using System;
using LinFu.AOP.Cecil.Interfaces;
using LinFu.IoC.Configuration;
using LinFu.IoC.Interfaces;
using Mono.Cecil;

namespace LinFu.AOP.Cecil.Factories
{
    /// <summary>
    ///     Represents a class that generates <see cref="Action{T1,T2}" /> instances
    ///     that apply a specific method weaver (with the name given in the first delegate parameter)
    ///     to a specific <see cref="TypeDefinition" /> instance.
    /// </summary>
    [Factory(typeof(Action<string, TypeDefinition>), ServiceName = "TypeWeaver")]
    public class TypeWeaverActionFactory : IFactory
    {
        /// <summary>
        ///     Generates the <see cref="Action{T1, T2}" /> instance that will
        ///     weave the target type.
        /// </summary>
        /// <param name="request">The <see cref="IFactoryRequest" /> that describes the service request.</param>
        /// <returns>The <see cref="Action{T1, T2}" /> instance that will weave the target type.</returns>
        public object CreateInstance(IFactoryRequest request)
        {
            var container = request.Container;
            Action<string, TypeDefinition> result =
                (weaverName, type) =>
                {
                    // Get the method weaver instance that matches the weaverName
                    var methodWeaver =
                        (IHostWeaver<TypeDefinition>)
                        container.GetService(weaverName, typeof(IHostWeaver<TypeDefinition>));

                    // Wrap it in a type weaver
                    var typeWeaver =
                        (ITypeWeaver) container.GetService("AutoMethodWeaver", typeof(ITypeWeaver), methodWeaver);

                    var module = type.Module;
                    if (!typeWeaver.ShouldWeave(type))
                        return;

                    // Modify the host module
                    typeWeaver.ImportReferences(module);
                    typeWeaver.AddAdditionalMembers(module);

                    // Weave the type itself
                    typeWeaver.Weave(type);
                };


            return result;
        }
    }
}