Fix ordering in prev/next

src/Build.hs

@@ -62,7 +62,7 @@ buildArticles navbar inputs = do
     templateArticle <- readFileUtf8 "template/article.html"
     templateIndex <- readFileUtf8 "template/index.html"
 
-    articlesInput' <- read extraMeta `mapM` inputs
+    articlesInput' <- sortArticlesPlus <$> read extraMeta `mapM` inputs
     let neighbors = getNeighbors $ snd <$> articlesInput'
     -- TODO Refactor!
     let articlesInput = map (\((prevM, nextM), (path, art)) -> (path, addMeta (Meta $ Map.fromList [("prev", fromMaybe (MetaString "") prevM), ("next", fromMaybe (MetaString "") nextM)]) art)) (zip neighbors articlesInput')
@@ -78,7 +78,8 @@ buildArticles navbar inputs = do
 
 getNeighbors :: [Pandoc] -> [(Maybe MetaValue, Maybe MetaValue)]
 getNeighbors articles = f <$> [0..(length articles - 1)] where
-    f n = (getLink =<< articles `safeIndex` (n-1), getLink =<< articles `safeIndex` (n+1))
+    -- Index + 1 is previous as the newest is first in the list
+    f n = (getLink =<< articles `safeIndex` (n+1), getLink =<< articles `safeIndex` (n-1))
 
 getLink :: Pandoc -> Maybe MetaValue
 getLink (Pandoc meta _) = lookupMeta "link" meta
@@ -93,13 +94,20 @@ safeIndex (_:xs) n = safeIndex xs (n-1)
 -- | Generate an index page from a list of Articles.
 -- Expects each article to contain a meta value "link" with its link path.
 generateIndex :: Meta -> [Pandoc] -> Pandoc
-generateIndex extraMeta = generateIndex' . sort where
-    sort = sortOn (Down . (\(Pandoc meta _) -> lookupMeta "date" meta))
+generateIndex extraMeta = generateIndex' {- . sortArticles -} where  -- Sorting is done right at the beginning now
     generateIndex' articles = Pandoc metaOutput [] where
         metaOutput = extraMeta <> Meta (Map.fromList
             [("pagetitle", MetaString "Home"), ("articles", MetaList articlesOutput)])
         articlesOutput = generateIndexMeta <$> articles
 
+-- TODO only plus is needed, refactor
+-- | Sorts a list of pandocuments by their date meta values.
+sortArticles :: [Pandoc] -> [Pandoc]
+sortArticles = sortOn (Down . (\(Pandoc meta _) -> lookupMeta "date" meta))
+
+sortArticlesPlus :: [(a, Pandoc)] -> [(a, Pandoc)]
+sortArticlesPlus = sortOn (Down . (\(_, (Pandoc meta _)) -> lookupMeta "date" meta))
+
 -- | Generates the Pandoc MetaMap for a document for the index page.
 -- It contains the meta of the source, the link and the body.
 generateIndexMeta :: Pandoc -> MetaValue