group gallery items by year

make-pages/GalleryPage.hs

@@ -1,9 +1,8 @@
 module GalleryPage (make) where
 
 import Control.Exception
-import Data.Function (on)
-import Data.List (sortBy)
-import Data.Ord (comparing)
+import Data.Function (on, (&))
+import Data.List (sortBy, groupBy)
 import qualified Data.Text.Lazy as Lazy
 import Data.Text.Lazy.Builder (Builder, toLazyText)
 import System.FilePath ((</>), takeDirectory)
@@ -42,9 +41,25 @@ make' title nsfw infos = [b|@0
     </main>
   |]
  where
-  items = map (uncurry makeItem) infos
-  infos = sortBy (cmpInfo `on` snd) infos'
-  cmpInfo = flip (comparing #date) <> comparing #title
+  items = map (uncurry $ makeYearItems nsfw) infosByYear
+  infosByYear =
+    infos & sortBy  (cmpInfo `on` #second)
+          & map     (\fi -> (fi, #year $ #second fi))
+          & groupBy ((==) `on` #second)
+          & map     (\ys -> (#second (head ys), map #first ys))
+  cmpInfo (Info {date = d1, title = t1}) (Info {date = d2, title = t2}) =
+    compare d2 d1 <> compare t1 t2
+
+makeYearItems :: Bool -- ^ nsfw
+              -> Integer -- ^ year
+              -> [(FilePath, Info)]
+              -> Builder
+makeYearItems nsfw year infos = [b|@4
+    <li class="item year-marker">
+      <span class=year-text>$^year</span>
+    $4.items
+  |]
+  where items = map (uncurry $ makeItem nsfw) infos
 
 makeItem :: Bool -> FilePath -> Info -> Builder
 makeItem nsfw file info = [b|@4