ImageViewer: Use `LibFileSystemAccessClient`

This commit also starts the adoption of ErrorOr<T> and the String class
in ImageViewer. However, there is still a few more changes that could
be made.

Since the actions of using LibFSAC and using String in more places are
tightly coupled, I decided to put them in one commit.

4 files changed, 83 insertions, 46 deletions

diff --git a/Userland/Applications/ImageViewer/CMakeLists.txt b/Userland/Applications/ImageViewer/CMakeLists.txt
index 0826d53a56..717a88c95e 100644
--- a/Userland/Applications/ImageViewer/CMakeLists.txt
+++ b/Userland/Applications/ImageViewer/CMakeLists.txt
@@ -12,4 +12,4 @@ set(SOURCES
 )
 
 serenity_app(ImageViewer ICON filetype-image)
-target_link_libraries(ImageViewer PRIVATE LibCore LibDesktop LibGUI LibGfx LibConfig LibImageDecoderClient LibMain)
+target_link_libraries(ImageViewer PRIVATE LibCore LibDesktop LibFileSystemAccessClient LibGUI LibGfx LibConfig LibImageDecoderClient LibMain)
diff --git a/Userland/Applications/ImageViewer/ViewWidget.cpp b/Userland/Applications/ImageViewer/ViewWidget.cpp
index 61818e6d22..ee31d37025 100644
--- a/Userland/Applications/ImageViewer/ViewWidget.cpp
+++ b/Userland/Applications/ImageViewer/ViewWidget.cpp
@@ -4,6 +4,7 @@
  * Copyright (c) 2021, Mohsan Ali <mohsan0073@gmail.com>
  * Copyright (c) 2022, Mustafa Quraish <mustafa@serenityos.org>
  * Copyright (c) 2022, the SerenityOS developers.
+ * Copyright (c) 2023, Caoimhe Byrne <caoimhebyrne06@gmail.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -16,6 +17,7 @@
 #include <LibCore/MappedFile.h>
 #include <LibCore/MimeData.h>
 #include <LibCore/Timer.h>
+#include <LibFileSystemAccessClient/Client.h>
 #include <LibGUI/Application.h>
 #include <LibGUI/MessageBox.h>
 #include <LibGfx/Bitmap.h>
@@ -71,6 +73,13 @@ bool ViewWidget::is_previous_available() const
     return false;
 }
 
+// FIXME: Convert to `String` & use LibFileSystemAccessClient + `Core::System::unveil(nullptr, nullptr)`
+//        - Converting to String is not super-trivial due to the LexicalPath usage, while we can do a bunch of
+//          String::from_deprecated_string() and String.to_deprecated_string(), it is quite ugly to read and
+//          probably not the best approach.
+//
+//        - If we go full-unveil (`Core::System::unveil(nullptr, nullptr)`) this functionality does not work,
+//          we can not access the list of contents of a directory through LibFileSystemAccessClient at the moment.
 Vector<DeprecatedString> ViewWidget::load_files_from_directory(DeprecatedString const& path) const
 {
     Vector<DeprecatedString> files_in_directory;
@@ -86,11 +95,11 @@ Vector<DeprecatedString> ViewWidget::load_files_from_directory(DeprecatedString
     return files_in_directory;
 }
 
-void ViewWidget::set_path(DeprecatedString const& path)
+void ViewWidget::set_path(String const& path)
 {
     m_path = path;
-    m_files_in_same_dir = load_files_from_directory(path);
-    m_current_index = m_files_in_same_dir.find_first_index(path);
+    m_files_in_same_dir = load_files_from_directory(path.to_deprecated_string());
+    m_current_index = m_files_in_same_dir.find_first_index(path.to_deprecated_string());
 }
 
 void ViewWidget::navigate(Directions direction)
@@ -110,8 +119,14 @@ void ViewWidget::navigate(Directions direction)
         index = m_files_in_same_dir.size() - 1;
     }
 
+    auto result = FileSystemAccessClient::Client::the().request_file_read_only_approved(window(), m_files_in_same_dir.at(index));
+    if (result.is_error())
+        return;
+
     m_current_index = index;
-    this->load_from_file(m_files_in_same_dir.at(index));
+
+    auto value = result.release_value();
+    open_file(value.filename(), value.stream());
 }
 
 void ViewWidget::doubleclick_event(GUI::MouseEvent&)
@@ -147,39 +162,34 @@ void ViewWidget::mouseup_event(GUI::MouseEvent& event)
     GUI::AbstractZoomPanWidget::mouseup_event(event);
 }
 
-void ViewWidget::load_from_file(DeprecatedString const& path)
+void ViewWidget::open_file(String const& path, Core::File& file)
 {
-    auto show_error = [&] {
-        GUI::MessageBox::show(window(), DeprecatedString::formatted("Failed to open {}", path), "Cannot open image"sv, GUI::MessageBox::Type::Error);
-    };
+    auto open_result = try_open_file(path, file);
+    if (open_result.is_error()) {
+        auto error = open_result.release_error();
+        auto user_error_message = String::formatted("Failed to open the image: {}.", error).release_value_but_fixme_should_propagate_errors();
 
-    auto file_or_error = Core::MappedFile::map(path);
-    if (file_or_error.is_error()) {
-        show_error();
-        return;
+        GUI::MessageBox::show_error(nullptr, user_error_message);
     }
+}
 
-    auto& mapped_file = *file_or_error.value();
-
+ErrorOr<void> ViewWidget::try_open_file(String const& path, Core::File& file)
+{
     // Spawn a new ImageDecoder service process and connect to it.
-    auto client = ImageDecoderClient::Client::try_create().release_value_but_fixme_should_propagate_errors();
+    auto client = TRY(ImageDecoderClient::Client::try_create());
     auto mime_type = Core::guess_mime_type_based_on_filename(path);
-    auto decoded_image_or_error = client->decode_image(mapped_file.bytes(), mime_type);
-    if (!decoded_image_or_error.has_value()) {
-        show_error();
-        return;
+    auto decoded_image_or_none = client->decode_image(TRY(file.read_until_eof()), mime_type);
+    if (!decoded_image_or_none.has_value()) {
+        return Error::from_string_literal("Failed to decode image");
     }
 
-    m_decoded_image = decoded_image_or_error.release_value();
+    m_decoded_image = decoded_image_or_none.release_value();
     m_bitmap = m_decoded_image->frames[0].bitmap;
     if (m_bitmap.is_null()) {
-        show_error();
-        return;
+        return Error::from_string_literal("Image didn't contain a bitmap");
     }
 
     set_original_rect(m_bitmap->rect());
-    if (on_image_change)
-        on_image_change(m_bitmap);
 
     if (m_decoded_image->is_animated && m_decoded_image->frames.size() > 1) {
         auto const& first_frame = m_decoded_image->frames[0];
@@ -190,13 +200,18 @@ void ViewWidget::load_from_file(DeprecatedString const& path)
         m_timer->stop();
     }
 
-    m_path = Core::DeprecatedFile::real_path_for(path);
-    GUI::Application::the()->set_most_recently_open_file(String::from_utf8(path).release_value_but_fixme_should_propagate_errors());
+    set_path(path);
+    GUI::Application::the()->set_most_recently_open_file(path);
+
+    if (on_image_change)
+        on_image_change(m_bitmap);
 
     if (scaled_for_first_image())
         scale_image_for_window();
     else
         reset_view();
+
+    return {};
 }
 
 void ViewWidget::drag_enter_event(GUI::DragEvent& event)
diff --git a/Userland/Applications/ImageViewer/ViewWidget.h b/Userland/Applications/ImageViewer/ViewWidget.h
index 4d6d7043e6..96ff096c17 100644
--- a/Userland/Applications/ImageViewer/ViewWidget.h
+++ b/Userland/Applications/ImageViewer/ViewWidget.h
@@ -4,6 +4,7 @@
  * Copyright (c) 2021, Mohsan Ali <mohsan0073@gmail.com>
  * Copyright (c) 2022, Mustafa Quraish <mustafa@serenityos.org>
  * Copyright (c) 2022, the SerenityOS developers.
+ * Copyright (c) 2023, Caoimhe Byrne <caoimhebyrne06@gmail.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -30,12 +31,12 @@ public:
     virtual ~ViewWidget() override = default;
 
     Gfx::Bitmap const* bitmap() const { return m_bitmap.ptr(); }
-    DeprecatedString const& path() const { return m_path; }
+    String const& path() const { return m_path; }
     void set_toolbar_height(int height) { m_toolbar_height = height; }
     int toolbar_height() { return m_toolbar_height; }
     bool scaled_for_first_image() { return m_scaled_for_first_image; }
     void set_scaled_for_first_image(bool val) { m_scaled_for_first_image = val; }
-    void set_path(DeprecatedString const& path);
+    void set_path(String const& path);
     void resize_window();
     void scale_image_for_window();
     void set_scaling_mode(Gfx::Painter::ScalingMode);
@@ -47,7 +48,7 @@ public:
     void flip(Gfx::Orientation);
     void rotate(Gfx::RotationDirection);
     void navigate(Directions);
-    void load_from_file(DeprecatedString const&);
+    void open_file(String const&, Core::File&);
 
     Function<void()> on_doubleclick;
     Function<void(const GUI::DropEvent&)> on_drop;
@@ -66,8 +67,9 @@ private:
     void set_bitmap(Gfx::Bitmap const* bitmap);
     void animate();
     Vector<DeprecatedString> load_files_from_directory(DeprecatedString const& path) const;
+    ErrorOr<void> try_open_file(String const&, Core::File&);
 
-    DeprecatedString m_path;
+    String m_path;
     RefPtr<Gfx::Bitmap const> m_bitmap;
     Optional<ImageDecoderClient::DecodedImage> m_decoded_image;
 
diff --git a/Userland/Applications/ImageViewer/main.cpp b/Userland/Applications/ImageViewer/main.cpp
index 49d4f8470e..ab8bf6c57f 100644
--- a/Userland/Applications/ImageViewer/main.cpp
+++ b/Userland/Applications/ImageViewer/main.cpp
@@ -1,6 +1,7 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
  * Copyright (c) 2021, Mohsan Ali <mohsan0073@gmail.com>
+ * Copyright (c) 2023, Caoimhe Byrne <caoimhebyrne06@gmail.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -12,6 +13,7 @@
 #include <LibCore/ArgsParser.h>
 #include <LibCore/System.h>
 #include <LibDesktop/Launcher.h>
+#include <LibFileSystemAccessClient/Client.h>
 #include <LibGUI/Action.h>
 #include <LibGUI/ActionGroup.h>
 #include <LibGUI/Application.h>
@@ -49,6 +51,12 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     TRY(Desktop::Launcher::add_allowed_handler_with_only_specific_urls("/bin/Help", { URL::create_with_file_scheme("/usr/share/man/man1/ImageViewer.md") }));
     TRY(Desktop::Launcher::seal_allowlist());
 
+    // FIXME: Use unveil when we solve the issue with ViewWidget::load_files_from_directory, an explanation is given in ViewWidget.cpp
+    // TRY(Core::System::unveil("/tmp/session/%sid/portal/filesystemaccess", "rw"));
+    // TRY(Core::System::unveil("/tmp/session/%sid/portal/image", "rw"));
+    // TRY(Core::System::unveil("/res", "r"));
+    // TRY(Core::System::unveil(nullptr, nullptr));
+
     auto app_icon = GUI::Icon::default_icon("filetype-image"sv);
 
     StringView path;
@@ -68,9 +76,6 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto main_toolbar = TRY(toolbar_container->try_add<GUI::Toolbar>());
 
     auto widget = TRY(root_widget->try_add<ViewWidget>());
-    if (!path.is_empty()) {
-        widget->set_path(path);
-    }
     widget->on_scale_change = [&](float scale) {
         if (!widget->bitmap()) {
             window->set_title("Image Viewer");
@@ -96,8 +101,12 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         window->move_to_front();
 
         auto path = urls.first().path();
-        widget->set_path(path);
-        widget->load_from_file(path);
+        auto result = FileSystemAccessClient::Client::the().request_file_read_only_approved(window, path);
+        if (result.is_error())
+            return;
+
+        auto value = result.release_value();
+        widget->open_file(value.filename(), value.stream());
 
         for (size_t i = 1; i < urls.size(); ++i) {
             Desktop::Launcher::open(URL::create_with_file_scheme(urls[i].path().characters()), "/bin/ImageViewer");
@@ -112,11 +121,12 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     // Actions
     auto open_action = GUI::CommonActions::make_open_action(
         [&](auto&) {
-            auto path = GUI::FilePicker::get_open_filepath(window, "Open Image");
-            if (path.has_value()) {
-                widget->set_path(path.value());
-                widget->load_from_file(path.value());
-            }
+            auto result = FileSystemAccessClient::Client::the().open_file(window, "Open Image");
+            if (result.is_error())
+                return;
+
+            auto value = result.release_value();
+            widget->open_file(value.filename(), value.stream());
         });
 
     auto delete_action = GUI::CommonActions::make_delete_action(
@@ -294,8 +304,12 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     TRY(file_menu->add_recent_files_list([&](auto& action) {
         auto path = action.text();
-        widget->set_path(path);
-        widget->load_from_file(path);
+        auto result = FileSystemAccessClient::Client::the().request_file_read_only_approved(window, path);
+        if (result.is_error())
+            return;
+
+        auto value = result.release_value();
+        widget->open_file(value.filename(), value.stream());
     }));
 
     TRY(file_menu->try_add_action(quit_action));
@@ -346,13 +360,19 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     })));
     TRY(help_menu->try_add_action(GUI::CommonActions::make_about_action("Image Viewer", app_icon, window)));
 
+    window->show();
+
+    // We must do this here and not any earlier, as we need a visible window to call FileSystemAccessClient::Client::request_file_read_only_approved();
     if (path != nullptr) {
-        widget->load_from_file(path);
+        auto result = FileSystemAccessClient::Client::the().request_file_read_only_approved(window, path);
+        if (result.is_error())
+            return 1;
+
+        auto value = result.release_value();
+        widget->open_file(value.filename(), value.stream());
     } else {
         widget->clear();
     }
 
-    window->show();
-
     return app->exec();
 }