Handle articles dates and tags into the articles JSON

src/JSON.hs

@@ -1,4 +1,5 @@
 {-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE NamedFieldPuns #-}
 module JSON (
     generate
   ) where
@@ -8,40 +9,57 @@ import qualified Article (Article(..))
 import Blog (Blog)
 import qualified Blog (Blog(..), get)
 import Control.Monad.IO.Class (MonadIO(..))
-import Control.Monad.Reader (ReaderT)
+import Control.Monad.Reader (ReaderT, ask)
 import Data.Aeson (ToJSON(..), genericToEncoding, defaultOptions, encode)
 import Data.ByteString.Lazy (writeFile)
-import qualified Data.Map as Map (elems)
+import Data.Map (Map, (!), foldlWithKey, mapKeys, mapWithKey)
+import qualified Data.Map as Map (empty, filter, insert, keys)
+import qualified Data.Set as Set (elems, member)
 import System.FilePath.Posix ((</>), (<.>))
+import System.Posix.Files (modificationTime)
+import System.Posix.Types (EpochTime, FileID)
 import Prelude hiding (writeFile)
 import GHC.Generics
 
+type ArticleID = Int
+
 data ArticleExport = ArticleExport {
       source :: String
     , title :: String
+    , date :: EpochTime
+    , tagged :: [String]
   } deriving (Generic)
 
 instance ToJSON ArticleExport where
   toEncoding = genericToEncoding defaultOptions
 
 data BlogDB = BlogDB {
-    articles :: [ArticleExport]
+      articles :: Map ArticleID ArticleExport
+    , tags :: Map String [ArticleID]
   } deriving (Generic)
 
 instance ToJSON BlogDB where
   toEncoding = genericToEncoding defaultOptions
 
-export :: Article -> ArticleExport
-export article = ArticleExport {
+remap :: (Ord k1, Enum k2, Ord k2) => Map k1 a -> Map k1 k2
+remap =
+  snd . foldlWithKey (\(i, tempMap) key _ -> (succ i, Map.insert key i tempMap)) (toEnum 0, Map.empty)
+
+export :: Blog -> FileID -> Article -> ArticleExport
+export blog fileID article = ArticleExport {
       source = "/" </> Article.urlPath article <.> "md"
     , title = Article.title article
+    , date = modificationTime $ Article.fileStatus article
+    , tagged = Map.keys . Map.filter (Set.member fileID) $ Blog.tags blog
   }
 
 exportBlog :: ReaderT Blog IO BlogDB
 exportBlog = do
-  allArticles <- Blog.get Blog.articles
+  blog <- ask
+  let reindex = remap $ Blog.articles blog
   return $ BlogDB {
-      articles = export <$> Map.elems allArticles
+        articles = mapKeys (reindex !) $ mapWithKey (export blog) (Blog.articles blog)
+      , tags = fmap (reindex !) . Set.elems <$> Blog.tags blog
     }
 
 generate :: ReaderT Blog IO ()