From 69902de571af7712e2aca40e1b5e2ade100d622c Mon Sep 17 00:00:00 2001
From: Sergey Suprunenko <suprunenko.s@gmail.com>
Date: Sun, 30 Aug 2020 18:43:45 +0200
Subject: [PATCH] Handle hashtags followed by skipped html tags

---
 CHANGELOG.md          |  4 ++++
 lib/linkify/parser.ex | 19 +++++++++++++++
 test/linkify_test.exs | 55 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 78 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d5554c8..9d86357 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Hashtags followed by HTML tags "a", "code" and "pre" were not detected
+
 ## 0.2.0 - 2020-07-21
 
 ### Added
diff --git a/lib/linkify/parser.ex b/lib/linkify/parser.ex
index 75717de..a8bcf57 100644
--- a/lib/linkify/parser.ex
+++ b/lib/linkify/parser.ex
@@ -22,6 +22,8 @@ defmodule Linkify.Parser do
 
   @match_hashtag ~r/^(?<tag>\#[[:word:]_]*[[:alpha:]_·][[:word:]_·\p{M}]*)/u
 
+  @match_skipped_tag ~r/^(?<tag>(a|code|pre)).*>*/
+
   @prefix_extra [
     "magnet:?",
     "dweb://",
@@ -84,6 +86,23 @@ defmodule Linkify.Parser do
   defp do_parse({"@" <> text, user_acc}, opts, {buffer, acc, :skip}),
     do: do_parse({text, user_acc}, opts, {"", accumulate(acc, buffer, "@"), :skip})
 
+  defp do_parse(
+         {"<" <> text, user_acc},
+         %{hashtag: true} = opts,
+         {"#" <> _ = buffer, acc, :parsing}
+       ) do
+    {buffer, user_acc} = link(buffer, opts, user_acc)
+
+    case Regex.run(@match_skipped_tag, text, capture: [:tag]) do
+      [tag] ->
+        text = String.trim_leading(text, tag)
+        do_parse({text, user_acc}, opts, {"", accumulate(acc, buffer, "<#{tag}"), :skip})
+
+      nil ->
+        do_parse({text, user_acc}, opts, {"<", acc, {:open, 1}})
+    end
+  end
+
   defp do_parse({"<a" <> text, user_acc}, opts, {buffer, acc, :parsing}),
     do: do_parse({text, user_acc}, opts, {"", accumulate(acc, buffer, "<a"), :skip})
 
diff --git a/test/linkify_test.exs b/test/linkify_test.exs
index c92e9fa..9eece61 100644
--- a/test/linkify_test.exs
+++ b/test/linkify_test.exs
@@ -178,6 +178,61 @@ defmodule LinkifyTest do
                "<a href=\"https://example.com/user/hello\">#hello</a> <a href=\"https://example.com/user/world\">#world</a>"
 
       assert MapSet.to_list(tags) == ["#hello", "#world"]
+
+      text = "#cofe <br><a href=\"https://pleroma.social/\">Source</a>"
+
+      {_result_text, %{tags: tags}} =
+        Linkify.link_map(text, %{tags: MapSet.new()},
+          hashtag: true,
+          hashtag_handler: handler,
+          hashtag_prefix: "https://example.com/tag/"
+        )
+
+      assert MapSet.to_list(tags) == ["#cofe"]
+
+      text = "#cofe<br><a href=\"https://pleroma.social/\">Source</a>"
+
+      {_result_text, %{tags: tags}} =
+        Linkify.link_map(text, %{tags: MapSet.new()},
+          hashtag: true,
+          hashtag_handler: handler,
+          hashtag_prefix: "https://example.com/tag/"
+        )
+
+      assert MapSet.to_list(tags) == ["#cofe"]
+
+      text = "#cofe<a href=\"https://pleroma.social/\">Source</a>"
+
+      {_result_text, %{tags: tags}} =
+        Linkify.link_map(text, %{tags: MapSet.new()},
+          hashtag: true,
+          hashtag_handler: handler,
+          hashtag_prefix: "https://example.com/tag/"
+        )
+
+      assert MapSet.to_list(tags) == ["#cofe"]
+
+      text = "#cofe<code>fetch()</code>"
+
+      {_result_text, %{tags: tags}} =
+        Linkify.link_map(text, %{tags: MapSet.new()},
+          hashtag: true,
+          hashtag_handler: handler,
+          hashtag_prefix: "https://example.com/tag/"
+        )
+
+      assert MapSet.to_list(tags) == ["#cofe"]
+
+      text = "#cofe<pre>fetch()</pre>"
+
+      {_result_text, %{tags: tags}} =
+        Linkify.link_map(text, %{tags: MapSet.new()},
+          hashtag: true,
+          hashtag_handler: handler,
+          hashtag_prefix: "https://example.com/tag/"
+        )
+
+      assert MapSet.to_list(tags) == ["#cofe"]
     end
 
     test "mention handler and hashtag prefix" do