using System;
using System.Collections.Generic;
using Chernobyl.Collections.Generic.Event;
using NUnit.Framework;
// ReSharper disable ObjectCreationAsStatement

namespace Chernobyl.Collections.Generic.Hierarchy
{
    [TestFixture, Description("Tests for the Children type and its subtypes.")]
    public class ChildrenTests : CollectionTests<ParentTests.Hierarchy>
    {
        public ChildrenTests()
            : base(false)
        {}

        //------------------------------------------------------------------
        // Children(TParent, Func<TChild, IDynamicContainer<TParent>>) Tests
        //------------------------------------------------------------------

        [Test, Description("Ensures the Children(TParent, Func<TChild, IDynamicContainer<TParent>>) " +
            "constructor throws an ArgumentNullException when the first argument is null.")]
        public void ConstructorTParentFuncFirstArgumentNullException()
        {
            Assert.Throws<ArgumentNullException>(
                () => new Children<ParentTests.Hierarchy, ParentTests.Hierarchy>(null, hierarchy => hierarchy.Parent));
        }

        [Test, Description("Ensures the Children(TParent, Func<TChild, IDynamicContainer<TParent>>) " +
            "constructor throws an ArgumentNullException when the second argument is null.")]
        public void ConstructorTParentFuncSecondArgumentNullException()
        {
            var parent = new ParentTests.Hierarchy();
            Assert.Throws<ArgumentNullException>(() =>
                new Children<ParentTests.Hierarchy, ParentTests.Hierarchy>(parent, null));
        }

        //------------------------------------------------------------------
        // Children(TParent, Func<TChild, IDynamicContainer<TParent>>, IEventCollection<TChild>) Tests
        //------------------------------------------------------------------

        [Test, Description("Ensures the Children(TParent, Func<TChild, IDynamicContainer<TParent>>, IEventCollection<TChild>) " +
            "constructor throws an ArgumentNullException when the first argument is null.")]
        public void ConstructorTParentFuncEventCollectionFirstArgumentNullException()
        {
            Assert.Throws<ArgumentNullException>(() =>
                new Children<ParentTests.Hierarchy, ParentTests.Hierarchy>(null, hierarchy => hierarchy.Parent));
        }

        [Test, Description("Ensures the Children(TParent, Func<TChild, IDynamicContainer<TParent>>, IEventCollection<TChild>) " +
            "constructor throws an ArgumentNullException when the second argument is null.")]
        public void ConstructorTParentFuncEventCollectionSecondArgumentNullException()
        {
            var parent = new ParentTests.Hierarchy();
            Assert.Throws<ArgumentNullException>(() =>
                new Children<ParentTests.Hierarchy, ParentTests.Hierarchy>(parent, null));
        }

        [Test, Description("Ensures the Children(TParent, Func<TChild, IDynamicContainer<TParent>>, IEventCollection<TChild>) " +
            "constructor throws an ArgumentNullException when the third argument is null.")]
        public void ConstructorTParentFuncEventCollectionThirdArgumentNullException()
        {
            var parent = new ParentTests.Hierarchy();
            Assert.Throws<ArgumentNullException>(() =>
                new Children<ParentTests.Hierarchy, ParentTests.Hierarchy>(parent, hierarchy => hierarchy.Parent, null));
        }

        [Test, Description("Ensures the Children(TParent, Func<TChild, IDynamicContainer<TParent>>, IEventCollection<TChild>) " +
            "constructor throws an ArgumentException when the third argument contains items.")]
        public void ConstructorTParentFuncEventCollectionThirdArgumentHasItemsException()
        {
            DecoratingEventList<ParentTests.Hierarchy> implementation = new DecoratingEventList<ParentTests.Hierarchy>();
            implementation.Add(new ParentTests.Hierarchy());

            var parent = new ParentTests.Hierarchy();
            Assert.Throws<ArgumentException>(() =>
                new Children<ParentTests.Hierarchy, ParentTests.Hierarchy>(parent, hierarchy => hierarchy.Parent, implementation));
        }

        //------------------------------------------------------------------
        // Utility
        //------------------------------------------------------------------

        protected override ICollection<ParentTests.Hierarchy> CreateCollection()
        {
            ParentTests.Hierarchy first = new ParentTests.Hierarchy();

            first.Children.AddRange(new[] { new ParentTests.Hierarchy(),
                                            new ParentTests.Hierarchy(),
                                            new ParentTests.Hierarchy(),
                                            new ParentTests.Hierarchy(),
                                            new ParentTests.Hierarchy(),
                                            new ParentTests.Hierarchy(),
                                            new ParentTests.Hierarchy() });

            return first.Children;
        }

        protected override ICollection<ParentTests.Hierarchy> CreateReadOnlyCollection()
        {
            // Read only Children not supported.
            return null;
        }

        protected override ParentTests.Hierarchy CreateItem()
        {
            return new ParentTests.Hierarchy();
        }
    }
}