-- | Various functions generated as builtins
module Haste.Builtins (toBuiltin) where
import GhcPlugins as P
import Data.JSTarget as J
import Control.Applicative

toBuiltin :: P.Var -> Maybe J.Var
toBuiltin v =
  case (modname, varname) of
    (Just "GHC.Prim", "coercionToken#") ->
      Just $ foreignVar "coercionToken"
    (Just "GHC.Prim", "realWorld#") ->
      Just $ foreignVar "realWorld"
    (Just "GHC.Err", "error") ->
      Just $ foreignVar "err"

    -- Everything to do with unpacking had better be built in for compactness,
    -- efficiency and space reasons.
    (Just "GHC.CString", "unpackCString#") ->
      Just $ foreignVar "unCStr"
    (Just "GHC.CString", "unpackCStringUtf8#") ->
      Just $ foreignVar "unCStr"
    (Just "GHC.CString", "unpackAppendCString#") ->
      Just $ foreignVar "unAppCStr"
    (Just "GHC.CString", "unpackFoldrCString#") ->
      Just $ foreignVar "unFoldrCStr"

    -- Primitive needs of the Haste standard library
    (Just "Haste.Prim", "toJSStr") ->
      Just $ foreignVar "toJSStr"
    (Just "Haste.Prim", "fromJSStr") ->
      Just $ foreignVar "fromJSStr"
    (Just "Haste.Prim", "jsRound") ->
      Just $ foreignVar "Math.round"
    (Just "Haste.Prim", "jsCeiling") ->
      Just $ foreignVar "Math.ceil"
    (Just "Haste.Prim", "jsFloor") ->
      Just $ foreignVar "Math.floor"
    _ | otherwise ->
      Nothing
  where
    modname = moduleNameString . moduleName <$> nameModule_maybe (varName v)
    varname = occNameString $ nameOccName $ varName v