LibWebView: Support custom search engines

This allows the user to store custom search engines via about:settings.
Custom engines will be displayed below the builtin engines in the drop-
down to select the default engine.

A couple of edge cases here:

1. We currently reject a custom engine if one with the same name already
   exists. In the future, we should allow editing custom engines.

2. If a custom engine which was the default engine is removed, we will
   disable search rather than falling back to any other engine.

Libraries/LibWebView/SearchEngine.cpp

@@ -4,13 +4,12 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/Find.h>
 #include <LibURL/URL.h>
 #include <LibWebView/SearchEngine.h>
 
 namespace WebView {
 
-static auto builtin_search_engines = to_array<SearchEngine>({
+static auto s_builtin_search_engines = to_array<SearchEngine>({
     { "Bing"_string, "https://www.bing.com/search?q=%s"_string },
     { "Brave"_string, "https://search.brave.com/search?q=%s"_string },
     { "DuckDuckGo"_string, "https://duckduckgo.com/?q=%s"_string },
@@ -23,16 +22,9 @@ static auto builtin_search_engines = to_array<SearchEngine>({
     { "Yandex"_string, "https://yandex.com/search/?text=%s"_string },
 });
 
-ReadonlySpan<SearchEngine> search_engines()
+ReadonlySpan<SearchEngine> builtin_search_engines()
 {
-    return builtin_search_engines;
-}
-
-Optional<SearchEngine> find_search_engine_by_name(StringView name)
-{
-    return find_value(builtin_search_engines, [&](auto const& engine) {
-        return engine.name == name;
-    });
+    return s_builtin_search_engines;
 }
 
 String SearchEngine::format_search_query_for_display(StringView query) const

Libraries/LibWebView/SearchEngine.h

@@ -20,7 +20,6 @@ struct SearchEngine {
     String query_url;
 };
 
-ReadonlySpan<SearchEngine> search_engines();
-Optional<SearchEngine> find_search_engine_by_name(StringView name);
+ReadonlySpan<SearchEngine> builtin_search_engines();
 
 }

Libraries/LibWebView/Settings.cpp

@@ -5,6 +5,7 @@
  */
 
 #include <AK/ByteString.h>
+#include <AK/Find.h>
 #include <AK/JsonArray.h>
 #include <AK/JsonObject.h>
 #include <AK/JsonValue.h>
@@ -26,7 +27,9 @@ static constexpr auto languages_key = "languages"sv;
 static auto default_language = "en"_string;
 
 static constexpr auto search_engine_key = "searchEngine"sv;
+static constexpr auto search_engine_custom_key = "custom"sv;
 static constexpr auto search_engine_name_key = "name"sv;
+static constexpr auto search_engine_url_key = "url"sv;
 
 static constexpr auto autocomplete_engine_key = "autocompleteEngine"sv;
 static constexpr auto autocomplete_engine_name_key = "name"sv;
@@ -89,8 +92,18 @@ Settings Settings::create(Badge<Application>)
         settings.m_languages = parse_json_languages(*languages);
 
     if (auto search_engine = settings_json.value().get_object(search_engine_key); search_engine.has_value()) {
+        if (auto custom_engines = search_engine->get_array(search_engine_custom_key); custom_engines.has_value()) {
+            custom_engines->for_each([&](JsonValue const& engine) {
+                auto custom_engine = parse_custom_search_engine(engine);
+                if (!custom_engine.has_value() || settings.find_search_engine_by_name(custom_engine->name).has_value())
+                    return;
+
+                settings.m_custom_search_engines.append(custom_engine.release_value());
+            });
+        }
+
         if (auto search_engine_name = search_engine->get_string(search_engine_name_key); search_engine_name.has_value())
-            settings.m_search_engine = find_search_engine_by_name(*search_engine_name);
+            settings.m_search_engine = settings.find_search_engine_by_name(*search_engine_name);
     }
 
     if (auto autocomplete_engine = settings_json.value().get_object(autocomplete_engine_key); autocomplete_engine.has_value()) {
@@ -144,12 +157,25 @@ JsonValue Settings::serialize_json() const
 
     settings.set(languages_key, move(languages));
 
-    if (m_search_engine.has_value()) {
+    JsonArray custom_search_engines;
+    custom_search_engines.ensure_capacity(m_custom_search_engines.size());
+
+    for (auto const& engine : m_custom_search_engines) {
         JsonObject search_engine;
+        search_engine.set(search_engine_name_key, engine.name);
+        search_engine.set(search_engine_url_key, engine.query_url);
+
+        custom_search_engines.must_append(move(search_engine));
+    }
+
+    JsonObject search_engine;
+    if (!custom_search_engines.is_empty())
+        search_engine.set(search_engine_custom_key, move(custom_search_engines));
+    if (m_search_engine.has_value())
         search_engine.set(search_engine_name_key, m_search_engine->name);
 
+    if (!search_engine.is_empty())
         settings.set(search_engine_key, move(search_engine));
-    }
 
     if (m_autocomplete_engine.has_value()) {
         JsonObject autocomplete_engine;
@@ -184,6 +210,7 @@ void Settings::restore_defaults()
     m_new_tab_page_url = URL::about_newtab();
     m_languages = { default_language };
     m_search_engine.clear();
+    m_custom_search_engines.clear();
     m_autocomplete_engine.clear();
     m_autoplay = SiteSetting {};
     m_do_not_track = DoNotTrack::No;
@@ -250,6 +277,62 @@ void Settings::set_search_engine(Optional<StringView> search_engine_name)
         observer.search_engine_changed();
 }
 
+Optional<SearchEngine> Settings::parse_custom_search_engine(JsonValue const& search_engine)
+{
+    if (!search_engine.is_object())
+        return {};
+
+    auto name = search_engine.as_object().get_string(search_engine_name_key);
+    auto url = search_engine.as_object().get_string(search_engine_url_key);
+    if (!name.has_value() || !url.has_value())
+        return {};
+
+    auto parsed_url = URL::Parser::basic_parse(*url);
+    if (!parsed_url.has_value())
+        return {};
+
+    return SearchEngine { .name = name.release_value(), .query_url = url.release_value() };
+}
+
+void Settings::add_custom_search_engine(SearchEngine search_engine)
+{
+    if (find_search_engine_by_name(search_engine.name).has_value())
+        return;
+
+    m_custom_search_engines.append(move(search_engine));
+    persist_settings();
+}
+
+void Settings::remove_custom_search_engine(SearchEngine const& search_engine)
+{
+    auto reset_default_search_engine = m_search_engine.has_value() && m_search_engine->name == search_engine.name;
+    if (reset_default_search_engine)
+        m_search_engine.clear();
+
+    m_custom_search_engines.remove_all_matching([&](auto const& engine) {
+        return engine.name == search_engine.name;
+    });
+
+    persist_settings();
+
+    if (reset_default_search_engine) {
+        for (auto& observer : m_observers)
+            observer.search_engine_changed();
+    }
+}
+
+Optional<SearchEngine> Settings::find_search_engine_by_name(StringView name)
+{
+    auto comparator = [&](auto const& engine) { return engine.name == name; };
+
+    if (auto result = find_value(builtin_search_engines(), comparator); result.has_value())
+        return result.copy();
+    if (auto result = find_value(m_custom_search_engines, comparator); result.has_value())
+        return result.copy();
+
+    return {};
+}
+
 void Settings::set_autocomplete_engine(Optional<StringView> autocomplete_engine_name)
 {
     if (autocomplete_engine_name.has_value())

Libraries/LibWebView/Settings.h

@@ -60,6 +60,10 @@ public:
     Optional<SearchEngine> const& search_engine() const { return m_search_engine; }
     void set_search_engine(Optional<StringView> search_engine_name);
 
+    static Optional<SearchEngine> parse_custom_search_engine(JsonValue const&);
+    void add_custom_search_engine(SearchEngine);
+    void remove_custom_search_engine(SearchEngine const&);
+
     Optional<AutocompleteEngine> const& autocomplete_engine() const { return m_autocomplete_engine; }
     void set_autocomplete_engine(Optional<StringView> autocomplete_engine_name);
 
@@ -80,11 +84,14 @@ private:
 
     void persist_settings();
 
+    Optional<SearchEngine> find_search_engine_by_name(StringView name);
+
     ByteString m_settings_path;
 
     URL::URL m_new_tab_page_url;
     Vector<String> m_languages;
     Optional<SearchEngine> m_search_engine;
+    Vector<SearchEngine> m_custom_search_engines;
     Optional<AutocompleteEngine> m_autocomplete_engine;
     SiteSetting m_autoplay;
     DoNotTrack m_do_not_track { DoNotTrack::No };

Libraries/LibWebView/WebUI/SettingsUI.cpp

@@ -34,6 +34,12 @@ void SettingsUI::register_interfaces()
     register_interface("setSearchEngine"sv, [this](auto const& data) {
         set_search_engine(data);
     });
+    register_interface("addCustomSearchEngine"sv, [this](auto const& data) {
+        add_custom_search_engine(data);
+    });
+    register_interface("removeCustomSearchEngine"sv, [this](auto const& data) {
+        remove_custom_search_engine(data);
+    });
     register_interface("setAutocompleteEngine"sv, [this](auto const& data) {
         set_autocomplete_engine(data);
     });
@@ -94,7 +100,7 @@ void SettingsUI::set_languages(JsonValue const& languages)
 void SettingsUI::load_available_engines()
 {
     JsonArray search_engines;
-    for (auto const& engine : WebView::search_engines())
+    for (auto const& engine : WebView::builtin_search_engines())
         search_engines.must_append(engine.name);
 
     JsonArray autocomplete_engines;
@@ -116,6 +122,22 @@ void SettingsUI::set_search_engine(JsonValue const& search_engine)
         WebView::Application::settings().set_search_engine(search_engine.as_string());
 }
 
+void SettingsUI::add_custom_search_engine(JsonValue const& search_engine)
+{
+    if (auto custom_engine = Settings::parse_custom_search_engine(search_engine); custom_engine.has_value())
+        WebView::Application::settings().add_custom_search_engine(custom_engine.release_value());
+
+    load_current_settings();
+}
+
+void SettingsUI::remove_custom_search_engine(JsonValue const& search_engine)
+{
+    if (auto custom_engine = Settings::parse_custom_search_engine(search_engine); custom_engine.has_value())
+        WebView::Application::settings().remove_custom_search_engine(*custom_engine);
+
+    load_current_settings();
+}
+
 void SettingsUI::set_autocomplete_engine(JsonValue const& autocomplete_engine)
 {
     if (autocomplete_engine.is_null())

Libraries/LibWebView/WebUI/SettingsUI.h

@@ -24,6 +24,8 @@ private:
 
     void load_available_engines();
     void set_search_engine(JsonValue const&);
+    void add_custom_search_engine(JsonValue const&);
+    void remove_custom_search_engine(JsonValue const&);
     void set_autocomplete_engine(JsonValue const&);
 
     void load_forcibly_enabled_site_settings();