;; -*- mode: scheme -*-
;;
;; a simple setup for testing ideas about visual programming
;;
;; copyright (C) 2004 FoAM vzw
;;  You are granted the rights to distribute and use this software 
;;  under the terms of the GNU Lesser General Public License as 
;;  published by the Free Software Foundation; either version 2.1 of
;;  the License, or (at your option) any later version. The LGPL is
;;  distributed with this code (see: LICENCE) and available online 
;;  at http://www.gnu.org/copyleft/lesser.html

;; authors
;;  - nik gaffney <nik@fo.am>

;; requirements
;;  - based on the MrEd environment for PLT scheme
;;  - uses MrLib for graph display and editing

;; commentary
;;  aims to provide a simple framework for testing VPL models, ideas
;;  or techniques. this code is based around the implicit assumption
;;  that a VPL will be a graph based representation which is mapable
;;  to a sexp (or collection of sexps), so some things should be 
;;  reasonably common between different (although admittedly graph 
;;  based) VPLs, for example graph traversal, node placement and layout.
;;  it is not intended to be complete, exhaustive, or stable.

;; changes
;;  2006-09-11
;;  - scraped into coherence from various sources
;;  2006-09-14
;;  - fixed tree-colouring and traversal
;;  2006-11-10
;;  - scattered energy stabilisation attempts
;;  - scattered modules and files

 
(module eddies mzscheme

  (require (lib "misc.ss" "swindle")
           (lib "mred.ss" "mred")
           (lib "class.ss")
           ;(lib "list.ss")
           ;(lib "math.ss")
           "scritch.scm"
           "snipets.scm"
           "graph.scm")
           
  (provide (all-defined))


  ;;;;;;;;; ;; ;;     ;; 
  ;;
  ;; graphs, graphing and graphics
  ;;
  ;;;;;; ; ;;; ; ;;; ; ;       ; 
  
  (define graph-pasteboard%
    (class (graph-pasteboard-mixin pasteboard%)
      (define/augment (on-delete snip)
        ;; remove from parent list of children
        (for-each (lambda (child)
                    (send child remove-parent snip))
                  (send snip get-children))
        ;; remove from child list of parents
        (for-each (lambda (parent)
                    (send parent remove-child snip))
                  (send snip get-parents)))
      (define/public (zoom n)
        ;; zoom in/out by a given factor
        (let ([snip (send this find-first-snip)])
          (while snip
                 (send snip resize 
                       (* n (snip-width snip))
                       (* n (snip-height snip)))
                 (send snip move
                       (* n (snip-x snip))
                       (* n (snip-y snip)))
                 (set! snip (send snip next)))))
      (super-new)))
  
  ;; nodes can contain any valid expression, which is stored as text [for now]
  ;; able to be read by read-string.  the field 'value' may contain a precomputed
  ;; value of the nodes subtree, and the 'dirty' flag indicates wheter the subtree
  ;; (ie. any of its children) have changed.
  
  (define node-snip%
    (class (graph-snip-mixin editor-snip%)
      (init-field (value ()))
      (init-field (dirty #f))
      (inherit-field parent-links)
      (define/public (set-value v)
        (set! value v))
      (define/public (besmirch)
        (debug 2 "smirched: ~a ~%" this)
        (set! dirty #t)
        (map (lambda (x) (send x besmirch))
             (send this get-children)))
      (define/public (clean)
        (set! dirty #f))
      
      (define/public (move x y)
        (let ([p (send (send this get-admin) get-editor)])
          (send p move-to this x y)
          (send p set-modified #t)))
      
      ;; should be more coarse grained than 'on-event', but what?+
      (define/override (on-char dc x y editorx editory event)
        (if (eqv? (send event get-key-code) #\return)
            (begin (send event set-key-code #\nul)
                   (besmirch))
            (set! dirty #t))
        (super on-char dc x y editorx editory event))
      (define/override (own-caret own-it?)
        (if own-it?
            (debug 3 "node: ~a got keybrd focus~%" this)
            (if dirty 
                (begin (debug 3 "node: ~a lost keybrd focus~%" this)
                       (send this besmirch)
                       (send this clean))))
        (super own-caret own-it?))
      ;; links
      (define/public (get-parent-links) parent-links)
      (super-new)))
  
  ;; of suns, and of planets, and fields of wheat... 
  (define (make-node-snip)
    (new node-snip% 
         (with-border? #t) 
         (left-margin 3)
         (top-margin 3)
         (right-margin 4)
         (bottom-margin 2)
         (left-inset 1)
         (top-inset 1)
         (right-inset 1)
         (bottom-inset 1)))
  
  
  ;; .. edges? 
  ;;  would require modifying private methods in graph. 
  ;;  see -> draw-non-self-connection for example
  
  ;; maybe directly modify the list via get-parent-links
  ;;  see -> (define-local-member-name get-parent-links)
  
  ;; an output snip will display or modify its contents when besmirched.. .
  (define output-snip%
    (class node-snip%
      (define/override (besmirch)
        (send (send this get-editor) erase)
        (eval-tree this))
      (super-new)))
  
  ;; a recursive-snip can contain other node-snips,.
  ;; should be incorporated into basic node-snips
  
;;  (define recursive-snip% 
;;     (graph-snipboard-mixin editor-snip%))

  (define recursive-snip%
    (class (graph-snip-mixin editor-snip%) 
      ;; details..
      (define (insert)
        (debug "recurse..." this))
      (super-new)))
  
  
  ;; node/graph utils,.
  (define (insert-nodes p . nodes)
    (for-each (lambda (x) (send p insert x)) nodes))
  
  ;; insert non specific data into a node's text-field%
  (define (set-node-text node data)
    (send (send node get-editor) 
          insert (to-string data)))
  
  ;; get the text from a node
  (define (get-node-text node)
    (send (send node get-editor) get-text))
  
  ;; partial [e]valuation
  (define (set-node-value node value)
    (send node set-value value))
  
  (define (get-node-value node)
    (send node value))
  
  ;; convert given object to string
  (define (to-string x)
    (cond ((string? x) x)
          ((char? x) (list->string (list x)))
          ((number? x) (number->string x))
          ((symbol? x) (symbol->string x))
          ((list? x) (apply string-append (map to-string x))) 
          (else (error "don't know how to convert to string: " x))))
  
  ;; copypaste 
  (define (copypaste pb)
    (debug 1 "selection: " (selected-snips pb))
    )
  
  ;; decor
  ;; brushes/ pens see -> 6.15  pen%
  ;; colours -> 6.7  color-database<%>
  
  ;; function links -> active/inactive 
  (define pen1 (send the-pen-list find-or-create-pen "Red" 1 'solid))
  (define brush1 (send the-brush-list find-or-create-brush "orange" 'solid))
  (define pen2 (send the-pen-list find-or-create-pen "DarkSeaGreen" 1 'solid))
  (define brush2 (send the-brush-list find-or-create-brush "Gold" 'solid))
  ;; data links -> active/inactive 
  (define pen3 (send the-pen-list find-or-create-pen "orange" 1 'solid))
  (define brush3 (send the-brush-list find-or-create-brush "yellow" 'solid))
  (define pen4 (send the-pen-list find-or-create-pen "DarkSeaGreen" 1 'solid))
  (define brush4 (send the-brush-list find-or-create-brush "Beige" 'solid))
  
  ;;;;;;;;; ; ;   ;;      ;
  ;;
  ;; re-traversal
  ;;
  ;;;;;;;;; ;;  ;;  
  
  ;; build a tree from a given list, starting from the node% parent, 
  ;; drawing to the graph-pasteboard% pb .. .
  (define (draw-parse-tree tree x y parent pb)
    (if (list? tree)
        (begin
          (let ((size 5)
                (root (car tree))
                (node (make-node-snip)))    
            (debug 2 "root: ~a ~%" root)         
            (draw-parse-tree root x y parent pb)
            ;; function node  
            (send pb insert node)
            (add-links node parent pen1 pen2 brush1 brush2)
            (send (send node get-editor) insert (to-string root))
            ;; subtrees, or args
            (for-each
             (lambda (child)        
               (if (list? child)  
                   (draw-parse-tree child x y node pb)
                   (let ((sibling (make-node-snip)))         
                     (send pb insert sibling)
                     (add-links sibling node pen3 pen4 brush3 brush4)
                     (send (send sibling get-editor) insert (to-string child)))))
             (cdr tree))))))
  
  ;; tree colouring, using pens, brushes and wax.
  ;; where the given node is the root of the tree to be traversed 
  (define (colour-tree node pb)
    (let ([parents (send node get-parents)])
      (if (not (empty? parents))
          (begin (debug 1 "tree-coloring: ~a ~%" node)
                 (colour-links node 
                               (list pen1 pen2 brush1 brush2)  ;; functions
                               (list pen3 pen4 brush3 brush4)) ;; elements
                 ;; function node  
                 ;;   - set pens and brushes...
                 ;; subtrees, or args
                 (for-each
                  (lambda (parent)        
                    (colour-tree parent pb))
                  parents)))))
  
  ;; link colouring, of each link from a given node
  ;; *-colours are each a list of 4 pens & brushes
  (define (colour-links node fcn-colours elt-colours)
    (let* ([parents (send node get-parents)]
           [links (send node get-parent-links)])
      (let-values ([(fp1 fp2 fb1 fb2) (split-colours fcn-colours)]
                   [(ep1 ep2 eb1 eb2) (split-colours elt-colours)])
        (debug 1 "link-coloring: ~a  -> ~a ~%" node parents)
        (if (not (empty? links))
            (for-each 
             (lambda (parent)
               (if (empty? (send parent get-parents))
                   ;; elements)
                   (let ([link (find-link node parent)])    
                     (set-colours link ep1 ep2 eb1 eb2)) 
                   ;; functions
                   (let ([link (find-link node parent)])  
                     (set-colours link fp1 fp2 fb1 fb2))))   
             parents)))))
  
  ;; find a link from one node to another
  (define (find-link n1 n2)
    (let ([links (send n1 get-parent-links)]
          [result #f])
      (map (lambda (link)
             (debug 2 "finding link: ~a -> ~a~%" n2 (link-snip link))
             (if (equal? (link-snip link) n2) 
                 (set! result link))) links) result))
  
  ;; relabel
  ;;  note that this uses a mutable global so is not threadsafe
  (define *travail* 0)
  
  (define (re-label! link)
    (let ([label (link-label link)])
      (set! *travail* (+ 1 *travail*))
      (set-link-label! link (string-append (if label label "")
                                           (format ".~a." *travail*)))))
  
  
  ;; multicolour
  (define (set-colours link p1 p2 b1 b2)
    (set-link-dark-pen! link p1)
    (set-link-dark-brush! link b1)
    (set-link-light-pen! link p2)
    (set-link-light-brush! link b2))
  
  ;; return pens & brushes form a list as mulitple-values
  (define (split-colours c)
    (values (list-ref c 0) 
            (list-ref c 1) 
            (list-ref c 2) 
            (list-ref c 3)))
  
  ;;;; ; ;;; ;  ;   ;  ; ; ;   ;
  ;;
  ;; translation, evaluation, circumspection
  ;;
  ;;;;;; ;   ;;  ;
  
  ;; eval [sub]graph from a node. ..
  ;;  absolutely no chekcing or error handling yet.
  (define (eval-tree node)
    (set-node-text node 
                   (eval (tree->sexp (car (send node get-parents))))))
  
  ;; traverse a tree [or graph] to create a corresponding s-expresion
  ;; doesnt cope with cycles, nor multiple children (if a node has muliple
  ;; children, it is translated into separate expressions)  
  (define (tree->sexp node)
    (let ([parents (send node get-parents)]
          [data (get-node-text node)]
          [out ()])
      (if (not (null? parents))
          (set! out (cons (read-from-string data) 
                          (reverse (map tree->sexp parents))))
          (set! out (read-from-string data)))
      (debug 1 "tree->sexp: ~a ~%" out)         
      out))

  ;; return a list of the selected snips
  (define (selected-snips pb) 
    (let* ((snip (send pb find-next-selected-snip #f))
           (selection (list snip)))
      (while snip
        (set! snip (send pb find-next-selected-snip snip))
        (if snip
            (set! selection (cons snip selection)) #f))
      selection))

  
  ;; convert a given selection to a (pseudonymous) function, given a list of
  ;; nodes, and a pasteboard to draw to. namespace is currently unspecified,
  ;; values not yet multiple.
  (define (encapsulate selection pb)
    (let* ((fname (string->symbol (symbol->string (gensym "q-"))))
          (nodes selection)
          (inputs (find-inputs nodes))
          (outputs (find-outputs nodes)))

      (debug 1 "function: ~a~%" fname)
      (debug 1 "nodes: ~a~%" nodes)
      (debug 1 "input: ~a~%" inputs)
      (debug 1 "outpt: ~a~%" outputs)

      ;; subtree -> leaves ie. no inputs, single output
      (cond ((empty? inputs)
             (debug 1 "grnks...~%")
             (let* ((fnode (make-node-snip))
                   (prune (caar outputs)) ;; map -> multiple
                   (graft (cadar outputs)))
               
               (debug 1 "prune ~a~%" prune)
               (debug 1 "graft ~a -> ~a ~% " graft (send graft get-parents))
               (send pb insert fnode)
               (add-links fnode graft pen1 pen2 brush1 brush2)
               (send (send fnode get-editor) insert (format "(~a)" (to-string fname)))
               (send graft remove-parent prune)
               (debug 1 "fdef ~a ~%"
                      (eval `(define ,fname (lambda () ,(tree->sexp prune)))))
                           
      )))))

            
            
  ;; find the nodes leading into/outof a subgraph, given as a list returns a
  ;; list of lists (node in the subgraph, followed by nodes to which it
  ;; connects)

  (define (find-inputs nodes)
    (if nodes
        (let ((inputs
               (filter
                (lambda (l) (< 1 (length l)))
                (map
                  (lambda (node)
                    (cons node (remove* nodes (send node get-parents))))
                  nodes))))
          inputs)
        #f))
  
  (define (find-outputs nodes)
    (if nodes
        (let ((outputs
               (filter
                (lambda (l) (< 1 (length l)))
                (map
                  (lambda (node)
                    (cons node (remove* nodes (send node get-children))))
                  nodes))))
          outputs)
        #f))
  

  ) ;; end of module