using System;

using UnityEngine;

using Framework.Services;

namespace Framework.State {

  /// <summary>Manages the state of the game in the current scene</summary>
  [ServiceScope(Scope.Session)]
  public class StateManager : Service, IStateManager {

    /// <summary>Triggered when the game is being paused</summary>
    public event Action Paused;

    /// <summary>Triggered when the game resume from pause mode</summary>
    public event Action Resumed;

    /// <summary>Pauses the game</summary>
    public void Pause() {
      if(!this.paused) {
        this.previousTimeScale = Time.timeScale;
        Time.timeScale = 0.0f;
        OnPaused();
        this.paused = true;
      }
    }

    /// <summary>Resumes the game</summary>
    public void Resume() {
      if(this.paused) {
        Time.timeScale = this.previousTimeScale;
        OnResumed();
        this.paused = false;
      }
    }

    /// <summary>Whether the game is currently paused</summary>
    public bool IsPaused {
      get { return this.paused; }
    }

    /// <summary>Fires the <see cref="Paused" /> event</summary>
    protected virtual void OnPaused() {
      if(Paused != null) {
        Paused();
      }
    }

    /// <summary>Fires the <see cref="Resumed" /> event</summary>
    protected virtual void OnResumed() {
      if(Resumed != null) {
        Resumed();
      }
    }

    /// <summary>Whether the game is paused</summary>
    private bool paused;

    /// <summary>Time scale that was present before the game was paused</summary>
    private float previousTimeScale;

  }

} // namespace Framework.State