{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE NamedFieldPuns #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE NoImplicitPrelude #-}

module App (run, helpText) where

import qualified Brick as B
import qualified Brick.Widgets.Border as B
import qualified Brick.Widgets.Center as B
import qualified Brick.Widgets.List as B
import qualified Data.List.NonEmpty as NE
import qualified Data.Sequence as S
import qualified Data.Set as Set
import qualified Data.Text as T
import qualified Graphics.Vty as V
import InvertedIndex
import PathStats
import Protolude
import qualified System.HrfSize as HRF

data Widgets
  = WidgetPrevPane
  | WidgetCurrPane
  | WidgetNextPane
  | WidgetWhyDepends
  | WidgetSearch
  deriving (Show, Eq, Ord)

data Modal s
  = ModalHelp
  | ModalWhyDepends (B.GenericList Widgets Seq (NonEmpty (Path s)))
  | ModalSearch Text Text (B.GenericList Widgets Seq (Path s))

data AppEnv s = AppEnv
  { aeActualStoreEnv :: StoreEnv s (PathStats s),
    aeInvertedIndex :: InvertedIndex,
    aePrevPane :: List s,
    aeCurrPane :: List s,
    aeNextPane :: List s,
    aeParents :: [List s],
    aeOpenModal :: Maybe (Modal s),
    aeShowInfoPane :: Bool
  }

type Path s = StorePath s (StoreName s) (PathStats s)

type List s = B.GenericList Widgets Seq (Path s)

attrTerminal :: B.AttrName
attrTerminal = "terminal"

run :: StoreEnv s (PathStats s) -> IO ()
run env = void . B.defaultMain app =<< appEnv
  where
    appEnv = do
      let ii = iiFromList . toList . map (storeNameToText . spName) $ seAll env
      _ <- forkIO $ evaluate (rnf ii)
      return $
        AppEnv
          { aeActualStoreEnv =
              env,
            aeInvertedIndex =
              ii,
            aePrevPane =
              B.list WidgetPrevPane S.empty 0,
            aeCurrPane =
              B.list WidgetCurrPane (S.fromList . NE.toList $ seGetRoots env) 0,
            aeNextPane =
              B.list WidgetNextPane S.empty 0,
            aeParents =
              [],
            aeOpenModal =
              Nothing,
            aeShowInfoPane =
              True
          }
          & repopulateNextPane

renderList ::
  Bool ->
  List s ->
  B.Widget Widgets
renderList isFocused list =
  B.renderList
    ( \_
       StorePath
         { spName,
           spPayload = PathStats {psTotalSize, psAddedSize},
           spRefs
         } ->
          let color =
                if null spRefs
                  then B.withAttr attrTerminal
                  else identity
           in color $
                B.padRight B.Max (B.txt $ storeNameToShortText spName)
                  B.<+> B.padLeft
                    B.Max
                    ( B.txt $
                        prettySize psTotalSize
                          <> if not (null spRefs)
                            then
                              " ("
                                <> prettySize psAddedSize
                                <> ")"
                            else mempty
                    )
    )
    isFocused
    list

app :: B.App (AppEnv s) () Widgets
app =
  B.App
    { B.appDraw = \env@AppEnv {aeOpenModal} ->
        [ case aeOpenModal of
            Nothing -> B.emptyWidget
            Just ModalHelp -> renderHelpModal
            Just (ModalWhyDepends l) -> renderWhyDependsModal l
            Just (ModalSearch l r xs) -> renderSearchModal l r xs,
          renderMainScreen env
        ],
      B.appChooseCursor = \_ -> const Nothing,
      B.appHandleEvent = \s e ->
        case (e, aeOpenModal s) of
          -- main screen
          (B.VtyEvent (V.EvKey k []), Nothing)
            | k `elem` [V.KChar 'q', V.KEsc] ->
              B.halt s
          (B.VtyEvent (V.EvKey (V.KChar '?') []), Nothing) ->
            B.continue s {aeOpenModal = Just ModalHelp}
          (B.VtyEvent (V.EvKey (V.KChar 'w') []), Nothing) ->
            B.continue $ showWhyDepends s
          (B.VtyEvent (V.EvKey (V.KChar '/') []), Nothing) ->
            B.continue $ showAndUpdateSearch "" "" s
          (B.VtyEvent (V.EvKey (V.KChar 'i') []), Nothing) ->
            B.continue $ s {aeShowInfoPane = not (aeShowInfoPane s)}
          (B.VtyEvent (V.EvKey k []), Nothing)
            | k `elem` [V.KChar 'h', V.KLeft] ->
              B.continue $ moveLeft s
          (B.VtyEvent (V.EvKey k []), Nothing)
            | k `elem` [V.KChar 'j', V.KDown, V.KChar '\t'] ->
              B.continue $ move B.listMoveDown s
          (B.VtyEvent (V.EvKey k []), Nothing)
            | k `elem` [V.KChar 'k', V.KUp, V.KBackTab] ->
              B.continue $ move B.listMoveUp s
          (B.VtyEvent (V.EvKey k []), Nothing)
            | k `elem` [V.KChar 'l', V.KRight] ->
              B.continue $ moveRight s
          (B.VtyEvent (V.EvKey V.KPageUp []), Nothing) ->
            B.continue =<< moveF B.listMovePageUp s
          (B.VtyEvent (V.EvKey V.KPageDown []), Nothing) ->
            B.continue =<< moveF B.listMovePageDown s
          -- why-depends modal
          (B.VtyEvent (V.EvKey k []), Just (ModalWhyDepends _))
            | k `elem` [V.KChar 'q', V.KEsc] ->
              B.continue s {aeOpenModal = Nothing}
          (B.VtyEvent (V.EvKey k []), Just (ModalWhyDepends l))
            | k `elem` [V.KChar 'j', V.KDown, V.KChar '\t'] ->
              B.continue s {aeOpenModal = Just $ ModalWhyDepends (B.listMoveDown l)}
          (B.VtyEvent (V.EvKey k []), Just (ModalWhyDepends l))
            | k `elem` [V.KChar 'k', V.KUp, V.KBackTab] ->
              B.continue s {aeOpenModal = Just $ ModalWhyDepends (B.listMoveUp l)}
          (B.VtyEvent (V.EvKey V.KPageUp []), Just (ModalWhyDepends l)) ->
            B.listMovePageUp l >>= \l' ->
              B.continue s {aeOpenModal = Just $ ModalWhyDepends l'}
          (B.VtyEvent (V.EvKey V.KPageDown []), Just (ModalWhyDepends l)) ->
            B.listMovePageDown l >>= \l' ->
              B.continue s {aeOpenModal = Just $ ModalWhyDepends l'}
          (B.VtyEvent (V.EvKey V.KEnter []), Just (ModalWhyDepends l)) ->
            let closed = s {aeOpenModal = Nothing}
             in case B.listSelectedElement l of
                  Nothing -> B.continue closed
                  Just (_, path) -> B.continue $ selectPath path closed
          -- search modal
          (B.VtyEvent (V.EvKey V.KEsc []), Just (ModalSearch _ _ _)) ->
            B.continue s {aeOpenModal = Nothing}
          (B.VtyEvent (V.EvKey k []), Just (ModalSearch l r xs))
            | k `elem` [V.KDown, V.KChar '\t'] ->
              B.continue s {aeOpenModal = Just $ ModalSearch l r (B.listMoveDown xs)}
          (B.VtyEvent (V.EvKey k []), Just (ModalSearch l r xs))
            | k `elem` [V.KUp, V.KBackTab] ->
              B.continue s {aeOpenModal = Just $ ModalSearch l r (B.listMoveUp xs)}
          (B.VtyEvent (V.EvKey V.KLeft []), Just (ModalSearch l r xs)) ->
            B.continue
              s
                { aeOpenModal =
                    Just $ ModalSearch (T.dropEnd 1 l) (T.takeEnd 1 l <> r) (B.listMoveUp xs)
                }
          (B.VtyEvent (V.EvKey V.KRight []), Just (ModalSearch l r xs)) ->
            B.continue
              s
                { aeOpenModal =
                    Just $ ModalSearch (l <> T.take 1 r) (T.drop 1 r) (B.listMoveUp xs)
                }
          (B.VtyEvent (V.EvKey (V.KChar c) []), Just (ModalSearch l r _))
            | c `Set.member` allowedSearchChars ->
              B.continue (showAndUpdateSearch (l <> T.singleton c) r s)
          (B.VtyEvent (V.EvKey (V.KBS) []), Just (ModalSearch l r _)) ->
            B.continue (showAndUpdateSearch (T.dropEnd 1 l) r s)
          (B.VtyEvent (V.EvKey V.KEnter []), Just (ModalSearch _ _ xs)) ->
            let closed = s {aeOpenModal = Nothing}
             in case B.listSelectedElement xs of
                  Nothing -> B.continue closed
                  Just (_, path) ->
                    B.continue $
                      selectPath
                        (shortestPathTo (aeActualStoreEnv s) (spName path))
                        closed
          _ ->
            B.continue s,
      B.appStartEvent = \s -> return s,
      B.appAttrMap = \_ ->
        B.attrMap
          (V.white `B.on` V.black)
          [ (B.listSelectedFocusedAttr, V.black `B.on` V.white),
            (attrTerminal, B.fg V.blue)
          ]
    }
  where
    allowedSearchChars :: Set Char
    allowedSearchChars =
      Set.fromList
        ( mconcat
            [ ['a' .. 'z'],
              ['A' .. 'Z'],
              ['0' .. '9'],
              "+-.=?_"
            ]
        )

renderMainScreen :: AppEnv s -> B.Widget Widgets
renderMainScreen env@AppEnv {aePrevPane, aeCurrPane, aeNextPane, aeShowInfoPane} =
  (B.joinBorders . B.border)
    ( B.hBox
        [ renderList True aePrevPane,
          B.vBorder,
          renderList True aeCurrPane,
          B.vBorder,
          renderList False aeNextPane
        ]
    )
    B.<=> if aeShowInfoPane then renderInfoPane env else renderModeline env

renderModeline :: AppEnv s -> B.Widget Widgets
renderModeline env =
  let selected = selectedPath env
   in B.txt $
        T.intercalate
          " - "
          [ T.pack $ storeNameToPath (spName selected),
            "NAR Size: " <> prettySize (spSize selected),
            "Closure Size: " <> prettySize (psTotalSize $ spPayload selected)
          ]

renderInfoPane :: AppEnv s -> B.Widget Widgets
renderInfoPane env =
  let selected = selectedPath env
      immediateParents = psImmediateParents $ spPayload selected
   in B.txt $
        T.intercalate
          "\n"
          [ T.pack $ storeNameToPath (spName selected),
            "NAR Size: " <> prettySize (spSize selected),
            "Closure Size: " <> prettySize (psTotalSize $ spPayload selected),
            if null immediateParents
              then "Immediate Parents: -"
              else
                "Immediate Parents (" <> T.pack (show $ length immediateParents) <> "): "
                  <> T.intercalate ", " (map storeNameToShortText immediateParents)
          ]

renderModal :: Text -> B.Widget a -> B.Widget a
renderModal title widget =
  widget
    & B.borderWithLabel (B.txt title)
    & B.hLimitPercent 90
    & B.vLimitPercent 60
    & B.centerLayer

helpText :: Text
helpText =
  T.intercalate
    "\n"
    [ "hjkl/Arrow Keys : Navigate",
      "q/Esc:          : Quit / close modal",
      "w               : Open why-depends mode",
      "/               : Open search mode",
      "i               : Toggle modeline",
      "?               : Show help"
    ]

renderHelpModal :: B.Widget a
renderHelpModal = renderModal "Help" (B.txt helpText)

renderWhyDependsModal ::
  B.GenericList Widgets Seq (NonEmpty (Path s)) ->
  B.Widget Widgets
renderWhyDependsModal l =
  renderModal "why-depends" (B.renderList renderDepends True l)
  where
    renderDepends _ =
      B.txt . pathsToText
    pathsToText xs =
      xs
        & NE.toList
        & fmap (storeNameToShortText . spName)
        & T.intercalate " → "

showWhyDepends :: AppEnv s -> AppEnv s
showWhyDepends env@AppEnv {aeActualStoreEnv} =
  env
    { aeOpenModal =
        Just . ModalWhyDepends $
          let selected = selectedPath env
              route = selectedPaths env
              xs = S.fromList $ whyDepends aeActualStoreEnv (spName selected)
           in B.list WidgetWhyDepends xs 1
                & B.listMoveTo
                  (fromMaybe 0 $ (((==) `on` fmap spName) route) `S.findIndexL` xs)
    }

renderSearchModal :: Text -> Text -> B.GenericList Widgets Seq (Path s) -> B.Widget Widgets
renderSearchModal left right list =
  renderModal "Search" window
  where
    window =
      B.txt left B.<+> B.txt "|" B.<+> B.txt right
        B.<=> B.hBorder
        B.<=> renderList True list

showAndUpdateSearch :: Text -> Text -> AppEnv s -> AppEnv s
showAndUpdateSearch left right env@AppEnv {aeActualStoreEnv, aeInvertedIndex} =
  env {aeOpenModal = Just $ ModalSearch left right results}
  where
    results =
      let xs =
            iiSearch (left <> right) aeInvertedIndex
              & (S.fromList . Set.toList)
              & fmap (seLookup aeActualStoreEnv . StoreName)
       in B.list WidgetSearch xs 1

move :: (List s -> List s) -> AppEnv s -> AppEnv s
move f = runIdentity . moveF (Identity . f)

moveF :: Applicative f => (List s -> f (List s)) -> AppEnv s -> f (AppEnv s)
moveF f env@AppEnv {aeCurrPane} =
  repopulateNextPane . (\p -> env {aeCurrPane = p}) <$> f aeCurrPane

moveLeft :: AppEnv s -> AppEnv s
moveLeft env@AppEnv {aeParents = []} = env
moveLeft env@AppEnv {aePrevPane, aeCurrPane, aeParents = parent : grandparents} =
  env
    { aeParents = grandparents,
      aePrevPane = parent,
      aeCurrPane = aePrevPane {B.listName = WidgetCurrPane},
      aeNextPane = aeCurrPane {B.listName = WidgetNextPane}
    }

moveRight :: AppEnv s -> AppEnv s
moveRight env@AppEnv {aePrevPane, aeCurrPane, aeNextPane, aeParents}
  | null (B.listElements aeNextPane) = env
  | otherwise =
    env
      { aePrevPane = aeCurrPane {B.listName = WidgetPrevPane},
        aeCurrPane = aeNextPane {B.listName = WidgetCurrPane},
        aeParents = aePrevPane : aeParents
      }
      & repopulateNextPane

repopulateNextPane :: AppEnv s -> AppEnv s
repopulateNextPane env@AppEnv {aeActualStoreEnv, aeNextPane} =
  let ref = selectedPath env
   in env
        { aeNextPane =
            B.listReplace
              ( S.sortOn (Down . psTotalSize . spPayload)
                  . S.fromList
                  . map (seLookup aeActualStoreEnv)
                  $ spRefs ref
              )
              (Just 0)
              aeNextPane
        }

selectedPath :: AppEnv s -> Path s
selectedPath = NE.head . selectedPaths

selectedPaths :: AppEnv s -> NonEmpty (Path s)
selectedPaths AppEnv {aePrevPane, aeCurrPane, aeParents} =
  let parents =
        mapMaybe
          (fmap snd . B.listSelectedElement)
          (aePrevPane : aeParents)
   in case B.listSelectedElement aeCurrPane of
        Nothing -> panic "invariant violation: no selected element"
        Just (_, p) -> p :| parents

selectPath :: NonEmpty (Path s) -> AppEnv s -> AppEnv s
selectPath path env
  | (spName <$> path) == (spName <$> selectedPaths env) =
    env
selectPath path env@AppEnv {aeActualStoreEnv} =
  let root :| children = NE.reverse path
      lists =
        NE.scanl
          ( \(_, prev) curr ->
              ( map (seLookup aeActualStoreEnv) $
                  spRefs prev,
                curr
              )
          )
          (NE.toList (seGetRoots aeActualStoreEnv), root)
          children
          & NE.reverse
          & fmap
            (\(possible, selected) -> mkList WidgetPrevPane possible selected)
          & (<> (emptyPane :| []))
   in case lists of
        (curr :| prevs) ->
          let (prev, parents) = case prevs of
                [] -> (emptyPane, [])
                p : ps -> (p, ps)
           in env
                { aeParents = parents,
                  aePrevPane = prev,
                  aeCurrPane = curr {B.listName = WidgetCurrPane}
                }
                & repopulateNextPane
  where
    mkList name possible selected =
      let contents = S.sortOn (Down . psTotalSize . spPayload) (S.fromList possible)
       in B.list name contents 1
            & B.listMoveTo
              (fromMaybe (0) $ (((==) `on` spName) selected) `S.findIndexL` contents)
    emptyPane =
      B.list WidgetPrevPane S.empty 0

-- Utils

prettySize :: Int -> T.Text
prettySize size = case HRF.convertSize $ fromIntegral size of
  HRF.Bytes d -> T.pack (show d)
  HRF.KiB d -> T.pack (show d) <> " KiB"
  HRF.MiB d -> T.pack (show d) <> " MiB"
  HRF.GiB d -> T.pack (show d) <> " GiB"
  HRF.TiB d -> T.pack (show d) <> " TiB"