feat: Slugify tag names

Uses the already installed dependency `slugify` instead of depending on
`MDEx.anchorize/1`, and exposed via `Tableau.Extension.Common`.

I added the `slug` configuration to the site configuration because I
believe that such conversion should be consistent for a site.

Resolves: #160

Author: halostatue

lib/tableau.ex

@@ -10,6 +10,7 @@ defmodule Tableau do
   * `:converters` - mapping of file extensions to converter module. Defaults to `[md: Tableau.MDExConverter]`
   * `:markdown` - keyword
       * `:mdex` - keyword - Options to pass to `MDEx.to_html/2`
+  * `:slug` - keyword - Options to pass to `Slug.slugify/2`
 
   ### Example
 
@@ -25,6 +26,9 @@ defmodule Tableau do
       md: Tableau.MDExConverter,
       dj: MySite.DjotConverter
     ],
+    slug: [
+      lowercase: false
+    ],
     markdown: [
       mdex: [
         extension: [

lib/tableau/config.ex

@@ -10,6 +10,7 @@ defmodule Tableau.Config do
     out_dir: "_site",
     timezone: "Etc/UTC",
     reload_log: false,
+    slug: [],
     converters: [md: Tableau.MDExConverter],
     markdown: [mdex: []]
   ]
@@ -32,6 +33,13 @@ defmodule Tableau.Config do
         optional(:reload_log) => bool(),
         optional(:converters) => keyword(values: atom()),
         optional(:markdown) => keyword(values: list()),
+        optional(:slug) =>
+          keyword(%{
+            optional(:separator) => oneof([str(), int()]),
+            optional(:lowercase) => bool(),
+            optional(:truncate) => int(),
+            optional(:ignore) => oneof([str(), list(oneof([str(), int()]))])
+          }),
         optional(:base_path) => str(),
         url: str()
       },

lib/tableau/extensions/common.ex

@@ -8,6 +8,27 @@ defmodule Tableau.Extension.Common do
     wildcard |> Path.wildcard() |> Enum.sort()
   end
 
+  @doc """
+  Transform strings from any language into slugs using `Slug.slugify/1`.
+
+  Returns the original string if the slug cannot be generated.
+  """
+  def slugify(string, overrides \\ [])
+
+  def slugify(string, %{site: %{config: config}}) do
+    Slug.slugify(string, config.slug) || string
+  end
+
+  def slugify(string, config) when is_map(config) do
+    slugify(string)
+  end
+
+  def slugify(string, overrides) do
+    {:ok, config} = Tableau.Config.get()
+
+    Slug.slugify(string, Keyword.merge(config.slug, overrides)) || string
+  end
+
   @doc """
   Build content entries from a list of paths.
 

lib/tableau/extensions/tag_extension.ex

@@ -6,6 +6,8 @@ defmodule Tableau.TagExtension do
 
   The `@page` assign passed to the `layout` provided in the configuration is described by `t:page/0`.
 
+  Tag names will be converted to slugs using `Slug.slugify/2` with options provided in Tableau configuration.
+
   ## Configuration
 
   - `:enabled` - boolean - Extension is active or not.
@@ -79,6 +81,8 @@ defmodule Tableau.TagExtension do
 
   import Schematic
 
+  alias Tableau.Extension.Common
+
   @type page :: %{
           title: String.t(),
           tag: String.t(),
@@ -89,7 +93,8 @@ defmodule Tableau.TagExtension do
   @type tag :: %{
           title: String.t(),
           tag: String.t(),
-          permalink: String.t()
+          permalink: String.t(),
+          slug: String.t()
         }
 
   @type tags :: %{
@@ -119,9 +124,10 @@ defmodule Tableau.TagExtension do
     tags =
       for post <- posts, tag <- post |> Map.get(:tags, []) |> Enum.uniq(), reduce: Map.new() do
         acc ->
-          permalink = Path.join(permalink, tag)
+          slug = Common.slugify(tag, token)
+          permalink = Path.join(permalink, slug)
 
-          tag = %{title: tag, permalink: permalink, tag: tag}
+          tag = %{title: tag, permalink: permalink, tag: tag, slug: slug}
           Map.update(acc, tag, [post], &[post | &1])
       end
 

test/tableau/extensions/tag_extension_test.exs

@@ -12,7 +12,8 @@ defmodule Tableau.TagExtensionTest do
         # dedups tags
         post(1, tags: ["post", "post"]),
         # post can have multiple tags, includes posts from same tag
-        post(2, tags: ["til", "post"]),
+        # tags will be converted to slugs for linking
+        post(2, tags: ["til", "post", "Today I Learned"]),
         post(3, tags: ["recipe"])
       ]
 
@@ -27,9 +28,20 @@ defmodule Tableau.TagExtensionTest do
 
       assert %{
                tags: %{
-                 %{tag: "post", title: "post", permalink: "/tags/post"} => [%{title: "Post 2"}, %{title: "Post 1"}],
-                 %{tag: "recipe", title: "recipe", permalink: "/tags/recipe"} => [%{title: "Post 3"}],
-                 %{tag: "til", title: "til", permalink: "/tags/til"} => [%{title: "Post 2"}]
+                 %{tag: "post", title: "post", permalink: "/tags/post", slug: "post"} => [
+                   %{title: "Post 2"},
+                   %{title: "Post 1"}
+                 ],
+                 %{tag: "recipe", title: "recipe", permalink: "/tags/recipe", slug: "recipe"} => [%{title: "Post 3"}],
+                 %{tag: "til", title: "til", permalink: "/tags/til", slug: "til"} => [%{title: "Post 2"}],
+                 %{
+                   tag: "Today I Learned",
+                   title: "Today I Learned",
+                   permalink: "/tags/today-i-learned",
+                   slug: "today-i-learned"
+                 } => [
+                   %{title: "Post 2"}
+                 ]
                },
                graph: graph
              } = token
@@ -39,6 +51,7 @@ defmodule Tableau.TagExtensionTest do
       assert Enum.any?(vertices, &page_with_permalink?(&1, "/tags/post"))
       assert Enum.any?(vertices, &page_with_permalink?(&1, "/tags/recipe"))
       assert Enum.any?(vertices, &page_with_permalink?(&1, "/tags/til"))
+      assert Enum.any?(vertices, &page_with_permalink?(&1, "/tags/today-i-learned"))
 
       assert Layout in vertices
     end