extra metadata loading from a yaml file

Types.hs

@@ -20,9 +20,7 @@
 -- | Separated-out main types of the deployment scriptage.
 module Types where
 
-import AesonUtils
 import Control.Monad.Trans.State.Lazy
-import qualified Data.ByteString.UTF8
 import qualified Data.Map as M
 import qualified Data.Set as S
 import qualified Data.Yaml as Y
@@ -40,6 +38,14 @@ data PageInfo = PageInfo
 
 makeLenses ''PageInfo
 
+-- | Information about where to source all extra metadata
+data MetaSpec
+  = MetaSpecInline String
+  | MetaSpecFile FilePath
+  deriving (Show)
+
+makeLenses ''MetaSpec
+
 -- | Complete internal state of the deployment process that holds all data
 data SiteState = SiteState
   { _pages :: M.Map FilePath PageInfo -- ^ Map of page mounts to `PageInfo`
@@ -62,6 +68,7 @@ data SiteState = SiteState
   , _tagTemplate :: FilePath -- ^ Name of the template for category pages
   , _listTemplate :: FilePath -- ^ Name of the template for listing pages
   , _extraMeta :: Y.Value -- ^ Extra metadata added to rendering of all templates
+  , _extraMetaSpec :: [MetaSpec] -- ^ sources for the extra metadata
   , _metadataSuffix :: FilePath -- ^ File suffix to search for a extra metadata (e.g., if the suffix is ".extra", the extra metadata for file "page.md" will be looked for in "page.md.extra"). These are best autogenerated with a script that sources the data from git or so.
   , _indexFile :: FilePath -- ^ Name of the "index" files to be generated.
   , _urlBase :: FilePath -- ^ "Root route" to prepend to all absolute links.
@@ -151,20 +158,20 @@ siteOptions' = do
                "Suffix for YAML files with base metadata for each markdown page. Metadata from files override the extra metadata specified on commandline, but are overridden by metadata specified directly in the markdown header of the pages."
           <> value ".metadata.yml"
           <> showDefault
-  _extraMeta <-
-    let processKeyVal :: String -> Y.Value
-        processKeyVal opt =
-          case Y.decodeEither' $ Data.ByteString.UTF8.fromString opt of
-            Right v -> v
-            Left err ->
-              error
-                $ "cannot parse YAML in --extra-metadata: "
-                    ++ Y.prettyPrintParseException err
-     in fmap (foldl objMerge Y.Null . map processKeyVal) . many . strOption
-          $ long "extra-metadata"
-              <> short 'e'
-              <> help
-                   "Extra metadata to add to pages rendering in YAML format. May be specified multiple times."
+  _extraMetaSpec <-
+    many
+      $ asum
+          [ fmap MetaSpecInline . strOption
+              $ long "extra-metadata"
+                  <> short 'e'
+                  <> help
+                       "Extra metadata to add to pages rendering in YAML format. May be specified multiple times."
+          , fmap MetaSpecFile . strOption
+              $ long "extra-metadata-file"
+                  <> short 'E'
+                  <> help
+                       "Extra metadata to add to pages rendering, loaded from a YAML file. May be specified multiple times."
+          ]
   _urlBase <-
     strOption
       $ long "url-base"
@@ -199,6 +206,7 @@ siteOptions' = do
       , _installs = S.empty
       , _targets = S.empty
       , _templates = M.empty
+      , _extraMeta = Y.Null
       , ..
       }
 

reploy.hs

@@ -26,6 +26,7 @@ import qualified Data.Aeson as AE
 import qualified Data.Aeson.Key as K
 import qualified Data.Aeson.KeyMap as KM
 import qualified Data.ByteString.Lazy as B
+import qualified Data.ByteString.UTF8
 import Data.Digest.Pure.SHA (sha256, showDigest)
 import Data.Foldable (traverse_)
 import Data.List (inits, nub, sort)
@@ -511,10 +512,37 @@ renderSearchData = use searchDataOut >>= traverse_ go
         putStrLn $ "S -> " ++ out
         AE.encodeFile out $ Y.array (concat ps)
 
+-- | Souce extra metadata accordingly to the metadata specifications
+sourceExtraMetadata :: Site ()
+sourceExtraMetadata = do
+  use extraMetaSpec
+    >>= fmap (foldl objMerge Y.Null) . traverse loadSpec
+    >>= assign extraMeta
+  where
+    loadSpec :: MetaSpec -> Site Y.Value
+    loadSpec (MetaSpecInline yaml) =
+      case Y.decodeEither' $ Data.ByteString.UTF8.fromString yaml of
+        Right v -> pure v
+        Left err ->
+          error
+            $ "cannot parse extra metadata from inline YAML: "
+                ++ Y.prettyPrintParseException err
+    loadSpec (MetaSpecFile path) = do
+      res <- io $ Y.decodeFileEither path
+      case res of
+        Right v -> pure v
+        Left err ->
+          error
+            $ "cannot load YAML metadata from "
+                ++ path
+                ++ ": "
+                ++ Y.prettyPrintParseException err
+
 -- | Build the whole site.
 main = do
   init <- Options.Applicative.execParser siteOptions
   flip runStateT init $ do
+    sourceExtraMetadata
     installAssets
     use sourceDirs >>= traverse sourcePages
     use sourceDirs >>= traverse sourceTagMeta

templates/header.html

@@ -1,4 +1,10 @@
 <header>
+  {{?menu_items}}Menu:
+  <ul>
+  {{#menu_items}}<li>{{.}}</li>{{/menu_items}}
+  </ul>
+  {{/menu_items}}
+
   Navigation:
   <ul>
     <li><a href="{{#pageLink}}/{{/pageLink}}">{{#pageName}}/{{/pageName}}</a></li>

test.yml

@@ -0,0 +1,3 @@
+menu_items:
+  - item1
+  - item2