using System;
using global::System.Reflection;

namespace Pilz.Collections.SimpleHistory
{
    public class ObjectState : ObjectBase
    {

        /// <summary>
        /// The Object including the members to patch.
        /// </summary>
        /// <returns></returns>
        public object Object { get; set; } = null;
        /// <summary>
        /// The name of the Member to patch.
        /// </summary>
        /// <returns></returns>
        public string MemberName { get; set; } = "";
        /// <summary>
        /// The Value that should be patched.
        /// </summary>
        /// <returns></returns>
        public object ValueToPatch { get; set; } = null;
        /// <summary>
        /// The member types to include at searching for the member.
        /// </summary>
        /// <returns></returns>
        public ObjectValueType MemberType { get; set; } = ObjectValueType.Field;
        /// <summary>
        /// The Binding Flags that are used at searching for the member.
        /// </summary>
        /// <returns></returns>
        public BindingFlags MemberFlags { get; set; } = BindingFlags.Default;

        /// <summary>
        /// Creates a new Instance of ObjectState from input.
        /// </summary>
        /// <param name="obj">The Object including the members to patch.</param>
        /// <param name="valname">The name of the Member to patch.</param>
        /// <param name="valToPatch">The member types to include at searching for the member.</param>
        /// <param name="valtype">The Binding Flags that are used at searching for the member.</param>
        public ObjectState(object obj, string valname, object valToPatch, ObjectValueType valtype)
        {
            Object = obj;
            MemberName = valname;
            ValueToPatch = valToPatch;
            MemberType = valtype;
        }

        /// <summary>
        /// Creates a new Instance of ObjectState.
        /// </summary>
        public ObjectState()
        {
        }

        internal void Patch()
        {
            var t = Object.GetType();
            switch (MemberType)
            {
                case ObjectValueType.Field:
                    {
                        var f = t.GetField(MemberName, MemberFlags);
                        object temp = null;
                        if (f is object)
                        {
                            temp = f.GetValue(Object);
                            f.SetValue(Object, ValueToPatch);
                            ValueToPatch = temp;
                        }

                        break;
                    }

                case ObjectValueType.Property:
                    {
                        var p = t.GetProperty(MemberName, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Static);
                        object temp = null;
                        if (p is object)
                        {
                            temp = p.GetValue(Object);
                            p.SetValue(Object, ValueToPatch);
                            ValueToPatch = temp;
                        }

                        break;
                    }

                default:
                    {
                        throw new Exception("ValueType is invalid!");
                        break;
                    }
            }
        }
    }
}