Help: Follow clicked links

This also adds a toolbar and a menu which allow you to
navigate back and forth through history ^)

Applications/Help/History.cpp

@@ -0,0 +1,33 @@
+#include "History.h"
+
+void History::push(const StringView& history_item)
+{
+    m_items.shrink(m_current_history_item + 1);
+    m_items.append(history_item);
+    m_current_history_item++;
+}
+
+String History::current()
+{
+    if (m_current_history_item == -1)
+        return {};
+    return m_items[m_current_history_item];
+}
+
+void History::go_back()
+{
+    ASSERT(can_go_back());
+    m_current_history_item--;
+}
+
+void History::go_forward()
+{
+    ASSERT(can_go_forward());
+    m_current_history_item++;
+}
+
+void History::clear()
+{
+    m_items = {};
+    m_current_history_item = -1;
+}

Applications/Help/History.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include <AK/String.h>
+#include <AK/Vector.h>
+
+class History final {
+public:
+    void push(const StringView& history_item);
+    String current();
+
+    void go_back();
+    void go_forward();
+
+    bool can_go_back() { return m_current_history_item > 0; }
+    bool can_go_forward() { return m_current_history_item + 1 < m_items.size(); }
+
+    void clear();
+
+private:
+    Vector<String> m_items;
+    int m_current_history_item { -1 };
+};

Applications/Help/Makefile

@@ -1,9 +1,10 @@
 include ../../Makefile.common
 
 OBJS = \
-		ManualModel.o \
-		ManualSectionNode.o \
-		ManualPageNode.o \
+    ManualModel.o \
+    ManualSectionNode.o \
+    ManualPageNode.o \
+    History.o \
     main.o
 
 APP = Help

Applications/Help/main.cpp

@@ -1,10 +1,17 @@
+#include "History.h"
 #include "ManualModel.h"
 #include <LibCore/CFile.h>
 #include <LibDraw/PNGLoader.h>
+#include <LibGUI/GAboutDialog.h>
+#include <LibGUI/GAction.h>
 #include <LibGUI/GApplication.h>
+#include <LibGUI/GBoxLayout.h>
+#include <LibGUI/GMenu.h>
+#include <LibGUI/GMenuBar.h>
 #include <LibGUI/GMessageBox.h>
 #include <LibGUI/GSplitter.h>
 #include <LibGUI/GTextEditor.h>
+#include <LibGUI/GToolBar.h>
 #include <LibGUI/GTreeView.h>
 #include <LibGUI/GWindow.h>
 #include <LibHTML/HtmlView.h>
@@ -12,6 +19,7 @@
 #include <LibHTML/Parser/CSSParser.h>
 #include <LibHTML/Parser/HTMLParser.h>
 #include <LibMarkdown/MDDocument.h>
+#include <libgen.h>
 
 int main(int argc, char* argv[])
 {
@@ -21,7 +29,13 @@ int main(int argc, char* argv[])
     window->set_title("Help");
     window->set_rect(300, 200, 570, 500);
 
-    auto splitter = GSplitter::construct(Orientation::Horizontal, nullptr);
+    auto widget = GWidget::construct();
+    widget->set_layout(make<GBoxLayout>(Orientation::Vertical));
+    widget->layout()->set_spacing(0);
+
+    auto toolbar = GToolBar::construct(widget);
+
+    auto splitter = GSplitter::construct(Orientation::Horizontal, widget);
 
     auto model = ManualModel::create();
 
@@ -36,8 +50,17 @@ int main(int argc, char* argv[])
     String css = default_stylesheet_source;
     auto sheet = parse_css(css);
 
-    tree_view->on_selection_change = [&] {
-        String path = model->page_path(tree_view->selection().first());
+    History history;
+
+    RefPtr<GAction> go_back_action;
+    RefPtr<GAction> go_forward_action;
+
+    auto update_actions = [&]() {
+        go_back_action->set_enabled(history.can_go_back());
+        go_forward_action->set_enabled(history.can_go_forward());
+    };
+
+    auto open_page = [&](String path) {
         if (path.is_null()) {
             html_view->set_document(nullptr);
             return;
@@ -70,7 +93,66 @@ int main(int argc, char* argv[])
         window->set_title(String::format("Help: %s", page_and_section.characters()));
     };
 
-    window->set_main_widget(splitter);
+    tree_view->on_selection_change = [&] {
+        String path = model->page_path(tree_view->selection().first());
+        if (path.is_null()) {
+            html_view->set_document(nullptr);
+            return;
+        }
+        history.push(path);
+        update_actions();
+        open_page(path);
+    };
+
+    html_view->on_link_click = [&](const String& href) {
+        char* current_path = strdup(history.current().characters());
+        char* dir_path = dirname(current_path);
+        char* path = realpath(String::format("%s/%s", dir_path, href.characters()).characters(), nullptr);
+        free(current_path);
+        history.push(path);
+        update_actions();
+        open_page(path);
+        free(path);
+    };
+
+    go_back_action = GAction::create("Go Back", { Mod_Alt, Key_Left }, GraphicsBitmap::load_from_file("/res/icons/16x16/go-back.png"), [&](const GAction&) {
+        history.go_back();
+        update_actions();
+        open_page(history.current());
+    });
+
+    go_forward_action = GAction::create("Go Forward", { Mod_Alt, Key_Right }, GraphicsBitmap::load_from_file("/res/icons/16x16/go-forward.png"), [&](const GAction&) {
+        history.go_forward();
+        update_actions();
+        open_page(history.current());
+    });
+
+    go_back_action->set_enabled(false);
+    go_forward_action->set_enabled(false);
+
+    toolbar->add_action(*go_back_action);
+    toolbar->add_action(*go_forward_action);
+
+    auto menubar = make<GMenuBar>();
+
+    auto app_menu = make<GMenu>("Help");
+    app_menu->add_action(GAction::create("About", [&](const GAction&) {
+        GAboutDialog::show("Help", load_png("/res/icons/16x16/book.png"), window);
+    }));
+    app_menu->add_separator();
+    app_menu->add_action(GCommonActions::make_quit_action([](auto&) {
+        GApplication::the().quit(0);
+    }));
+    menubar->add_menu(move(app_menu));
+
+    auto go_menu = make<GMenu>("Go");
+    go_menu->add_action(*go_back_action);
+    go_menu->add_action(*go_forward_action);
+    menubar->add_menu(move(go_menu));
+
+    app.set_menubar(move(menubar));
+
+    window->set_main_widget(widget);
     window->show();
 
     window->set_icon(load_png("/res/icons/16x16/book.png"));