start with input

apps/flecs-test/main.cpp

@@ -0,0 +1,38 @@
+#include <input/input.h>
+#include <window/window.h>
+#include <flecs.h>
+#include <iostream>
+
+#include <GLFW/glfw3.h>
+
+int main()
+{
+    glfwInit();
+
+    flecs::world world;
+    flecs::entity window_entity = world.entity();
+    window_entity.add<Input::State<Input::KeyCode>>();
+    Window window(&world, window_entity);
+
+    window_entity.observe<Input::KeyInput>([window_entity](Input::KeyInput& key_input) {
+        auto* key_state = window_entity.get_mut<Input::State<Input::KeyCode>>();
+
+        if (key_input.action == static_cast<Input::Action>(GLFW_PRESS)) {
+            key_state->press(key_input.key_code);
+        } else if (key_input.action == static_cast<Input::Action>(GLFW_RELEASE)) {
+            key_state->release(key_input.key_code);
+        }
+    });
+
+    while (glfwWindowShouldClose(&window.handle()) == GLFW_FALSE) {
+        glfwPollEvents();
+
+        // X just pressed
+        auto* keycode= window_entity.get<Input::State<Input::KeyCode>>();
+        if (keycode->just_pressed(Input::KeyCode{GLFW_KEY_X}))
+            std::cout << "X was just pressed!\n";
+
+        Input::State<Input::KeyCode>::update_state(window_entity);
+        glfwSwapBuffers(&window.handle());
+    }
+}