module BinSearchTreeImage

/* Instructions:

(1) copy BinTree.(i/d)cl and BinSearchTree.(i/d)cl from Practicum to
    {iTasks-SDK}\Experiments\SVG_tests\
    
(2) in these modules change the type

    :: Tree a = Node a (Tree a) (Tree a) | Leaf
    
    to
    
    :: BTree a = BLeaf | BNode a (BTree a) (BTree a)	// ORDER OF DATACONSTRUCTORS IS ESSENTIAL!!
    
    and adapt the corresponding function definitions.
    
(3) this main file (BinSearchTreeImage.icl) must be in the same folder:
    {iTasks-SDK}\Experiments\SVG_tests\
    
(4) create a new project and set de environment to 'iTasks'

(5) Bring-Up-To-Date and start generated application

(6) Open a browser and navigate to localhost.
    The application creates two tasks:
    (a) The task on the left allows you to enter subsequent elements that are inserted in the tree, one after another.
    (b) The task on the right must be finished by you by writing the function treeImage. This function must render the tree structure in such a way
        that Nodes of the same depth have the same y-coordinate, and the root having the smallest y-coordinate.
*/

import iTasks								// de algemene iTask API
import iTasks.API.Extensions.SVG.SVGlet		// specialiseer task editors
from   StdFunc import flip

import BinSearchTree						// type definition of Tree and sample trees z0 .. z8
derive class iTask BTree

Start				:: *World -> *World
Start world			= startEngine [publish "/" (WebApp []) (\_ -> task)] world

task				:: Task [Int]
task				= withShared [] (\sharedList ->
						(  (updateSharedInformation (Title "Edit list") [] sharedList <<@ ArrangeHorizontal)
						   -||-
						   (viewSharedInformation (Title "Tree view") [imageView treeImage` (\_ _ -> Nothing)] sharedList <<@ ArrangeHorizontal)
						) <<@ ArrangeHorizontal
					  ) <<@ FullScreen

font				= normalFontDef "Courier New" fonthoogte
fonthoogte			= 14.0

treeImage`			:: [Int] *TagSource -> Image m
treeImage` nrs tags	= fst(treeImage (foldl (flip insertTree) BLeaf nrs) tags)

TMargin = 10.0

treeImage			:: (BTree Int) *TagSource -> (Image m, *TagSource)
treeImage BLeaf ts = (margin (px zero, px TMargin) (circle (px fonthoogte)), ts)
treeImage (BNode x t1 t2) [(tg1, utg1),(tg2, utg2):ts]
= (above (repeat AtMiddleX) [] [textbox, lines, subtrees] Nothing, ts2)
	where
		(i1, ts1) = treeImage t1 ts
		(i2, ts2) = treeImage t2 ts1
		subtrees = beside (repeat AtTop) [] [tag utg1 i1, tag utg2 i2] Nothing
		box = rect (textxspan font (toString x)) (px fonthoogte) <@< {fill=toSVGColor "none"}
		lines_with_subtrees = above (repeat AtMiddleX) [] [lines, subtrees] Nothing
		textbox = overlay (repeat (AtMiddleX, AtMiddleY)) [] [box, text font (toString x)] Nothing
		lines = beside (repeat AtBottom) [] [
			empty (((imagexspan tg1) /. 2) - ((imagexspan tg2) /. 2)) (px TMargin), // ignored if negative
			line Nothing Slash ((imagexspan tg2) /. 2) (px TMargin),
			line Nothing Backslash ((imagexspan tg1) /. 2) (px TMargin),
			empty (((imagexspan tg2) /. 2) - ((imagexspan tg1) /. 2)) (px TMargin)] // ignored if negative
			Nothing