{-# LANGUAGE DataKinds #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE OverloadedLabels #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE PolyKinds #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE UndecidableInstances #-}
module Main where

import Control.Monad.Trans.Class (lift)
import Control.Monad.IO.Class (liftIO)
import Control.Monad.Trans.State
import Data.Bifunctor
import Data.Int (Int64)
import Data.Map.Strict (Map)
import qualified Data.Map.Strict as Map
import qualified Data.Text as T
import Hedgehog
import qualified Hedgehog.Gen as Gen
import qualified Hedgehog.Range as Range
import Test.Tasty
import Test.Tasty.Hedgehog

import Array
import AST
import AST.Pretty
import AST.UnMonoid
import CHAD.Top
import CHAD.Types
import CHAD.Types.ToTan
import Compile
import qualified Example
import qualified Example.GMM as Example
import ForwardAD
import Interpreter
import Interpreter.Rep
import Language
import Simplify


data SimplIters = SimplIters Int | SimplFix
  deriving (Show)

simplifyIters :: SimplIters -> SList STy env -> Ex env t -> Ex env t
simplifyIters iters env | Dict <- envKnown env =
  case iters of
    SimplIters n -> simplifyN n
    SimplFix -> simplifyFix

-- In addition to the gradient, also returns the pretty-printed differentiated term.
gradientByCHAD :: forall env. SimplIters -> SList STy env -> Ex env (TScal TF64) -> SList Value env -> (String, (Double, SList Value (D2E env)))
gradientByCHAD simplIters env term input =
  let dterm = simplifyIters simplIters env $ ELet ext (EConst ext STF64 1.0) $ chad' defaultConfig env term
      (out, grad) = interpretOpen False input dterm
  in (ppExpr env dterm, (out, unTup vUnpair (d2e env) (Value grad)))

-- In addition to the gradient, also returns the pretty-printed differentiated term.
gradientByCHAD' :: SimplIters -> SList STy env -> Ex env (TScal TF64) -> SList Value env -> (String, (Double, SList Value (TanE env)))
gradientByCHAD' simplIters env term input =
  second (second (toTanE env input)) $
    gradientByCHAD simplIters env term input

gradientByForward :: SList STy env -> Ex env (TScal TF64) -> SList Value env -> SList Value (TanE env)
gradientByForward env term input = drevByFwd env term input 1.0

closeIsh' :: Double -> Double -> Double -> Bool
closeIsh' h a b =
  abs (a - b) < h || (let scale = min (abs a) (abs b) in scale > 10*h && abs (a - b) / scale < h)

closeIsh :: Double -> Double -> Bool
closeIsh = closeIsh' 1e-5

data a :$ b = a :$ b deriving (Show) ; infixl :$

-- An empty name means "no restrictions".
data TplConstr = C String  -- ^ name; @""@ means anonymous
                   Int     -- ^ minimum value to generate

type family DimNames n where
  DimNames Z = ()
  DimNames (S Z) = TplConstr
  DimNames (S n) = DimNames n :$ TplConstr

type family Tpl t where
  Tpl (TArr n t) = DimNames n
  Tpl (TPair a b) = (Tpl a, Tpl b)
  -- If you add equations here, don't forget to update genValue! It currently
  -- just emptyTpl's things out.
  Tpl _ = ()

data a :& b = a :& b deriving (Show) ; infixl :&

type family TemplateE env where
  TemplateE '[] = ()
  TemplateE '[t] = Tpl t
  TemplateE (t : ts) = TemplateE ts :& Tpl t

emptyDimNames :: SNat n -> DimNames n
emptyDimNames SZ = ()
emptyDimNames (SS SZ) = C "" 0
emptyDimNames (SS n@SS{}) = emptyDimNames n :$ C "" 0

emptyTpl :: STy t -> Tpl t
emptyTpl (STArr n _) = emptyDimNames n
emptyTpl (STPair a b) = (emptyTpl a, emptyTpl b)
emptyTpl (STScal _) = ()
emptyTpl _ = error "too lazy"

emptyTemplateE :: SList STy env -> TemplateE env
emptyTemplateE SNil = ()
emptyTemplateE (t `SCons` SNil) = emptyTpl t
emptyTemplateE (t `SCons` ts@SCons{}) = emptyTemplateE ts :& emptyTpl t

genShape :: SNat n -> DimNames n -> StateT (Map String Int) Gen (Shape n)
genShape = \n tpl -> do
  sh <- genShapeNaive n tpl
  let sz = shapeSize sh
      factor = sz `div` 100 + 1
  return (shapeDiv sh factor)
  where
    genShapeNaive :: SNat n -> DimNames n -> StateT (Map String Int) Gen (Shape n)
    genShapeNaive SZ () = return ShNil
    genShapeNaive (SS SZ) name = ShCons ShNil <$> genNamedDim name
    genShapeNaive (SS n@SS{}) (tpl :$ name) = ShCons <$> genShapeNaive n tpl <*> genNamedDim name

    genNamedDim :: TplConstr -> StateT (Map String Int) Gen Int
    genNamedDim (C "" lo) = genDim lo
    genNamedDim (C name lo) = gets (Map.lookup name) >>= \case
      Nothing -> do
        dim <- genDim lo
        modify (Map.insert name dim)
        return dim
      Just dim -> return dim

    genDim :: Int -> StateT (Map String Int) Gen Int
    genDim lo = Gen.integral (Range.linear lo 10)

    shapeDiv :: Shape n -> Int -> Shape n
    shapeDiv ShNil _ = ShNil
    shapeDiv (sh `ShCons` n) f = shapeDiv sh f `ShCons` (n `div` f)

genArray :: STy a -> Shape n -> Gen (Value (TArr n a))
genArray t sh =
  Value <$> arrayGenerateLinM sh (\_ ->
              unValue <$> evalStateT (genValue t (emptyTpl t)) mempty)

genValue :: STy t -> Tpl t -> StateT (Map String Int) Gen (Value t)
genValue topty tpl = case topty of
  STNil -> return (Value ())
  STPair a b -> liftV2 (,) <$> genValue a (fst tpl) <*> genValue b (snd tpl)
  STEither a b -> Gen.choice [liftV Left <$> genValue a (emptyTpl a)
                             ,liftV Right <$> genValue b (emptyTpl b)]
  STMaybe t -> Gen.choice [return (Value Nothing)
                          ,liftV Just <$> genValue t (emptyTpl t)]
  STArr n t -> genShape n tpl >>= lift . genArray t
  STScal sty -> case sty of
    STF32 -> Value <$> Gen.realFloat (Range.linearFracFrom 0 (-10) 10)
    STF64 -> Value <$> Gen.realFloat (Range.linearFracFrom 0 (-10) 10)
    STI32 -> Value <$> Gen.integral (Range.linearFrom 0 (-10) 10)
    STI64 -> Value <$> Gen.integral (Range.linearFrom 0 (-10) 10)
    STBool -> Gen.choice [return (Value False), return (Value True)]
  STAccum{} -> error "Cannot generate inputs for accumulators"

genEnv :: SList STy env -> TemplateE env -> StateT (Map String Int) Gen (SList Value env)
genEnv SNil () = return SNil
genEnv (t `SCons` SNil) tpl = SCons <$> genValue t tpl <*> pure SNil
genEnv (t `SCons` env@SCons{}) (tmpl :& tpl) = SCons <$> genValue t tpl <*> genEnv env tmpl

adTest :: forall env. KnownEnv env => TestName -> Ex env (TScal TF64) -> TestTree
adTest name = adTestCon name (const True)

adTestCon :: forall env. KnownEnv env => TestName -> (SList Value env -> Bool) -> Ex env (TScal TF64) -> TestTree
adTestCon name constr term =
  let env = knownEnv
  in adTestGen name term (Gen.filter constr (evalStateT (genEnv env (emptyTemplateE env)) mempty))

adTestTp :: forall env. KnownEnv env
         => TestName -> TemplateE env -> Ex env (TScal TF64) -> TestTree
adTestTp name tmpl term = adTestGen name term (evalStateT (genEnv knownEnv tmpl) mempty)

adTestGen :: forall env. KnownEnv env
          => TestName -> Ex env (TScal TF64) -> Gen (SList Value env) -> TestTree
adTestGen name expr envGenerator =
  withCompiled expr $ \getprimalfun ->
  testProperty name $ property $ do
  let env = knownEnv @env

  annotate (concat (unSList (\t -> ppSTy 0 t ++ " -> ") env) ++ ppSTy 0 (typeOf expr))

  let dtermChad0 = ELet ext (EConst ext STF64 1.0) $ chad' defaultConfig env expr
      dtermChadS = simplifyFix dtermChad0
      dtermChadS20 = simplifyN 20 dtermChad0

  -- pack Text for less GC pressure (these values are retained for some reason)
  diff (T.pack (ppExpr env dtermChadS)) (==) (T.pack (ppExpr env dtermChadS20))

  input <- forAllWith (showEnv env) envGenerator

  let convGrad :: Rep (Tup (D2E env)) -> SList Value (TanE env)
      convGrad = toTanE env input . unTup vUnpair (d2e env) . Value

  let outPrimalI = interpretOpen False input expr
  outPrimal <- liftIO $ getprimalfun >>= ($ input)
  diff outPrimal (closeIsh' 1e-8) outPrimalI

  let (outChad0, gradChad0) = second convGrad $ interpretOpen False input dtermChad0
      (outChadS, gradChadS) = second convGrad $ interpretOpen False input dtermChadS
      scChad = envScalars env gradChad0
      scChadS = envScalars env gradChadS
      gradFwd = gradientByForward knownEnv expr input
      scFwd = envScalars env gradFwd

  -- annotate (ppExpr knownEnv expr)
  -- annotate (ppExpr env dtermChad0)
  -- annotate (ppExpr env dtermChadS)
  diff outChadS closeIsh outChad0
  diff outChadS closeIsh outPrimal
  diff scChadS (\x y -> and (zipWith closeIsh x y)) scChad
  diff scChadS (\x y -> and (zipWith closeIsh x y)) scFwd
  where
    envScalars :: SList STy env' -> SList Value (TanE env') -> [Double]
    envScalars SNil SNil = []
    envScalars (t `SCons` ts) (Value x `SCons` xs) = tanScalars t x ++ envScalars ts xs

withCompiled :: KnownEnv env => Ex env t -> (IO (SList Value env -> IO (Rep t)) -> TestTree) -> TestTree
withCompiled expr = withResource (compile knownEnv expr) (\_ -> pure ())

term_build1_sum :: Ex '[TArr N1 (TScal TF64)] (TScal TF64)
term_build1_sum = fromNamed $ lambda #x $ body $
  idx0 $ sum1i $
    build (SS SZ) (shape #x) $ #idx :-> #x ! #idx

term_pairs :: Ex [TScal TF64, TScal TF64] (TScal TF64)
term_pairs = fromNamed $ lambda #x $ lambda #y $ body $
  let_ #p (pair #x #y) $
  let_ #q (pair (snd_ #p * fst_ #p + #y) #x) $
    fst_ #q * #x + snd_ #q * fst_ #p

term_sparse :: Ex '[TArr N1 (TScal TF64)] (TScal TF64)
term_sparse = fromNamed $ lambda #inp $ body $
  let_ #n (snd_ (shape #inp)) $
  let_ #arr (build1 #n (#i :-> #inp ! pair nil #i)) $
  let_ #a (build1 #n (#i :-> #arr ! pair nil 2)) $
  let_ #b (build1 #n (#i :-> #arr ! pair nil 3)) $
  let_ #c (build1 #n (#i :-> #arr ! pair nil 4)) $
    idx0 (sum1i #a) + idx0 (sum1i #b) + idx0 (sum1i #c)

term_mulmatvec :: Ex [TArr N1 (TScal TF64), TArr N2 (TScal TF64)] (TScal TF64)
term_mulmatvec = fromNamed $ lambda @(TArr N2 _) #mat $ lambda @(TArr N1 _) #vec $ body $
  idx0 $ sum1i $
    let_ #hei (snd_ (fst_ (shape #mat))) $
    let_ #wid (snd_ (shape #mat)) $
      build1 #hei $ #i :->
        idx0 (sum1i (build1 #wid $ #j :->
                       #mat ! pair (pair nil #i) #j * #vec ! pair nil #j))

tests :: TestTree
tests = testGroup "AD"
  [adTest "id" $ fromNamed $ lambda #x $ body $ #x

  ,adTest "idx0" $ fromNamed $ lambda #x $ body $ idx0 #x

  ,adTest "operators" $ fromNamed $ lambda #x $ lambda #y $ body $
      let_ #i (round_ #x) $
      let_ #j (round_ #y) $
      let_ #a1 (#x + #y) $
      let_ #a2 (#x - #y) $
      let_ #a3 (#x * #y) $
      let_ #a4 (#x / (#y * #y + 1)) $
      let_ #b1 (#i + #j) $
      let_ #b2 (#i - #j) $
      let_ #b3 (#i * #j) $
      let_ #b4 (#i `idiv` (#j * #j + 1)) $
        #a1 + #a2 + #a3 + #a4 +
        toFloat_ (#b1 + #b2 + #b3 + #b4)

  ,adTest "order-of-operations" $ fromNamed $ body $
      toFloat_ (3 * (3 `idiv` 2))  -- Compile had a pretty-printing bug at some point

  ,adTest "sum-vec" $ fromNamed $ lambda #x $ body $ idx0 (sum1i #x)

  ,adTest "sum-replicate" $ fromNamed $ lambda #x $ body $
      idx0 $ sum1i $ replicate1i 10 #x

  ,adTest "pairs" term_pairs

  ,adTest "build0 const" $ fromNamed $ lambda @(TScal TF64) #x $ body $
      idx0 $ build SZ nil $ #idx :-> const_ 0.0

  ,adTest "build0" $ fromNamed $ lambda @(TArr N0 _) #x $ body $
      idx0 $
        build SZ (shape #x) $ #idx :-> #x ! #idx

  ,adTest "build1-sum" term_build1_sum

  ,adTest "build2-sum" $ fromNamed $ lambda @(TArr N2 _) #x $ body $
      idx0 $ sum1i . sum1i $
        build (SS (SS SZ)) (shape #x) $ #idx :-> #x ! #idx

  ,adTestCon "maximum" (\(Value a `SCons` _) -> let _ `ShCons` n = arrayShape a in n > 0) $
      fromNamed $ lambda @(TArr N2 (TScal TF64)) #x $ body $
        idx0 $ sum1i $ maximum1i #x

  ,adTestCon "minimum" (\(Value a `SCons` _) -> let _ `ShCons` n = arrayShape a in n > 0) $
      fromNamed $ lambda @(TArr N2 (TScal TF64)) #x $ body $
        idx0 $ sum1i $ minimum1i #x

  ,adTest "unused" $ fromNamed $ lambda @(TArr N1 (TScal TF64)) #x $ body $
    let_ #a (build1 (snd_ (shape #x)) (#i :-> #x ! pair nil #i)) $
      42

  ,adTestTp "sparse" (C "" 5) term_sparse

  ,adTestGen "neural" Example.neural genNeural

  ,adTestGen "neural-unMonoid" (unMonoid (simplifyFix Example.neural)) genNeural

  ,adTestTp "logsumexp" (C "" 1) $
      fromNamed $ lambda @(TArr N1 _) #vec $ body $
      let_ #m (maximum1i #vec) $
        log (idx0 (sum1i (map_ (#x :-> exp (#x - idx0 #m)) #vec))) + idx0 #m

  ,adTestTp "mulmatvec" ((C "" 0 :$ C "n" 0) :& C "n" 0) term_mulmatvec

  ,adTestGen "gmm-wrong" (Example.gmmObjective True) genGMM

  ,adTestGen "gmm-wrong-unMonoid" (unMonoid (simplifyFix (Example.gmmObjective True))) genGMM

  ,adTestGen "gmm" (Example.gmmObjective False) genGMM

  ,adTestGen "gmm-unMonoid" (unMonoid (simplifyFix (Example.gmmObjective False))) genGMM
  ]
  where
    genGMM = do
      -- The input ranges here are completely arbitrary.
      let tR = STScal STF64
      kN <- Gen.integral (Range.linear 1 10)
      kD <- Gen.integral (Range.linear 1 10)
      kK <- Gen.integral (Range.linear 1 10)
      let i2i64 = fromIntegral @Int @Int64
      valpha <- genArray tR (ShNil `ShCons` kK)
      vM <- genArray tR (ShNil `ShCons` kK `ShCons` kD)
      vQ <- genArray tR (ShNil `ShCons` kK `ShCons` kD)
      vL <- genArray tR (ShNil `ShCons` kK `ShCons` (kD * (kD - 1) `div` 2))
      vX <- genArray tR (ShNil `ShCons` kN `ShCons` kD)
      vgamma <- Gen.realFloat (Range.linearFracFrom 0 (-10) 10)
      vm <- Gen.integral (Range.linear 0 5)
      let k1 = 0.5 * fromIntegral (kN * kD) * log (2 * pi)
          k2 = 0.5 * vgamma * vgamma
          k3 = 0.42  -- don't feel like multigammaing today
      return (Value k3 `SCons` Value k2 `SCons` Value k1 `SCons`
              Value vm `SCons` vX `SCons`
              vL `SCons` vQ `SCons` vM `SCons` valpha `SCons`
              Value (i2i64 kK) `SCons` Value (i2i64 kD) `SCons` Value (i2i64 kN) `SCons`
              SNil)

    genNeural = do
      let tR = STScal STF64
      let genLayer nin nout =
            liftV2 (,) <$> genArray tR (ShNil `ShCons` nout `ShCons` nin)
                       <*> genArray tR (ShNil `ShCons` nout)
      nin <- Gen.integral (Range.linear 1 10)
      n1 <- Gen.integral (Range.linear 1 10)
      n2 <- Gen.integral (Range.linear 1 10)
      input <- genArray tR (ShNil `ShCons` nin)
      lay1 <- genLayer nin n1
      lay2 <- genLayer n1 n2
      lay3 <- genArray tR (ShNil `ShCons` n2)
      return (input `SCons` lay3 `SCons` lay2 `SCons` lay1 `SCons` SNil)

main :: IO ()
main = defaultMain tests