module PriorityQueue where
import qualified Data.List as L

type Point = (Int, Int)

data Node = Node { point :: Point
                  ,parent :: Maybe Node
                  ,g :: Double
                  ,h :: Double
                 } deriving (Show)

instance Eq Node where
  -- (==) = on (==) (g + h) -- miks ei toimi
  (Node a1 parent1 g1 h1) == (Node a2 parent2 g2 h2) = (g1 + h1) == (g2 + h2)

instance Ord Node where
  -- (>=) = on (>=) (g + h) -- miks ei toimi
  (Node a1 parent1 g1 h1) `compare` (Node a2 parent2 g2 h2) = (g1 + h1) `compare` (g2 + h2)

priority :: Node -> Double
priority (Node a parent g h) = g + h

getHighestPrioElem :: [Node] -> Maybe Node
getHighestPrioElem [] = Nothing
getHighestPrioElem xs = Just $ head (L.sort xs)

popHighestPrioElem :: [Node] -> Maybe [Node]
popHighestPrioElem [] = Nothing
popHighestPrioElem xs = Just $ tail (L.sort xs)

insertWithPriority :: Node -> [Node] -> [Node]
insertWithPriority node xs
 = L.sort (node:xs)