{-# LANGUAGE BlockArguments        #-}
{-# LANGUAGE DataKinds             #-}
{-# LANGUAGE DerivingStrategies    #-}
{-# LANGUAGE DeriveGeneric         #-}
{-# LANGUAGE FlexibleContexts      #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE TypeApplications      #-}

module MetaBrush.Document
  ( AABB(..)
  , Document(..), currentDocument
  , Stroke(..)
  , PointData(..), BrushPointData(..)
  , FocusState(..)
  , _selection, _brush
  )
  where

-- containers
import Data.IntMap.Strict
  ( IntMap )
import qualified Data.IntMap.Strict as IntMap
  ( lookup )
import Data.Sequence
  ( Seq )
import GHC.Generics
  ( Generic )

-- generic-lens
import Data.Generics.Product.Fields
  ( field' )
import Data.Generics.Product.Typed
  ( HasType(typed) )

-- lens
import Control.Lens
  ( Lens' )

-- text
import Data.Text
  ( Text )

-- stm
import qualified Control.Concurrent.STM      as STM
  ( atomically )
import qualified Control.Concurrent.STM.TVar as STM
  ( TVar, readTVar )

-- MetaBrush
import Math.Bezier.Stroke
  ( StrokePoint(..) )
import Math.Vector2D
  ( Point2D )
import MetaBrush.Unique
  ( Unique )

--------------------------------------------------------------------------------

data AABB
  = AABB
  { topLeft  :: !( Point2D Double )
  , botRight :: !( Point2D Double )
  }
  deriving stock Show

data Document
  = Document
    { displayName    :: !Text
    , filePath       :: !( Maybe FilePath )
    , unsavedChanges :: !Bool
    , strokes        :: ![ Stroke ]
    , bounds         :: !AABB
    , viewportCenter :: !( Point2D Double )
    , zoomFactor     :: !Double
    }
  deriving stock ( Show, Generic )

data Stroke
  = Stroke
  { strokePoints  :: !( Seq ( StrokePoint PointData ) )
  , strokeName    :: Text
  , strokeVisible :: !Bool
  , strokeUnique  :: Unique
  }
  deriving stock ( Show, Generic )

data PointData
  = PointData
  { pointState :: FocusState
  , brushShape :: Seq ( StrokePoint BrushPointData )
  }
  deriving stock ( Show, Generic )

data BrushPointData
  = BrushPointData
  { brushPointState :: FocusState }
  deriving stock ( Show, Generic )

data FocusState
  = Normal
  | Hover
  | Selected
  deriving stock ( Show, Eq )

_selection :: HasType FocusState pt => Lens' ( StrokePoint pt ) FocusState
_selection = field' @"pointData" . typed @FocusState

_brush :: Lens' ( StrokePoint PointData ) ( Seq ( StrokePoint BrushPointData ) )
_brush = field' @"pointData" . field' @"brushShape"

currentDocument :: STM.TVar ( Maybe Int ) -> STM.TVar ( IntMap Document ) -> IO ( Maybe Document )
currentDocument activeDocumentTVar openDocumentsTVar = STM.atomically do
  mbActive <- STM.readTVar activeDocumentTVar
  case mbActive of
    Nothing -> pure Nothing
    Just i  -> do
      docs <- STM.readTVar openDocumentsTVar
      pure ( IntMap.lookup i docs )