using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;
using Metronome.Shared;
using Xamarin.Forms;

namespace MyProject.Views
{
  public partial class MainPage : ContentPage
  {
    public MainPage()
    {
      InitializeComponent();
    }

    protected override void OnPropertyChanging([CallerMemberName] string propertyName = null)
    {
      base.OnPropertyChanging(propertyName);
      if (propertyName == nameof(BindingContext) && BindingContext is IFlashlight flashlight)
        SetEventHandler(false);
    }

    protected override void OnBindingContextChanged()
    {
      base.OnBindingContextChanged();
      SetEventHandler(true);
    }

    protected override void OnAppearing()
    {
      base.OnAppearing();
      SetEventHandler(true);
    }

    protected override void OnDisappearing()
    {
      SetEventHandler(false);
      base.OnDisappearing();
    }

    bool isAttached;
    void SetEventHandler(bool attach)
    {
      if (isAttached == attach) return;

      if (BindingContext is IFlashlight flashlight)
      {
        if (attach)
          flashlight.Flash += OnFlash;
        else
          flashlight.Flash -= OnFlash;
      }

      isAttached = attach;
    }

    private void OnFlash(bool obj)
    {

    }


  }
}