Web server with recipe index page

- Add Roux.Server: WAI application using wai+warp directly
  - Scans .cook files from recipe directory on startup
  - GET / → HTML index page listing all recipes
  - Other routes → 404
- Add Roux.RecipeIndex: directory scanning and recipe parsing
  - scanRecipes: lists .cook files, parses each, extracts titles
  - Falls back to filename when metadata title is absent
- Add Roux.Html: blaze-html rendering with Pico CSS
  - indexPage: renders recipe list with links
  - urlEncode: percent-encodes filenames for URLs
- Update Roux.hs: re-exports Server.app and Types
- Add filepath to dependencies

package.yaml

@@ -31,6 +31,7 @@ dependencies:
   - bytestring
   - containers
   - directory
+  - filepath
   - http-types
   - optparse-applicative
   - parsec

roux-server.cabal

@@ -17,7 +17,10 @@ build-type:     Simple
 library
   exposed-modules:
       Roux
+      Roux.Html
       Roux.Parser
+      Roux.RecipeIndex
+      Roux.Server
       Roux.Types
   other-modules:
       Paths_roux_server
@@ -36,6 +39,7 @@ library
     , bytestring
     , containers
     , directory
+    , filepath
     , http-types
     , optparse-applicative
     , parsec
@@ -64,6 +68,7 @@ executable roux-server
     , bytestring
     , containers
     , directory
+    , filepath
     , http-types
     , optparse-applicative
     , parsec
@@ -96,6 +101,7 @@ test-suite roux-server-test
     , bytestring
     , containers
     , directory
+    , filepath
     , hspec
     , http-types
     , optparse-applicative

src/Roux.hs

@@ -4,17 +4,5 @@ module Roux (
     module X,
 ) where
 
-import qualified Network.HTTP.Types as HTTP
+import Roux.Server (app)
-import qualified Network.Wai as Wai
-
 import Roux.Types as X
-
--- | Build the WAI 'Application' given a path to the recipe directory.
-app :: FilePath -> IO Wai.Application
-app _recipeDir =
-    pure $ \_request respond ->
-        respond $
-            Wai.responseLBS
-                HTTP.status200
-                [("Content-Type", "text/plain")]
-                "Hello from Roux!"

src/Roux/Html.hs

@@ -0,0 +1,55 @@
+{- | HTML rendering for the Roux web interface.
+
+Uses blaze-html directly.  Styling via Pico CSS (inlined in the page).
+-}
+module Roux.Html (
+    indexPage,
+) where
+
+import Data.ByteString.Lazy (ByteString)
+import Data.Text (Text)
+import qualified Data.Text as T
+import qualified Text.Blaze.Html.Renderer.Utf8 as R
+import Text.Blaze.Html5 as H
+import Text.Blaze.Html5.Attributes as A
+
+import qualified Roux.RecipeIndex as Idx
+
+-- | Render the recipe index page.
+indexPage :: [Idx.RecipeInfo] -> ByteString
+indexPage recipes =
+    R.renderHtml $
+        H.docTypeHtml $ do
+            H.head $ do
+                H.meta ! A.charset "utf-8"
+                H.meta ! A.name "viewport" ! A.content "width=device-width, initial-scale=1"
+                H.title "Roux — Recipes"
+                H.link ! A.rel "stylesheet" ! A.href "https://cdn.jsdelivr.net/npm/@picocss/pico@2/css/pico.min.css"
+            H.body $ do
+                H.main ! A.class_ "container" $ do
+                    H.h1 "Roux"
+                    H.p "Your personal recipe collection."
+                    H.h2 "Recipes"
+                    H.ul $ mapM_ recipeItem recipes
+
+-- | Render a single recipe list item.
+recipeItem :: Idx.RecipeInfo -> Html
+recipeItem info =
+    H.li $ case Idx.riRecipe info of
+        Left _err ->
+            H.span ! A.class_ "error" $ do
+                H.toHtml (Idx.riTitle info)
+                " (parse error)"
+        Right _recipe ->
+            H.a ! A.href (H.toValue ("/recipes/" <> urlEncode (Idx.riFilename info))) $
+                H.toHtml (Idx.riTitle info)
+
+-- | Percent-encode a filename for use in a URL path segment.
+urlEncode :: FilePath -> Text
+urlEncode = T.pack . concatMap encodeChar
+  where
+    encodeChar c
+        | c == ' ' = "%20"
+        | c == '#' = "%23"
+        | c == '%' = "%25"
+        | otherwise = [c]

src/Roux/RecipeIndex.hs

@@ -0,0 +1,55 @@
+-- | Scanning and indexing of Cooklang recipe files on disk.
+module Roux.RecipeIndex (
+    RecipeInfo (..),
+    scanRecipes,
+) where
+
+import Data.Text (Text)
+import qualified Data.Text as T
+import System.Directory (listDirectory)
+import System.FilePath (takeBaseName, takeExtension, (</>))
+
+import Roux.Parser (parseCookFile)
+import Roux.Types
+
+-- | Metadata about a single recipe discovered on disk.
+data RecipeInfo = RecipeInfo
+    { riFilename :: FilePath
+    -- ^ Path relative to the recipe directory
+    , riTitle :: Text
+    -- ^ Display title (from metadata or filename)
+    , riRecipe :: Either String Recipe
+    -- ^ Parsed recipe (or error message)
+    }
+    deriving stock (Eq, Show)
+
+-- | Scan a directory for @.cook@ files and parse each one.
+scanRecipes :: FilePath -> IO [RecipeInfo]
+scanRecipes dir = do
+    entries <- listDirectory dir
+    let cookFiles = filter ((== ".cook") . takeExtension) entries
+    mapM (loadRecipe dir) cookFiles
+
+-- | Load and parse a single recipe file.
+loadRecipe :: FilePath -> FilePath -> IO RecipeInfo
+loadRecipe dir filename = do
+    content <- readFile (dir </> filename)
+    let parsed = parseCookFile (T.pack content)
+        title = case parsed of
+            Right r -> extractTitle r filename
+            Left _err -> T.pack (takeBaseName filename)
+    return
+        RecipeInfo
+            { riFilename = filename
+            , riTitle = title
+            , riRecipe = parsed
+            }
+
+{- | Extract a display title from the recipe's metadata or fall back to the
+filename.
+-}
+extractTitle :: Recipe -> FilePath -> Text
+extractTitle recipe filename =
+    case metaTitle (recipeMetadata recipe) of
+        Just t -> t
+        Nothing -> T.pack (takeBaseName filename)

src/Roux/Server.hs

@@ -0,0 +1,63 @@
+{- | WAI application for the Roux recipe server.
+
+Handles HTTP requests directly via wai — no framework.  Currently serves
+a single index page listing all discovered recipes.
+-}
+module Roux.Server (
+    app,
+) where
+
+import Control.Monad (when)
+import Data.ByteString.Lazy (ByteString)
+import qualified Network.HTTP.Types as HTTP
+import qualified Network.Wai as Wai
+
+import qualified Roux.Html as Html
+import qualified Roux.RecipeIndex as Idx
+
+{- | Build the WAI 'Application' given a path to the recipe directory.
+
+Recipes are scanned once at startup.  A future improvement could watch
+the directory for changes and rebuild the index.
+-}
+app :: FilePath -> IO Wai.Application
+app recipeDir = do
+    putStrLn $ "[roux] scanning recipes from " <> recipeDir
+    recipes <- Idx.scanRecipes recipeDir
+    let count = length recipes
+        ok = length [() | r <- recipes, isRight (Idx.riRecipe r)]
+        errs = count - ok
+    putStrLn $ "[roux] found " <> show count <> " recipe(s)"
+    when (errs > 0) $
+        putStrLn $
+            "[roux] " <> show errs <> " had parse errors"
+    -- Return the application; recipes are captured in the closure.
+    pure (handleRequest recipes)
+
+-- | Route an incoming request to the appropriate handler.
+handleRequest :: [Idx.RecipeInfo] -> Wai.Application
+handleRequest recipes request respond =
+    case Wai.pathInfo request of
+        [] -> respond (htmlResponse (Html.indexPage recipes))
+        _ -> respond notFound
+
+-- | Build a 200 HTML response.
+htmlResponse :: ByteString -> Wai.Response
+htmlResponse body =
+    Wai.responseLBS
+        HTTP.status200
+        [("Content-Type", "text/html; charset=utf-8")]
+        body
+
+-- | 404 response.
+notFound :: Wai.Response
+notFound =
+    Wai.responseLBS
+        HTTP.status404
+        [("Content-Type", "text/plain")]
+        "Not found"
+
+-- | Check if an 'Either' is 'Right'.
+isRight :: Either a b -> Bool
+isRight (Right _) = True
+isRight (Left _) = False