))

  (define (print-room-description room)
    (newline)
    (display (set-text '(bold) (get-name room)))
    (if (devmode-enabled?) (display (set-text '(bold fg-green) (string-append " [" (symbol->string room) "]"))))
    (newline)
    (display "    ")
    (fmt #t (dsp (wrap-lines (get-description room))))
    (newline)
    (display "You see: ")
    (map (lambda (n)
	   (if (not (get-hidden n))
	       (begin
		 (display (get-name n))
		 (display " ")
		 (if (devmode-enabled?)
		     (display (set-text '(bold fg-green) (string-append "[" (symbol->string n) "] "))))))) (remove (curry eq? 'you) (get-contents room)))
    (newline))

  (define (do-command-enter tag)
    (let ((object (match-object tag (visible-objects 'you))))
      (if (not object)
	  (show "You cannot go that way.")
	  (let ((destination (get-destination object)))
	    (if (not destination)
		(show "You cannot enter that.")
		(begin
		  (move-object 'you destination)
		  (perhaps show (get-enter-message object))
		  (print-room-description (get-container 'you))))))))

  (define (do-command-save)
    (let ((save-name (prompt-default "Enter save name: " "kekkonen.sav")))
      (if (or (not (file-exists? save-name)) (prompt-yn "That file already exists. Overwrite? "))
	  (begin
	    (show "Saving database, please wait...")
	    (database-save save-name)
	    (show "Done.")))))

  (define (do-command-load)
    (let ((save-name (prompt-default "Enter save file name to load: " "kekkonen.sav")))
      (if (not (file-exists? save-name))
	  (show "That file does not exist.")
	  (begin
	    (show "Loading database, please wait...")
	    (database-load save-name)
	    (show "Done.")))))

  (define (do-command-look)
    (print-room-description (get-container 'you)))

  (define (do-command-examine tag)
    (let ((object (match-object tag (visible-objects 'you))))
      (if (not object)
	  (show "You cannot see that here.")
	  (show (get-description object)))))

  (define (do-command-inventory)
    (map (compose show get-name) (get-contents 'you)))

  (define (do-command-take tag)
    (if (not (symbol? tag))
	(show "I didn't quite understand that.")
	(let ((object (match-object tag (if (devmode-enabled?)
					    (get-all-objects)
					    (visible-objects 'you)))))
	  (if (or (not object) (and (fixed? object) (not (devmode-enabled?))))
	      (if object
		  (show "That is fixed in place.")
		  (show "You cannot see that here."))
	      (begin
		(show (string-append "You get " (get-name object) "."))
		(move-object object 'you))))))

  (define (do-command-drop tag)
    (if (not (symbol? tag))
	(show "I didn't quite understand that.")
	(let ((object (match-object tag (get-contents 'you))))
	  (if (not object)
	      (show "You are not carrying that.")
	      (begin
		(show (string-append "You drop " (get-name object) "."))
		(move-object object (get-container 'you)))))))

  (define (do-command-put tag destination-tag)
    (let ((object (match-object tag (get-contents 'you))))
      (if (not object)
	  (show "You are not carrying that.")
	  (let ((destination-object (match-object destination-tag (visible-objects 'you))))
	    (if (not destination-object)
		(show "You cannot see that here.")
		(move-object object (get-destination destination-object)))))))

  (define (do-command-devmode)
    (toggle-devmode)
    (if (devmode-enabled?)
	(show "Development mode enabled.")
	(show "Development mode disabled.")))

  (define (do-command-create tag name description)
    (if (not (and (symbol? tag) (string? name) (string? description)))
	(show "I didn't quite understand that.")
	(if (object-exists? tag)
	    (show "That object already exists.")
	    (begin
	      (create-object tag name description)
	      (move-object tag (get-container 'you))))))

  (define (do-setter-command tag value type? setter)
    (if (not (and (symbol? tag) (type? value)))
	(show "I didn't quite understand that.")
	(let ((object (match-object tag (visible-objects 'you))))
	  (if (not object)
	      (show "You can't see that here.")
	      (begin
		(setter object value)
		(show "You set a value."))))))

  (define (do-command-rename tag name)
    (do-setter-command tag name string? set-name))

  (define (do-command-describe tag description)
    (do-setter-command tag description string? set-description))

  (define (do-command-flag tag flag)
    (if (not (and (symbol? tag) (symbol? flag)))
	(show "I didn't quite understand that.")
	(let ((object (match-object tag (visible-objects 'you))))
	  (if (not object)
	      (show "You can't see that here.")
	      (begin
		(case flag
		  ((fixed) (set-fixed object #t))
		  ((hidden) (set-hidden object #t))
		  (else (show "Invalid flag name."))))))))

  (define (do-command-unflag tag flag)
    (if (not (and (symbol? tag) (symbol? flag)))
	(show "I didn't quite understand that.")
	(let ((object (match-object tag (visible-objects 'you))))
	  (if (not object)
	      (show "You can't see that here.")
	      (begin
		(case flag
		  ((fixed) (set-fixed object #f))
		  ((hidden) (set-hidden object #f))
		  (else (show "Invalid flag name."))))))))

  (define (do-command-alias tag alias)
    (if (not (and (symbol? tag) (symbol? alias)))
	(show "I didn't quite understand that.")
	(let ((object (match-object tag (visible-objects 'you))))
	  (if (not object)
	      (show "You can't see that here.")
	      (begin
		(add-alias object alias)
		(show "You add an alias."))))))

  (define (do-command-unalias tag alias)
    (if (not (and (symbol? tag) (symbol? alias)))
	(show "I didn't quite understand that.")
	(let ((object (match-object tag (visible-objects 'you))))
	  (if (not object)
	      (show "You can't see that here.")
	      (begin
		(remove-alias object alias)
		(show "You remove an alias."))))))

  (define (do-command-destroy tag)
    (if (not (symbol? tag))
	(show "I didn't quite understand that.")
	(database-remove tag)))

  (define (do-command-aliases tag)
    (if (not (symbol? tag))
	(show "I didn't quite understand that.")
	(let ((object (match-object tag (visible-objects 'you))))
	  (if (not object)
	      (show "You can't see that here.")
	      (begin
		(newline)
		(map (lambda (x) (display x) (display " ")) (get-aliases object))
		(newline))))))

  (define (do-command-message tag message-tag message)
    (if (not (and (symbol? tag) (symbol? message-tag) (string? message)))
	(show "I didn't quite understand that.")
	(let ((object (match-object tag (visible-objects 'you))))
	  (if (not object)
	      (show "You can't see that here.")
	      (case message-tag
		((enter) (set-enter-message object message))
		(else (show "Invalid message name.")))))))

  (define (do-command-goto tag)
    (if (not (symbol? tag))
	(show "I didn't quite understand that.")
	(begin
	  (move-object 'you tag)
	  (print-room-description (get-container 'you)))))

  (define (get-cardinal-set direction)
    (find (curry member direction) +cardinal-sets+))

  (define (get-cardinal-aliases direction)
    (perhaps (curry remove (curry eq? direction)) (get-cardinal-set direction)))

  (define (cardinal-direction? direction)
    (list? (member direction (flatten +cardinal-sets+))))

  (define (get-inverse-direction direction)
    (perhaps cdr (assoc direction +cardinal-opposites+)))

  (define (get-canonical-cardinal-direction-name direction)
    (perhaps car (get-cardinal-set direction)))

  (define (do-command-dig direction destination)
    (if (not (and (symbol? direction) (symbol? destination)))
	(show "I didn't quite understand that.")
	(if (not (cardinal-direction? direction))
	    (show "You must specify a compass rose direction or up and down.")
	    (let ((canonical-direction (get-canonical-cardinal-direction-name direction)))
	      (let ((exit-tag (compose-symbols canonical-direction (get-container 'you) destination)))
		(if (object-exists? exit-tag)
		    (show "An exit like that already exists.")
		    (begin
		      (move-object exit-tag (get-container 'you))
		      (set-hidden exit-tag #t)
		      (set-destination exit-tag destination)
		      (map (curry add-alias exit-tag) (get-cardinal-set direction))
		      (show "You create a passage."))))))))
  
  (define (do-command-exit)
    (show "Goodbye, see you later...")
    (set! *exit-adventure* #t))

  (define (alias-transform input)
    (match input
      (('quit) '(exit))
      (('i) '(inventory))
      (('inv) '(inventory))
      (('look x) `(examine ,x))
      (('go x) `(enter ,x))
      (('get x) `(take ,x))
      ((x) (if (cardinal-direction? x)
 	       `(enter ,x)
	       input))
      (_ input)))

  (define (dispatch-command input)
    (let ((success #t))
      (match input
	(('look) (do-command-look))
	(('save) (do-command-save))
	(('load) (do-command-load))
	(('devmode) (do-command-devmode))
	(('exit) (do-command-exit))
	(('enter x) (do-command-enter x))
	(('take x) (do-command-take x))
	(('drop x) (do-command-drop x))
	(('inventory) (do-command-inventory))
	(('examine x) (do-command-examine x))
	(('put x y) (do-command-put x y))
	(_ (if (devmode-enabled?)
	       (match input
		 (('create x y z) (do-command-create x y z))
		 (('rename x y) (do-command-rename x y))
		 (('describe x y) (do-command-describe x y))
		 (('dig x y) (do-command-dig x y))
		 (('flag x y) (do-command-flag x y))
		 (('unflag x y) (do-command-unflag x y))
		 (('alias x y) (do-command-alias x y))
		 (('unalias x y) (do-command-unalias x y))
		 (('destroy x) (do-command-destroy x))
		 (('aliases x) (do-command-aliases x))
		 (('message x y z) (do-command-message x y z))
		 (('goto x) (do-command-goto x))
		 (_ (set! success #f)))
	       (set! success #f))))
      success))
  
  (define (adventure)
    (let ((success (dispatch-command (alias-transform (adventure-prompt)))))
      (if (not success)
	  (begin
	    (show "I didn't quite understand that.")
	    (adventure))
	  (if *exit-adventure*
	      (show "Exiting..."); (display *database*)
	      (adventure))))))