using System;
using System.Reflection;
using System.Runtime.CompilerServices;

namespace Swan.Reflection {
  /// <summary>
  /// Represents a generic class to store getters and setters.
  /// </summary>
  /// <typeparam name="TClass">The type of the class.</typeparam>
  /// <typeparam name="TProperty">The type of the property.</typeparam>
  /// <seealso cref="IPropertyProxy" />
  public sealed class PropertyProxy<TClass, TProperty> : IPropertyProxy where TClass : class {
    private readonly Func<TClass, TProperty> _getter;
    private readonly Action<TClass, TProperty> _setter;

    /// <summary>
    /// Initializes a new instance of the <see cref="PropertyProxy{TClass, TProperty}"/> class.
    /// </summary>
    /// <param name="property">The property.</param>
    public PropertyProxy(PropertyInfo property) {
      if(property == null) {
        throw new ArgumentNullException(nameof(property));
      }

      MethodInfo getterInfo = property.GetGetMethod(false);
      if(getterInfo != null) {
        this._getter = (Func<TClass, TProperty>)Delegate.CreateDelegate(typeof(Func<TClass, TProperty>), getterInfo);
      }

      MethodInfo setterInfo = property.GetSetMethod(false);
      if(setterInfo != null) {
        this._setter = (Action<TClass, TProperty>)Delegate.CreateDelegate(typeof(Action<TClass, TProperty>), setterInfo);
      }
    }

    /// <inheritdoc />
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    Object IPropertyProxy.GetValue(Object instance) => this._getter(instance as TClass);

    /// <inheritdoc />
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    void IPropertyProxy.SetValue(Object instance, Object value) => this._setter(instance as TClass, (TProperty)value);
  }
}