-----------------------------------------------------------------------------
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE OverloadedStrings #-}
-----------------------------------------------------------------------------
-- |
-- Module      :  Miso.Diff
-- Copyright   :  (C) 2016-2025 David M. Johnson
-- License     :  BSD3-style (see the file LICENSE)
-- Maintainer  :  David M. Johnson <code@dmj.io>
-- Stability   :  experimental
-- Portability :  non-portable
--
-- Functions and helpers for Virtual DOM diffing.
--
----------------------------------------------------------------------------
module Miso.Diff
  ( diff
  , mountElement
  ) where
-----------------------------------------------------------------------------
import qualified Miso.FFI.Internal as FFI
import           Miso.Types
import           Miso.DSL
-----------------------------------------------------------------------------
-- | diffing / patching a given element
diff :: Maybe VTree -> Maybe VTree -> JSVal -> IO ()
diff :: Maybe VTree -> Maybe VTree -> JSVal -> IO ()
diff Maybe VTree
current Maybe VTree
new_ JSVal
mountEl =
  case (Maybe VTree
current, Maybe VTree
new_) of
    (Maybe VTree
Nothing, Maybe VTree
Nothing) -> () -> IO ()
forall a. a -> IO a
forall (f :: * -> *) a. Applicative f => a -> f a
pure ()
    (Just (VTree Object
current'), Just (VTree Object
new')) -> do
      Object -> Object -> JSVal -> IO ()
FFI.diff Object
current' Object
new' JSVal
mountEl
      IO ()
FFI.flush
    (Maybe VTree
Nothing, Just (VTree Object
new')) -> do
      Object -> Object -> JSVal -> IO ()
FFI.diff (JSVal -> Object
Object JSVal
jsNull) Object
new' JSVal
mountEl
      IO ()
FFI.flush
    (Just (VTree Object
current'), Maybe VTree
Nothing) -> do
      Object -> Object -> JSVal -> IO ()
FFI.diff Object
current' (JSVal -> Object
Object JSVal
jsNull) JSVal
mountEl
      IO ()
FFI.flush
-----------------------------------------------------------------------------
-- | return the configured mountPoint element or the body
mountElement :: MisoString -> IO JSVal
mountElement :: MisoString -> IO JSVal
mountElement = \case
  MisoString
"body" -> IO JSVal
FFI.getBody
  MisoString
e -> MisoString -> IO JSVal
FFI.getElementById MisoString
e
-----------------------------------------------------------------------------