{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE Strict #-}

-- | @futhark dataset@
module Futhark.CLI.Dataset (main) where

import Control.Monad
import Control.Monad.ST
import qualified Data.Binary as Bin
import qualified Data.ByteString.Lazy.Char8 as BS
import qualified Data.Map.Strict as M
import qualified Data.Text as T
import Data.Vector.Generic (freeze)
import qualified Data.Vector.Storable as SVec
import qualified Data.Vector.Storable.Mutable as USVec
import Data.Word
import Futhark.Test.Values
import Futhark.Util.Options
import Language.Futhark.Parser
import Language.Futhark.Pretty ()
import Language.Futhark.Prop (UncheckedTypeExp, namesToPrimTypes)
import Language.Futhark.Syntax hiding
  ( FloatValue (..),
    IntValue (..),
    PrimValue (..),
    Value,
    ValueType,
  )
import System.Exit
import System.IO
import System.Random.PCG (Variate, initialize, uniformR)

-- | Run @futhark dataset@.
main :: String -> [String] -> IO ()
main = mainWithOptions initialDataOptions commandLineOptions "options..." f
  where
    f [] config
      | null $ optOrders config = Just $ do
        maybe_vs <- readValues <$> BS.getContents
        case maybe_vs of
          Nothing -> do
            hPutStrLn stderr "Malformed data on standard input."
            exitFailure
          Just vs ->
            case format config of
              Text -> mapM_ (putStrLn . pretty) vs
              Binary -> mapM_ (BS.putStr . Bin.encode) vs
              Type -> mapM_ (putStrLn . pretty . valueType) vs
      | otherwise =
        Just $
          zipWithM_
            ($)
            (optOrders config)
            [fromIntegral (optSeed config) ..]
    f _ _ =
      Nothing

data OutputFormat
  = Text
  | Binary
  | Type
  deriving (Eq, Ord, Show)

data DataOptions = DataOptions
  { optSeed :: Int,
    optRange :: RandomConfiguration,
    optOrders :: [Word64 -> IO ()],
    format :: OutputFormat
  }

initialDataOptions :: DataOptions
initialDataOptions = DataOptions 1 initialRandomConfiguration [] Text

commandLineOptions :: [FunOptDescr DataOptions]
commandLineOptions =
  [ Option
      "s"
      ["seed"]
      ( ReqArg
          ( \n ->
              case reads n of
                [(n', "")] ->
                  Right $ \config -> config {optSeed = n'}
                _ ->
                  Left $ do
                    hPutStrLn stderr $ "'" ++ n ++ "' is not an integer."
                    exitFailure
          )
          "SEED"
      )
      "The seed to use when initialising the RNG.",
    Option
      "g"
      ["generate"]
      ( ReqArg
          ( \t ->
              case tryMakeGenerator t of
                Right g ->
                  Right $ \config ->
                    config
                      { optOrders =
                          optOrders config
                            ++ [g (optRange config) (format config)]
                      }
                Left err ->
                  Left $ do
                    hPutStrLn stderr err
                    exitFailure
          )
          "TYPE"
      )
      "Generate a random value of this type.",
    Option
      []
      ["text"]
      (NoArg $ Right $ \opts -> opts {format = Text})
      "Output data in text format (must precede --generate).",
    Option
      "b"
      ["binary"]
      (NoArg $ Right $ \opts -> opts {format = Binary})
      "Output data in binary Futhark format (must precede --generate).",
    Option
      "t"
      ["type"]
      (NoArg $ Right $ \opts -> opts {format = Type})
      "Output the type (textually) rather than the value (must precede --generate).",
    setRangeOption "i8" seti8Range,
    setRangeOption "i16" seti16Range,
    setRangeOption "i32" seti32Range,
    setRangeOption "i64" seti64Range,
    setRangeOption "u8" setu8Range,
    setRangeOption "u16" setu16Range,
    setRangeOption "u32" setu32Range,
    setRangeOption "u64" setu64Range,
    setRangeOption "f32" setf32Range,
    setRangeOption "f64" setf64Range
  ]

setRangeOption ::
  Read a =>
  String ->
  (Range a -> RandomConfiguration -> RandomConfiguration) ->
  FunOptDescr DataOptions
setRangeOption tname set =
  Option
    ""
    [name]
    ( ReqArg
        ( \b ->
            let (lower, rest) = span (/= ':') b
                upper = drop 1 rest
             in case (reads lower, reads upper) of
                  ([(lower', "")], [(upper', "")]) ->
                    Right $ \config ->
                      config {optRange = set (lower', upper') $ optRange config}
                  _ ->
                    Left $ do
                      hPutStrLn stderr $ "Invalid bounds for " ++ tname ++ ": " ++ b
                      exitFailure
        )
        "MIN:MAX"
    )
    $ "Range of " ++ tname ++ " values."
  where
    name = tname ++ "-bounds"

tryMakeGenerator ::
  String ->
  Either String (RandomConfiguration -> OutputFormat -> Word64 -> IO ())
tryMakeGenerator t
  | Just vs <- readValues $ BS.pack t =
    return $ \_ fmt _ -> mapM_ (outValue fmt) vs
  | otherwise = do
    t' <- toValueType =<< either (Left . show) Right (parseType name (T.pack t))
    return $ \conf fmt seed -> do
      let v = randomValue conf t' seed
      outValue fmt v
  where
    name = "option " ++ t
    outValue Text = putStrLn . pretty
    outValue Binary = BS.putStr . Bin.encode
    outValue Type = putStrLn . pretty . valueType

toValueType :: UncheckedTypeExp -> Either String ValueType
toValueType TETuple {} = Left "Cannot handle tuples yet."
toValueType TERecord {} = Left "Cannot handle records yet."
toValueType TEApply {} = Left "Cannot handle type applications yet."
toValueType TEArrow {} = Left "Cannot generate functions."
toValueType TESum {} = Left "Cannot handle sumtypes yet."
toValueType (TEUnique t _) = toValueType t
toValueType (TEArray t d _) = do
  d' <- constantDim d
  ValueType ds t' <- toValueType t
  return $ ValueType (d' : ds) t'
  where
    constantDim (DimExpConst k _) = Right k
    constantDim _ = Left "Array has non-constant dimension declaration."
toValueType (TEVar (QualName [] v) _)
  | Just t <- M.lookup v namesToPrimTypes = Right $ ValueType [] t
toValueType (TEVar v _) =
  Left $ "Unknown type " ++ pretty v

-- | Closed interval, as in @System.Random@.
type Range a = (a, a)

data RandomConfiguration = RandomConfiguration
  { i8Range :: Range Int8,
    i16Range :: Range Int16,
    i32Range :: Range Int32,
    i64Range :: Range Int64,
    u8Range :: Range Word8,
    u16Range :: Range Word16,
    u32Range :: Range Word32,
    u64Range :: Range Word64,
    f32Range :: Range Float,
    f64Range :: Range Double
  }

-- The following lines provide evidence about how Haskells record
-- system sucks.
seti8Range :: Range Int8 -> RandomConfiguration -> RandomConfiguration
seti8Range bounds config = config {i8Range = bounds}

seti16Range :: Range Int16 -> RandomConfiguration -> RandomConfiguration
seti16Range bounds config = config {i16Range = bounds}

seti32Range :: Range Int32 -> RandomConfiguration -> RandomConfiguration
seti32Range bounds config = config {i32Range = bounds}

seti64Range :: Range Int64 -> RandomConfiguration -> RandomConfiguration
seti64Range bounds config = config {i64Range = bounds}

setu8Range :: Range Word8 -> RandomConfiguration -> RandomConfiguration
setu8Range bounds config = config {u8Range = bounds}

setu16Range :: Range Word16 -> RandomConfiguration -> RandomConfiguration
setu16Range bounds config = config {u16Range = bounds}

setu32Range :: Range Word32 -> RandomConfiguration -> RandomConfiguration
setu32Range bounds config = config {u32Range = bounds}

setu64Range :: Range Word64 -> RandomConfiguration -> RandomConfiguration
setu64Range bounds config = config {u64Range = bounds}

setf32Range :: Range Float -> RandomConfiguration -> RandomConfiguration
setf32Range bounds config = config {f32Range = bounds}

setf64Range :: Range Double -> RandomConfiguration -> RandomConfiguration
setf64Range bounds config = config {f64Range = bounds}

initialRandomConfiguration :: RandomConfiguration
initialRandomConfiguration =
  RandomConfiguration
    (minBound, maxBound)
    (minBound, maxBound)
    (minBound, maxBound)
    (minBound, maxBound)
    (minBound, maxBound)
    (minBound, maxBound)
    (minBound, maxBound)
    (minBound, maxBound)
    (0.0, 1.0)
    (0.0, 1.0)

randomValue :: RandomConfiguration -> ValueType -> Word64 -> Value
randomValue conf (ValueType ds t) seed =
  case t of
    Signed Int8 -> gen i8Range Int8Value
    Signed Int16 -> gen i16Range Int16Value
    Signed Int32 -> gen i32Range Int32Value
    Signed Int64 -> gen i64Range Int64Value
    Unsigned Int8 -> gen u8Range Word8Value
    Unsigned Int16 -> gen u16Range Word16Value
    Unsigned Int32 -> gen u32Range Word32Value
    Unsigned Int64 -> gen u64Range Word64Value
    FloatType Float32 -> gen f32Range Float32Value
    FloatType Float64 -> gen f64Range Float64Value
    Bool -> gen (const (False, True)) BoolValue
  where
    gen range final = randomVector (range conf) final ds seed

randomVector ::
  (SVec.Storable v, Variate v) =>
  Range v ->
  (SVec.Vector Int -> SVec.Vector v -> Value) ->
  [Int] ->
  Word64 ->
  Value
randomVector range final ds seed = runST $ do
  -- USe some nice impure computation where we can preallocate a
  -- vector of the desired size, populate it via the random number
  -- generator, and then finally reutrn a frozen binary vector.
  arr <- USVec.new n
  g <- initialize 6364136223846793006 seed
  let fill i
        | i < n = do
          v <- uniformR range g
          USVec.write arr i v
          fill $! i + 1
        | otherwise =
          final (SVec.fromList ds) . SVec.convert <$> freeze arr
  fill 0
  where
    n = product ds