{-# LANGUAGE OverloadedStrings #-}

module State
  ( initialState,
    prepareView
  )
where

import Types (AppState(..), Chapter(chapterTags, chapterTitle), ChapterView(..), EpubEnv, ChapterIndex(..))

-- Get an element from a list without crashing
safeGet :: ChapterIndex -> [a] -> Maybe a
safeGet (ChapterIndex n) xs
  | n < 0 = Nothing
  | otherwise = case drop n xs of
      (x : _) -> Just x
      [] -> Nothing

-- loading template
initialState :: EpubEnv -> AppState
initialState env =
  AppState
    { cEnv = env,
      cIdx = ChapterIndex 0,
      cSpine = [],
      bTitle = "Svitak - Loading...",
      zoomlvl = 1.0,
      activeTask = Nothing,
      cAllChapters = [],
      taskVersion = 0
    }

-- prepare the data for the UI
prepareView :: AppState -> ChapterIndex -> Maybe ChapterView
prepareView st index = do
  chapter <- safeGet index (cAllChapters st)
  pure $ ChapterView
    { viewTitle = bTitle st <> " - " <> chapterTitle chapter
    , viewHtml  = chapterTags chapter
    , viewIdx   = index
    }