LibGUI: Add up & down arrow hooks and input history to TextBox

This patch adds the ability to enable "input history" on a textbox,
allowing to navigate between the history with the arrow keys.

Also removes a custom TextBox subclass from HackStudio that added
the exact same hooks, and moves it to use the now standard ones.

Libraries/LibGUI/TextBox.cpp

@@ -37,4 +37,55 @@ TextBox::~TextBox()
 {
 }
 
+void TextBox::keydown_event(GUI::KeyEvent& event)
+{
+    TextEditor::keydown_event(event);
+
+    if (event.key() == Key_Up) {
+        if (on_up_pressed)
+            on_up_pressed();
+
+        if (has_no_history() || !can_go_backwards_in_history())
+            return;
+
+        if (m_history_index >= static_cast<int>(m_history.size()))
+            m_saved_input = text();
+
+        m_history_index--;
+        set_text(m_history[m_history_index]);
+    } else if (event.key() == Key_Down) {
+        if (on_down_pressed)
+            on_down_pressed();
+
+        if (has_no_history())
+            return;
+
+        if (can_go_forwards_in_history()) {
+            m_history_index++;
+            set_text(m_history[m_history_index]);
+        } else if (m_history_index < static_cast<int>(m_history.size())) {
+            m_history_index++;
+            set_text(m_saved_input);
+        }
+    }
+}
+
+void TextBox::add_current_text_to_history()
+{
+    if (!m_history_enabled)
+        return;
+    
+    auto input = text();
+    if (m_history.is_empty() || m_history.last() != input)
+        add_input_to_history(input);
+    m_history_index = static_cast<int>(m_history.size());
+    m_saved_input = {};
+}
+
+void TextBox::add_input_to_history(String input)
+{
+    m_history.append(move(input));
+    m_history_index++;
+}
+
 }

Libraries/LibGUI/TextBox.h

@@ -35,6 +35,25 @@ class TextBox : public TextEditor {
 public:
     TextBox();
     virtual ~TextBox() override;
+
+    Function<void()> on_up_pressed;
+    Function<void()> on_down_pressed;
+
+    void set_history_enabled(bool enabled) { m_history_enabled = enabled; }
+    void add_current_text_to_history();
+
+private:
+    virtual void keydown_event(GUI::KeyEvent&) override;
+
+    bool has_no_history() const { return !m_history_enabled || m_history.is_empty(); }
+    bool can_go_backwards_in_history() const { return m_history_index > 0; }
+    bool can_go_forwards_in_history() const { return m_history_index < static_cast<int>(m_history.size()) - 1; }
+    void add_input_to_history(String);
+
+    bool m_history_enabled { false };
+    Vector<String> m_history;
+    int m_history_index { -1 };
+    String m_saved_input;
 };
 
 }