{-# LANGUAGE LambdaCase #-}
module Algorithms.Geometry.DelaunayTriangulation.DTSpec where

import Util

import Test.Hspec
import Control.Lens
import Data.Geometry
import Data.Maybe(mapMaybe, fromJust)
import Algorithms.Geometry.DelaunayTriangulation.Types
import qualified Algorithms.Geometry.DelaunayTriangulation.DivideAndConqueror as DC
import qualified Algorithms.Geometry.DelaunayTriangulation.Naive              as Naive
import qualified Data.List.NonEmpty as NonEmpty
import Data.Geometry.Ipe
import Data.Ext
import Data.Traversable(traverse)
import qualified Data.CircularList.Util as CU
import qualified Data.Map as M
import qualified Data.Vector as V


dtEdges :: (Fractional r, Ord r)
        => NonEmpty.NonEmpty (Point 2 r :+ p) -> [(VertexID, VertexID)]
dtEdges = tEdges . DC.delaunayTriangulation

take'   :: Int -> NonEmpty.NonEmpty a -> NonEmpty.NonEmpty a
take' i = NonEmpty.fromList . NonEmpty.take i

--------------------------------------------------------------------------------

spec :: Spec
spec = do
  describe "Testing Divide and Conqueror Algorithm for Delaunay Triangulation" $ do
    it "singleton " $ do
      dtEdges (take' 1 myPoints) `shouldBe` []
    toSpec (TestCase "myPoints" myPoints)
    toSpec (TestCase "myPoints'" myPoints')
    ipeSpec

ipeSpec :: Spec
ipeSpec = testCases "test/Algorithms/Geometry/SmallestEnclosingDisk/manual.ipe"

testCases    :: FilePath -> Spec
testCases fp = (runIO $ readInput fp) >>= \case
    Left e    -> it "reading Delaunay Triangulation disk file" $
                   expectationFailure $ "Failed to read ipe file " ++ show e
    Right tcs -> mapM_ toSpec tcs


-- | Point sets per color, Crosses form the solution
readInput    :: FilePath -> IO (Either ConversionError [TestCase Rational])
readInput fp = fmap f <$> readSinglePageFile fp
  where
    f page = [ TestCase "?" $ fmap (\p -> p^.core.symbolPoint :+ ()) pSet
             | pSet <- byStrokeColour' syms
             ]
      where
        syms = page^..content.traverse._IpeUse
        byStrokeColour' = mapMaybe NonEmpty.nonEmpty . byStrokeColour



data TestCase r = TestCase { _color    :: String
                           , _pointSet :: NonEmpty.NonEmpty (Point 2 r :+ ())
                           } deriving (Show,Eq)


toSpec                    :: (Fractional r, Ord r, Show r) => TestCase r -> Spec
toSpec (TestCase c pts) = describe ("testing on " ++ c ++ " points") $ do
                            sameAsNaive c pts

sameAsNaive       :: (Fractional r, Ord r, Show p, Show r)
                  => String -> NonEmpty.NonEmpty (Point 2 r :+ p) -> Spec
sameAsNaive s pts = it ("Divide And Conqueror same answer as Naive on " ++ s) $
                      (Naive.delaunayTriangulation pts
                       `sameEdges`
                       DC.delaunayTriangulation pts) `shouldBe` True


sameEdges             :: Triangulation p r -> Triangulation p r -> Bool
triA `sameEdges` triB = all sameAdj . M.assocs $ mapping'
  where
    sameAdj (a, b) = (f $ adjA V.! a) `CU.isShiftOf` (adjB V.! b)

    adjA = triA^.neighbours
    adjB = triB^.neighbours

    mapping' = M.fromList $ zip (M.elems $ triA^.vertexIds) (M.elems $ triB^.vertexIds)

    f = fmap (fromJust . flip M.lookup mapping')

myPoints :: NonEmpty.NonEmpty (Point 2 Rational :+ ())
myPoints = NonEmpty.fromList . map ext $
           [ point2 1  3
           , point2 4  26
           , point2 5  17
           , point2 6  7
           , point2 12 16
           , point2 19 4
           , point2 20 0
           , point2 20 11
           , point2 23 23
           , point2 31 14
           , point2 33 5
           ]

myPoints' :: NonEmpty.NonEmpty (Point 2 Rational :+ ())
myPoints' = NonEmpty.fromList . map ext $
            [ point2 64  736
            , point2 96 688
            , point2 128 752
            , point2 160 704
            , point2 128 672
            , point2 64 656
            , point2 192 736
            , point2 208 704
            , point2 192 672
            ]