implement sourcing of timestamp files

Types.hs

@@ -58,6 +58,7 @@ data SiteState =
     , _redirectTemplate :: FilePath -- ^ Name of the template for redirect pages
     , _tagTemplate :: FilePath -- ^ Name of the template for category pages
     , _listTemplate :: FilePath -- ^ Name of the template for listing pages
+    , _timestampSuffix :: FilePath -- ^ File to search for a timestamp (e.g., if the prefix is ".ts", a timestamp for file "page.md" will be looked for in "page.md.ts"). These are best autogenerated with a script that sources the data from git or so.
     , _urlBase :: FilePath -- ^ "Root route" to prepend to all absolute links.
     , _dumpFinalState :: Bool -- ^ Triggers printing out the structure when the processing finishes.
     }
@@ -128,6 +129,10 @@ siteOptions' = do
     strOption $
     long "url-base" <>
     short 'u' <> help "Base absolute URL" <> value "/" <> showDefault
+  _timestampSuffix <-
+    strOption $
+    long "timestamp-prefix" <>
+    help "Timestamp file suffix for markdowns" <> value ".timestamp" <> showDefault
   _dumpFinalState <-
     switch $
     long "dump-state" <>

reploy.cabal

@@ -11,6 +11,7 @@ executable site
                   , bytestring
                   , containers
                   , data-default
+                  , directory
                   , extra
                   , filepath
                   , hakyll == 4.16.*
@@ -23,8 +24,8 @@ executable site
                   , pandoc
                   , pandoc-types
                   , parsec
-                  , SHA
                   , scientific
+                  , SHA
                   , text
                   , transformers
                   , yaml

site.hs

@@ -4,7 +4,7 @@
 module Main where
 
 import Control.Monad ((>=>), filterM, join, unless, when)
-import Control.Monad.Extra (whenM)
+import Control.Monad.Extra (ifM, whenM)
 import Control.Monad.Trans.State.Lazy
 import qualified Data.Aeson as AE
 import qualified Data.Aeson.Key as K
@@ -27,10 +27,13 @@ import Lens.Micro
 import Lens.Micro.Aeson
 import Lens.Micro.Mtl
 import qualified Options.Applicative
+import System.Directory (doesFileExist)
 import System.FilePath
   ( (</>)
   , isAbsolute
+  , joinPath
   , splitDirectories
+  , splitFileName
   , splitPath
   , takeDirectory
   , takeFileName
@@ -171,6 +174,24 @@ addGlobalMeta (Y.Object m) = do
   r <- fromString <$> use urlBase
   pure . Y.Object $ KM.insert "root" r m
 
+-- | Get the expected timestamp file for a given filepath
+timestampFile :: FilePath -> Site FilePath
+timestampFile fp = do
+  sfx <- use timestampSuffix
+  pure . uncurry (</>) . fmap (++ sfx) . splitFileName $ fp
+
+-- | If a timestamp file for the page exists, add the timestamp metadata.
+addTimeMeta :: PageInfo -> Y.Value -> Site Y.Value
+addTimeMeta pi m'@(Y.Object m) = do
+  tspath <- timestampFile $ pi ^. pagePath
+  io $
+    ifM
+      (doesFileExist tspath)
+      (do putStrLn $ "timestamp <- " ++ tspath
+          ts <- Y.String <$> TIO.readFile tspath
+          pure . Y.Object $ KM.insert "timestamp" ts m)
+      (pure m')
+
 -- | Add page-specific information to the metadata. In this instance, this just
 -- expands the tags for rendering. Eventually would be nice to have the timestamps
 -- and possibly other info sourced right here.
@@ -182,7 +203,7 @@ addPageMeta pi (Y.Object m) = do
     _String .
     to T.unpack .
     to splitDirectories
-  pure . Y.Object $ KM.insert "htags" (Y.array htagMeta) m
+  addTimeMeta pi . Y.Object $ KM.insert "htags" (Y.array htagMeta) m
 
 -- | If viable for a page (by config), add the TOC field
 addTOC :: PageInfo -> Text.Pandoc.Definition.Pandoc -> Y.Value -> Site Y.Value
@@ -358,7 +379,7 @@ listFilename tag = indexFilename $ "list" </> tag
 
 -- | Fold the hierarchical tag bits to a slashed path.
 tagPath :: [String] -> FilePath
-tagPath = foldr (</>) ""
+tagPath = joinPath
 
 -- | Make a link to the tag page
 tagLink :: [String] -> Site FilePath
@@ -366,11 +387,11 @@ tagLink = rootUrl . ("tag" </>) . tagPath
 
 -- | Fold the hierarchical tag bits to a slashed path.
 listPath :: [String] -> FilePath
-listPath = foldr (</>) ""
+listPath = joinPath
 
 -- | Make a link to the tag page
 listLink :: [String] -> Site FilePath
-listLink = rootUrl . ("list" </>) . tagPath
+listLink = rootUrl . ("list" </>) . listPath
 
 -- | Make metadata for printing out a single hierarchical tag (all levels clickable)
 makeHTagMeta :: ([String] -> Site FilePath) -> [String] -> Site Y.Value

templates/header.html

@@ -22,33 +22,5 @@
 <main>
   <div class="flex-sidefill-l"></div>
   <div class="content-holder">
-    <div class="sidebox">
-      <div class="sidebox-right">
-        <a href="{{root}}">Home</a>
-        |
-        <a href="{{root}}tag">Categories</a>
-        |
-        <a href="{{root}}search">Search</a>
-      </div>
-      {{?htags}}
-      <div class="sidebox-header">
-        Card categories
-      </div>
-      <div class="sidebox-values">
-        <ul>
-        {{#htags}}
-        <li class="sidebox-tag">{{#.}}<a href="{{href}}">{{^tag}}all{{/tag}}{{?tag}} » {{tag}}{{/tag}}{{/.}}</a></li>
-        {{/htags}}
-        </ul>
-      </div>
-      {{/htags}}
-      {{?toc}}
-      <div class="sidebox-header">
-        Card outline
-      </div>
-      <div class="sidebox-values sidebox-toc">
-        {{{toc}}}
-      </div>
-      {{/toc}}
-    </div>
+    {{> sidebox.html}}
     <div class="content width-content">

templates/sidebox.html

@@ -0,0 +1,37 @@
+<div class="sidebox">
+  <div class="sidebox-right">
+    <a href="{{root}}">Home</a>
+    |
+    <a href="{{root}}tag">Categories</a>
+    |
+    <a href="{{root}}search">Search</a>
+  </div>
+  {{?htags}}
+  <div class="sidebox-header">
+    Card categories
+  </div>
+  <div class="sidebox-values">
+    <ul>
+    {{#htags}}
+    <li class="sidebox-tag">{{#.}}<a href="{{href}}">{{^tag}}all{{/tag}}{{?tag}} » {{tag}}{{/tag}}{{/.}}</a></li>
+    {{/htags}}
+    </ul>
+  </div>
+  {{/htags}}
+  {{?toc}}
+  <div class="sidebox-header">
+    Card outline
+  </div>
+  <div class="sidebox-values sidebox-toc">
+    {{{toc}}}
+  </div>
+  {{/toc}}
+  {{?timestamp}}
+  <div class="sidebox-header">
+    Last modification
+  </div>
+  <div class="sidebox-values sidebox-toc">
+    {{timestamp}}
+  </div>
+  {{/timestamp}}
+</div>