Use comonads

src/Main.hs

@@ -1,4 +1,5 @@
 {-# LANGUAGE DeriveAnyClass      #-}
+{-# LANGUAGE DeriveFunctor       #-}
 {-# LANGUAGE DeriveGeneric       #-}
 {-# LANGUAGE OverloadedStrings   #-}
 {-# LANGUAGE RecordWildCards     #-}
@@ -9,24 +10,33 @@ module Main where
 
 import           Codec.Picture
 import           Codec.Picture.Extra   (scaleBilinear)
+import           Control.Comonad       (extend, extract)
+import           Control.Comonad.Store (Store, experiment, seek, store)
 import           Control.Exception     (SomeException, try)
 import           Control.Monad         (forM_, void, when)
 import           Data.Bits
 import qualified Data.BKTree           as BK
 import           Data.List             (foldl')
+import           Data.Maybe            (fromMaybe)
 import           Data.Word             (Word64)
 import           Options.Generic
 import           Pipes
 import           Pipes.Files
 import qualified Pipes.Prelude         as P
 import           Pipes.Safe            (runSafeT)
-import           System.Directory    (createDirectoryIfMissing, createFileLink)
+import           System.Directory      (createDirectoryIfMissing,
+                                        createFileLink)
 import           System.FilePath       (takeFileName, (</>))
 
 
+data Alg = Average | DHash deriving (Read, Show, Generic)
+
+instance ParseField Alg
+
 data Cmd = Cmd { source    :: FilePath
                , target    :: FilePath
-               , recursive :: Bool
+               , range     :: Maybe Int
+               , algorithm :: Maybe Alg
                } deriving (Show, Generic, ParseRecord)
 
 data Fingerprint =
@@ -40,29 +50,48 @@ instance BK.Metric Fingerprint where
     let xored = a `xor` b
     in foldr (\shiftA acc -> acc + if 1 `shift` shiftA .&. xored > 0 then 1 else 0) 0 [0..63]
 
-
-fingerprint :: DynamicImage -> Word64
-fingerprint = hash . grey . scale . convertRGB8
+fingerprint :: Alg -> DynamicImage -> Word64
+fingerprint alg = hash . grey . scale . convertRGB8
   where
     scale :: Image PixelRGB8 -> Image PixelRGB8
     scale = scaleBilinear 8 8
     grey :: Image PixelRGB8 -> Image Pixel8
     grey = pixelMap (\(PixelRGB8 r g b) -> ceiling ((fromIntegral r * (0.3 :: Double)) + (fromIntegral g * 0.59) + (fromIntegral b * 0.11)))
+    indexes = [(x,y) | x <- [0..7], y <- [0..7]]
+    hashWith :: Image Pixel8 -> (Store (Int, Int) Pixel8 -> Bool) -> Word64
+    hashWith img f =
+      let s = store (uncurry (pixelAt img)) (0,0)
+          img' = extend f s
+          at pos = extract $ seek pos img'
+      in foldr (\(shiftA, b) acc -> if b then 1 `shift` shiftA .|. acc else acc) 0 $ zip [0..] $ map at indexes
     hash :: Image Pixel8 -> Word64
-    hash img = -- the average fingerprint method
-      let avg = fromIntegral (foldl' (\acc (x,y) -> acc + fromIntegral (pixelAt img x y)) (0 :: Int) [(x,y) | x <- [0..7], y <- [0..7]] `div` 64)
-      in foldr (\(shiftA, b) acc -> if b then 1 `shift` shiftA .|. acc else acc) 0 $ zip [0..] [pixelAt img x y > avg | x <- [0..7], y <- [0..7]]
+    hash img = case alg of
+                Average ->
+                  let avg = fromIntegral (foldl' (\acc (x,y) -> acc + fromIntegral (pixelAt img x y)) (0 :: Int) [(x,y) | (x,y) <- indexes] `div` 64)
+                  in img `hashWith` (avgAlg avg)
+                DHash -> img `hashWith` dAlg
+    dAlg :: Store (Int, Int) Pixel8 -> Bool
+    dAlg img = case experiment (\(x,y) -> [(x,y), (succ x `mod` 8, y)]) img of
+                    [l,r] -> l > r
+                    _     -> False
+    avgAlg :: Pixel8 -> Store (Int, Int) Pixel8 -> Bool
+    avgAlg avg img = extract img > avg
 
 main :: IO ()
 main = do
   Cmd{..} <- getRecord "Image duplicate finder"
-  -- XXX: This is a really long line, split it up
-  index <- runSafeT (P.fold (\acc -> either (const acc) (\x -> x `seq` BK.insert x acc)) BK.empty id (find source (glob "*.jpg" <> regular) >-> P.mapM (\path -> liftIO (putStrLn path) >> fmap (path,) <$> liftIO (readImage path)) >-> P.map (fmap (\(path, img) -> Fingerprint path (fingerprint img)))))
+  index <- runSafeT (P.fold foldTree BK.empty id (find source (glob "*.jpg" <> regular)
+    >-> P.mapM readImg
+    >-> P.map (fmap (toFingerprint (fromMaybe Average algorithm)))))
   forM_ index $ \fp -> do
-    let similar = BK.search 1 fp index
+    let similar = BK.search (fromMaybe 1 range) fp index
     when (length similar > 1) $ do
       print similar
       let targetDir = target </> show (hash fp)
       createDirectoryIfMissing True targetDir
       forM_ similar $ \fp' ->
         void $ try @SomeException (createFileLink (imagePath fp') (targetDir </> takeFileName (imagePath fp')))
+  where
+    readImg path = liftIO (putStrLn path >> fmap (path,) <$> readImage path)
+    foldTree acc = either (const acc) (\x -> x `seq` BK.insert x acc)
+    toFingerprint alg (path,img) = Fingerprint path (fingerprint alg img)