{-|
Module      : Monomer.Widgets.Singles.Button
Copyright   : (c) 2018 Francisco Vallarino
License     : BSD-3-Clause (see the LICENSE file)
Maintainer  : fjvallarino@gmail.com
Stability   : experimental
Portability : non-portable

Button widget, with support for multiline text. At the most basic level, a
button consists of a caption and an event to raise when clicked.
-}
{-# LANGUAGE BangPatterns #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE StrictData #-}

module Monomer.Widgets.Singles.Button (
  -- * Configuration
  ButtonCfg,
  -- * Constructors
  button,
  button_,
  mainButton,
  mainButton_
) where

import Control.Applicative ((<|>))
import Control.Lens ((&), (^.), (.~))
import Data.Default
import Data.Maybe
import Data.Text (Text)

import qualified Data.Sequence as Seq

import Monomer.Widgets.Container
import Monomer.Widgets.Singles.Label

import qualified Monomer.Lens as L

data ButtonType
  = ButtonNormal
  | ButtonMain
  deriving (Eq, Show)

{-|
Configuration options for button:

- 'trimSpaces': whether to remove leading/trailing spaces in the caption.
- 'ellipsis': if ellipsis should be used for overflown text.
- 'multiline': if text may be split in multiple lines.
- 'maxLines': maximum number of text lines to show.
- 'resizeFactor': flexibility to have more or less spaced assigned.
- 'resizeFactorW': flexibility to have more or less horizontal spaced assigned.
- 'resizeFactorH': flexibility to have more or less vertical spaced assigned.
- 'onFocus': event to raise when focus is received.
- 'onFocusReq': 'WidgetRequest' to generate when focus is received.
- 'onBlur': event to raise when focus is lost.
- 'onBlurReq': 'WidgetRequest' to generate when focus is lost.
- 'onClick': event to raise when button is clicked.
- 'onClickReq': 'WidgetRequest' to generate when button is clicked.
-}
data ButtonCfg s e = ButtonCfg {
  _btnButtonType :: Maybe ButtonType,
  _btnIgnoreTheme :: Maybe Bool,
  _btnLabelCfg :: LabelCfg s e,
  _btnOnFocusReq :: [Path -> WidgetRequest s e],
  _btnOnBlurReq :: [Path -> WidgetRequest s e],
  _btnOnClickReq :: [WidgetRequest s e]
}

instance Default (ButtonCfg s e) where
  def = ButtonCfg {
    _btnButtonType = Nothing,
    _btnIgnoreTheme = Nothing,
    _btnLabelCfg = def,
    _btnOnFocusReq = [],
    _btnOnBlurReq = [],
    _btnOnClickReq = []
  }

instance Semigroup (ButtonCfg s e) where
  (<>) t1 t2 = ButtonCfg {
    _btnButtonType = _btnButtonType t2 <|> _btnButtonType t1,
    _btnIgnoreTheme = _btnIgnoreTheme t2 <|> _btnIgnoreTheme t1,
    _btnLabelCfg = _btnLabelCfg t1 <> _btnLabelCfg t2,
    _btnOnFocusReq = _btnOnFocusReq t1 <> _btnOnFocusReq t2,
    _btnOnBlurReq = _btnOnBlurReq t1 <> _btnOnBlurReq t2,
    _btnOnClickReq = _btnOnClickReq t1 <> _btnOnClickReq t2
  }

instance Monoid (ButtonCfg s e) where
  mempty = def

instance CmbIgnoreTheme (ButtonCfg s e) where
  ignoreTheme_ ignore = def {
    _btnIgnoreTheme = Just ignore
  }

instance CmbTrimSpaces (ButtonCfg s e) where
  trimSpaces_ trim = def {
    _btnLabelCfg = trimSpaces_ trim
  }

instance CmbEllipsis (ButtonCfg s e) where
  ellipsis_ ellipsis = def {
    _btnLabelCfg = ellipsis_ ellipsis
  }

instance CmbMultiline (ButtonCfg s e) where
  multiline_ multi = def {
    _btnLabelCfg = multiline_ multi
  }

instance CmbMaxLines (ButtonCfg s e) where
  maxLines count = def {
    _btnLabelCfg = maxLines count
  }

instance CmbResizeFactor (ButtonCfg s e) where
  resizeFactor s = def {
    _btnLabelCfg = resizeFactor s
  }

instance CmbResizeFactorDim (ButtonCfg s e) where
  resizeFactorW w = def {
    _btnLabelCfg = resizeFactorW w
  }
  resizeFactorH h = def {
    _btnLabelCfg = resizeFactorH h
  }

instance WidgetEvent e => CmbOnFocus (ButtonCfg s e) e Path where
  onFocus fn = def {
    _btnOnFocusReq = [RaiseEvent . fn]
  }

instance CmbOnFocusReq (ButtonCfg s e) s e Path where
  onFocusReq req = def {
    _btnOnFocusReq = [req]
  }

instance WidgetEvent e => CmbOnBlur (ButtonCfg s e) e Path where
  onBlur fn = def {
    _btnOnBlurReq = [RaiseEvent . fn]
  }

instance CmbOnBlurReq (ButtonCfg s e) s e Path where
  onBlurReq req = def {
    _btnOnBlurReq = [req]
  }

instance WidgetEvent e => CmbOnClick (ButtonCfg s e) e where
  onClick handler = def {
    _btnOnClickReq = [RaiseEvent handler]
  }

instance CmbOnClickReq (ButtonCfg s e) s e where
  onClickReq req = def {
    _btnOnClickReq = [req]
  }

mainConfig :: ButtonCfg s e
mainConfig = def {
  _btnButtonType = Just ButtonMain
}

-- | Creates a button with main styling. Useful for dialogs.
mainButton :: WidgetEvent e => Text -> e -> WidgetNode s e
mainButton caption handler = button_ caption handler [mainConfig]

-- | Creates a button with main styling. Useful for dialogs. Accepts config.
mainButton_ :: WidgetEvent e => Text -> e -> [ButtonCfg s e] -> WidgetNode s e
mainButton_ caption handler configs = button_ caption handler newConfigs where
  newConfigs = mainConfig : configs

-- | Creates a button with normal styling.
button :: WidgetEvent e => Text -> e -> WidgetNode s e
button caption handler = button_ caption handler def

-- | Creates a button with normal styling. Accepts config.
button_ :: WidgetEvent e => Text -> e -> [ButtonCfg s e] -> WidgetNode s e
button_ caption handler configs = buttonNode where
  config = onClick handler <> mconcat configs
  widget = makeButton caption config
  !buttonNode = defaultWidgetNode "button" widget
    & L.info . L.focusable .~ True

makeButton :: WidgetEvent e => Text -> ButtonCfg s e -> Widget s e
makeButton !caption !config = widget where
  widget = createContainer () def {
    containerAddStyleReq = False,
    containerDrawDecorations = False,
    containerUseScissor = True,
    containerGetBaseStyle = getBaseStyle,
    containerInit = init,
    containerMerge = merge,
    containerHandleEvent = handleEvent,
    containerResize = resize
  }

  !buttonType = fromMaybe ButtonNormal (_btnButtonType config)

  getBaseStyle wenv node
    | ignoreTheme = Nothing
    | otherwise = case buttonType of
        ButtonNormal -> Just (collectTheme wenv L.btnStyle)
        ButtonMain -> Just (collectTheme wenv L.btnMainStyle)
    where
      ignoreTheme = _btnIgnoreTheme config == Just True

  createChildNode wenv node = newNode where
    nodeStyle = node ^. L.info . L.style
    labelCfg = _btnLabelCfg config
    labelCurrStyle = labelCurrentStyle childOfFocusedStyle
    !labelNode = label_ caption [ignoreTheme, labelCfg, labelCurrStyle]
      & L.info . L.style .~ nodeStyle
    !newNode = node
      & L.children .~ Seq.singleton labelNode

  init wenv node = result where
    result = resultNode (createChildNode wenv node)

  merge wenv node oldNode oldState = result where
    result = resultNode (createChildNode wenv node)

  handleEvent wenv node target evt = case evt of
    Focus prev -> handleFocusChange node prev (_btnOnFocusReq config)
    Blur next -> handleFocusChange node next (_btnOnBlurReq config)

    KeyAction mode code status
      | isSelectKey code && status == KeyPressed -> Just result
      where
        isSelectKey code = isKeyReturn code || isKeySpace code

    Click p _ _
      | isPointInNodeVp node p -> Just result

    ButtonAction p btn BtnPressed 1 -- Set focus on click
      | mainBtn btn && pointInVp p && not focused -> Just resultFocus

    _ -> Nothing
    where
      mainBtn btn = btn == wenv ^. L.mainButton
      focused = isNodeFocused wenv node
      pointInVp p = isPointInNodeVp node p
      reqs = _btnOnClickReq config
      result = resultReqs node reqs
      resultFocus = resultReqs node [SetFocus (node ^. L.info . L.widgetId)]

  resize wenv node viewport children = resized where
    assignedAreas = Seq.fromList [viewport]
    resized = (resultNode node, assignedAreas)