Track metadata dependencies

I had to prepend some Rules to global Rules set. This might be possible
to replaced by a correct Store.set call.
I also had to prepend some Compile rules.

4 files changed, 44 insertions, 14 deletions

diff --git a/src/Hakyll/Core/Metadata.hs b/src/Hakyll/Core/Metadata.hs
index 7902b94..a330636 100644
--- a/src/Hakyll/Core/Metadata.hs
+++ b/src/Hakyll/Core/Metadata.hs
@@ -5,6 +5,7 @@ module Hakyll.Core.Metadata
     , getMetadataField
     , getMetadataField'
     , makePatternDependency
+    , metadataFiles
     ) where
 
 
@@ -12,6 +13,7 @@ module Hakyll.Core.Metadata
 import           Control.Monad                  (forM)
 import           Data.Map                       (Map)
 import qualified Data.Map                       as M
+import           System.FilePath.Posix          ((</>), takeDirectory)
 
 
 --------------------------------------------------------------------------------
@@ -61,3 +63,11 @@ makePatternDependency :: MonadMetadata m => Pattern -> m Dependency
 makePatternDependency pattern = do
     matches' <- getMatches pattern
     return $ PatternDependency pattern matches'
+
+--------------------------------------------------------------------------------
+-- | Returns a list of all directory-wise metadata files, subdir first, global last
+metadataFiles :: Identifier -> [Identifier]
+metadataFiles = go . takeDirectory . toFilePath where
+    go "." = [fromFilePath "metadata"]
+    go dir = fromFilePath (dir </> "metadata") : go (takeDirectory dir)
+
diff --git a/src/Hakyll/Core/Provider/Metadata.hs b/src/Hakyll/Core/Provider/Metadata.hs
index 8f39f22..4331861 100644
--- a/src/Hakyll/Core/Provider/Metadata.hs
+++ b/src/Hakyll/Core/Provider/Metadata.hs
@@ -44,7 +44,7 @@ loadMetadata p identifier = do
         Nothing  -> return M.empty
         Just mi' -> loadMetadataFile $ resourceFilePath p mi'
 
-    gmd <- loadGlobalMetadata p $ toFilePath identifier
+    gmd <- loadGlobalMetadata p identifier
 
     return (M.unions [md, emd, gmd], body)
   where
@@ -141,21 +141,17 @@ page = do
 
 --------------------------------------------------------------------------------
 -- | Load directory-wise metadata
-loadGlobalMetadata :: Provider -> FilePath -> IO (M.Map String String)
-loadGlobalMetadata p fp = liftM M.fromList $ loadgm $ takeDirectory fp where 
-    loadgm :: FilePath -> IO [(String, String)]
-    loadgm dir | dir == "." = return []
-               | otherwise = do
-        let mfp = fromFilePath $ combine dir "metadata"
-        md <- if resourceExists p mfp then loadOne mfp dir else return []
-        others <- loadgm (takeDirectory dir)
-        return $ others ++ md 
-    loadOne mfp dir =
+loadGlobalMetadata :: Provider -> Identifier -> IO Metadata
+loadGlobalMetadata p fp = liftM M.fromList $ loadgm fp where 
+    loadgm :: Identifier -> IO [(String, String)]
+    loadgm = liftM concat . mapM loadOne . reverse . filter (resourceExists p) . metadataFiles
+    loadOne mfp =
         let path = resourceFilePath p mfp
+            dir = takeDirectory $ toFilePath mfp
         -- TODO: It might be better to print warning and continue
         in either (error.show) (findMetadata dir) . P.parse namedMetadata path <$> readFile path
     findMetadata dir = 
-        concatMap snd . filter (flip matches (fromFilePath fp) . fromGlob . combine dir . fst)
+        concatMap snd . filter (flip matches fp . fromGlob . combine dir . fst)
 
 namedMetadata :: Parser [(String, [(String, String)])]
 namedMetadata = P.many namedMetadataBlock
diff --git a/src/Hakyll/Core/Rules/Default.hs b/src/Hakyll/Core/Rules/Default.hs
new file mode 100644
index 0000000..ccca1bd
--- /dev/null
+++ b/src/Hakyll/Core/Rules/Default.hs
@@ -0,0 +1,23 @@
+{-# LANGUAGE OverloadedStrings          #-}
+module Hakyll.Core.Rules.Default 
+    ( internalRules
+    , addMetadataDependencies 
+    )
+where
+import           Hakyll.Core.Rules
+import           Hakyll.Core.Compiler
+import           Hakyll.Core.Compiler.Internal (compilerTellDependencies)
+import           Hakyll.Core.Metadata          (getMatches, metadataFiles)
+import           Hakyll.Core.Identifier.Pattern(fromList)
+
+internalRules :: Rules ()
+internalRules  = do
+    match "metadata" $ compile $ makeItem ()
+    match "**/metadata" $ compile $ makeItem ()
+
+--------------------------------------------------------------------------------
+addMetadataDependencies :: Compiler ()
+addMetadataDependencies =
+    compilerTellDependencies . map IdentifierDependency =<< getMatches . fromList =<< fmap metadataFiles getUnderlying
+
+
diff --git a/src/Hakyll/Core/Runtime.hs b/src/Hakyll/Core/Runtime.hs
index 824d11b..4ef30df 100644
--- a/src/Hakyll/Core/Runtime.hs
+++ b/src/Hakyll/Core/Runtime.hs
@@ -35,6 +35,7 @@ import qualified Hakyll.Core.Logger            as Logger
 import           Hakyll.Core.Provider
 import           Hakyll.Core.Routes
 import           Hakyll.Core.Rules.Internal
+import           Hakyll.Core.Rules.Default
 import           Hakyll.Core.Store             (Store)
 import qualified Hakyll.Core.Store             as Store
 import           Hakyll.Core.Util.File
@@ -53,7 +54,7 @@ run config verbosity rules = do
     provider <- newProvider store (shouldIgnoreFile config) $
         providerDirectory config
     Logger.message logger "Running rules..."
-    ruleSet  <- runRules rules provider
+    ruleSet  <- runRules (internalRules >> rules) provider
 
     -- Get old facts
     mOldFacts <- Store.get store factsKey
@@ -186,7 +187,7 @@ chase trail id'
         config   <- runtimeConfiguration <$> ask
         Logger.debug logger $ "Processing " ++ show id'
 
-        let compiler = todo M.! id'
+        let compiler = addMetadataDependencies >> todo M.! id'
             read' = CompilerRead
                 { compilerConfig     = config
                 , compilerUnderlying = id'