module TextViewport.Render.RenderItem where

import Data.Hashable (Hashable)
import Data.Sequences (Index, Textual)
import TextViewport.Buffer.Item (Item(..))
import TextViewport.Render.CachedRender
import TextViewport.Render.RenderedItem
import TextViewport.Render.Segmentation (Segmenter(applySeg))


renderItem
  :: (Segmenter seg a, Hashable a, Textual a, Index a ~ Int)
  => Int -> Int -> Item a seg -> Maybe (CachedRender a seg)
  -> CachedRender a seg
renderItem width itemIx (Item txt strategy) mOld =
  case mOld of
    Just old
      | crWidth old == width
      , crText old  == txt
      -> old
    _ ->
      let linesV   = applySeg strategy width itemIx txt
          rendered = RenderedItem linesV
      in CachedRender
           { crWidth    = width
           , crStrategy = strategy
           , crText     = txt
           , crRendered = rendered
           }