{-# OPTIONS_GHC -fno-warn-unticked-promoted-constructors -fno-warn-orphans #-}

{-# LANGUAGE DataKinds             #-}
{-# LANGUAGE DeriveFunctor         #-}
{-# LANGUAGE FlexibleContexts      #-}
{-# LANGUAGE FlexibleInstances     #-}
{-# LANGUAGE GADTs                 #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE NamedFieldPuns        #-}
{-# LANGUAGE OverloadedLabels      #-}
{-# LANGUAGE OverloadedStrings     #-}
{-# LANGUAGE RecordWildCards       #-}
{-# LANGUAGE ScopedTypeVariables   #-}
{-# LANGUAGE TypeFamilies          #-}
{-# LANGUAGE TypeOperators         #-}

-- | Implementation of 'Gtk.Paned' as a declarative container.
module GI.Gtk.Declarative.Container.Paned
  ( Pane
  , PaneProperties (..)
  , defaultPaneProperties
  , pane
  , paned
  )
where

import           Data.Coerce                        (coerce)
import           Data.Default.Class                 (Default (def))
import           Data.Vector                        (Vector)
import qualified Data.Vector                        as Vector
import           GHC.Ptr                            (nullPtr)
import qualified GI.GLib                            as GLib
import qualified GI.Gtk                             as Gtk

import           GI.Gtk.Declarative.Attributes
import           GI.Gtk.Declarative.Container
import           GI.Gtk.Declarative.Container.Class
import           GI.Gtk.Declarative.EventSource
import           GI.Gtk.Declarative.Patch
import           GI.Gtk.Declarative.Widget

-- | Describes a pane to be packed with
-- 'Gtk.panePack1'/'Gtk.panePack2' in a 'Gtk.Paned'.
data Pane event = Pane
  { paneProperties :: PaneProperties
  , paneChild      :: Widget event
  }
  deriving (Functor)

-- | Values used when packing a pane into a 'Gtk.Paned'.
data PaneProperties = PaneProperties
  { resize :: Bool
  , shrink :: Bool
  }

-- | Defaults for 'PaneProperties'. Use these and override specific
-- fields.
defaultPaneProperties :: PaneProperties
defaultPaneProperties = PaneProperties {resize = False, shrink = True}

instance Default PaneProperties where
  def = defaultPaneProperties

-- | Construct a pane to be packed with
-- 'Gtk.panePack1'/'Gtk.panePack2' in a 'Gtk.Paned'.
pane :: PaneProperties -> Widget event -> Pane event
pane paneProperties paneChild = Pane {..}

instance Patchable Pane where
  create = create . paneChild
  patch s b1 b2 = patch s (paneChild b1) (paneChild b2)

instance EventSource Pane where
  subscribe Pane{..} = subscribe paneChild

-- | Construct a 'Gtk.Paned' based on attributes and two child 'Pane's.
paned :: Vector (Attribute Gtk.Paned event) -> Pane event -> Pane event -> Widget event
paned attrs p1 p2 = container Gtk.Paned attrs (Panes p1 p2)

data Panes child = Panes child child
  deriving (Functor)

instance IsContainer Gtk.Paned Pane where
  appendChild paned' Pane{paneProperties = PaneProperties{resize, shrink}} widget' = do
    c1 <- Gtk.panedGetChild1 paned'
    c2 <- Gtk.panedGetChild2 paned'
    case (c1, c2) of
      (Nothing, Nothing) -> Gtk.panedPack1 paned' widget' (coerce resize) (coerce shrink)
      (Just _, Nothing) -> Gtk.panedPack2 paned' widget' (coerce resize) (coerce shrink)
      _ -> GLib.logDefaultHandler
           (Just "gi-gtk-declarative")
           [GLib.LogLevelFlagsLevelWarning]
           (Just "appendChild: The `GI.Gtk.Paned` widget can only fit 2 panes. Additional children will be ignored.")
           nullPtr
  replaceChild paned' Pane{paneProperties = PaneProperties{resize, shrink}} i old new = do
    Gtk.widgetDestroy old
    case i of
      0 -> Gtk.panedPack1 paned' new (coerce resize) (coerce shrink)
      1 -> Gtk.panedPack2 paned' new (coerce resize) (coerce shrink)
      _ -> GLib.logDefaultHandler
           (Just "gi-gtk-declarative")
           [GLib.LogLevelFlagsLevelWarning]
           (Just "replaceChild: The `GI.Gtk.Paned` widget can only fit 2 panes. Additional children will be ignored.")
           nullPtr

instance ToChildren Gtk.Paned Panes Pane where
  toChildren _ (Panes p1 p2) = Children (Vector.fromList [p1, p2])