module Data.Text.ParagraphLayout.Internal.ResolvedBox
    ( ResolvedBox (..)
    , boxEndSpacing
    , boxLeftSpacing
    , boxRightSpacing
    , boxStartSpacing
    )
where

import Data.Int (Int32)
import Data.Text.Glyphize (Direction (DirLTR, DirRTL))

import Data.Text.ParagraphLayout.Internal.BoxOptions

-- | Internal structure describing an inline box.
-- May be shared by multiple fragments.
data ResolvedBox d = ResolvedBox
    { boxUserData :: d
    , boxIndex :: Int
    , boxOptions :: BoxOptions
    , boxDirection :: Direction
    }

instance Eq (ResolvedBox d) where
    a == b = boxIndex a == boxIndex b

boxLeftSpacing :: ResolvedBox d -> Int32
boxLeftSpacing rb = case boxSpacing $ boxOptions rb of
    BoxSpacingLeftRight s _ -> s

boxRightSpacing :: ResolvedBox d -> Int32
boxRightSpacing rb = case boxSpacing $ boxOptions rb of
    BoxSpacingLeftRight _ s -> s

-- | Spacing at the start of the given box.
boxStartSpacing :: ResolvedBox d -> Int32
boxStartSpacing rb = case (boxDirection rb, boxSpacing $ boxOptions rb) of
    (DirLTR, BoxSpacingLeftRight s _) -> s
    (DirRTL, BoxSpacingLeftRight _ s) -> s
    (_, _) -> 0

-- | Spacing at the end of the given box.
boxEndSpacing :: ResolvedBox d -> Int32
boxEndSpacing rb = case (boxDirection rb, boxSpacing $ boxOptions rb) of
    (DirLTR, BoxSpacingLeftRight _ s) -> s
    (DirRTL, BoxSpacingLeftRight s _) -> s
    (_, _) -> 0