-- SPDX-FileCopyrightText: 2020 Tocqueville Group
--
-- SPDX-License-Identifier: LicenseRef-MIT-TQ

-- | Module, containing function to interpret Michelson
-- instructions against given context and input stack.
module Michelson.Interpret
  ( ContractEnv (..)
  , InterpreterState (..)
  , MichelsonFailed (..)
  , RemainingSteps (..)
  , SomeItStack (..)
  , MorleyLogs (..)
  , noMorleyLogs

  , interpret
  , interpretInstr
  , ContractReturn

  , mkInitStack
  , fromFinalStack
  , InterpretError (..)
  , InterpretResult (..)
  , EvalM
  , InstrRunner
  , runInstr
  , runInstrNoGas
  , runUnpack

    -- * Internals
  , initInterpreterState
  , handleContractReturn
  , runInstrImpl
  ) where

import Prelude hiding (EQ, GT, LT)

import Control.Monad.Except (MonadError, throwError)
import Data.Default (Default(..))
import qualified Data.Map as Map
import qualified Data.Set as Set
import Data.Singletons (Sing)
import Data.Vinyl (Rec(..), (<+>))
import Fmt (Buildable(build), Builder, genericF)

import Michelson.Interpret.Pack (packValue')
import Michelson.Interpret.Unpack (UnpackError, unpackValue')
import Michelson.TypeCheck (SomeParamType(..), TcOriginatedContracts, matchTypes)
import Michelson.Typed
import qualified Michelson.Typed as T
import Michelson.Typed.Origination (OriginationOperation(..), mkOriginationOperationHash)
import qualified Michelson.Untyped as U
import Tezos.Address (Address(..), GlobalCounter(..), OriginationIndex(..), mkContractAddress)
import Tezos.Core (ChainId, Mutez, Timestamp)
import Tezos.Crypto (KeyHash, blake2b, checkSignature, hashKey, sha256, sha512)
import Util.Peano (LongerThan, Peano, SingNat(SS, SZ))
import Util.TH
import Util.Type
import Util.Typeable

-- | Environment for contract execution.
data ContractEnv = ContractEnv
  { ceNow :: Timestamp
  -- ^ Timestamp returned by the 'NOW' instruction.
  , ceMaxSteps :: RemainingSteps
  -- ^ Number of steps after which execution unconditionally terminates.
  , ceBalance :: Mutez
  -- ^ Current amount of mutez of the current contract.
  , ceContracts :: TcOriginatedContracts
  -- ^ Mapping from existing contracts' addresses to their executable
  -- representation.
  , ceSelf :: Address
  -- ^ Address of the interpreted contract.
  , ceSource :: Address
  -- ^ The contract that initiated the current transaction.
  , ceSender :: Address
  -- ^ The contract that initiated the current internal transaction.
  , ceAmount :: Mutez
  -- ^ Amount of the current transaction.
  , ceChainId :: ChainId
  -- ^ Identifier of the current chain.
  , ceOperationHash :: Maybe U.OperationHash
  -- ^ Hash of the currently executed operation, required for
  -- correct contract address computation in 'CREATE_CONTRACT' instruction.
  , ceGlobalCounter :: GlobalCounter
  -- ^ A global counter that is used to ensure newly created
  -- contracts have unique addresses.
  }

-- | Represents `[FAILED]` state of a Michelson program. Contains
-- value that was on top of the stack when `FAILWITH` was called.
data MichelsonFailed where
  MichelsonFailedWith :: (KnownT t) => T.Value t -> MichelsonFailed
  MichelsonArithError
    :: (Typeable n, Typeable m, Typeable instr)
    => ArithError (Value' instr n) (Value' instr m) -> MichelsonFailed
  MichelsonGasExhaustion :: MichelsonFailed
  MichelsonFailedTestAssert :: Text -> MichelsonFailed
  MichelsonAmbigousEpRef :: EpName -> EpAddress -> MichelsonFailed

deriving stock instance Show MichelsonFailed

instance Eq MichelsonFailed where
  MichelsonFailedWith v1 == MichelsonFailedWith v2 = v1 `eqParam1` v2
  MichelsonFailedWith _ == _ = False
  MichelsonArithError ae1 == MichelsonArithError ae2 = ae1 `eqParam2` ae2
  MichelsonArithError _ == _ = False
  MichelsonGasExhaustion == MichelsonGasExhaustion = True
  MichelsonGasExhaustion == _ = False
  MichelsonFailedTestAssert t1 == MichelsonFailedTestAssert t2 = t1 == t2
  MichelsonFailedTestAssert _ == _ = False
  MichelsonAmbigousEpRef ep1 epAddr1 == MichelsonAmbigousEpRef ep2 epAddr2 =
    ep1 == ep2 && epAddr1 == epAddr2
  MichelsonAmbigousEpRef _ _ == _ = False

instance Buildable MichelsonFailed where
  build =
    \case
      MichelsonFailedWith (v :: T.Value t) ->
        "Reached FAILWITH instruction with " <> formatValue v
      MichelsonArithError v -> build v
      MichelsonGasExhaustion ->
        "Gas limit exceeded on contract execution"
      MichelsonFailedTestAssert t -> build t
      MichelsonAmbigousEpRef instrEp epAddr ->
        "Ambigous entrypoint reference. `CONTRACT %" <> build instrEp <> "` \
        \called over address " <> build epAddr
    where
      formatValue :: forall t . SingI t => Value t -> Builder
      formatValue v =
        case T.checkOpPresence (sing @t) of
          OpPresent -> "<value with operations>"
          OpAbsent -> build (untypeValue v)

newtype InterpretError = InterpretError (MichelsonFailed, MorleyLogs)
  deriving stock (Generic)

deriving stock instance Show InterpretError

instance Buildable InterpretError where
  build = genericF

data InterpretResult where
  InterpretResult
    :: ( StorageScope st )
    => { iurOps :: [Operation]
       , iurNewStorage :: T.Value st
       , iurNewState   :: InterpreterState
       }
    -> InterpretResult

deriving stock instance Show InterpretResult

constructIR ::
  (StorageScope st) =>
  (([Operation], Value' Instr st), InterpreterState) ->
  InterpretResult
constructIR ((ops, val), st) =
  InterpretResult
  { iurOps = ops
  , iurNewStorage = val
  , iurNewState = st
  }

-- | Morley logs for interpreter state.
newtype MorleyLogs = MorleyLogs
  { unMorleyLogs :: [Text]
    -- ^ Logs in reverse order.
  } deriving stock (Eq, Show, Generic)
    deriving newtype (Default, Buildable)

instance NFData MorleyLogs

noMorleyLogs :: MorleyLogs
noMorleyLogs = MorleyLogs []

type ContractReturn st =
  (Either MichelsonFailed ([Operation], T.Value st), InterpreterState)

handleContractReturn
  :: (StorageScope st)
  => ContractReturn st -> Either InterpretError InterpretResult
handleContractReturn (ei, s) =
  bimap (InterpretError . (, isMorleyLogs s)) (constructIR . (, s)) ei

interpret'
  :: forall cp st arg.
     ContractCode cp st
  -> EntrypointCallT cp arg
  -> T.Value arg
  -> T.Value st
  -> ContractEnv
  -> InterpreterState
  -> ContractReturn st
interpret' instr epc param initSt env ist = first (fmap fromFinalStack) $
  runEvalOp
    (runInstr instr $ mkInitStack (liftCallArg epc param) initSt)
    env
    ist

mkInitStack :: T.Value param -> T.Value st -> Rec T.Value (ContractInp param st)
mkInitStack param st = T.VPair (param, st) :& RNil

fromFinalStack :: Rec T.Value (ContractOut st) -> ([T.Operation], T.Value st)
fromFinalStack (T.VPair (T.VList ops, st) :& RNil) =
  (map (\(T.VOp op) -> op) ops, st)

interpret
  :: ContractCode cp st
  -> EntrypointCallT cp arg
  -> T.Value arg
  -> T.Value st
  -> ContractEnv
  -> ContractReturn st
interpret instr epc param initSt env =
  interpret' instr epc param initSt env (initInterpreterState env)

initInterpreterState :: ContractEnv -> InterpreterState
initInterpreterState env = InterpreterState def (ceMaxSteps env) (OriginationIndex 0)

-- | Interpret an instruction in vacuum, putting no extra contraints on
-- its execution.
--
-- Mostly for testing purposes.
interpretInstr
  :: ContractEnv
  -> Instr inp out
  -> Rec T.Value inp
  -> Either MichelsonFailed (Rec T.Value out)
interpretInstr env instr inpSt =
  fst $
  runEvalOp
    (runInstr instr inpSt)
    env
    InterpreterState
      { isMorleyLogs = MorleyLogs []
      , isRemainingSteps = 9999999999
      , isOriginationNonce = OriginationIndex 0
      }

data SomeItStack where
  SomeItStack :: T.ExtInstr inp -> Rec T.Value inp -> SomeItStack

newtype RemainingSteps = RemainingSteps Word64
  deriving stock (Show, Generic)
  deriving newtype (Eq, Ord, Buildable, Num)

instance NFData RemainingSteps

data InterpreterState = InterpreterState
  { isMorleyLogs :: MorleyLogs
  , isRemainingSteps :: RemainingSteps
  , isOriginationNonce :: OriginationIndex
  } deriving stock (Show, Generic)

instance NFData InterpreterState

type EvalOp a =
  ExceptT MichelsonFailed
    (ReaderT ContractEnv
       (State InterpreterState)) a

runEvalOp
  :: EvalOp a
  -> ContractEnv
  -> InterpreterState
  -> (Either MichelsonFailed a, InterpreterState)
runEvalOp act env initSt =
  flip runState initSt $ usingReaderT env $ runExceptT act

type EvalM m =
  ( MonadReader ContractEnv m
  , MonadState InterpreterState m
  , MonadError MichelsonFailed m
  )

type InstrRunner m =
  forall inp out.
     Instr inp out
  -> Rec (T.Value) inp
  -> m (Rec (T.Value) out)

-- | Function to change amount of remaining steps stored in State monad
runInstr :: EvalM m => InstrRunner m
runInstr i@(Seq _i1 _i2) r = runInstrImpl runInstr i r
runInstr i@(InstrWithNotes _ _i1) r = runInstrImpl runInstr i r
runInstr i@(InstrWithVarNotes _ _i1) r = runInstrImpl runInstr i r
runInstr i@Nop r = runInstrImpl runInstr i r
runInstr i@(Nested _) r = runInstrImpl runInstr i r
runInstr i r = do
  rs <- gets isRemainingSteps
  if rs == 0
  then throwError $ MichelsonGasExhaustion
  else do
    modify (\s -> s {isRemainingSteps = rs - 1})
    runInstrImpl runInstr i r

runInstrNoGas :: EvalM m => InstrRunner m
runInstrNoGas = runInstrImpl runInstrNoGas

-- | Function to interpret Michelson instruction(s) against given stack.
runInstrImpl :: EvalM m => InstrRunner m -> InstrRunner m
runInstrImpl runner (Seq i1 i2) r = runner i1 r >>= \r' -> runner i2 r'
runInstrImpl runner (WithLoc _ i) r = runInstrImpl runner i r
runInstrImpl runner (InstrWithNotes _ i) r = runner i r
runInstrImpl runner (InstrWithVarNotes _ i) r = runner i r
runInstrImpl runner (FrameInstr (_ :: Proxy s) i) r = do
  let (inp, end) = rsplit @_ @_ @s r
  out <- runInstrImpl runner i inp
  return (out <+> end)
runInstrImpl _ Nop r = pure $ r
runInstrImpl _ (Ext nop) r = r <$ interpretExt (SomeItStack nop r)
runInstrImpl runner (Nested sq) r = runInstrImpl runner sq r
runInstrImpl runner (DocGroup _ sq) r = runInstrImpl runner sq r
runInstrImpl _ DROP (_ :& r) = pure $ r
runInstrImpl runner (DROPN s) stack =
  case s of
    SZ -> pure stack
    SS s' -> case stack of
      -- Note: we intentionally do not use `runner` to recursively
      -- interpret `DROPN` here.
      -- All these recursive calls together correspond to a single
      -- Michelson instruction call.
      -- This recursion is implementation detail of `DROPN`.
      -- The same reasoning applies to other instructions parameterized
      -- by a natural number like 'DIPN'.
      (_ :& r) -> runInstrImpl runner (DROPN s') r
runInstrImpl _ DUP (a :& r) = pure $ a :& a :& r
runInstrImpl _ SWAP (a :& b :& r) = pure $ b :& a :& r
runInstrImpl _ (DIG nSing0) input0 =
  pure $ go (nSing0, input0)
  where
    go :: forall (n :: Peano) inp out a. T.ConstraintDIG n inp out a =>
      (Sing n, Rec T.Value inp) -> Rec T.Value out
    go = \case
      (SZ, stack) ->  stack
      (SS nSing, b :& r) -> case go (nSing, r) of
        (a :& resTail) -> a :& b :& resTail
runInstrImpl _ (DUG nSing0) input0 =
  pure $ go (nSing0, input0)
  where
    go :: forall (n :: Peano) inp out a. T.ConstraintDUG n inp out a =>
      (Sing n, Rec T.Value inp) -> Rec T.Value out
    go = \case
      (SZ, stack) -> stack
      (SS s', a :& b :& r) -> b :& go (s', a :& r)
runInstrImpl _ SOME (a :& r) =
  withValueTypeSanity a $
    pure $ VOption (Just a) :& r
runInstrImpl _ (PUSH v) r = pure $ v :& r
runInstrImpl _ NONE r = pure $ VOption Nothing :& r
runInstrImpl _ UNIT r = pure $ VUnit :& r
runInstrImpl runner (IF_NONE _bNone bJust) (VOption (Just a) :& r) = runner bJust (a :& r)
runInstrImpl runner (IF_NONE bNone _bJust) (VOption Nothing :& r) = runner bNone r
runInstrImpl _ (AnnPAIR{}) (a :& b :& r) = pure $ VPair (a, b) :& r
runInstrImpl _ (AnnCAR _) (VPair (a, _b) :& r) = pure $ a :& r
runInstrImpl _ (AnnCDR _) (VPair (_a, b) :& r) = pure $ b :& r
runInstrImpl _ LEFT (a :& r) =
  withValueTypeSanity a $
    pure $ (VOr $ Left a) :& r
runInstrImpl _ RIGHT (b :& r) =
  withValueTypeSanity b $
    pure $ (VOr $ Right b) :& r
runInstrImpl runner (IF_LEFT bLeft _) (VOr (Left a) :& r) = runner bLeft (a :& r)
runInstrImpl runner (IF_LEFT _ bRight) (VOr (Right a) :& r) = runner bRight (a :& r)
-- More here
runInstrImpl _ NIL r = pure $ VList [] :& r
runInstrImpl _ CONS (a :& VList l :& r) = pure $ VList (a : l) :& r
runInstrImpl runner (IF_CONS _ bNil) (VList [] :& r) = runner bNil r
runInstrImpl runner (IF_CONS bCons _) (VList (lh : lr) :& r) = runner bCons (lh :& VList lr :& r)
runInstrImpl _ SIZE (a :& r) = pure $ (VNat $ (fromInteger . toInteger) $ evalSize a) :& r
runInstrImpl _ EMPTY_SET r = pure $ VSet Set.empty :& r
runInstrImpl _ EMPTY_MAP r = pure $ VMap Map.empty :& r
runInstrImpl _ EMPTY_BIG_MAP r = pure $ VBigMap Map.empty :& r
runInstrImpl runner (MAP ops) (a :& r) =
  case ops of
    (code :: Instr (MapOpInp c ': s) (b ': s)) -> do
      -- Evaluation must preserve all stack modifications that @MAP@'s does.
      (newStack, newList) <- foldlM (\(curStack, curList) (val :: T.Value (MapOpInp c)) -> do
        res <- runner code (val :& curStack)
        case res of
          ((nextVal :: T.Value b) :& nextStack) -> pure (nextStack, nextVal : curList))
        (r, []) (mapOpToList @c a)
      pure $ mapOpFromList a (reverse newList) :& newStack
runInstrImpl runner (ITER ops) (a :& r) =
  case ops of
    (code :: Instr (IterOpEl c ': s) s) ->
      case iterOpDetachOne @c a of
        (Just x, xs) -> do
          res <- runner code (x :& r)
          runner (ITER code) (xs :& res)
        (Nothing, _) -> pure r
runInstrImpl _ MEM (a :& b :& r) = pure $ (VBool (evalMem a b)) :& r
runInstrImpl _ GET (a :& b :& r) = pure $ VOption (evalGet a b) :& r
runInstrImpl _ UPDATE (a :& b :& c :& r) = pure $ evalUpd a b c :& r
runInstrImpl runner (IF bTrue _) (VBool True :& r) = runner bTrue r
runInstrImpl runner (IF _ bFalse) (VBool False :& r) = runner bFalse r
runInstrImpl _ (LOOP _) (VBool False :& r) = pure $ r
runInstrImpl runner (LOOP ops) (VBool True :& r) = do
  res <- runner ops r
  runner (LOOP ops) res
runInstrImpl _ (LOOP_LEFT _) (VOr (Right a) :&r) = pure $ a :& r
runInstrImpl runner (LOOP_LEFT ops) (VOr (Left a) :& r) = do
  res <- runner ops (a :& r)
  runner  (LOOP_LEFT ops) res
runInstrImpl _ (LAMBDA lam) r = pure $ lam :& r
runInstrImpl runner EXEC (a :& VLam (T.rfAnyInstr -> lBody) :& r) = do
  res <- runner lBody (a :& RNil)
  pure $ res <+> r
runInstrImpl _ APPLY ((a :: T.Value a) :& VLam lBody :& r) = do
  pure $ VLam (T.rfMapAnyInstr doApply lBody) :& r
  where
    doApply :: Instr ('TPair a i ': s) o -> Instr (i ': s) o
    doApply b = PUSH a `Seq` PAIR `Seq` Nested b
runInstrImpl runner (DIP i) (a :& r) = do
  res <- runner i r
  pure $ a :& res
runInstrImpl runner (DIPN s i) stack =
  case s of
    SZ -> runner i stack
    SS s' -> case stack of
      (a :& r) -> (a :&) <$> runInstrImpl runner (DIPN s' i) r
runInstrImpl _ FAILWITH (a :& _) = throwError $ MichelsonFailedWith a
runInstrImpl _ CAST (a :& r) = pure $ a :& r
runInstrImpl _ RENAME (a :& r) = pure $ a :& r
runInstrImpl _ PACK (a :& r) = pure $ (VBytes $ packValue' a) :& r
runInstrImpl _ UNPACK (VBytes a :& r) =
  pure $ (VOption . rightToMaybe $ runUnpack a) :& r
runInstrImpl _ CONCAT (a :& b :& r) = pure $ evalConcat a b :& r
runInstrImpl _ CONCAT' (VList a :& r) = pure $ evalConcat' a :& r
runInstrImpl _ SLICE (VNat o :& VNat l :& s :& r) =
  pure $ VOption (evalSlice o l s) :& r
runInstrImpl _ ISNAT (VInt i :& r) =
  if i < 0
  then pure $ VOption Nothing :& r
  else pure $ VOption (Just (VNat $ fromInteger i)) :& r
runInstrImpl _ ADD (l :& r :& rest) =
  (:& rest) <$> runArithOp (Proxy @Add) l r
runInstrImpl _ SUB (l :& r :& rest) = (:& rest) <$> runArithOp (Proxy @Sub) l r
runInstrImpl _ MUL (l :& r :& rest) = (:& rest) <$> runArithOp (Proxy @Mul) l r
runInstrImpl _ EDIV (l :& r :& rest) = pure $ evalEDivOp l r :& rest
runInstrImpl _ ABS (a :& rest) = pure $ (evalUnaryArithOp (Proxy @Abs) a) :& rest
runInstrImpl _ NEG (a :& rest) = pure $ (evalUnaryArithOp (Proxy @Neg) a) :& rest
runInstrImpl _ LSL (x :& s :& rest) = (:& rest) <$> runArithOp (Proxy @Lsl) x s
runInstrImpl _ LSR (x :& s :& rest) = (:& rest) <$> runArithOp (Proxy @Lsr) x s
runInstrImpl _ OR (l :& r :& rest) = (:& rest) <$> runArithOp (Proxy @Or) l r
runInstrImpl _ AND (l :& r :& rest) = (:& rest) <$> runArithOp (Proxy @And) l r
runInstrImpl _ XOR (l :& r :& rest) = (:& rest) <$> runArithOp (Proxy @Xor) l r
runInstrImpl _ NOT (a :& rest) = pure $ (evalUnaryArithOp (Proxy @Not) a) :& rest
runInstrImpl _ COMPARE (l :& r :& rest) = pure $ (T.VInt (compareOp l r)) :& rest
runInstrImpl _ EQ (a :& rest) = pure $ (evalUnaryArithOp (Proxy @Eq') a) :& rest
runInstrImpl _ NEQ (a :& rest) = pure $ (evalUnaryArithOp (Proxy @Neq) a) :& rest
runInstrImpl _ LT (a :& rest) = pure $ (evalUnaryArithOp (Proxy @Lt) a) :& rest
runInstrImpl _ GT (a :& rest) = pure $ (evalUnaryArithOp (Proxy @Gt) a) :& rest
runInstrImpl _ LE (a :& rest) = pure $ (evalUnaryArithOp (Proxy @Le) a) :& rest
runInstrImpl _ GE (a :& rest) = pure $ (evalUnaryArithOp (Proxy @Ge) a) :& rest
runInstrImpl _ INT (VNat n :& r) = pure $ (VInt $ toInteger n) :& r
runInstrImpl _ (SELF sepc :: Instr inp out) r = do
  ContractEnv{..} <- ask
  case Proxy @out of
    (_ :: Proxy ('TContract cp ': s)) -> do
      pure $ VContract ceSelf sepc :& r
runInstrImpl _ (CONTRACT (nt :: T.Notes a) instrEpName) (VAddress epAddr :& r) = do
  ContractEnv{..} <- ask
  let T.EpAddress addr addrEpName = epAddr
  epName <- case (instrEpName, addrEpName) of
    (DefEpName, DefEpName) -> pure DefEpName
    (DefEpName, en) -> pure en
    (en, DefEpName) -> pure en
    _ -> throwError $ MichelsonAmbigousEpRef instrEpName epAddr

  pure $ case addr of
    KeyAddress _ ->
      castContract addr epName T.tyImplicitAccountParam :& r
    ContractAddress ca ->
      case Map.lookup ca ceContracts of
        Just (SomeParamType _ paramNotes) ->
          castContract addr epName paramNotes :& r
        Nothing -> VOption Nothing :& r
  where
  castContract
    :: forall p. T.ParameterScope p
    => Address -> EpName -> T.ParamNotes p -> T.Value ('TOption ('TContract a))
  castContract addr epName param = VOption $ do
    -- As we are within Maybe monad, pattern-match failure results in Nothing
    MkEntrypointCallRes na epc <- T.mkEntrypointCall epName param
    Right (Refl, _) <- pure $ matchTypes nt na
    return $ VContract addr (T.SomeEpc epc)

runInstrImpl _ TRANSFER_TOKENS (p :& VMutez mutez :& contract :& r) =
  pure $ VOp (OpTransferTokens $ TransferTokens p mutez contract) :& r
runInstrImpl _ SET_DELEGATE (VOption mbKeyHash :& r) =
  case mbKeyHash of
    Just (VKeyHash k) -> pure $ VOp (OpSetDelegate $ SetDelegate $ Just k) :& r
    Nothing -> pure $ VOp (OpSetDelegate $ SetDelegate $ Nothing) :& r
runInstrImpl _ (CREATE_CONTRACT contract)
  (VOption mbKeyHash :& VMutez m :& g :& r) = do
  originator <- ceSelf <$> ask

  originationNonce <- gets isOriginationNonce
  globalCounter <- asks ceGlobalCounter
  opHash <- ceOperationHash <$> ask
  modify $ \iState ->
    iState { isOriginationNonce = OriginationIndex $ (unOriginationIndex $ isOriginationNonce iState) + 1 }
  let ops = cCode contract
  let resAddr =
        case opHash of
          Just hash -> mkContractAddress hash originationNonce globalCounter
          Nothing ->
            mkContractAddress
              (mkOriginationOperationHash (createOrigOp originator mbKeyHash m contract g))
              -- If opHash is Nothing it means that interpreter is running in some kind of test
              -- context, therefore we generate dummy contract address with its own origination
              -- operation.
              originationNonce
              globalCounter
  let resEpAddr = EpAddress resAddr DefEpName
  let resOp = CreateContract originator (unwrapMbKeyHash mbKeyHash) m g ops
  pure $ VOp (OpCreateContract resOp)
      :& (VAddress resEpAddr)
      :& r
runInstrImpl _ IMPLICIT_ACCOUNT (VKeyHash k :& r) =
  pure $ VContract (KeyAddress k) sepcPrimitive :& r
runInstrImpl _ NOW r = do
  ContractEnv{..} <- ask
  pure $ (VTimestamp ceNow) :& r
runInstrImpl _ AMOUNT r = do
  ContractEnv{..} <- ask
  pure $ (VMutez ceAmount) :& r
runInstrImpl _ BALANCE r = do
  ContractEnv{..} <- ask
  pure $ (VMutez ceBalance) :& r
runInstrImpl _ CHECK_SIGNATURE (VKey k :& VSignature v :&
  VBytes b :& r) = pure $ (VBool $ checkSignature k v b) :& r
runInstrImpl _ SHA256 (VBytes b :& r) = pure $ (VBytes $ sha256 b) :& r
runInstrImpl _ SHA512 (VBytes b :& r) = pure $ (VBytes $ sha512 b) :& r
runInstrImpl _ BLAKE2B (VBytes b :& r) = pure $ (VBytes $ blake2b b) :& r
runInstrImpl _ HASH_KEY (VKey k :& r) = pure $ (VKeyHash $ hashKey k) :& r
runInstrImpl _ SOURCE r = do
  ContractEnv{..} <- ask
  pure $ (VAddress $ EpAddress ceSource DefEpName) :& r
runInstrImpl _ SENDER r = do
  ContractEnv{..} <- ask
  pure $ (VAddress $ EpAddress ceSender DefEpName) :& r
runInstrImpl _ ADDRESS (VContract a sepc :& r) =
  pure $ (VAddress $ EpAddress a (sepcName sepc)) :& r
runInstrImpl _ CHAIN_ID r = do
  ContractEnv{..} <- ask
  pure $ VChainId ceChainId :& r

-- | Evaluates an arithmetic operation and either fails or proceeds.
runArithOp
  :: (ArithOp aop n m, Typeable n, Typeable m, EvalM monad)
  => proxy aop
  -> Value n
  -> Value m
  -> monad (Value (ArithRes aop n m))
runArithOp op l r = case evalOp op l r of
  Left  err -> throwError (MichelsonArithError err)
  Right res -> pure res

-- | Unpacks given raw data into a typed value.
runUnpack
  :: forall t. (UnpackedValScope t)
  => ByteString
  -> Either UnpackError (T.Value t)
runUnpack bs =
  -- TODO [TM-80] Gas consumption here should depend on unpacked data size
  -- and size of resulting expression, errors would also spend some (all equally).
  -- Fortunatelly, the inner decoding logic does not need to know anything about gas use.
  unpackValue' bs

createOrigOp
  :: (ParameterScope param, StorageScope store)
  => Address
  -> Maybe (T.Value 'T.TKeyHash)
  -> Mutez
  -> Contract param store
  -> Value' Instr store
  -> OriginationOperation
createOrigOp originator mbDelegate bal contract storage =
  OriginationOperation
    { ooOriginator = originator
    , ooDelegate = unwrapMbKeyHash mbDelegate
    , ooBalance = bal
    , ooStorage = storage
    , ooContract = contract
    }

unwrapMbKeyHash :: Maybe (T.Value 'T.TKeyHash) -> Maybe KeyHash
unwrapMbKeyHash mbKeyHash = mbKeyHash <&> \(VKeyHash keyHash) -> keyHash

interpretExt :: EvalM m => SomeItStack -> m ()
interpretExt (SomeItStack (T.PRINT (T.PrintComment pc)) st) = do
  let getEl (Left l) = l
      getEl (Right str) = withStackElem str st show
  modify (\s -> s {isMorleyLogs = MorleyLogs $ mconcat (map getEl pc) : unMorleyLogs (isMorleyLogs s)})

interpretExt (SomeItStack (T.TEST_ASSERT (T.TestAssert nm pc instr)) st) = do
  ost <- runInstrNoGas instr st
  let ((T.fromVal -> succeeded) :& _) = ost
  unless succeeded $ do
    interpretExt (SomeItStack (T.PRINT pc) st)
    throwError $ MichelsonFailedTestAssert $ "TEST_ASSERT " <> nm <> " failed"

interpretExt (SomeItStack T.DOC_ITEM{} _) = pass
interpretExt (SomeItStack T.COMMENT_ITEM{} _) = pass

-- | Access given stack reference (in CPS style).
withStackElem
  :: forall st a.
     T.StackRef st
  -> Rec T.Value st
  -> (forall t. T.Value t -> a)
  -> a
withStackElem (T.StackRef sn) vals cont =
  loop (vals, sn)
  where
    loop
      :: forall s (n :: Peano). (LongerThan s n)
      => (Rec T.Value s, Sing n) -> a
    loop = \case
      (e :& _, SZ) -> cont e
      (_ :& es, SS n) -> loop (es, n)

(deriveGADTNFData ''MichelsonFailed)