Add handle_href option for href pre-processing

lib/linkify.ex

@@ -34,13 +34,14 @@ defmodule Linkify do
   * `email` - link email links (default: `false`)
   * `mention` - link @mentions (when `true`, requires `mention_prefix` or `mention_handler` options to be set) (default: `false`)
   * `mention_prefix` - a prefix to build a link for a mention (example: `https://example.com/user/`, default: `nil`)
-  * `mention_handler` - a custom handler to validate and formart a mention (default: `nil`)
+  * `mention_handler` - a custom handler to validate and format a mention (default: `nil`)
   * `hashtag: false` - link #hashtags (when `true`, requires `hashtag_prefix` or `hashtag_handler` options to be set)
   * `hashtag_prefix: nil` - a prefix to build a link for a hashtag (example: `https://example.com/tag/`)
-  * `hashtag_handler: nil` - a custom handler to validate and formart a hashtag
+  * `hashtag_handler: nil` - a custom handler to validate and format a hashtag
   * `extra: false` - link urls with rarely used schemes (magnet, ipfs, irc, etc.)
   * `validate_tld: true` - Set to false to disable TLD validation for urls/emails, also can be set to :no_scheme to validate TLDs only for urls without a scheme (e.g `example.com` will be validated, but `http://example.loki` won't)
   * `iodata` - Set to `true` to return iodata as a result, or `:safe` for iodata with linkified anchor tags wrapped in Phoenix.HTML `:safe` tuples (removes need for further sanitization)
+  * `href_handler: nil` - a custom handler to process a url before it is set as the link href, useful for generating exit links
   """
   def link(text, opts \\ []) do
     parse(text, opts)

lib/linkify/builder.ex

@@ -42,8 +42,11 @@ defmodule Linkify.Builder do
     end
   end
 
-  defp build_attrs(attrs, url, _opts, :href) do
-    [{:href, url} | attrs]
+  defp build_attrs(attrs, url, opts, :href) do
+    case Map.get(opts, :href_handler) do
+      handler when is_function(handler) -> [{:href, handler.(url)} | attrs]
+      _ -> [{:href, url} | attrs]
+    end
   end
 
   defp add_scheme("http://" <> _ = url), do: url

test/linkify_test.exs

@@ -339,6 +339,14 @@ defmodule LinkifyTest do
 
       assert MapSet.to_list(mentions) == [{"@friend", "friend"}]
     end
+
+    test "href handler" do
+      text = ~s(google.com)
+
+      result_text = Linkify.link(text, href_handler: & "/redirect?#{URI.encode_query(to: &1)}")
+
+      assert result_text == ~s(<a href="/redirect?to=http%3A%2F%2Fgoogle.com">google.com</a>)
+    end
   end
 
   describe "mentions" do