-- | To be able to run this example,
--
-- * install the GLFW-b library (for example using cabal)
-- 
-- * download the STIX2 font files in OTF format from <https://github.com/stipub/stixfonts>, 
-- and put them in this directory (5 files with @.otf@ extension)
--
-- * compile this source file with @ghc -O --make -threaded@
--

module Main where

--------------------------------------------------------------------------------

import Data.Char hiding ( Space )

import Control.Monad
import Data.IORef
import System.IO.Unsafe as Unsafe

import qualified Data.Map as Map ; import Data.Map (Map)

import Graphics.Rendering.OpenGL as GL
import Graphics.UI.GLFW ( Window )

import Graphics.Rendering.MiniTypeset

import GL
import UnicodeMath

--------------------------------------------------------------------------------
-- * The \"document\" we want to render (normally you want to generate this)

document :: Document String
document 
  = Identified "document" 
  $ VertCat AlignRight
      [ block12
      , Space
      , block3
      ]

block12 = HorzCat AlignBottom [ block1 , Space , block2 ]

block1 = Identified "block1" 
       $ VertCat AlignLeft  [line1a,line1b,line1c,line1d]

block2 = VertCat AlignRight [line2a,line2b,line2c,line2d,line2e]

block3 = Identified "block3" 
       $ VertCat AlignLeft [ WithColor (Col 1 1 0) (String greeks), Space, WithColor (Col 1 1 1) equ ]

line1a = String "Lorem ipsum dolor sit amet,"
line1b = WithColor (Col 0.7 0 0) 
       $ String "consectetur adipiscing elit,"
line1c = Identified "line1c"
       $ WithStyle Italic      
       $ String "sed do eiusmod tempor incididunt"
line1d = HorzCat AlignBottom
       [ String "ut labore et "
       , Identified "dolore" $ WithStyle BoldItalic $ WithColor (Col 0 0 0.75) $ String "dolore"
       , String " magna aliqua."
       ]

line2a = String "Ut enim ad minim veniam,"
line2b = Identified "line2b"
       $ WithStyle Bold
       $ String "quis nostrud exercitation"
line2c = String "ullamco laboris nisi ut"
line2d = WithColor (Col 0 0.4 0) 
       $ WithStyle BoldItalic
       $ String "aliquip ex ea commodo"
line2e = String "consequat."

equ = HorzCat AlignBottom
  [ String $ take 8 math_test 
  , Identified "formula" $ WithColor (Col 0.5 0.5 1) $ String $ take 5 (drop 8 math_test)
  , String $ drop 13 math_test
  ]

--------------------------------------------------------------------------------

-- | An enum encoding the font files we use
data MyFontFile
  = Stix2TextRegular
  | Stix2TextBold
  | Stix2TextItalic
  | Stix2TextBoldItalic 
  | Stix2Math
  deriving (Eq,Ord,Show)

-- | An enum encoding our typeface variations
data MyStyle
  = MyRegular 
  | MyBold
  | MyItalic
  | MyBoldItalic
  | MyMath
  deriving (Eq,Ord,Show)

-- | Mapping standard typeface variations to ours
myStyleMap :: BasicStyle -> MyStyle
myStyleMap s = case s of
  Regular    -> MyRegular 
  Bold       -> MyBold
  Italic     -> MyItalic
  BoldItalic -> MyBoldItalic

-- | Mapping typeface variatons to abstract fonts (not always necessary) 
myStyleDefaultFont :: MyStyle -> MyFontFile
myStyleDefaultFont style = case style of
  MyRegular    -> Stix2TextRegular
  MyBold       -> Stix2TextBold
  MyItalic     -> Stix2TextItalic
  MyBoldItalic -> Stix2TextBoldItalic 
  MyMath       -> Stix2Math

-- | Mapping abstract font files to concrete font files
myFontFileMap :: MyFontFile -> FilePath
myFontFileMap ff = case ff of
  Stix2TextRegular    -> "STIX2Text-Regular.otf"
  Stix2TextBold       -> "STIX2Text-Bold.otf"
  Stix2TextItalic     -> "STIX2Text-Italic.otf"
  Stix2TextBoldItalic -> "STIX2Text-BoldItalic.otf"
  Stix2Math           -> "STIX2Math.otf"

-- | Mapping (style,codepoint) pairs to (abstract) font files.
-- For example mathematical symbols are not present in the regular fonts, so 
-- we always map them to the math font.
--
myCharMap :: MyStyle -> Char -> MyFontFile  
myCharMap MyMath  _ = Stix2Math
myCharMap style ch
  | o <= 0x2100  = myStyleDefaultFont style
  | o >= 0xfb00  = myStyleDefaultFont style
  | otherwise    = Stix2Math
  where
    o = ord ch

-- | Our \"multifont\" configuration
myUFC :: UserFontConfig MyFontFile MyStyle 
myUFC = UserFontConfig
  { _ufcFontFiles = myFontFileMap
  , _ufcCharMap   = myCharMap
  , _ufcStyleMap  = myStyleMap
  }

theMultiFont :: IORef (MultiFont MyFontFile MyStyle)
theMultiFont = Unsafe.unsafePerformIO $ newIORef $ error "multifont not loaded"

--------------------------------------------------------------------------------

display :: Window -> Double -> IO ()
display window time = do
  
  clearColor $=! (Color4 0.5 0.5 0.5 1)  
  clear [ColorBuffer,DepthBuffer]
  setWindowCoordSystem 

  mf <- readIORef theMultiFont

  -- create layout
  lout <- createLayout mf (Height 40) document

  -- top-left corner of the rendered text
  let pos0 = Pos 16 16

  -- query bounding box positions, and render them
  usertable  <- dryrunLayout lout pos0
  color $ Color4 1 1 1 (0.1 :: Double)
  blend $=! Enabled
  blendFunc $=! (SrcAlpha,One) -- MinusSrcAlpha)
  mapM_ renderOuterBoxQuad (Map.elems usertable) 
  blend $=! Disabled

  -- render the text
  renderLayout lout pos0

  return ()

--------------------------------------------------------------------------------

initMultifont = do
  mf <- newMultiFont myUFC 
  writeIORef theMultiFont mf  
  return ()

main = do
  initGL initMultifont (\() -> display) 

--------------------------------------------------------------------------------