module DecisionTree
    where

import IO
import List

data DecisionTree 
    = Test String String String DecisionTree DecisionTree
    | Value String Double Double
    deriving (Show, Eq, Ord, Read)

readDecisionTree :: String -> DecisionTree
readDecisionTree s = 
    let (_, wholeTree, subTrees) = readDecisionTree' False subTrees (filter (/=[]) (lines s))
    in  wholeTree

readDecisionTree' :: Bool -> [(String,DecisionTree)] -> [String] -> ([String], DecisionTree, [(String,DecisionTree)])
readDecisionTree' _ subTrees [] = ([], Value "" 0 0, subTrees)
readDecisionTree' areValue subTrees (x:xs) =
    let (lineDepth, lineType, values') = readLine x
	subTreesX = if xs /= [] && "Subtree" `isPrefixOf` head xs
		      then readSubTrees subTrees xs
		      else subTrees
	(xs',   lhs,   subTrees')   = readDecisionTree' False subTreesX  xs
	(xs'' , rhs,   subTrees'')  = readDecisionTree' False subTrees' xs'
	(xs''', other, subTrees''') = readDecisionTree' True  subTreesX  xs
	values = values' ++ ["0.0"]
    in  if lineType   -- are we a value
	  then if areValue
		 then (xs,    Value (values !! 3) (read (values !! 4)) (read (values !! 5)), subTreesX)
	         else (xs''', Test (values !! 0) (values !! 1) (values !! 2) 
		                (Value (values !! 3) (read (values !! 4)) (read (values !! 5)))
		                other,
	               subTrees''')
	  else if '[' == head (last values')   -- are we a subtree?
	         then case lookup (last values') subTreesX of
		        Nothing -> error "could not find subtree"
		        Just dt -> (xs'', Test (values !! 0) (values !! 1) (values !! 2) dt lhs, subTrees')
		 else (xs'', Test (values !! 0) (values !! 1) (values !! 2) lhs rhs, subTrees'')

readSubTrees subTrees [] = subTrees
readSubTrees subTrees (x:xs)
    | "Subtree" `isPrefixOf` x =
	let name = (words x) !! 1
	    treeDef = takeWhile (\x -> not ("Subtree" `isPrefixOf` x)) xs
	    rest    = dropWhile (\x -> not ("Subtree" `isPrefixOf` x)) xs
	    (_, thisDT, _) = readDecisionTree' False subTrees treeDef
	in  readSubTrees ((name,thisDT):subTrees) xs

readLine :: String -> (Int,Bool,[String])  -- True = Value, False = Test
readLine s = (length (elemIndices '|' s), ')' `elem` s, vals)
    where vals = words $
		 map (\x -> if x `elem` ":()/" then ' ' else x) $
		 dropWhile (`elem` "| ") s

simpleDT = 
   ["localDefCountSum <= 4 : p (101.0/6.0)",
    "localDefCountSum > 4 : u (7.0)"]

simpleDT2 = [
    "isArgument0 = t: u (33.0/1.4)",
    "isArgument0 = f:",
    "|   isArgument1 = f: u (9.0/1.3)",
    "|   isArgument1 = t:",
    "|   |   isRecursive1 = t: s (945.0/39.8)",
    "|   |   isRecursive1 = f: u (2.0/1.0)"]

{-
Test "isArgument0" "=" "t" 
  (Value "u" 33.0 1.4) 
  (Test "isArgument0" "=" "f" 
    (Test "isArgument1" "=" "f" 
      (Value "u" 9.0 1.3) 
      (Test "isArgument1" "=" "t" 
        (Test "isRecursive1" "=" "t" 
  	  (Value "s" 945.0 39.8) 
	  (Value "u" 2.0 1.0)) 
	(Value "" 0.0 0.0))) 
    (Value "" 0.0 0.0))
-}

simpleDT3 = [
    "isArgument0 = t: u (33.0/1.4)",
    "isArgument0 = f:",
    "|   isArgument1 = f :[S1]",
    "|   isArgument1 = t:",
    "|   |   isRecursive1 = t: s (945.0/39.8)",
    "|   |   isRecursive1 = f: u (2.0/1.0)",
    "",
    "Subtree [S1]",
    "",
    "localDefCount <= 15 : u (281.0/1.4)",
    "localDefCount > 15 : s (139.0/11.8)"]