Add basic intro countdown and game states

Assets/Scripts/GameStateManager.cs

@@ -0,0 +1,84 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+public class GameStateManager : MonoBehaviour
+{
+    
+    public static GameStateManager Instace{  get; private set; }
+
+    public event EventHandler OnStateChanged;
+
+    private enum State
+    {
+        WaitingToStart,
+        StartingCountdown,
+        GamePlaying,
+        GameOver,
+    }
+
+    private State state;
+
+    // --- Timers ---
+    private float waitingToStartTimer = 1f;
+    private float countdownToStartTimer = 3f;
+    private float gamePlayTimer = 10f;
+
+    private void Awake()
+    {
+        state = State.WaitingToStart;
+        Instace = this;
+    }
+
+    private void Update()
+    {
+        switch (state)
+        {
+            case State.WaitingToStart:
+                waitingToStartTimer -= Time.deltaTime;
+                if (waitingToStartTimer < 0f)
+                {
+                    state = State.StartingCountdown;
+                    OnStateChanged?.Invoke(this, EventArgs.Empty);
+                }
+                break;
+            case State.StartingCountdown:
+                countdownToStartTimer -= Time.deltaTime;
+                if (countdownToStartTimer < 0f)
+                {
+                    state = State.GamePlaying;
+                    OnStateChanged?.Invoke(this, EventArgs.Empty);
+                }
+                break;
+            case State.GamePlaying:
+                gamePlayTimer -= Time.deltaTime;
+                if (gamePlayTimer < 0f)
+                {
+                    state = State.GameOver;
+                    OnStateChanged?.Invoke(this, EventArgs.Empty);
+                }
+                break;
+            case State.GameOver:
+                break;
+        }
+
+        Debug.Log(state);
+    }
+
+    public bool IsGamePlaying()
+    {
+        return state == State.GamePlaying;
+    }
+
+    public bool IsCountdownToStartActive()
+    {
+        return state == State.StartingCountdown;
+    }
+
+    public float GetCountdownToStartTimer()
+    {
+        return countdownToStartTimer;
+    }
+
+}