using System.ComponentModel;
using System.Runtime.CompilerServices;

/* Example for use:
  
public class MyViewModel : ViewModelBase
{
    private int myProperty;
    public int MyProperty
    {
        get { return myProperty; }
        set { SetProperty(ref myProperty, value);
    }
}

*/


namespace FSI.Lib.MVVM
{
    public class ViewModelBase : INotifyPropertyChanged
    {
        /// <summary>
        /// Multicast event for property change notifications.
        /// </summary>
        public event PropertyChangedEventHandler PropertyChanged;

        /// <summary>
        /// Checks if a property already matches the desired value.  Sets the property and
        /// notifies listeners only when necessary.
        /// </summary>
        /// <typeparam name="T">Type of the property.</typeparam>
        /// <param name="storage">Reference to a property with both getter and setter.</param>
        /// <param name="value">Desired value for the property.</param>
        /// <param name="propertyName">Name of the property used to notify listeners.This
        /// value is optional and can be provided automatically when invoked from compilers that
        /// support CallerMemberName.</param>
        /// <returns>True if the value was changed, false if the existing value matched the
        /// desired value.</returns>
        protected virtual bool SetProperty<T>(ref T storage, T value, [CallerMemberName] string propertyName = null)
        {
            if (object.Equals(storage, value)) return false;
            storage = value;
            // Log.DebugFormat("{0}.{1} = {2}", this.GetType().Name, propertyName, storage);
            this.OnPropertyChanged(propertyName);
            return true;
        }


        /// <summary>
        /// Notifies listeners that a property value has changed.
        /// </summary>
        /// <param name="propertyName">Name of the property used to notify listeners.  This
        /// value is optional and can be provided automatically when invoked from compilers
        /// that support <see cref="CallerMemberNameAttribute"/>.</param>
        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}
