using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using LinFu.IoC.Configuration.Interfaces;
using LinFu.IoC.Interfaces;

namespace LinFu.IoC.Configuration
{
    /// <summary>
    ///     A default implementation of the <see cref="IMemberInjectionFilter{TMember}" />
    ///     class that returns methods which have the <see cref="InjectAttribute" />
    ///     defined.
    /// </summary>
    public class AttributedMethodInjectionFilter : BaseMemberInjectionFilter<MethodInfo>
    {
        private readonly Type _attributeType;

        /// <summary>
        ///     Initializes the class with the <see cref="InjectAttribute" /> as the
        ///     default injection attribute.
        /// </summary>
        public AttributedMethodInjectionFilter()
        {
            _attributeType = typeof(InjectAttribute);
        }

        /// <summary>
        ///     Initializes the class and uses the <paramref name="attributeType" />
        ///     as the custom injection attribute.
        /// </summary>
        /// <param name="attributeType"></param>
        public AttributedMethodInjectionFilter(Type attributeType)
        {
            _attributeType = attributeType;
        }

        /// <summary>
        ///     Returns the methods that have the custom attribute type defined.
        /// </summary>
        /// <param name="targetType">The target type that contains the target methods.</param>
        /// <param name="container">The host container.</param>
        /// <returns>The list of methods that have the custom attribute type defined.</returns>
        protected override IEnumerable<MethodInfo> GetMembers(Type targetType,
            IServiceContainer container)
        {
            var results =
                from method in targetType.GetMethods(BindingFlags.Public | BindingFlags.Instance)
                let attributes = _attributeType != null
                    ? method.GetCustomAttributes(_attributeType, false)
                    : null
                where attributes != null && attributes.Length > 0
                select method;

            return results;
        }
    }
}