using System;
using System.Collections.Generic;
using System.Reflection;

namespace XXX.Common
{
    internal interface INamedMemberAccessor
    {
        object GetValue(object instance);
        void SetValue(object instance, object newValue);
    }

    /// <summary>
    /// Abstraction of the function of accessing member of a object at runtime.
    /// </summary>
    public interface IMemberAccessor
    {
        /// <summary>
        /// Get the member value of an object.
        /// </summary>
        /// <param name="instance">The object to get the member value from.</param>
        /// <param name="memberName">The member name, could be the name of a property of field. Must be public member.</param>
        /// <returns>The member value</returns>
        object GetValue(object instance, string memberName);

        /// <summary>
        /// Set the member value of an object.
        /// </summary>
        /// <param name="instance">The object to get the member value from.</param>
        /// <param name="memberName">The member name, could be the name of a property of field. Must be public member.</param>
        /// <param name="newValue">The new value of the property for the object instance.</param>
        void SetValue(object instance, string memberName, object newValue);
    }

    internal class PropertyAccessor<T, P> : INamedMemberAccessor
    {
        private Func<T, P> m_GetValueDelegate;
        private Action<T, P> m_SetValueDelegate;

        public PropertyAccessor(PropertyInfo propertyInfo)
        {
            Guard.ArgumentNotNull(propertyInfo, "Property can't be null");

            var getMethodInfo = propertyInfo.GetGetMethod();
            if (null != getMethodInfo)
            {
                m_GetValueDelegate = (Func<T, P>)Delegate.CreateDelegate(typeof(Func<T, P>), getMethodInfo);
            }

            var setMethodInfo = propertyInfo.GetSetMethod();
            if (null != setMethodInfo)
            {
                m_SetValueDelegate = (Action<T, P>)Delegate.CreateDelegate(typeof(Action<T, P>), setMethodInfo);
            }
        }

        public object GetValue(object instance)
        {
            Guard.ArgumentNotNull(m_GetValueDelegate, "The Property doesn't have GetMethod");
            return m_GetValueDelegate((T)instance);
        }

        public void SetValue(object instance, object newValue)
        {
            Guard.ArgumentNotNull(m_SetValueDelegate, "The Property doesn't have SetMethod");
            m_SetValueDelegate((T)instance, (P)newValue);