{-# LANGUAGE OverloadedStrings #-}

module Hledger.UI.UIUtils (
  pushScreen
 ,popScreen
 ,screenEnter
 ,getViewportSize
 -- ,margin
 ,withBorderAttr
 ,topBottomBorderWithLabel
 ,topBottomBorderWithLabels
 ,defaultLayout
 ,borderQueryStr
 ,borderDepthStr
 ,borderKeysStr
 ) where

import Control.Lens ((^.))
-- import Control.Monad
-- import Control.Monad.IO.Class
-- import Data.Default
import Data.List
import Data.Monoid
import Data.Time.Calendar (Day)
import Brick
-- import Brick.Widgets.List
import Brick.Widgets.Border
import Brick.Widgets.Border.Style
import Graphics.Vty as Vty

import Hledger.UI.UITypes
import Hledger.Utils (applyN)

pushScreen :: Screen -> AppState -> AppState
pushScreen scr st = st{aPrevScreens=(aScreen st:aPrevScreens st)
                      ,aScreen=scr
                      }

popScreen :: AppState -> AppState
popScreen st@AppState{aPrevScreens=s:ss} = st{aScreen=s, aPrevScreens=ss}
popScreen st = st

-- clearScreens :: AppState -> AppState
-- clearScreens st = st{aPrevScreens=[]}

-- | Enter a new screen, saving the old screen & state in the
-- navigation history and initialising the new screen's state.
screenEnter :: Day -> Screen -> AppState -> AppState
screenEnter d scr st = (sInitFn scr) d $
                       pushScreen scr
                       st

-- | In the EventM monad, get the named current viewport's width and height,
-- or (0,0) if the named viewport is not found.
getViewportSize :: Name -> EventM (Int,Int)
getViewportSize name = do
  mvp <- lookupViewport name
  let (w,h) = case mvp of
        Just vp -> vp ^. vpSize
        Nothing -> (0,0)
  -- liftIO $ putStrLn $ show (w,h)
  return (w,h)

defaultLayout toplabel bottomlabel =
  topBottomBorderWithLabels (str " "<+>toplabel<+>str " ") (str " "<+>bottomlabel<+>str " ") .
  margin 1 0 Nothing
  -- topBottomBorderWithLabel2 label .
  -- padLeftRight 1 -- XXX should reduce inner widget's width by 2, but doesn't
                    -- "the layout adjusts... if you use the core combinators"

topBottomBorderWithLabel label = \wrapped ->
  Widget Greedy Greedy $ do
    c <- getContext
    let (_w,h) = (c^.availWidthL, c^.availHeightL)
        h' = h - 2
        wrapped' = vLimit (h') wrapped
        debugmsg =
          ""
          -- "  debug: "++show (_w,h')
    render $
      hBorderWithLabel (label <+> str debugmsg)
      <=>
      wrapped'
      <=>
      hBorder

topBottomBorderWithLabels toplabel bottomlabel = \wrapped ->
  Widget Greedy Greedy $ do
    c <- getContext
    let (_w,h) = (c^.availWidthL, c^.availHeightL)
        h' = h - 2
        wrapped' = vLimit (h') wrapped
        debugmsg =
          ""
          -- "  debug: "++show (_w,h')
    render $
      hBorderWithLabel (toplabel <+> str debugmsg)
      <=>
      wrapped'
      <=>
      hBorderWithLabel bottomlabel

-- XXX should be equivalent to the above, but isn't (page down goes offscreen)
_topBottomBorderWithLabel2 label = \wrapped ->
 let debugmsg = ""
 in hBorderWithLabel (label <+> str debugmsg)
    <=>
    wrapped
    <=>
    hBorder

-- XXX superseded by pad, in theory
-- | Wrap a widget in a margin with the given horizontal and vertical
-- thickness, using the current background colour or the specified
-- colour.
-- XXX May disrupt border style of inner widgets.
-- XXX Should reduce the available size visible to inner widget, but doesn't seem to (cf drawRegisterScreen2).
margin :: Int -> Int -> Maybe Color -> Widget -> Widget
margin h v mcolour = \w ->
  Widget Greedy Greedy $ do
    c <- getContext
    let w' = vLimit (c^.availHeightL - v*2) $ hLimit (c^.availWidthL - h*2) w
        attr = maybe currentAttr (\c -> c `on` c) mcolour
    render $
      withBorderAttr attr $
      withBorderStyle (borderStyleFromChar ' ') $
      applyN v (hBorder <=>) $
      applyN h (vBorder <+>) $
      applyN v (<=> hBorder) $
      applyN h (<+> vBorder) $
      w'

   -- withBorderAttr attr .
   -- withBorderStyle (borderStyleFromChar ' ') .
   -- applyN n border

withBorderAttr attr = updateAttrMap (applyAttrMappings [(borderAttr, attr)])

-- _ui = vCenter $ vBox [ hCenter box
--                       , str " "
--                       , hCenter $ str "Press Esc to exit."
--                       ]

borderQueryStr :: String -> Widget
borderQueryStr ""  = str ""
borderQueryStr qry = str " matching " <+> withAttr (borderAttr <> "query") (str qry)

borderDepthStr :: Maybe Int -> Widget
borderDepthStr Nothing  = str ""
borderDepthStr (Just d) = str " to " <+> withAttr (borderAttr <> "depth") (str $ "depth "++show d)

borderKeysStr :: [(String,String)] -> Widget
borderKeysStr keydescs =
  hBox $
  intersperse sep $
  [withAttr (borderAttr <> "keys") (str keys) <+> str ": " <+> str desc | (keys, desc) <- keydescs]
  where
    sep = str " | "
    -- sep = "  "