{-|
  Copyright   :  (C) 2012-2016, University of Twente
  License     :  BSD2 (see the file LICENSE)
  Maintainer  :  Christiaan Baaij <christiaan.baaij@gmail.com>

  Assortment of utility function used in the Clash library
-}

{-# LANGUAGE CPP #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE MagicHash #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE RankNTypes #-}

{-# OPTIONS_GHC -fno-warn-orphans #-}

module Clash.Util
  ( module Clash.Util
  , module X
  , makeLenses
  , SrcSpan
  , noSrcSpan
  , HasCallStack
  )
where

import Control.Arrow                  as X ((***),(&&&),first,second)
import qualified Control.Exception    as Exception
import Control.Lens
import Control.Monad                  as X ((<=<),(>=>))
import Control.Monad.State            (MonadState,StateT)
import qualified Control.Monad.State  as State
import Data.Function                  as X (on)
import Data.Hashable                  (Hashable)
import Data.HashMap.Lazy              (HashMap)
import qualified Data.HashMap.Lazy    as HashMapL
import qualified Data.List.Extra      as List
import Data.Maybe                     (fromMaybe, listToMaybe, catMaybes)
import Data.Text.Prettyprint.Doc
import Data.Text.Prettyprint.Doc.Render.String
import Data.Time.Clock                (UTCTime)
import qualified Data.Time.Clock      as Clock
import qualified Data.Time.Format     as Clock
import Data.Typeable                  (Typeable)
import Data.Version                   (Version)
import GHC.Base                       (Int(..),isTrue#,(==#),(+#))
import GHC.Integer.Logarithms         (integerLogBase#)
import qualified GHC.LanguageExtensions.Type as LangExt
import GHC.Stack                      (HasCallStack, callStack, prettyCallStack)
import Type.Reflection                (tyConPackage, typeRepTyCon, typeOf)
import qualified Language.Haskell.TH  as TH

import SrcLoc                         (SrcSpan, noSrcSpan)

import Clash.Debug
import Clash.Unique

#ifdef CABAL
import qualified Paths_clash_lib      (version)
#endif

data ClashException = ClashException SrcSpan String (Maybe String)

instance Show ClashException where
  show (ClashException _ s eM) = s ++ "\n" ++ maybe "" id eM

instance Exception.Exception ClashException

assertPanic
  :: String -> Int -> a
assertPanic file ln = Exception.throw
  (ClashException noSrcSpan ("ASSERT failed! file " ++ file ++ ", line " ++ show ln) Nothing)

assertPprPanic
  :: HasCallStack => String -> Int -> Doc ann -> a
assertPprPanic _file _line msg = pprPanic "ASSERT failed!" doc
 where
  doc = sep [ msg, callStackDoc ]

pprPanic
  :: String -> Doc ann -> a
pprPanic heading prettyMsg = Exception.throw
  (ClashException noSrcSpan (renderString (layoutPretty defaultLayoutOptions doc)) Nothing)
 where
  doc = sep [pretty heading, nest 2 prettyMsg]

callStackDoc
  :: HasCallStack => Doc ann
callStackDoc =
  "Call stack:" <+> hang 4
    (vcat (map pretty (lines (prettyCallStack callStack))))

warnPprTrace
  :: HasCallStack
  => Bool
  -- ^ Trigger warning?
  -> String
  -- ^ File name
  -> Int
  -- ^ Line number
  -> Doc ann
  -- ^ Message
  -> a
  -- ^ Pass value (like trace)
  -> a
warnPprTrace _     _ _ _ x | not debugIsOn = x
warnPprTrace False _ _ _ x = x
warnPprTrace True  file ln msg x =
  pprDebugAndThen trace (vcat [heading0, heading1]) msg x
 where
  heading0 = hsep ["WARNING: file", pretty file <> comma, "line", pretty ln]
  heading1 = "WARNING CALLSTACK:" <> line <> pretty (prettyCallStack callStack)

pprTrace
  :: String -> Doc ann -> a -> a
pprTrace str = pprDebugAndThen trace (pretty str)

pprTraceDebug
  :: String -> Doc ann -> a -> a
pprTraceDebug str doc x
  | debugIsOn = pprTrace str doc x
  | otherwise = x

pprDebugAndThen
  :: (String -> a) -> Doc ann -> Doc ann -> a
pprDebugAndThen cont heading prettyMsg =
  cont (renderString (layoutPretty defaultLayoutOptions doc))
 where
  doc = sep [heading, nest 2 prettyMsg]

-- | A class that can generate unique numbers
class Monad m => MonadUnique m where
  -- | Get a new unique
  getUniqueM :: m Int

instance Monad m => MonadUnique (StateT Int m) where
  getUniqueM = do
    supply <- State.get
    State.modify (+1)
    return supply

-- | Create a TH expression that returns the a formatted string containing the
-- name of the module 'curLoc' is spliced into, and the line where it was spliced.
curLoc :: TH.Q TH.Exp
curLoc = do
  (TH.Loc _ _ modName (startPosL,_) _) <- TH.location
  TH.litE (TH.StringL $ modName ++ "(" ++ show startPosL ++ "): ")

-- | Cache the result of a monadic action
makeCached :: (MonadState s m, Hashable k, Eq k)
           => k -- ^ The key the action is associated with
           -> Lens' s (HashMap k v) -- ^ The Lens to the HashMap that is the cache
           -> m v -- ^ The action to cache
           -> m v
makeCached key l create = do
  cache <- use l
  case HashMapL.lookup key cache of
    Just value -> return value
    Nothing -> do
      value <- create
      l %= HashMapL.insert key value
      return value

-- | Cache the result of a monadic action using a 'UniqMap'
makeCachedU
  :: (MonadState s m, Uniquable k)
  => k
  -- ^ Key the action is associated with
  -> Lens' s (UniqMap v)
  -- ^ Lens to the cache
  -> m v
  -- ^ Action to cache
  -> m v
makeCachedU key l create = do
  cache <- use l
  case lookupUniqMap key cache of
    Just value -> return value
    Nothing -> do
      value <- create
      l %= extendUniqMap key value
      return value

combineM :: (Applicative f)
         => (a -> f b)
         -> (c -> f d)
         -> (a,c)
         -> f (b,d)
combineM f g (x,y) = (,) <$> f x <*> g y

-- | Same as 'indexNote' with last two arguments swapped
indexNote'
  :: HasCallStack
  => String
  -- ^ Error message to display
  -> Int
  -- ^ Index /n/
  -> [a]
  -- ^ List to index
  -> a
  -- ^ Error or element /n/
indexNote' = flip . indexNote

-- | Unsafe indexing, return a custom error message when indexing fails
indexNote
  :: HasCallStack
  => String
  -- ^ Error message to display
  -> [a]
  -- ^ List to index
  -> Int
  -- ^ Index /n/
  -> a
  -- ^ Error or element /n/
indexNote note = \xs i -> fromMaybe (error note) (List.indexMaybe xs i)

clashLibVersion :: Version
#ifdef CABAL
clashLibVersion = Paths_clash_lib.version
#else
clashLibVersion = error "development version"
#endif

-- | \x y -> floor (logBase x y), x > 1 && y > 0
flogBase :: Integer -> Integer -> Maybe Int
flogBase x y | x > 1 && y > 0 = Just (I# (integerLogBase# x y))
flogBase _ _ = Nothing

-- | \x y -> ceiling (logBase x y), x > 1 && y > 0
clogBase :: Integer -> Integer -> Maybe Int
clogBase x y | x > 1 && y > 0 =
  case y of
    1 -> Just 0
    _ -> let z1 = integerLogBase# x y
             z2 = integerLogBase# x (y-1)
         in  if isTrue# (z1 ==# z2)
                then Just (I# (z1 +# 1#))
                else Just (I# z1)
clogBase _ _ = Nothing

-- | Get the package id of the type of a value
-- >>> pkgIdFromTypeable (undefined :: TopEntity)
-- "clash-prelude-0.99.3-64904d90747cb49e17166bbc86fec8678918e4ead3847193a395b258e680373c"
pkgIdFromTypeable :: Typeable a => a -> String
pkgIdFromTypeable = tyConPackage . typeRepTyCon . typeOf

reportTimeDiff :: UTCTime -> UTCTime -> String
reportTimeDiff start end =
  Clock.formatTime Clock.defaultTimeLocale fmt
    (Clock.UTCTime (toEnum 0) (fromRational (toRational diff)))
 where
  diff = Clock.diffUTCTime start end
  fmt  | diff >= 3600
       = "%-Hh%-Mm%-S%03Qs"
       | diff >= 60
       = "%-Mm%-S%03Qs"
       | otherwise
       = "%-S%03Qs"

-- | Left-biased choice on maybes
orElse :: Maybe a -> Maybe a -> Maybe a
orElse x@(Just _) _y = x
orElse _x y = y

-- | Left-biased choice on maybes
orElses :: [Maybe a] -> Maybe a
orElses = listToMaybe . catMaybes

-- These language extensions are used for
--  * the interactive session inside clashi
--  * compiling files with clash
--  * running output tests with runghc
--  * compiling (local) Template/Blackbox functions with Hint
wantedLanguageExtensions :: [LangExt.Extension]
wantedLanguageExtensions =
  [ LangExt.BinaryLiterals
  , LangExt.ConstraintKinds
  , LangExt.DataKinds
  , LangExt.DeriveAnyClass
  , LangExt.DeriveGeneric
  , LangExt.DeriveLift
  , LangExt.DerivingStrategies
  , LangExt.ExplicitForAll
  , LangExt.ExplicitNamespaces
  , LangExt.FlexibleContexts
  , LangExt.FlexibleInstances
  , LangExt.KindSignatures
  , LangExt.MagicHash
  , LangExt.MonoLocalBinds
  , LangExt.QuasiQuotes
  , LangExt.ScopedTypeVariables
  , LangExt.TemplateHaskell
  , LangExt.TemplateHaskellQuotes
  , LangExt.TypeApplications
  , LangExt.TypeFamilies
  , LangExt.TypeOperators
#if !MIN_VERSION_ghc(8,6,0)
  , LangExt.TypeInType
#endif
  ]

unwantedLanguageExtensions :: [LangExt.Extension]
unwantedLanguageExtensions =
  [ LangExt.ImplicitPrelude
  , LangExt.MonomorphismRestriction
#if MIN_VERSION_ghc(8,6,0)
  , LangExt.StarIsType
#endif
  , LangExt.Strict
  , LangExt.StrictData
  ]