{-# OPTIONS_GHC -F -pgmF htfpp #-}

module DPM.Core.ReverseDependencies where

import qualified Data.Map as Map
import Test.Framework

import DPM.Core.DataTypes ( PatchID )

type Map = Map.Map

data RevDeps a = RevDeps  { rd_map :: Map a [a] }

type PatchRevDeps = RevDeps PatchID

getRevDeps :: Ord a => RevDeps a -> a -> [a]
getRevDeps rd key = Map.findWithDefault [] key (rd_map rd)

getMaxChainLen :: Ord a => RevDeps a -> a -> Int
getMaxChainLen rd key =
    case Map.lookup key (rd_map rd) of
      Nothing -> 0
      Just l -> 1 + maximum (map (getMaxChainLen rd) l)

buildRevDeps :: Ord a => [(a, [a])] -> RevDeps a
buildRevDeps list = RevDeps $ foldr add Map.empty list
    where
      add (x,ys) m0 =
          foldr (\y m -> Map.insertWith (++) y [x] m) m0 ys

prop_hasMapping :: [(Int, [Int])] -> Bool
prop_hasMapping list =
    let rd = buildRevDeps list
    in all (hasMapping rd) list
    where
      hasMapping rd (val, keys) =
          all (\k -> val `elem` getRevDeps rd k) keys