From 74c65157407af9063a4709f83aa51af04e0b96cc Mon Sep 17 00:00:00 2001
From: Aleksei Matiushkin <aleksei.matiushkin@kantox.com>
Date: Sun, 27 Aug 2023 08:54:41 +0200
Subject: [PATCH] Cosmetics + several classes for blocks

---
 .credo.exs                      |  2 +-
 lib/md/parser.ex                |  1 +
 lib/md/parser/engine.ex         | 15 ++++++++++++---
 lib/md/parser/syntax/default.ex |  2 +-
 test/md_test.exs                | 16 ++++++++++------
 5 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/.credo.exs b/.credo.exs
index 6c15930..d95867b 100644
--- a/.credo.exs
+++ b/.credo.exs
@@ -105,7 +105,7 @@
         ## Refactoring Opportunities
         #
         {Credo.Check.Refactor.CondStatements, []},
-        {Credo.Check.Refactor.CyclomaticComplexity, max_complexity: 42},
+        {Credo.Check.Refactor.CyclomaticComplexity, max_complexity: 50},
         {Credo.Check.Refactor.FunctionArity, []},
         {Credo.Check.Refactor.LongQuoteBlocks, max_line_count: 300},
         {Credo.Check.Refactor.MapInto, false},
diff --git a/lib/md/parser.ex b/lib/md/parser.ex
index 11583a2..7641bb6 100644
--- a/lib/md/parser.ex
+++ b/lib/md/parser.ex
@@ -76,6 +76,7 @@ defmodule Md.Parser do
     {ast, acc} =
       case walker do
         nil -> {ast, nil}
+        fun when is_function(fun, 1) -> {XmlBuilder.prewalk(ast, fun), nil}
         fun when is_function(fun, 2) -> XmlBuilder.prewalk(ast, %{}, fun)
         {:pre, fun} when is_function(fun, 1) -> {XmlBuilder.prewalk(ast, fun), nil}
         {:post, fun} when is_function(fun, 1) -> {XmlBuilder.postwalk(ast, fun), nil}
diff --git a/lib/md/parser/engine.ex b/lib/md/parser/engine.ex
index b3f6239..ad6913a 100644
--- a/lib/md/parser/engine.ex
+++ b/lib/md/parser/engine.ex
@@ -1610,8 +1610,17 @@ defmodule Md.Engine do
 
       defp update_attrs({tag, attrs, [value | rest]} = full_tag, pop) do
         case pop do
-          %{^tag => attr} -> {tag, Map.put(attrs || %{}, attr, value), rest}
-          _ -> full_tag
+          %{^tag => attr} when is_atom(attr) ->
+            {tag, Map.put(attrs || %{}, attr, value), rest}
+
+          %{^tag => attr} when is_list(attr) ->
+            attr_value =
+              attr |> Keyword.get(:prefixes, [""]) |> Enum.map_join(" ", &(&1 <> value))
+
+            {tag, Map.put(attrs || %{}, attr[:attribute], attr_value), rest}
+
+          _ ->
+            full_tag
         end
       end
 
@@ -1672,7 +1681,7 @@ defmodule Md.Engine do
         do: {nest(:span), %{class: "empty-anchor"}, content}
 
       defp maybe_hide({tag, attrs, []}),
-        do: {tag, Map.put(attrs || %{}, :class, :"empty-tag"), []}
+        do: {tag, Map.put(attrs || %{}, :class, "empty-tag"), []}
 
       defp maybe_hide({_tag, _attrs, _branch} = trace), do: trace
 
diff --git a/lib/md/parser/syntax/default.ex b/lib/md/parser/syntax/default.ex
index 337bfbe..0d893f3 100644
--- a/lib/md/parser/syntax/default.ex
+++ b/lib/md/parser/syntax/default.ex
@@ -47,7 +47,7 @@ defmodule Md.Parser.Syntax.Default do
         {"http://", %{transform: Anchor, terminators: [], greedy: :left}}
       ],
       block: [
-        {"```", %{tag: [:pre, :code], pop: %{code: :class}}}
+        {"```", %{tag: [:pre, :code], pop: %{code: [attribute: :class, prefixes: ["", "lang-"]]}}}
       ],
       shift: [
         {"    ", %{tag: [:div, :code], attributes: %{class: "pre"}}}
diff --git a/test/md_test.exs b/test/md_test.exs
index aaf5381..6dc3e0b 100644
--- a/test/md_test.exs
+++ b/test/md_test.exs
@@ -170,7 +170,8 @@ defmodule MdTest do
              {:p, nil, ["foo"]},
              {:pre, nil,
               [
-                {:code, %{class: "elixir"}, ["def foo, do: :ok\n\ndef bar, do: :error\n"]}
+                {:code, %{class: "elixir lang-elixir"},
+                 ["def foo, do: :ok\n\ndef bar, do: :error\n"]}
               ]}
            ] ==
              Md.parse(input).ast
@@ -405,7 +406,7 @@ defmodule MdTest do
 
     assert [
              {:blockquote, nil,
-              [{:p, nil, ["line 1", "\n", {:i, %{class: :"empty-tag"}, []}, "line 2"]}]}
+              [{:p, nil, ["line 1", "\n", {:i, %{class: "empty-tag"}, []}, "line 2"]}]}
            ] ==
              Md.parse(">line 1\n>_\n>line 2").ast
 
@@ -413,7 +414,7 @@ defmodule MdTest do
              {:blockquote, nil,
               [
                 {:p, nil,
-                 ["line 1", "\n", {:em, nil, [{:i, %{class: :"empty-tag"}, []}]}, "line 2"]}
+                 ["line 1", "\n", {:em, nil, [{:i, %{class: "empty-tag"}, []}]}, "line 2"]}
               ]}
            ] ==
              Md.parse(">line 1\n>___\n>line 2").ast
@@ -425,8 +426,8 @@ defmodule MdTest do
                  [
                    "line 1",
                    "\n",
-                   {:em, %{class: :"empty-tag"}, []},
-                   {:em, nil, [{:i, %{class: :"empty-tag"}, []}]},
+                   {:em, %{class: "empty-tag"}, []},
+                   {:em, nil, [{:i, %{class: "empty-tag"}, []}]},
                    "line 2"
                  ]}
               ]}
@@ -691,7 +692,10 @@ defmodule MdTest do
                 ]},
                {:p, nil, ["Hi ", {:a, %{href: "https://anchor.com"}, ["anchor"]}, " 1!"]},
                {:pre, nil,
-                [{:code, %{class: "elixir"}, ["def foo, do: :ok\n\ndef bar, do: :error\n"]}]},
+                [
+                  {:code, %{class: "elixir lang-elixir"},
+                   ["def foo, do: :ok\n\ndef bar, do: :error\n"]}
+                ]},
                {:ul, nil,
                 [
                   {:li, nil,