From a0ad8e7ed6ddea7b9794a93cb68fe4fbafaefdad Mon Sep 17 00:00:00 2001
From: NaiJi <naijiworld@protonmail.com>
Date: Tue, 3 Aug 2021 21:42:58 +0300
Subject: [PATCH] Implement state machine infrastructure

---
 include/application.h      | 20 +++++---------------
 include/gui/state.h        | 21 ++++++++++++++++++---
 src/application.cpp        | 35 ++++++++++++++++++++++-------------
 src/gui/gamestate.cpp      | 37 +++++++++++++++++++++++++++++++++++++
 src/gui/gamestate.h        | 37 +++++++++++++++++++++++++++++++++++++
 src/gui/mainmenu.cpp       | 22 +++++++++++++++-------
 src/gui/mainmenu.h         | 13 +++++++++++--
 src/gui/widgets/widget.cpp |  8 ++++++++
 src/gui/widgets/widget.h   |  2 ++
 9 files changed, 155 insertions(+), 40 deletions(-)
 create mode 100644 src/gui/gamestate.cpp
 create mode 100644 src/gui/gamestate.h

diff --git a/include/application.h b/include/application.h
index 8ab52f5..fe72d4c 100644
--- a/include/application.h
+++ b/include/application.h
@@ -2,6 +2,7 @@
 #define APPLICATION_H
 
 #include <memory>
+#include <array>
 #include <SFML/System/Clock.hpp>
 #include <SFML/Window/Keyboard.hpp>
 #include <SFML/Window/Event.hpp>
@@ -12,18 +13,6 @@
 class Application
 {
 public:
-
-    enum State
-    {
-        SPLASH_SCREEN,
-        MAIN_MENU,
-        GAME_PICKER,
-        GAME,
-        EDITOR_PICKER,
-        EDITOR,
-        SETTINGS
-    };
-
     Application();
     void run();
     void input();
@@ -31,13 +20,14 @@ public:
     void draw();
 
 private:
-    std::stack<std::shared_ptr<GUIState>> _states;
+    std::array<std::shared_ptr<GUIState>, GUIState::Tag::AMOUNT> _states;
+    std::vector<std::shared_ptr<GUIState>> _state_stack;
+
     sf::RenderWindow _game_window;
     std::shared_ptr<Game> _game;
 
-    State _state;
-
     void exec();
+    void emplaceState(GUIState::Tag new_state);
 };
 
 #endif // APPLICATION_H
diff --git a/include/gui/state.h b/include/gui/state.h
index 398be7e..ddf9ac6 100644
--- a/include/gui/state.h
+++ b/include/gui/state.h
@@ -3,14 +3,29 @@
 #include <stack>
 #include <memory>
 #include <SFML/Window/Event.hpp>
-#include <SFML/Graphics/Drawable.hpp>
 
-class GUIState : public sf::Drawable
+class GUIState
 {
 public:
+
+    enum Tag {
+        SPLASH_SCREEN,
+        MAIN_MENU,
+        GAME_PICKER,
+        GAME,
+        EDITOR_PICKER,
+        EDITOR,
+        SETTINGS,
+
+        AMOUNT
+    };
+
     virtual ~GUIState() = default;
 
     virtual void input(const sf::Event& event) = 0;
     virtual void update() = 0;
-    virtual void draw(sf::RenderTarget& target, sf::RenderStates states) const = 0;
+    virtual void draw() const = 0;
+
+    virtual void enter() = 0;
+    virtual void leave() = 0;
 };
diff --git a/src/application.cpp b/src/application.cpp
index c5f59a9..7efc616 100644
--- a/src/application.cpp
+++ b/src/application.cpp
@@ -5,6 +5,7 @@
 #include "classicgame/classicgraphicsmanager.h"
 
 #include "gui/mainmenu.h"
+#include "gui/gamestate.h"
 
 #include <iostream>
 
@@ -19,13 +20,19 @@ Application::Application() :
     _game_window.setMouseCursorGrabbed(false);
     _game_window.setVerticalSyncEnabled(true);
 
-    _states.push(std::make_shared<MainMenu>(_game_window));
+    MainMenu::Callbacks callbacks = {[&](){ emplaceState(GUIState::Tag::GAME); }};
+
+    const auto main_menu = std::make_shared<MainMenu>(_game_window, std::move(callbacks));
+    const auto game_state = std::make_shared<GameState>(_game_window, _game, GameState::Callbacks());
+    _states[GUIState::Tag::MAIN_MENU] = main_menu;
+    _states[GUIState::Tag::GAME] = game_state;
+
+    _state_stack.emplace_back(_states.at(GUIState::Tag::MAIN_MENU));
 }
 
 void Application::run()
 {
     _game_window.display();
-
     exec();
 }
 
@@ -61,16 +68,8 @@ void Application::input()
             _game_window.close();
             break;
 
-        case sf::Event::KeyPressed:
-        case sf::Event::KeyReleased:
-        case sf::Event::MouseButtonReleased:
-        case sf::Event::MouseButtonPressed:
-            if (event.key.code == sf::Keyboard::Escape)
-                _game_window.close();
-            _states.top()->input(event);
-            break;
-
         default:
+            _state_stack.back()->input(event);
             break;
         }
     }
@@ -78,12 +77,22 @@ void Application::input()
 
 void Application::update()
 {
-    _states.top()->update();
+    _state_stack.back()->update();
 }
 
 void Application::draw()
 {
     _game_window.clear();
-    _game_window.draw(*_states.top());
+
+    for (const auto& state : _state_stack)
+        state->draw();
+
     _game_window.display();
 }
+
+void Application::emplaceState(GUIState::Tag new_state)
+{
+    _state_stack.back()->leave();
+    _state_stack.emplace_back(_states.at(new_state));
+    _state_stack.back()->enter();
+}
diff --git a/src/gui/gamestate.cpp b/src/gui/gamestate.cpp
new file mode 100644
index 0000000..a5af5b2
--- /dev/null
+++ b/src/gui/gamestate.cpp
@@ -0,0 +1,37 @@
+#include "gamestate.h"
+#include "widgets/button.h"
+#include "widgets/group.h"
+
+#include "game/game.h"
+
+GameState::GameState(sf::RenderWindow& game_window, const std::shared_ptr<Game>& game,
+                     Callbacks&& callbacks) :
+    _game(game),
+    _game_window(game_window),
+    _onLeaveGameCallback(callbacks.onLeaveGame)
+{}
+
+void GameState::input(const sf::Event& event)
+{
+    _game->input({0, event});
+}
+
+void GameState::update()
+{
+    _game->update();
+}
+
+void GameState::draw() const
+{
+    _game->draw();
+}
+
+void GameState::enter()
+{
+    _game->run();
+}
+
+void GameState::leave()
+{
+    _onLeaveGameCallback();
+}
diff --git a/src/gui/gamestate.h b/src/gui/gamestate.h
new file mode 100644
index 0000000..68be7d0
--- /dev/null
+++ b/src/gui/gamestate.h
@@ -0,0 +1,37 @@
+#pragma once
+
+#include "gui/state.h"
+#include <SFML/Graphics/RenderWindow.hpp>
+
+class Group;
+class Game;
+
+class GameState : public GUIState
+{
+public:
+
+    struct Callbacks
+    {
+        std::function<void(void)> onLeaveGame;
+    };
+
+
+    explicit GameState(sf::RenderWindow& game_window,
+                       const std::shared_ptr<Game>& game,
+                       Callbacks&& callbacks);
+
+    virtual void input(const sf::Event& event) override;
+    virtual void update() override;
+    virtual void draw() const override;
+
+    virtual void enter() override;
+    virtual void leave() override;
+
+private:
+    std::shared_ptr<Game> _game;
+    sf::RenderWindow& _game_window;
+
+    std::function<void(void)> _onEnterGameCallback;
+    std::function<void(void)> _onLeaveGameCallback;
+};
+
diff --git a/src/gui/mainmenu.cpp b/src/gui/mainmenu.cpp
index 818b217..bf9b202 100644
--- a/src/gui/mainmenu.cpp
+++ b/src/gui/mainmenu.cpp
@@ -2,16 +2,13 @@
 #include "widgets/button.h"
 #include "widgets/group.h"
 
-MainMenu::MainMenu(sf::RenderWindow& game_window) :
+MainMenu::MainMenu(sf::RenderWindow& game_window, Callbacks&& callbacks) :
     _buttons(std::make_shared<Group>()),
     _game_window(game_window)
 {
     std::shared_ptr<Button> button_start = std::make_shared<Button>("Start");
     button_start->setRect(sf::FloatRect(140, 140, 500, 100));
-    button_start->setCallback([&]()
-    {
-        _game_window.close();
-    });
+    button_start->setCallback(callbacks.onAppendGameState);
 
     std::shared_ptr<Button> button_exit = std::make_shared<Button>("Exit");
     button_exit->setRect(sf::FloatRect(140, 140, 400, 100));
@@ -35,7 +32,18 @@ void MainMenu::update()
     _buttons->update();
 }
 
-void MainMenu::draw(sf::RenderTarget& target, sf::RenderStates states) const
+void MainMenu::draw() const
+{
+    _game_window.draw(*_buttons);
+}
+
+void MainMenu::enter()
 {
-    target.draw(*_buttons, states);
+    _buttons->setVisibility();
 }
+
+void MainMenu::leave()
+{
+    _buttons->setVisibility(false);
+}
+
diff --git a/src/gui/mainmenu.h b/src/gui/mainmenu.h
index b75bea5..d1d96db 100644
--- a/src/gui/mainmenu.h
+++ b/src/gui/mainmenu.h
@@ -8,10 +8,19 @@ class Group;
 class MainMenu : public GUIState
 {
 public:
-    MainMenu(sf::RenderWindow& game_window);
+
+    struct Callbacks
+    {
+        std::function<void(void)> onAppendGameState;
+    };
+
+    MainMenu(sf::RenderWindow& game_window, Callbacks&& callbacks);
     virtual void input(const sf::Event& event) override;
     virtual void update() override;
-    virtual void draw(sf::RenderTarget& target, sf::RenderStates states) const override;
+    virtual void draw() const override;
+
+    virtual void enter() override;
+    virtual void leave() override;
 
 private:
     std::shared_ptr<Group> _buttons;
diff --git a/src/gui/widgets/widget.cpp b/src/gui/widgets/widget.cpp
index 12c5727..c4f5998 100644
--- a/src/gui/widgets/widget.cpp
+++ b/src/gui/widgets/widget.cpp
@@ -14,10 +14,18 @@ void Widget::update()
 
 void Widget::draw(sf::RenderTarget& target, sf::RenderStates states) const
 {
+    if (!_is_visible)
+        return;
+
     for (auto& child : _children)
         child->draw(target, states);
 }
 
+void Widget::setVisibility(bool is_visible)
+{
+    _is_visible = is_visible;
+}
+
 void Widget::addChild(const std::shared_ptr<Widget> &child)
 {
     child->_parent = shared_from_this();
diff --git a/src/gui/widgets/widget.h b/src/gui/widgets/widget.h
index ef2cc8f..d27fabb 100644
--- a/src/gui/widgets/widget.h
+++ b/src/gui/widgets/widget.h
@@ -18,10 +18,12 @@ public:
     virtual void setPosition(const sf::Vector2f& position) = 0;
     virtual bool isUnderMouse(int mouse_x, int mouse_y) const = 0;
 
+    void setVisibility(bool is_visible = true);
     void addChild(const std::shared_ptr<Widget>& child);
 
 protected:
     std::vector<std::shared_ptr<Widget>> _children;
     std::shared_ptr<Widget> _parent;
+    bool _is_visible = true;
 };