module LaantasImage
  (Item (..), splitItem, splitItem', makeItem)
where

import Lang
import Text.Pandoc.Definition
import Data.Bifunctor
import Data.Function
import Data.Maybe
import Data.Map (Map)
import qualified Data.Map as Map
import Data.Text (Text)
import qualified Data.Text as Text
import qualified Data.Text.Lazy as Lazy
import qualified Laantas
import Data.Char (isSpace)


data Item =
  Item {
    text, title  :: Text,
    size, stroke :: Double,
    width        :: Double,
    color        :: Text,
    showText     :: Bool
  } deriving (Eq, Show)

splitItem :: Vars => Text -> Maybe Item
splitItem (Text.uncons -> Just (c, txt))
  | c == '!' = Just $ splitItem' txt
  | c == '#' = Just $ (splitItem' txt) {showText = False}
splitItem _ = Nothing

splitItem' :: Vars => Text -> Item
splitItem' txt₀ =
  case imageOpts txt₀ of
    Just (txt, opts) -> defaultItem txt ?defColor
      & withOpt opts "size"   (\s i -> i {size   = readt s})
      & withOpt opts "stroke" (\k i -> i {stroke = readt k})
      & withOpt opts "width"  (\w i -> i {width  = readt w})
      & withOpt opts "color"  (\c i -> i {color  = c})
    Nothing -> defaultItem txt₀ ?defColor
  where readt x = read $ Text.unpack x

withOpt :: Ord k => Map k v -> k -> (v -> a -> a) -> (a -> a)
withOpt m k f =
  case Map.lookup k m of
    Just v  -> f v
    Nothing -> id

defaultItem :: Text -> Text -> Item
defaultItem txt color =
    Item {
      text = Text.filter notPunc txt,
      title = toTitle txt,
      size = 2,
      stroke = 1.25,
      width = 600,
      color = color,
      showText = True
    }

split1 :: Text -> Text -> Maybe (Text, Text)
split1 s txt =
  let (a, b) = Text.breakOn s txt in
  if Text.null b then
    Nothing
  else
    Just (Text.strip a, Text.strip $ Text.drop (Text.length s) b)

type Opts = Map Text Text

imageOpts :: Text -> Maybe (Text, Opts)
imageOpts = fmap (second splitOpts) . getOpts

getOpts :: Text -> Maybe (Text, Text)
getOpts = split1 "|"

splitOpts :: Text -> Map Text Text
splitOpts = Map.fromList . map splitOpt . Text.splitOn ";" where
  splitOpt txt = fromMaybe ("file", txt) $ split1 "=" txt

toTitle :: Text -> Text
toTitle = Text.filter \c -> c /= '\\' && c /= '#'

makeItem :: Item -> Inline
makeItem (Item {..}) =
  let env = Laantas.E {..}
      words = Laantas.split text in
  RawInline "html" $
    Lazy.toStrict $ Lazy.dropAround isSpace $ Laantas.prettyText $
    Laantas.doGlyphsNoDoctype words env `Laantas.with`
      [Laantas.Class_ Laantas.<<- "scr"]

notPunc :: Char -> Bool
notPunc c = c `notElem` ("{}·" :: String)