Hashtag searches now return real results from the database

lib/pleroma/hashtag.ex

@@ -130,4 +130,23 @@ defmodule Pleroma.Hashtag do
   end
 
   def get_recipients_for_activity(_activity), do: []
+
+  def search(query, options \\ []) do
+    limit = Keyword.get(options, :limit, 20)
+    offset = Keyword.get(options, :offset, 0)
+
+    query
+    |> String.downcase()
+    |> String.trim()
+    |> then(fn search_term ->
+      from(ht in Hashtag,
+        where: fragment("LOWER(?) LIKE ?", ht.name, ^"%#{search_term}%"),
+        order_by: [asc: ht.name],
+        limit: ^limit,
+        offset: ^offset
+      )
+      |> Repo.all()
+      |> Enum.map(& &1.name)
+    end)
+  end
 end

lib/pleroma/web/mastodon_api/controllers/search_controller.ex

@@ -7,6 +7,7 @@ defmodule Pleroma.Web.MastodonAPI.SearchController do
 
   alias Pleroma.Repo
   alias Pleroma.User
+  alias Pleroma.Hashtag
   alias Pleroma.Web.ControllerHelper
   alias Pleroma.Web.Endpoint
   alias Pleroma.Web.MastodonAPI.AccountView
@@ -120,69 +121,14 @@ defmodule Pleroma.Web.MastodonAPI.SearchController do
   defp resource_search(:v2, "hashtags", query, options) do
     tags_path = Endpoint.url() <> "/tag/"
 
-    query
-    |> prepare_tags(options)
+    Hashtag.search(query, options)
     |> Enum.map(fn tag ->
       %{name: tag, url: tags_path <> tag}
     end)
   end
 
   defp resource_search(:v1, "hashtags", query, options) do
-    prepare_tags(query, options)
-  end
-
-  defp prepare_tags(query, options) do
-    tags =
-      query
-      |> preprocess_uri_query()
-      |> String.split(~r/[^#\w]+/u, trim: true)
-      |> Enum.uniq_by(&String.downcase/1)
-
-    explicit_tags = Enum.filter(tags, fn tag -> String.starts_with?(tag, "#") end)
-
-    tags =
-      if Enum.any?(explicit_tags) do
-        explicit_tags
-      else
-        tags
-      end
-
-    tags = Enum.map(tags, fn tag -> String.trim_leading(tag, "#") end)
-
-    tags =
-      if Enum.empty?(explicit_tags) && !options[:skip_joined_tag] do
-        add_joined_tag(tags)
-      else
-        tags
-      end
-
-    Pleroma.Pagination.paginate_list(tags, options)
-  end
-
-  defp add_joined_tag(tags) do
-    tags
-    |> Kernel.++([joined_tag(tags)])
-    |> Enum.uniq_by(&String.downcase/1)
-  end
-
-  # If `query` is a URI, returns last component of its path, otherwise returns `query`
-  defp preprocess_uri_query(query) do
-    if query =~ ~r/https?:\/\// do
-      query
-      |> String.trim_trailing("/")
-      |> URI.parse()
-      |> Map.get(:path)
-      |> String.split("/")
-      |> Enum.at(-1)
-    else
-      query
-    end
-  end
-
-  defp joined_tag(tags) do
-    tags
-    |> Enum.map(fn tag -> String.capitalize(tag) end)
-    |> Enum.join()
+    Hashtag.search(query, options)
   end
 
   defp with_fallback(f, fallback \\ []) do