module Functions.Template
  ( Template(..)
  , makeTemplate
  , applyTemplate
  ) where

import Types (IsFunction(..), Token)
import DependencyGenerator (DepGenM, TokenableTo(..), toTupleToken, runFunction)

import Data.Text (Text)
import qualified Data.Text as T

data Template = TemplateParts Text Text
  deriving (Eq, Show)

data MakeTemplate = MakeTemplate deriving Show
instance IsFunction MakeTemplate (Text, Text) Template where
  evalFunction MakeTemplate (t, c) =
    let (beforeContent, after) = T.breakOn c t
        afterContent = T.drop (T.length c) after
    in TemplateParts beforeContent afterContent

makeTemplate :: (TokenableTo Text a, TokenableTo Text b) => a -> b -> DepGenM (Token Template)
makeTemplate a b = runFunction MakeTemplate =<< toTupleToken a b


data ApplyTemplate = ApplyTemplate deriving Show
instance IsFunction ApplyTemplate (Template, Text) Text where
  evalFunction ApplyTemplate (TemplateParts beforeContent afterContent, t) =
    T.concat [beforeContent, t, afterContent]

applyTemplate :: (TokenableTo Template a, TokenableTo Text b) => a -> b -> DepGenM (Token Text)
applyTemplate a b = runFunction ApplyTemplate =<< toTupleToken a b