Set note date when the path begin with a timestamp (#552)

This change simplifies timeline creation by setting the date metadata
from the filename when it begins with `YYYY-MM-DD-`.

docs/guide/yaml-config.md

@@ -21,6 +21,9 @@ Notice how this page's sidebar colorscheme has [changed to green]{.greenery}? Vi
 
 - `page.image`: The image to use for the page. This is used for the [[ogp]] meta tag `og:image` meta tag. If not specified, the first image in the page is used. Relative URLs are automatically rewritten to absolute URLs if `page.siteUrl` is non-empty.
 
+- `date`: The note timestamp. This is used to order note chronologically, such as for the timeline [[query|query]].
+  The value can be set from the filename if it begins with `YYYY-MM-DD`, which is useful for including the date in the note URL.
+  In case of conflict, the date from the YAML configuration takes priority.
 
 ## Examples
 

emanote/CHANGELOG.md

@@ -24,6 +24,7 @@
   - Lua filters: filter paths will now be looked up in all layers now.
   - Live server now uses Tailwind 3 ([\#503](https://github.com/srid/emanote/pull/503))
   - Enable auto identifier for org files ([\#502](https://github.com/srid/emanote/pull/502))
+  - Support date metadata from the filename when it begins with YYYY-MM-DD ([\#552](https://github.com/srid/emanote/pull/552)).
 - Bug fixes:
   - Emanote no longer crashes when run on an empty directory ([\#487](https://github.com/srid/emanote/issues/487))
   - Stork search fixes

emanote/emanote.cabal

@@ -1,6 +1,6 @@
 cabal-version:      2.4
 name:               emanote
-version:            1.3.17.1
+version:            1.3.18.0
 license:            AGPL-3.0-only
 copyright:          2022 Sridhar Ratnakumar
 maintainer:         [email protected]

emanote/src/Emanote/Model/Note.hs

@@ -10,6 +10,7 @@ import Control.Monad.Logger (MonadLogger)
 import Control.Monad.Writer (MonadWriter (tell), WriterT, runWriterT)
 import Data.Aeson qualified as Aeson
 import Data.Aeson.Optics qualified as AO
+import Data.Char (isDigit)
 import Data.Default (Default (def))
 import Data.IxSet.Typed (Indexable (..), IxSet, ixFun, ixList)
 import Data.IxSet.Typed qualified as Ix
@@ -29,14 +30,15 @@ import Network.URI.Slug (Slug)
 import Optics.Core ((%), (.~))
 import Optics.TH (makeLenses)
 import Relude
-import System.FilePath ((</>))
+import System.FilePath (takeFileName, (</>))
 import Text.Pandoc (readerExtensions, runPure)
 import Text.Pandoc.Builder qualified as B
 import Text.Pandoc.Definition (Pandoc (..))
 import Text.Pandoc.Extensions
 import Text.Pandoc.Readers.Org (readOrg)
 import Text.Pandoc.Scripting (ScriptingEngine)
 import Text.Pandoc.Walk qualified as W
+import Text.Parsec qualified as P
 import UnliftIO.Directory (doesPathExist)
 
 data Feed = Feed
@@ -316,7 +318,19 @@ parseNote scriptingEngine pluginBaseDir r src@(_, fp) s = do
         parseNoteMarkdown scriptingEngine pluginBaseDir fp s
       R.LMLRoute_Org _ -> do
         parseNoteOrg s
-  pure $ mkNoteWith r (Just src) doc meta errs
+  let metaWithDateFromPath = case P.parse dateParser mempty (takeFileName fp) of
+        Left _ -> meta
+        Right date -> SData.modifyAeson (pure "date") (Just . fromMaybe (Aeson.String date)) meta
+  pure $ mkNoteWith r (Just src) doc metaWithDateFromPath errs
+  where
+    dateParser = do
+      year <- replicateM 4 P.digit
+      _ <- P.char '-'
+      month <- replicateM 2 P.digit
+      _ <- P.char '-'
+      day <- replicateM 2 P.digit
+      _ <- P.satisfy (not . isDigit)
+      pure $ toText $ mconcat [year, "-", month, "-", day]
 
 parseNoteOrg :: (MonadWriter [Text] m) => Text -> m (Pandoc, Aeson.Value)
 parseNoteOrg s =