{-# LANGUAGE DataKinds           #-}
{-# LANGUAGE GADTs               #-}
{-# LANGUAGE LambdaCase          #-}
{-# LANGUAGE RecordWildCards     #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TemplateHaskell     #-}
{-# LANGUAGE TupleSections       #-}

module Data.Graph.Dynamic.EulerTour.Tests where

import           Control.Monad                        (foldM, forM_)
import           Control.Monad.ST
import           Data.Graph.Dynamic.Action
import qualified Data.Graph.Dynamic.EulerTour         as ET
import           Data.Graph.Dynamic.Internal.Tree     (Tree)
import qualified Data.Graph.Dynamic.Program           as Program
import qualified Data.Graph.Dynamic.Slow              as Slow
import           Data.Hashable                        (Hashable)
import           Data.List                            (mapAccumL, foldl')
import           Data.Maybe                           (catMaybes)
import           Test.Framework
import           Test.Framework.Providers.QuickCheck2
import           Test.Framework.TH
import qualified Test.QuickCheck                      as QC

runForestAction
    :: (Eq v, Hashable v, Monoid a, Tree tree)
    => ET.Forest tree a s v -> [Bool] -> Action t v -> ST s [Bool]
runForestAction etf xs (Cut x y) = ET.cut etf x y >> return xs
runForestAction etf xs (Link x y) = ET.link etf x y >> return xs
runForestAction etf xs (Toggle x y) = ET.edge etf x y >>= \case
  True -> ET.cut etf x y >> return xs
  False -> ET.link etf x y >> return xs
runForestAction etf xs (Query x y) =
  ET.connected etf x y >>= \q -> return (q:xs)

checkActions :: QC.Positive Int -> [Action t Int] -> QC.Property
checkActions (QC.Positive n) actions = slowResult QC.=== result
  where
    actions' = map (fmap (`mod` n)) actions
    initialGraph = Slow.edgeless [0..n-1]
    slowResult = catMaybes $ snd $ mapAccumL runSlowForestAction initialGraph actions'
    result :: [Bool]
    result = runST $ do
      initialForest <- ET.edgeless' [0..n-1]
      results <- foldM (runForestAction initialForest) [] actions'
      return $ reverse results

prop_forest_linkcut :: QC.Positive Int -> [Action 'LinkCut Int] -> QC.Property
prop_forest_linkcut = checkActions

prop_forest_toggle :: QC.Positive Int -> [Action 'Toggl Int] -> QC.Property
prop_forest_toggle = checkActions

prop_program :: Program.IntTreeProgram -> ()
prop_program (Program.IntTreeProgram p) = runST $ do
    f <- ET.empty'
    Program.runProgram f p

prop_spanningTree :: QC.Positive Int -> [Action 'LinkCut Int] -> QC.Property
prop_spanningTree (QC.Positive n) actions =
    Slow.isSpanningForest spanningForest slow QC.=== True
  where
    actions' = map (fmap (`mod` n)) actions

    spanningForest = runST $ do
        et <- ET.edgeless' [0 .. n - 1]
        forM_ actions' $ \action -> runForestAction et [] action
        ET.spanningForest et

    slow = foldl'
        (\g a -> fst $ runSlowForestAction g a)
        (Slow.edgeless [0 .. n - 1])
        actions'

tests :: Test
tests = $testGroupGenerator