;;This addition provides a directory-tree-browsing-functionality.
;;This means:
;;When using it you hand over a list of strings, that shall be
;;interpreted as paths and a string that represents the path, relative to
;;which the path-list is given.
;;In the result-window of the NUIT a file-browsing screen is shown
;;which you can browse in using arrow-keys and enter. You can also
;;select some items and paste them into the upper window.

;;If there are paths to files handed over that do not exist, they will not be 
;;displayed in the browser!

;;If the given path does not exist you will not be able to navigate!

(define key-m 109)
(define key-u 117)

(define-record-type browse-dir-list-res-obj browse-dir-list-res-obj
  (make-browse-dir-list-res-obj pos-y
				pos-x
				file-list
				result-text
				working-directory
				width
				initial-wd
				marked-items
				res-marked-items
				c-x-pressed)
  browse-dir-list-res-obj?
  (pos-y browse-dir-list-res-obj-pos-y)
  (pos-x browse-dir-list-res-obj-pos-x)
  (file-list browse-dir-list-res-obj-file-list)
  (result-text browse-dir-list-res-obj-result-text)
  (working-directory browse-dir-list-res-obj-working-directory)
  (width browse-dir-list-res-obj-width)
  (initial-wd browse-dir-list-res-obj-initial-wd)
  (marked-items browse-dir-list-res-obj-marked-items)
  (res-marked-items browse-dir-list-res-obj-res-marked-items)
  (c-x-pressed browse-dir-list-res-obj-c-x-pressed))

(define (layout-dir-list files wdir width)
  (let ((marked-files (mark-special-files wdir files)))
    (append
     (list
      (if (<= (string-length wdir) (- width 25))
	  (string-append "Paths relative to " wdir  " :")
	  (let ((dir-string (substring wdir
                                         (- (string-length wdir) 
                                            (- width 25))
                                         (string-length wdir))))
	    (string-append "Paths relative to ..."
			   dir-string))))
     marked-files)))

(define (mark-special-files dir files)
  (map (lambda (file)
	 (let ((complete-name (string-append dir "/" file)))
	   (cond
	    ((file-directory? complete-name)
	     (string-append " " file "/"))
	    ((file-executable? complete-name)
	     (string-append "*" file))
	    ((file-symlink? complete-name)
	     (string-append "@" file))
	    (else
	     (string-append " " file)))))
       files))
   
;;selection->descend
(define selected-browse-dir-list
  (lambda (model)
    (let ((ln (browse-dir-list-res-obj-pos-y model))
	  (wd (browse-dir-list-res-obj-working-directory model)))
      (if (not (file-exists? wd))
	  model
	  (begin (chdir wd)
		 (if (or (>= ln (+ (length 
				    (browse-dir-list-res-obj-result-text model)) 1))
			 (<= ln 1))
		     model
		     (if (= ln 2)
			 (if (not (equal? "/" (cwd)))
			     (begin
			       (chdir "..")
			       (let* ((new-result (directory-files))
				      (width (browse-dir-list-res-obj-width model))
				      (new-text (layout-dir-list 
						 new-result (cwd) width))
				      (new-model (make-browse-dir-list-res-obj
						  2
						  1
						  new-result
						  new-text
						  (cwd)
						  width
						  (browse-dir-list-res-obj-initial-wd 
						   model)
						  (browse-dir-list-res-obj-marked-items
						   model)
						  (browse-dir-list-res-obj-res-marked-items
						   model)
						  (browse-dir-list-res-obj-c-x-pressed
						   model))))
				 new-model))
			     model)
			 (let* ((text (browse-dir-list-res-obj-result-text model))
				(ent (list-ref text (- ln 1)))
				(len (string-length ent))
				(last-char (substring ent (- len 1) len))
				(rest (substring ent 1 (- len 1))))
			   (if (equal? last-char "/")
			       (begin
				 (chdir wd)
				 (chdir rest)
				 (let* ((new-result (directory-files))
					(width (browse-dir-list-res-obj-width model))
					(new-text (layout-dir-list 
						   new-result (cwd) width))
					(new-model (make-browse-dir-list-res-obj
						    2
						    1
						    new-result
						    new-text
						    (cwd)
						    width
						    (browse-dir-list-res-obj-initial-wd
						     model)
						    (browse-dir-list-res-obj-marked-items
						     model)
						    (browse-dir-list-res-obj-res-marked-items
						     model)
						    (browse-dir-list-res-obj-c-x-pressed						   model))))
				   new-model))
			   model)))))))))

(define (init-with-list-of-files files dir width)
  (make-browse-dir-list-res-obj
   2 1
   files (layout-dir-list files dir width) dir
   width (cwd) '() '() #f))

(define browse-dir-list-receiver
  (lambda (message)
    (debug-message "browse-dir-list-receiver " message)
    (cond 

     ((init-with-result-message? message)
      (let ((fs-objects (init-with-result-message-result message)))
	(init-with-list-of-files
	 (map fs-object-name fs-objects) (cwd)
	 (init-with-result-message-width message))))

     ((next-command-message? message)
      (init-with-list-of-files (directory-files) (cwd)))

     ((print-message? message)
      (let* ((model (message-result-object message))
	     (pos-y (browse-dir-list-res-obj-pos-y model))
	     (pos-x (browse-dir-list-res-obj-pos-x model))
	     (text (browse-dir-list-res-obj-result-text model))
	     (marked-pos (get-marked-positions-3
			  (browse-dir-list-res-obj-file-list model)
			  (browse-dir-list-res-obj-marked-items model))))
	(debug-message "browse-dir-list-receiver "
		       "pos-y " pos-y " pos-x " pos-x
		       " marked-pos " marked-pos)
	(make-simple-result-buffer-printer
	 pos-y pos-x text (list pos-y) marked-pos)))

     ((key-pressed-message? message)
      (let* ((model (message-result-object message))
	     (key (key-pressed-message-key message))
	     (c-x-pressed (browse-dir-list-res-obj-c-x-pressed model)))
	
	(cond

	 ;; user pressed 'm' --- mark current entry
	 ((= key key-m)
	  (let* ((marked-items (browse-dir-list-res-obj-marked-items model))
		 (res-marked-items (browse-dir-list-res-obj-res-marked-items
				    model))
		 (actual-pos (browse-dir-list-res-obj-pos-y model))
		 (all-items (browse-dir-list-res-obj-file-list model)))
	    (if (<= actual-pos 2)
		model
		(let* ((actual-item (list-ref all-items (- actual-pos 3)))
                       (actual-res-item 
                        (if (not (string=? (cwd) "/"))
                            (string-append (cwd) "/" actual-item)
                            (string-append "/" actual-item))))
		    (if (member actual-res-item marked-items)
			model
			(let* ((new-res-marked-items (append res-marked-items
							     (list 
							      actual-res-item)))
			       (new-marked-items (append marked-items
							 (list actual-item)))
			       (new-model (make-browse-dir-list-res-obj
					   (browse-dir-list-res-obj-pos-y model)
					   (browse-dir-list-res-obj-pos-x model)
					   (browse-dir-list-res-obj-file-list 
					    model)
					   (browse-dir-list-res-obj-result-text 
					    model)
					   (browse-dir-list-res-obj-working-directory
					    model)
					   (browse-dir-list-res-obj-width model)
					   (browse-dir-list-res-obj-initial-wd
					    model)
					   new-marked-items
					   new-res-marked-items
					   #f)))
			  new-model))))))
	 
	 ;; user pressed 'u' --- unmark current entry
	 ((= key key-u)
	  (let* ((marked-items (browse-dir-list-res-obj-marked-items model))
		 (res-marked-items (browse-dir-list-res-obj-res-marked-items
				    model))
		 (actual-pos (browse-dir-list-res-obj-pos-y model))
		 (all-items (browse-dir-list-res-obj-file-list model)))
	    (if (<= actual-pos 2)
		model
		(let* ((actual-item (list-ref all-items (- actual-pos 3)))
		       (actual-res-item (string-append (cwd) "/" actual-item))
		       (rest (member actual-item marked-items))
		       (res-rest (member actual-res-item res-marked-items)))
		  (if (not res-rest)
		      model
		      (let* ((after-item (length rest))
			     (all-items (length marked-items))
			     (before-item (sublist marked-items
						   0 
						   (- all-items
						      after-item )))
			     (new-marked-items (append before-item
						       (list-tail rest 1)))
			     (after-res-item (length res-rest))
			     (all-res-items (length res-marked-items))
			     (before-res-item (sublist res-marked-items
						       0
						       (- all-res-items 
							  after-res-item)))
			     (new-res-marked-items (append before-res-item
							   (list-tail res-rest
								      1)))
			     (new-model (make-browse-dir-list-res-obj
					 (browse-dir-list-res-obj-pos-y model)
					 (browse-dir-list-res-obj-pos-x model)
					 (browse-dir-list-res-obj-file-list 
					  model)
					 (browse-dir-list-res-obj-result-text 
					  model)
					 (browse-dir-list-res-obj-working-directory
					  model)
					 (browse-dir-list-res-obj-width model)
					 (browse-dir-list-res-obj-initial-wd
					  model)
					 new-marked-items
					 new-res-marked-items
					 #f)))
			new-model))))))

	 ((= key key-up)
	  (let ((posy (browse-dir-list-res-obj-pos-y model)))
	    (if (<= posy 2)
		model
		(let* ((new-posy (- posy 1))
		       (new-model (make-browse-dir-list-res-obj 
				   new-posy
				   (browse-dir-list-res-obj-pos-x model)
				   (browse-dir-list-res-obj-file-list model)
				   (browse-dir-list-res-obj-result-text model)
				   (browse-dir-list-res-obj-working-directory 
				    model)
				   (browse-dir-list-res-obj-width model)
				   (browse-dir-list-res-obj-initial-wd model)
				   (browse-dir-list-res-obj-marked-items model)
				   (browse-dir-list-res-obj-res-marked-items 
				    model)
				   #f)))
		  new-model))))

	 ((= key key-down)
	  (let ((posy (browse-dir-list-res-obj-pos-y model))
		(num-lines (length 
			    (browse-dir-list-res-obj-result-text model))))
	    (if (>= posy num-lines)
		model
		(let* ((new-posy (+ posy 1))
		       (new-model (make-browse-dir-list-res-obj 
				   new-posy
				   (browse-dir-list-res-obj-pos-x model)
				   (browse-dir-list-res-obj-file-list model)
				   (browse-dir-list-res-obj-result-text model)
				   (browse-dir-list-res-obj-working-directory 
				    model)
				   (browse-dir-list-res-obj-width model)
				   (browse-dir-list-res-obj-initial-wd model)
				   (browse-dir-list-res-obj-marked-items model)
				   (browse-dir-list-res-obj-res-marked-items 
				    model)
				   #f)))
		  new-model))))
	 
	 ((= key 10)
	  (selected-browse-dir-list model))
	 
	 ;; user pressed C-x
	 ((= key 24)
	  (make-browse-dir-list-res-obj
 	   (browse-dir-list-res-obj-pos-y model)
 	   (browse-dir-list-res-obj-pos-x model)
 	   (browse-dir-list-res-obj-file-list model)
 	   (browse-dir-list-res-obj-result-text model)
 	   (browse-dir-list-res-obj-working-directory 
 	    model)
 	   (browse-dir-list-res-obj-width model)
 	   (browse-dir-list-res-obj-initial-wd model)
 	   (browse-dir-list-res-obj-marked-items model)
 	   (browse-dir-list-res-obj-res-marked-items 
 	    model)
 	   (not c-x-pressed)))
	 
	 (else model))))


     ((restore-message? message)
      (let* ((model (message-result-object message))
	     (initial-wd (browse-dir-list-res-obj-initial-wd model)))
	(chdir initial-wd)))
     
     ((selection-message? message)
      (let* ((model (message-result-object message))
	     (marked-items (browse-dir-list-res-obj-res-marked-items model)))
	(string-append "'" (exp->string marked-items)))))))

(define (list-of-fs-objects? thing)
  (and (proper-list? thing)
       (every fs-object? thing)))

(register-plugin! 
 (make-view-plugin browse-dir-list-receiver
		   list-of-fs-objects?))