using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;
using System.Reflection;

namespace RMock
{

    /// <summary>
    /// Facilitates the creation of mock classes for FCL objects.
    /// </summary>
    internal static class MockServices
    {

        /// <summary>
        /// Instantiates T without calling a constructor.
        /// Works well with otherwise uninstantiable objects.
        /// </summary>
        /// <typeparam name="T">Anything that does NOT derive
        /// from ContextBoundObject.</typeparam>
        /// <param name="Values">A dictionary of values to initialize
        /// the object in place of a constructor.</param>
        /// <returns>The newly created and instantiated object.</returns>
        public static T Create<T>(Dictionary<string, object> Values)
        {

            if (Values == null)
                throw new ArgumentNullException("Values", "Values is null.");

            return Fill<T>(
                CreateBlank<T>(),
                Values);

        }

        private static T CreateBlank<T>()
        {

            if (typeof(ContextBoundObject).IsAssignableFrom(typeof(T)) == true)
            {
                throw new ApplicationException(
                    "You can't use types that derive from ContextBoundObject.");
            }

            return (T)System.Runtime.Serialization.FormatterServices
                 .GetUninitializedObject(typeof(T));
        }


        private static T Fill<T>(T Source, Dictionary<string, object> Values)
        {
            if (Source == null)
                throw new ArgumentNullException("Source", "Source is null.");

            if (Values == null)
                throw new ArgumentNullException("Values", "Values is null");

            if (Values.Count == 0)
                return Source;

            FieldInfo[] EventFields = typeof(T)
                .GetFields(
                    BindingFlags.NonPublic |
                    BindingFlags.Public |
                    BindingFlags.Instance |
                    BindingFlags.DeclaredOnly);

            if (EventFields != null && EventFields.Count() > 0)
            {
                foreach (FieldInfo Field in EventFields)
                {
                    if (Values.ContainsKey(Field.Name) == true
                        && Field.FieldType
                            .IsAssignableFrom(Values[Field.Name]
                                .GetType()) == true)
                    {
                        Field.SetValue(Source, Values[Field.Name]);
                    }
                }
            }

            return Source;

        }

    }

}