{-# LANGUAGE DeriveGeneric #-}
module JSON (
    generate
  ) where

import Article (Article)
import qualified Article (Article(..))
import Blog (Blog)
import qualified Blog (Blog(..), get)
import Control.Monad.IO.Class (MonadIO(..))
import Control.Monad.Reader (ReaderT)
import Data.Aeson (ToJSON(..), genericToEncoding, defaultOptions, encode)
import Data.ByteString.Lazy (writeFile)
import qualified Data.Map as Map (elems)
import System.FilePath.Posix ((</>), (<.>))
import Prelude hiding (writeFile)
import GHC.Generics

data ArticleExport = ArticleExport {
      source :: String
    , title :: String
  } deriving (Generic)

instance ToJSON ArticleExport where
  toEncoding = genericToEncoding defaultOptions

data BlogDB = BlogDB {
    articles :: [ArticleExport]
  } deriving (Generic)

instance ToJSON BlogDB where
  toEncoding = genericToEncoding defaultOptions

export :: Article -> ArticleExport
export article = ArticleExport {
      source = "/" </> Article.urlPath article <.> "md"
    , title = Article.title article
  }

exportBlog :: ReaderT Blog IO BlogDB
exportBlog = do
  allArticles <- Blog.get Blog.articles
  return $ BlogDB {
      articles = export <$> Map.elems allArticles
    }

generate :: ReaderT Blog IO ()
generate = do
  path <- Blog.get Blog.root
  jsonContent <- exportBlog
  liftIO $ writeFile (path </> "articles.json") (encode jsonContent)