{-# LANGUAGE TypeFamilies #-}

module Phi.Border ( BorderWidth(..)
                  , simpleBorderWidth
                  , borderH
                  , borderV
                  , BorderConfig(..)
                  , defaultBorderConfig
                  , drawBorder
                  , roundRectangle
                  , border
                  ) where

import Phi.Types
import Phi.Widget

import Control.Monad

import Graphics.Rendering.Cairo


data BorderWidth = BorderWidth { borderTop    :: !Int 
                               , borderRight  :: !Int
                               , borderBottom :: !Int
                               , borderLeft   :: !Int
                               } deriving Show

simpleBorderWidth :: Int -> BorderWidth
simpleBorderWidth w = BorderWidth w w w w

borderH :: BorderWidth -> Int
borderH bw = borderLeft bw + borderRight bw

borderV :: BorderWidth -> Int
borderV bw = borderTop bw + borderBottom bw

data BorderState = BorderState [WidgetState] deriving Show

data BorderConfig = BorderConfig { margin          :: !BorderWidth
                                 , borderWidth     :: !Int
                                 , padding         :: !BorderWidth
                                 , borderColor     :: !Color
                                 , backgroundColor :: !Color
                                 , cornerRadius    :: !Double
                                 , borderWeight    :: !Float
                                 } deriving Show

defaultBorderConfig = BorderConfig { margin = simpleBorderWidth 0
                                   , borderWidth = 1
                                   , padding = simpleBorderWidth 1
                                   , borderColor = (0, 0, 0, 1)
                                   , backgroundColor = (0, 0, 0, 0)
                                   , cornerRadius = 0
                                   , borderWeight = 1
                                   }

data Border = Border BorderConfig [Widget] deriving Show

instance WidgetClass Border where
  type WidgetData Border = BorderState
  initWidget (Border _ widgets) phi disp = liftM BorderState $ mapM (createWidgetState phi disp) widgets
  
  minSize (Border config widgets) = sum (map (\(Widget w) -> minSize w) widgets) + borderH p + 2*bw + borderH m
    where
      m = margin config
      bw = borderWidth config
      p = padding config
  
  weight (Border config _) = borderWeight config
  
  layout (Border config _) (BorderState widgetStates) width height = BorderState $ layoutWidgets widgetStates x y width' height'
    where
      m = margin config
      bw = borderWidth config
      p = padding config

      x = borderLeft m + bw + borderLeft p
      y = borderTop m + bw + borderTop p
      width' = width - borderH m - 2*bw - borderH p
      height' = height - borderV m - 2*bw - borderV p

  render (Border config _) (BorderState widgetStates) w h = do
    drawBorder config 0 0 w h
    clip
    renderWidgets widgetStates
    
  handleMessage _ (BorderState widgetStates) m = BorderState $ handleMessageWidgets m widgetStates

drawBorder :: BorderConfig -> Int -> Int -> Int -> Int -> Render ()
drawBorder config dx dy w h = do
  roundRectangle x y width height radius
  
  save
  setSourceRGBA fr fg fb fa
  fillPreserve
  
  setSourceRGBA br bg bb ba
  setLineWidth $ fromIntegral bw
  strokePreserve
  restore
    where
      m = margin config
      bw = borderWidth config
      p = padding config
      radius = cornerRadius config
      
      x = (fromIntegral dx) + (fromIntegral $ borderLeft m) + (fromIntegral bw)/2
      y = (fromIntegral dy) + (fromIntegral $ borderTop m) + (fromIntegral bw)/2
      width = fromIntegral $ w - borderH m - bw
      height = fromIntegral $ h - borderV m - bw
      
      (br, bg, bb, ba) = borderColor config
      (fr, fg, fb, fa) = backgroundColor config

roundRectangle :: Double -> Double -> Double -> Double -> Double -> Render ()
roundRectangle x y width height radius = do
  newPath
  arc (x + width - radius) (y + radius) radius (-pi/2) 0
  arc (x + width - radius) (y + height - radius) radius 0 (pi/2)
  arc (x + radius) (y + height - radius) radius (pi/2) pi
  arc (x + radius) (y + radius) radius  pi (pi*3/2)
  closePath

border :: BorderConfig -> [Widget] -> Widget
border config widgets = Widget $ Border config widgets