-- The menu screen, showing other screens available in hledger-ui.

{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE RecordWildCards #-}

module Hledger.UI.MenuScreen
 (msNew
 ,msUpdate
 ,msDraw
 ,msHandle
 ,msSetSelectedScreen
 )
where

import Brick
import Brick.Widgets.List
import Control.Monad
import Control.Monad.IO.Class (liftIO)
import Data.Maybe
import qualified Data.Text as T
import Data.Time.Calendar (Day)
import qualified Data.Vector as V
import Data.Vector ((!?))
import Graphics.Vty (Event(..),Key(..),Modifier(..), Button (BLeft, BScrollDown, BScrollUp))
import Lens.Micro.Platform
import System.Console.ANSI
import System.FilePath (takeFileName)

import Hledger
import Hledger.Cli hiding (mode, progname, prognameandversion)
import Hledger.UI.UIOptions
import Hledger.UI.UITypes
import Hledger.UI.UIState
import Hledger.UI.UIUtils
import Hledger.UI.UIScreens
import Hledger.UI.ErrorScreen (uiReloadJournal, uiCheckBalanceAssertions, uiReloadJournalIfChanged)
import Hledger.UI.Editor (runIadd, runEditor, endPosition)
import Brick.Widgets.Edit (getEditContents, handleEditorEvent)


msDraw :: UIState -> [Widget Name]
msDraw UIState{aopts=_uopts@UIOpts{uoCliOpts=copts@CliOpts{reportspec_=_rspec}}
              ,ajournal=j
              ,aScreen=MS sst
              ,aMode=mode
              } = dbgui "msDraw" $
    case mode of
      Help              -> [helpDialog, maincontent]
      _                 -> [maincontent]
  where
    maincontent = Widget Greedy Greedy $ do
      render $ defaultLayout toplabel bottomlabel $ renderList msDrawItem True (sst ^. mssList)
      where
        toplabel =
              withAttr (attrName "border" <> attrName "filename") files
          <+> (if ignore_assertions_ . balancingopts_ $ inputopts_ copts
               then withAttr (attrName "border" <> attrName "query") (str " ignoring balance assertions")
               else str "")
          where
            files = case journalFilePaths j of
                           [] -> str ""
                           f:_ -> str $ takeFileName f
                           -- [f,_:[]] -> (withAttr ("border" <> "bold") $ str $ takeFileName f) <+> str " (& 1 included file)"
                           -- f:fs  -> (withAttr ("border" <> "bold") $ str $ takeFileName f) <+> str (" (& " ++ show (length fs) ++ " included files)")

        bottomlabel = case mode of
                        Minibuffer label ed -> minibuffer label ed
                        _                   -> quickhelp
          where
            quickhelp = borderKeysStr' [
               ("?", str "help")
--              ,("RIGHT", str "register")
              -- ,("t", renderToggle (tree_ ropts) "list" "tree")
              -- ,("t", str "tree")
              -- ,("l", str "list")
              -- ,("-+", str "depth")
              -- ,("H", renderToggle (not ishistorical) "end-bals" "changes")
              -- ,("F", renderToggle1 (isJust . forecast_ $ inputopts_ copts) "forecast")
              --,("/", "filter")
              --,("DEL", "unfilter")
              --,("ESC", "cancel/top")
              ,("a", str "add")
--               ,("g", "reload")
              ,("q", str "quit")
              ]

msDraw _ =  dbgui "msDraw" $ errorWrongScreenType "draw function"  -- PARTIAL:

-- msDrawItem :: (Int,Int) -> Bool -> MenuScreenItem -> Widget Name
-- msDrawItem (_acctwidth, _balwidth) _selected MenuScreenItem{..} =
msDrawItem :: Bool -> MenuScreenItem -> Widget Name
msDrawItem _selected MenuScreenItem{..} =
  Widget Greedy Fixed $ do
    render $ txt msItemScreenName

-- XXX clean up like asHandle
msHandle :: BrickEvent Name AppEvent -> EventM Name UIState ()
msHandle ev = do
  ui0 <- get'
  dbguiEv "msHandle"
  case ui0 of
    ui@UIState{
       aopts=UIOpts{uoCliOpts=copts}
      ,ajournal=j
      ,aMode=mode
      ,aScreen=MS sst
      } -> do
      let
        -- save the currently selected account, in case we leave this screen and lose the selection
        mselscr = case listSelectedElement $ _mssList sst of
                    Just (_, MenuScreenItem{..}) -> Just msItemScreen
                    Nothing -> Nothing
        nonblanks = V.takeWhile (not . T.null . msItemScreenName) $ listElements $ _mssList sst
        lastnonblankidx = max 0 (length nonblanks - 1)
      d <- liftIO getCurrentDay

      case mode of
        Minibuffer _ ed ->
          case ev of
            VtyEvent (EvKey KEsc   []) -> put' $ closeMinibuffer ui
            VtyEvent (EvKey KEnter []) -> put' $ regenerateScreens j d $
                case setFilter s $ closeMinibuffer ui of
                  Left bad -> showMinibuffer "Cannot compile regular expression" (Just bad) ui
                  Right ui' -> ui'
              where s = chomp $ unlines $ map strip $ getEditContents ed
            VtyEvent (EvKey (KChar 'l') [MCtrl]) -> redraw
            VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspend ui
            VtyEvent e -> do
              ed' <- nestEventM' ed $ handleEditorEvent (VtyEvent e)
              put' ui{aMode=Minibuffer "filter" ed'}
            AppEvent _  -> return ()
            MouseDown{} -> return ()
            MouseUp{}   -> return ()

        Help ->
          case ev of
            -- VtyEvent (EvKey (KChar 'q') []) -> halt
            VtyEvent (EvKey (KChar 'l') [MCtrl]) -> redraw
            VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspend ui
            _ -> helpHandle ev

        Normal ->
          case ev of
            VtyEvent (EvKey (KChar 'q') []) -> halt
            -- EvKey (KChar 'l') [MCtrl] -> do
            VtyEvent (EvKey KEsc        []) -> put' $ resetScreens d ui
            VtyEvent (EvKey (KChar c)   []) | c == '?' -> put' $ setMode Help ui
            -- XXX AppEvents currently handled only in Normal mode
            -- XXX be sure we don't leave unconsumed events piling up
            AppEvent (DateChange old _) | isStandardPeriod p && p `periodContainsDate` old ->
              put' $ regenerateScreens j d $ setReportPeriod (DayPeriod d) ui
              where
                p = reportPeriod ui
            e | e `elem` [VtyEvent (EvKey (KChar 'g') []), AppEvent FileChange] ->
              liftIO (uiReloadJournal copts d ui) >>= put'
            VtyEvent (EvKey (KChar 'I') []) -> put' $ uiCheckBalanceAssertions d (toggleIgnoreBalanceAssertions ui)
            VtyEvent (EvKey (KChar 'a') []) -> suspendAndResume $ clearScreen >> setCursorPosition 0 0 >> add copts j >> uiReloadJournalIfChanged copts d j ui
            VtyEvent (EvKey (KChar 'A') []) -> suspendAndResume $ void (runIadd (journalFilePath j)) >> uiReloadJournalIfChanged copts d j ui
            VtyEvent (EvKey (KChar 'E') []) -> suspendAndResume $ void (runEditor endPosition (journalFilePath j)) >> uiReloadJournalIfChanged copts d j ui

--             VtyEvent (EvKey (KChar 'B') []) -> put' $ regenerateScreens j d $ toggleConversionOp ui
--             VtyEvent (EvKey (KChar 'V') []) -> put' $ regenerateScreens j d $ toggleValue ui
--             VtyEvent (EvKey (KChar '0') []) -> put' $ regenerateScreens j d $ setDepth (Just 0) ui
--             VtyEvent (EvKey (KChar '1') []) -> put' $ regenerateScreens j d $ setDepth (Just 1) ui
--             VtyEvent (EvKey (KChar '2') []) -> put' $ regenerateScreens j d $ setDepth (Just 2) ui
--             VtyEvent (EvKey (KChar '3') []) -> put' $ regenerateScreens j d $ setDepth (Just 3) ui
--             VtyEvent (EvKey (KChar '4') []) -> put' $ regenerateScreens j d $ setDepth (Just 4) ui
--             VtyEvent (EvKey (KChar '5') []) -> put' $ regenerateScreens j d $ setDepth (Just 5) ui
--             VtyEvent (EvKey (KChar '6') []) -> put' $ regenerateScreens j d $ setDepth (Just 6) ui
--             VtyEvent (EvKey (KChar '7') []) -> put' $ regenerateScreens j d $ setDepth (Just 7) ui
--             VtyEvent (EvKey (KChar '8') []) -> put' $ regenerateScreens j d $ setDepth (Just 8) ui
--             VtyEvent (EvKey (KChar '9') []) -> put' $ regenerateScreens j d $ setDepth (Just 9) ui
--             VtyEvent (EvKey (KChar '-') []) -> put' $ regenerateScreens j d $ decDepth ui
--             VtyEvent (EvKey (KChar '_') []) -> put' $ regenerateScreens j d $ decDepth ui
--             VtyEvent (EvKey (KChar c)   []) | c `elem` ['+','='] -> put' $ regenerateScreens j d $ incDepth ui
--             VtyEvent (EvKey (KChar 'T') []) -> put' $ regenerateScreens j d $ setReportPeriod (DayPeriod d) ui

--             -- display mode/query toggles
--             VtyEvent (EvKey (KChar 'H') []) -> modify' (regenerateScreens j d . toggleHistorical) >> msCenterAndContinue
--             VtyEvent (EvKey (KChar 't') []) -> modify' (regenerateScreens j d . toggleTree) >> msCenterAndContinue
--             VtyEvent (EvKey (KChar c) []) | c `elem` ['z','Z'] -> modify' (regenerateScreens j d . toggleEmpty) >> msCenterAndContinue
--             VtyEvent (EvKey (KChar 'R') []) -> modify' (regenerateScreens j d . toggleReal) >> msCenterAndContinue
--             VtyEvent (EvKey (KChar 'U') []) -> modify' (regenerateScreens j d . toggleUnmarked) >> msCenterAndContinue
--             VtyEvent (EvKey (KChar 'P') []) -> modify' (regenerateScreens j d . togglePending) >> msCenterAndContinue
--             VtyEvent (EvKey (KChar 'C') []) -> modify' (regenerateScreens j d . toggleCleared) >> msCenterAndContinue
--             VtyEvent (EvKey (KChar 'F') []) -> modify' (regenerateScreens j d . toggleForecast d)

            -- VtyEvent (EvKey (KDown)     [MShift]) -> put' $ regenerateScreens j d $ shrinkReportPeriod d ui
            -- VtyEvent (EvKey (KUp)       [MShift]) -> put' $ regenerateScreens j d $ growReportPeriod d ui
            -- VtyEvent (EvKey (KRight)    [MShift]) -> put' $ regenerateScreens j d $ nextReportPeriod journalspan ui
            -- VtyEvent (EvKey (KLeft)     [MShift]) -> put' $ regenerateScreens j d $ previousReportPeriod journalspan ui
            VtyEvent (EvKey (KChar '/') []) -> put' $ regenerateScreens j d $ showMinibuffer "filter" Nothing ui
            VtyEvent (EvKey k           []) | k `elem` [KBS, KDel] -> (put' $ regenerateScreens j d $ resetFilter ui)

            VtyEvent (EvKey (KChar 'l') [MCtrl]) -> scrollSelectionToMiddle (_mssList sst) >> redraw
            VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspend ui

            -- RIGHT enters selected screen if there is one
            VtyEvent e | e `elem` moveRightEvents
                      , not $ isBlankElement $ listSelectedElement (_mssList sst) ->
              msEnterScreen d (fromMaybe Accounts mselscr) ui

            -- MouseDown is sometimes duplicated, https://github.com/jtdaugherty/brick/issues/347
            -- just use it to move the selection
            MouseDown _n BLeft _mods Location{loc=(_x,y)} | not $ (=="") clickedname -> do
              put' ui{aScreen=MS sst}  -- XXX does this do anything ?
              where
                item = listElements (_mssList sst) !? y
                clickedname = maybe "" msItemScreenName item
                -- mclickedscr  = msItemScreen <$> item
            -- and on MouseUp, enter the subscreen
            MouseUp _n (Just BLeft) Location{loc=(_x,y)} ->  -- | not $ (=="") clickedname ->
              case mclickedscr of
                Just scr -> msEnterScreen d scr ui
                Nothing  -> return ()
              where
                item = listElements (_mssList sst) !? y
                -- clickedname = maybe "" msItemScreenName item
                mclickedscr  = msItemScreen <$> item

            -- when selection is at the last item, DOWN scrolls instead of moving, until maximally scrolled
            VtyEvent e | e `elem` moveDownEvents, isBlankElement mnextelement -> do
              vScrollBy (viewportScroll $ (_mssList sst)^.listNameL) 1
              where mnextelement = listSelectedElement $ listMoveDown (_mssList sst)

            -- mouse scroll wheel scrolls the viewport up or down to its maximum extent,
            -- pushing the selection when necessary.
            MouseDown name btn _mods _loc | btn `elem` [BScrollUp, BScrollDown] -> do
              let scrollamt = if btn==BScrollUp then -1 else 1
              list' <- nestEventM' (_mssList sst) $ listScrollPushingSelection name (msListSize (_mssList sst)) scrollamt
              put' ui{aScreen=MS sst{_mssList=list'}}

            -- if page down or end leads to a blank padding item, stop at last non-blank
            VtyEvent e@(EvKey k           []) | k `elem` [KPageDown, KEnd] -> do
              l <- nestEventM' (_mssList sst) $ handleListEvent e
              if isBlankElement $ listSelectedElement l
              then do
                let l' = listMoveTo lastnonblankidx l
                scrollSelectionToMiddle l'
                put' ui{aScreen=MS sst{_mssList=l'}}
              else
                put' ui{aScreen=MS sst{_mssList=l}}

            -- fall through to the list's event handler (handles up/down)
            VtyEvent e -> do
              list' <- nestEventM' (_mssList sst) $ handleListEvent (normaliseMovementKeys e)
              put' ui{aScreen=MS $ sst & mssList .~ list'}

            MouseDown{} -> return ()
            MouseUp{}   -> return ()
            AppEvent _  -> return ()

    _ -> dbguiEv "msHandle" >> errorWrongScreenType "event handler"

msEnterScreen :: Day -> ScreenName -> UIState -> EventM Name UIState ()
msEnterScreen d scrname ui@UIState{ajournal=j, aopts=uopts} = do
  dbguiEv "msEnterScreen"
  let
    scr = case scrname of
      Accounts        -> asNew uopts d j Nothing
      Balancesheet    -> bsNew uopts d j Nothing
      Incomestatement -> isNew uopts d j Nothing
  put' $ pushScreen scr ui

-- | Set the selected list item on the menu screen. Has no effect on other screens.
msSetSelectedScreen :: Int -> Screen -> Screen
msSetSelectedScreen selidx (MS mss@MSS{_mssList=l}) = MS mss{_mssList=listMoveTo selidx l}
msSetSelectedScreen _ s = s

isBlankElement mel = ((msItemScreenName . snd) <$> mel) == Just ""

msListSize = V.length . V.takeWhile ((/="").msItemScreenName) . listElements