// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.Encodings.Web;
using System.Threading.Tasks;
using Microsoft.AspNet.Http;
using Microsoft.AspNet.Routing.Internal;
using Microsoft.AspNet.Routing.Template;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Testing;
using Microsoft.Extensions.ObjectPool;
using Microsoft.Extensions.Options;
using Microsoft.Extensions.WebEncoders.Testing;
using Moq;
using Xunit;

namespace Microsoft.AspNet.Routing.Tree
{
    public class TreeRouterTest
    {
        private static readonly RequestDelegate NullHandler = (c) => Task.FromResult(0);

        private static UrlEncoder Encoder = UrlTestEncoder.Default;
        private static ObjectPool<UriBuildingContext> Pool = new DefaultObjectPoolProvider().Create(
            new UriBuilderContextPooledObjectPolicy(Encoder));

        [Theory]
        [InlineData("template/5", "template/{parameter:int}")]
        [InlineData("template/5", "template/{parameter}")]
        [InlineData("template/5", "template/{*parameter:int}")]
        [InlineData("template/5", "template/{*parameter}")]
        [InlineData("template/{parameter}", "template/{parameter:alpha}")] // constraint doesn't match
        [InlineData("template/{parameter:int}", "template/{parameter}")]
        [InlineData("template/{parameter:int}", "template/{*parameter:int}")]
        [InlineData("template/{parameter:int}", "template/{*parameter}")]
        [InlineData("template/{parameter}", "template/{*parameter:int}")]
        [InlineData("template/{parameter}", "template/{*parameter}")]
        [InlineData("template/{*parameter:int}", "template/{*parameter}")]
        public async Task TreeRouter_RouteAsync_RespectsPrecedence(
            string firstTemplate,
            string secondTemplate)
        {
            // Arrange
            var expectedRouteGroup = string.Format("{0}&&{1}", 0, firstTemplate);

            var next = new Mock<IRouter>();
            next
                .Setup(r => r.RouteAsync(It.IsAny<RouteContext>()))
                .Callback<RouteContext>(c => c.Handler = NullHandler)
                .Returns(Task.FromResult(true))
                .Verifiable();

            var firstRoute = CreateMatchingEntry(next.Object, firstTemplate, order: 0);
            var secondRoute = CreateMatchingEntry(next.Object, secondTemplate, order: 0);

            // We setup the route entries in reverse order of precedence to ensure that when we
            // try to route the request, the route with a higher precedence gets tried first.
            var matchingRoutes = new[] { secondRoute, firstRoute };

            var linkGenerationEntries = Enumerable.Empty<TreeRouteLinkGenerationEntry>();

            var route = CreateAttributeRoute(next.Object, matchingRoutes, linkGenerationEntries);

            var context = CreateRouteContext("/template/5");

            // Act
            await route.RouteAsync(context);

            // Assert
            Assert.Equal(expectedRouteGroup, context.RouteData.Values["test_route_group"]);
        }

        [Theory]
        [InlineData("template/5", "template/{parameter:int}")]
        [InlineData("template/5", "template/{parameter}")]
        [InlineData("template/5", "template/{*parameter:int}")]
        [InlineData("template/5", "template/{*parameter}")]
        [InlineData("template/{parameter:int}", "template/{parameter}")]
        [InlineData("template/{parameter:int}", "template/{*parameter:int}")]
        [InlineData("template/{parameter:int}", "template/{*parameter}")]
        [InlineData("template/{parameter}", "template/{*parameter:int}")]
        [InlineData("template/{parameter}", "template/{*parameter}")]
        [InlineData("template/{*parameter:int}", "template/{*parameter}")]
        public async Task TreeRouter_RouteAsync_RespectsOrderOverPrecedence(
            string firstTemplate,
            string secondTemplate)
        {
            // Arrange
            var expectedRouteGroup = string.Format("{0}&&{1}", 0, secondTemplate);

            var next = new Mock<IRouter>();
            next
                .Setup(r => r.RouteAsync(It.IsAny<RouteContext>()))
                .Callback<RouteContext>(c => c.Handler = NullHandler)
                .Returns(Task.FromResult(true))
                .Verifiable();

            var firstRoute = CreateMatchingEntry(next.Object, firstTemplate, order: 1);
            var secondRoute = CreateMatchingEntry(next.Object, secondTemplate, order: 0);

            // We setup the route entries with a lower relative order and higher relative precedence
            // first to ensure that when we try to route the request, the route with the higher
            // relative order gets tried first.
            var matchingRoutes = new[] { firstRoute, secondRoute };

            var linkGenerationEntries = Enumerable.Empty<TreeRouteLinkGenerationEntry>();

            var route = CreateAttributeRoute(next.Object, matchingRoutes, linkGenerationEntries);

            var context = CreateRouteContext("/template/5");

            // Act
            await route.RouteAsync(context);

            // Assert
            Assert.Equal(expectedRouteGroup, context.RouteData.Values["test_route_group"]);
        }

        [Theory]
        [InlineData("template/5")]
        [InlineData("template/{parameter:int}")]
        [InlineData("template/{parameter}")]
        [InlineData("template/{*parameter:int}")]
        [InlineData("template/{*parameter}")]
        public async Task TreeRouter_RouteAsync_RespectsOrder(string template)
        {
            // Arrange
            var expectedRouteGroup = string.Format("{0}&&{1}", 0, template);

            var next = new Mock<IRouter>();
            next
                .Setup(r => r.RouteAsync(It.IsAny<RouteContext>()))
                .Callback<RouteContext>(c => c.Handler = NullHandler)
                .Returns(Task.FromResult(true))
                .Verifiable();

            var firstRoute = CreateMatchingEntry(next.Object, template, order: 1);
            var secondRoute = CreateMatchingEntry(next.Object, template, order: 0);

            // We setup the route entries with a lower relative order first to ensure that when
            // we try to route the request, the route with the higher relative order gets tried first.
            var matchingRoutes = new[] { firstRoute, secondRoute };

            var linkGenerationEntries = Enumerable.Empty<TreeRouteLinkGenerationEntry>();

            var route = CreateAttributeRoute(next.Object, matchingRoutes, linkGenerationEntries);

            var context = CreateRouteContext("/template/5");

            // Act
            await route.RouteAsync(context);

            // Assert
            Assert.Equal(expectedRouteGroup, context.RouteData.Values["test_route_group"]);
        }

        [Theory]
        [InlineData("template/{first:int}", "template/{second:int}")]
        [InlineData("template/{first}", "template/{second}")]
        [InlineData("template/{*first:int}", "template/{*second:int}")]
        [InlineData("template/{*first}", "template/{*second}")]
        public async Task TreeRouter_RouteAsync_EnsuresStableOrdering(string first, string second)
        {
            // Arrange
            var expectedRouteGroup = string.Format("{0}&&{1}", 0, first);

            var next = new Mock<IRouter>();
            next
                .Setup(r => r.RouteAsync(It.IsAny<RouteContext>()))
                .Callback<RouteContext>(c => c.Handler = NullHandler)
                .Returns(Task.FromResult(true))
                .Verifiable();

            var secondRouter = new Mock<IRouter>(MockBehavior.Strict);

            var firstRoute = CreateMatchingEntry(next.Object, first, order: 0);
            var secondRoute = CreateMatchingEntry(next.Object, second, order: 0);

            // We setup the route entries with a lower relative template order first to ensure that when
            // we try to route the request, the route with the higher template order gets tried first.
            var matchingRoutes = new[] { secondRoute, firstRoute };

            var linkGenerationEntries = Enumerable.Empty<TreeRouteLinkGenerationEntry>();

            var route = CreateAttributeRoute(next.Object, matchingRoutes, linkGenerationEntries);

            var context = CreateRouteContext("/template/5");

            // Act
            await route.RouteAsync(context);

            // Assert
            Assert.Equal(expectedRouteGroup, context.RouteData.Values["test_route_group"]);
        }

        [Theory]
        [InlineData("template/{parameter:int}", "/template/5", true)]
        [InlineData("template/{parameter:int?}", "/template/5", true)]
        [InlineData("template/{parameter:int?}", "/template", true)]
        [InlineData("template/{parameter:int?}", "/template/qwer", false)]
        public async Task TreeRouter_WithOptionalInlineConstraint(
            string template,
            string request,
            bool expectedResult)
        {
            // Arrange
            var expectedRouteGroup = string.Format("{0}&&{1}", 0, template);

            var next = new Mock<IRouter>();
            next
                .Setup(r => r.RouteAsync(It.IsAny<RouteContext>()))
                .Callback<RouteContext>(c => c.Handler = NullHandler)
                .Returns(Task.FromResult(true))
                .Verifiable();

            var firstRoute = CreateMatchingEntry(next.Object, template, order: 0);

            // We setup the route entries in reverse order of precedence to ensure that when we
            // try to route the request, the route with a higher precedence gets tried first.
            var matchingRoutes = new[] { firstRoute };

            var linkGenerationEntries = Enumerable.Empty<TreeRouteLinkGenerationEntry>();

            var route = CreateAttributeRoute(next.Object, matchingRoutes, linkGenerationEntries);

            var context = CreateRouteContext(request);

            // Act
            await route.RouteAsync(context);

            // Assert
            if (expectedResult)
            {
                Assert.NotNull(context.Handler);
                Assert.Equal(expectedRouteGroup, context.RouteData.Values["test_route_group"]);
            }
            else
            {
                Assert.Null(context.Handler);
            }
        }

        [Theory]
        [InlineData("moo/{p1}.{p2?}", "/moo/foo.bar", "foo", "bar", null)]
        [InlineData("moo/{p1?}", "/moo/foo", "foo", null, null)]
        [InlineData("moo/{p1?}", "/moo", null, null, null)]
        [InlineData("moo/{p1}.{p2?}", "/moo/foo", "foo", null, null)]
        [InlineData("moo/{p1}.{p2?}", "/moo/foo..bar", "foo.", "bar", null)]
        [InlineData("moo/{p1}.{p2?}", "/moo/foo.moo.bar", "foo.moo", "bar", null)]
        [InlineData("moo/{p1}.{p2}", "/moo/foo.bar", "foo", "bar", null)]
        [InlineData("moo/foo.{p1}.{p2?}", "/moo/foo.moo.bar", "moo", "bar", null)]
        [InlineData("moo/foo.{p1}.{p2?}", "/moo/foo.moo", "moo", null, null)]
        [InlineData("moo/.{p2?}", "/moo/.foo", null, "foo", null)]
        [InlineData("moo/{p1}.{p2?}", "/moo/....", "..", ".", null)]
        [InlineData("moo/{p1}.{p2?}", "/moo/.bar", ".bar", null, null)]
        [InlineData("moo/{p1}.{p2}.{p3?}", "/moo/foo.moo.bar", "foo", "moo", "bar")]
        [InlineData("moo/{p1}.{p2}.{p3?}", "/moo/foo.moo", "foo", "moo", null)]
        [InlineData("moo/{p1}.{p2}.{p3}.{p4?}", "/moo/foo.moo.bar", "foo", "moo", "bar")]
        [InlineData("{p1}.{p2?}/{p3}", "/foo.moo/bar", "foo", "moo", "bar")]
        [InlineData("{p1}.{p2?}/{p3}", "/foo/bar", "foo", null, "bar")]
        [InlineData("{p1}.{p2?}/{p3}", "/.foo/bar", ".foo", null, "bar")]
        public async Task TreeRouter_WithOptionalCompositeParameter_Valid(
            string template,
            string request,
            string p1,
            string p2,
            string p3)
        {
            // Arrange
            var expectedRouteGroup = string.Format("{0}&&{1}", 0, template);

            var next = new Mock<IRouter>();
            next
                .Setup(r => r.RouteAsync(It.IsAny<RouteContext>()))
                .Callback<RouteContext>(c => c.Handler = NullHandler)
                .Returns(Task.FromResult(true))
                .Verifiable();

            var firstRoute = CreateMatchingEntry(next.Object, template, order: 0);

            // We setup the route entries in reverse order of precedence to ensure that when we
            // try to route the request, the route with a higher precedence gets tried first.
            var matchingEntries = new[] { firstRoute };
            var linkGenerationEntries = Enumerable.Empty<TreeRouteLinkGenerationEntry>();
            var route = CreateAttributeRoute(next.Object, matchingEntries, linkGenerationEntries);
            var context = CreateRouteContext(request);

            // Act
            await route.RouteAsync(context);

            // Assert
            Assert.NotNull(context.Handler);
            if (p1 != null)
            {
                Assert.Equal(p1, context.RouteData.Values["p1"]);
            }
            if (p2 != null)
            {
                Assert.Equal(p2, context.RouteData.Values["p2"]);
            }
            if (p3 != null)
            {
                Assert.Equal(p3, context.RouteData.Values["p3"]);
            }
        }

        [Theory]
        [InlineData("moo/{p1}.{p2?}", "/moo/foo.")]
        [InlineData("moo/{p1}.{p2?}", "/moo/.")]
        [InlineData("moo/{p1}.{p2}", "/foo.")]
        [InlineData("moo/{p1}.{p2}", "/foo")]
        [InlineData("moo/{p1}.{p2}.{p3?}", "/moo/foo.moo.")]
        [InlineData("moo/foo.{p2}.{p3?}", "/moo/bar.foo.moo")]
        [InlineData("moo/foo.{p2}.{p3?}", "/moo/kungfoo.moo.bar")]
        [InlineData("moo/foo.{p2}.{p3?}", "/moo/kungfoo.moo")]
        [InlineData("moo/{p1}.{p2}.{p3?}", "/moo/foo")]
        [InlineData("{p1}.{p2?}/{p3}", "/foo./bar")]
        [InlineData("moo/.{p2?}", "/moo/.")]
        [InlineData("{p1}.{p2}/{p3}", "/.foo/bar")]
        public async Task TreeRouter_WithOptionalCompositeParameter_Invalid(
            string template,
            string request)
        {
            // Arrange
            var expectedRouteGroup = string.Format("{0}&&{1}", 0, template);

            var next = new Mock<IRouter>();
            next
                .Setup(r => r.RouteAsync(It.IsAny<RouteContext>()))
                .Callback<RouteContext>(c => c.Handler = NullHandler)
                .Returns(Task.FromResult(true))
                .Verifiable();

            var firstRoute = CreateMatchingEntry(next.Object, template, order: 0);

            // We setup the route entries in reverse order of precedence to ensure that when we
            // try to route the request, the route with a higher precedence gets tried first.
            var matchingEntries = new[] { firstRoute };
            var linkGenerationEntries = Enumerable.Empty<TreeRouteLinkGenerationEntry>();
            var route = CreateAttributeRoute(next.Object, matchingEntries, linkGenerationEntries);

            var context = CreateRouteContext(request);

            // Act
            await route.RouteAsync(context);

            // Assert
            Assert.Null(context.Handler);
        }

        [Theory]
        [InlineData("template", "{*url:alpha}", "/template?url=dingo&id=5")]
        [InlineData("{*url:alpha}", "{*url}", "/dingo?id=5")]
        [InlineData("{id}", "{*url}", "/5?url=dingo")]
        [InlineData("{id}", "{*url:alpha}", "/5?url=dingo")]
        [InlineData("{id:int}", "{id}", "/5?url=dingo")]
        [InlineData("{id}", "{id:alpha}/{url}", "/5?url=dingo")] // constraint doesn't match
        [InlineData("template/api/{*url}", "template/api", "/template/api/dingo?id=5")]
        [InlineData("template/api", "template/{*url}", "/template/api?url=dingo&id=5")]
        [InlineData("template/api", "template/api{id}location", "/template/api?url=dingo&id=5")]
        [InlineData("template/api{id}location", "template/{id:int}", "/template/api5location?url=dingo")]
        public void TreeRouter_GenerateLink(string firstTemplate, string secondTemplate, string expectedPath)
        {
            // Arrange
            var values = new Dictionary<string, object>
            {
                {"url", "dingo" },
                {"id", 5 }
            };

            var route = CreateAttributeRoute(firstTemplate, secondTemplate);
            var context = CreateVirtualPathContext(
                values: values,
                ambientValues: null);

            // Act
            var result = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(result);
            Assert.Equal(expectedPath, result.VirtualPath);
            Assert.Same(route, result.Router);
            Assert.Empty(result.DataTokens);
        }

        [Fact]
        public void TreeRouter_GenerateLink_LongerTemplateWithDefaultIsMoreSpecific()
        {
            // Arrange
            var firstTemplate = "template";
            var secondTemplate = "template/{parameter:int=1003}";

            var route = CreateAttributeRoute(firstTemplate, secondTemplate);
            var context = CreateVirtualPathContext(
                values: null,
                ambientValues: null);

            // Act
            var result = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(result);
            // The Binder binds to /template
            Assert.Equal("/template", result.VirtualPath);
            Assert.Same(route, result.Router);
            Assert.Empty(result.DataTokens);
        }

        [Theory]
        [InlineData("template/{parameter:int=5}", "template", "/template/5")]
        [InlineData("template/{parameter}", "template", "/template/5")]
        [InlineData("template/{parameter}/{id}", "template/{parameter}", "/template/5/1234")]
        public void TreeRouter_GenerateLink_OrderingAgnostic(
            string firstTemplate,
            string secondTemplate,
            string expectedPath)
        {
            // Arrange
            var route = CreateAttributeRoute(firstTemplate, secondTemplate);
            var parameter = 5;
            var id = 1234;
            var values = new Dictionary<string, object>
            {
                { nameof(parameter) , parameter},
                { nameof(id), id }
            };
            var context = CreateVirtualPathContext(
                values: null,
                ambientValues: values);

            // Act
            var result = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(result);
            Assert.Equal(expectedPath, result.VirtualPath);
            Assert.Same(route, result.Router);
            Assert.Empty(result.DataTokens);
        }

        [Theory]
        [InlineData("template", "template/{parameter}", "/template/5")]
        [InlineData("template/{parameter}", "template/{parameter}/{id}", "/template/5/1234")]
        [InlineData("template", "template/{parameter:int=5}", "/template/5")]
        public void TreeRouter_GenerateLink_UseAvailableVariables(
            string firstTemplate,
            string secondTemplate,
            string expectedPath)
        {
            // Arrange
            var route = CreateAttributeRoute(firstTemplate, secondTemplate);
            var parameter = 5;
            var id = 1234;
            var values = new Dictionary<string, object>
            {
                { nameof(parameter) , parameter},
                { nameof(id), id }
            };
            var context = CreateVirtualPathContext(
                values: null,
                ambientValues: values);

            // Act
            var result = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(result);
            Assert.Equal(expectedPath, result.VirtualPath);
            Assert.Same(route, result.Router);
            Assert.Empty(result.DataTokens);
        }

        [Theory]
        [InlineData("template/5", "template/{parameter:int}")]
        [InlineData("template/5", "template/{parameter}")]
        [InlineData("template/5", "template/{*parameter:int}")]
        [InlineData("template/5", "template/{*parameter}")]
        [InlineData("template/{parameter:int}", "template/{parameter}")]
        [InlineData("template/{parameter:int}", "template/{*parameter:int}")]
        [InlineData("template/{parameter:int}", "template/{*parameter}")]
        [InlineData("template/{parameter}", "template/{*parameter:int}")]
        [InlineData("template/{parameter}", "template/{*parameter}")]
        [InlineData("template/{*parameter:int}", "template/{*parameter}")]
        public void TreeRouter_GenerateLink_RespectsPrecedence(string firstTemplate, string secondTemplate)
        {
            // Arrange
            var matchingRoutes = Enumerable.Empty<TreeRouteMatchingEntry>();

            var firstEntry = CreateGenerationEntry(firstTemplate, requiredValues: null);
            var secondEntry = CreateGenerationEntry(secondTemplate, requiredValues: null, order: 0);

            // We setup the route entries in reverse order of precedence to ensure that when we
            // try to generate a link, the route with a higher precedence gets tried first.
            var linkGenerationEntries = new[] { secondEntry, firstEntry };

            var route = CreateAttributeRoute(matchingRoutes, linkGenerationEntries);

            var context = CreateVirtualPathContext(values: null, ambientValues: new { parameter = 5 });

            // Act
            var result = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(result);
            Assert.Equal("/template/5", result.VirtualPath);
            Assert.Same(route, result.Router);
            Assert.Empty(result.DataTokens);
        }

        [Theory]
        [InlineData("template/{parameter:int}", "/template/5", 5)]
        [InlineData("template/{parameter:int?}", "/template/5", 5)]
        [InlineData("template/{parameter:int?}", "/template", null)]
        [InlineData("template/{parameter:int?}", null, "asdf")]
        [InlineData("template/{parameter:alpha?}", "/template/asdf", "asdf")]
        [InlineData("template/{parameter:alpha?}", "/template", null)]
        [InlineData("template/{parameter:int:range(1,20)?}", "/template", null)]
        [InlineData("template/{parameter:int:range(1,20)?}", "/template/5", 5)]
        [InlineData("template/{parameter:int:range(1,20)?}", null, 21)]
        public void TreeRouter_GenerateLink_OptionalInlineParameter(
            string template,
            string expectedPath,
            object parameter)
        {
            // Arrange
            var matchingRoutes = Enumerable.Empty<TreeRouteMatchingEntry>();

            var entry = CreateGenerationEntry(template, requiredValues: null);

            var linkGenerationEntries = new[] { entry };

            var route = CreateAttributeRoute(matchingRoutes, linkGenerationEntries);

            VirtualPathContext context;
            if (parameter != null)
            {
                context = CreateVirtualPathContext(values: null, ambientValues: new { parameter = parameter });
            }
            else
            {
                context = CreateVirtualPathContext(values: null, ambientValues: null);
            }

            // Act
            var result = route.GetVirtualPath(context);

            // Assert
            if (expectedPath == null)
            {
                Assert.Null(result);
            }
            else
            {
                Assert.NotNull(result);
                Assert.Equal(expectedPath, result.VirtualPath);
                Assert.Same(route, result.Router);
                Assert.Empty(result.DataTokens);
            }
        }

        [Theory]
        [InlineData("template/5", "template/{parameter:int}")]
        [InlineData("template/5", "template/{parameter}")]
        [InlineData("template/5", "template/{*parameter:int}")]
        [InlineData("template/5", "template/{*parameter}")]
        [InlineData("template/{parameter:int}", "template/{parameter}")]
        [InlineData("template/{parameter:int}", "template/{*parameter:int}")]
        [InlineData("template/{parameter:int}", "template/{*parameter}")]
        [InlineData("template/{parameter}", "template/{*parameter:int}")]
        [InlineData("template/{parameter}", "template/{*parameter}")]
        [InlineData("template/{*parameter:int}", "template/{*parameter}")]
        public void TreeRouter_GenerateLink_RespectsOrderOverPrecedence(string firstTemplate, string secondTemplate)
        {
            // Arrange
            var matchingRoutes = Enumerable.Empty<TreeRouteMatchingEntry>();

            var firstRoute = CreateGenerationEntry(firstTemplate, requiredValues: null, order: 1);
            var secondRoute = CreateGenerationEntry(secondTemplate, requiredValues: null, order: 0);

            // We setup the route entries with a lower relative order and higher relative precedence
            // first to ensure that when we try to generate a link, the route with the higher
            // relative order gets tried first.
            var linkGenerationEntries = new[] { firstRoute, secondRoute };

            var route = CreateAttributeRoute(matchingRoutes, linkGenerationEntries);

            var context = CreateVirtualPathContext(null, ambientValues: new { parameter = 5 });

            // Act
            var result = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(result);
            Assert.Equal("/template/5", result.VirtualPath);
            Assert.Same(route, result.Router);
            Assert.Empty(result.DataTokens);
        }

        [Theory]
        [InlineData("template/5", "template/5")]
        [InlineData("template/{first:int}", "template/{second:int}")]
        [InlineData("template/{first}", "template/{second}")]
        [InlineData("template/{*first:int}", "template/{*second:int}")]
        [InlineData("template/{*first}", "template/{*second}")]
        public void TreeRouter_GenerateLink_RespectsOrder(string firstTemplate, string secondTemplate)
        {
            // Arrange
            var matchingRoutes = Enumerable.Empty<TreeRouteMatchingEntry>();

            var firstRoute = CreateGenerationEntry(firstTemplate, requiredValues: null, order: 1);
            var secondRoute = CreateGenerationEntry(secondTemplate, requiredValues: null, order: 0);

            // We setup the route entries with a lower relative order first to ensure that when
            // we try to generate a link, the route with the higher relative order gets tried first.
            var linkGenerationEntries = new[] { firstRoute, secondRoute };

            var route = CreateAttributeRoute(matchingRoutes, linkGenerationEntries);

            var context = CreateVirtualPathContext(values: null, ambientValues: new { first = 5, second = 5 });

            // Act
            var result = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(result);
            Assert.Equal("/template/5", result.VirtualPath);
            Assert.Same(route, result.Router);
            Assert.Empty(result.DataTokens);
        }

        [Theory]
        [InlineData("first/5", "second/5")]
        [InlineData("first/{first:int}", "second/{second:int}")]
        [InlineData("first/{first}", "second/{second}")]
        [InlineData("first/{*first:int}", "second/{*second:int}")]
        [InlineData("first/{*first}", "second/{*second}")]
        public void TreeRouter_GenerateLink_EnsuresStableOrder(string firstTemplate, string secondTemplate)
        {
            // Arrange
            var matchingRoutes = Enumerable.Empty<TreeRouteMatchingEntry>();

            var firstRoute = CreateGenerationEntry(firstTemplate, requiredValues: null, order: 0);
            var secondRoute = CreateGenerationEntry(secondTemplate, requiredValues: null, order: 0);

            // We setup the route entries with a lower relative template order first to ensure that when
            // we try to generate a link, the route with the higher template order gets tried first.
            var linkGenerationEntries = new[] { secondRoute, firstRoute };

            var route = CreateAttributeRoute(matchingRoutes, linkGenerationEntries);

            var context = CreateVirtualPathContext(values: null, ambientValues: new { first = 5, second = 5 });

            // Act
            var result = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(result);
            Assert.Equal("/first/5", result.VirtualPath);
            Assert.Same(route, result.Router);
            Assert.Empty(result.DataTokens);
        }

        public static IEnumerable<object[]> NamedEntriesWithDifferentTemplates
        {
            get
            {
                var data = new TheoryData<IEnumerable<TreeRouteLinkGenerationEntry>>();
                data.Add(new[]
                {
                        CreateGenerationEntry("template", null, 0, "NamedEntry"),
                        CreateGenerationEntry("otherTemplate", null, 0, "NamedEntry"),
                        CreateGenerationEntry("anotherTemplate", null, 0, "NamedEntry")
                });

                // Default values for parameters are taken into account by comparing the templates.
                data.Add(new[]
                {
                        CreateGenerationEntry("template/{parameter=0}", null, 0, "NamedEntry"),
                        CreateGenerationEntry("template/{parameter=1}", null, 0, "NamedEntry"),
                        CreateGenerationEntry("template/{parameter=2}", null, 0, "NamedEntry")
                });

                // Names for entries are compared ignoring casing.
                data.Add(new[]
                {
                        CreateGenerationEntry("template/{*parameter:int=0}", null, 0, "NamedEntry"),
                        CreateGenerationEntry("template/{*parameter:int=1}", null, 0, "NAMEDENTRY"),
                        CreateGenerationEntry("template/{*parameter:int=2}", null, 0, "namedentry")
                });
                return data;
            }
        }

        [Theory]
        [MemberData(nameof(TreeRouterTest.NamedEntriesWithDifferentTemplates))]
        public void TreeRouter_CreateTreeRouter_ThrowsIfDifferentEntriesHaveTheSameName(
            IEnumerable<TreeRouteLinkGenerationEntry> namedEntries)
        {
            // Arrange
            string expectedExceptionMessage = "Two or more routes named 'NamedEntry' have different templates." +
                Environment.NewLine +
                "Parameter name: linkGenerationEntries";

            var next = new Mock<IRouter>().Object;

            // Act
            var builder = new TreeRouteBuilder(next, NullLoggerFactory.Instance);
            var exception = Assert.Throws<ArgumentException>(
                "linkGenerationEntries",
                () =>
                {
                    foreach (var entry in namedEntries)
                    {
                        builder.Add(entry);
                    }

                    return builder.Build(version: 1);
                });

            Assert.Equal(expectedExceptionMessage, exception.Message, StringComparer.OrdinalIgnoreCase);
        }

        public static IEnumerable<object[]> NamedEntriesWithTheSameTemplate
        {
            get
            {
                var data = new TheoryData<IEnumerable<TreeRouteLinkGenerationEntry>>();

                data.Add(new[]
                {
                        CreateGenerationEntry("template", null, 0, "NamedEntry"),
                        CreateGenerationEntry("template", null, 1, "NamedEntry"),
                        CreateGenerationEntry("template", null, 2, "NamedEntry")
                });

                // Templates are compared ignoring casing.
                data.Add(new[]
                {
                        CreateGenerationEntry("template", null, 0, "NamedEntry"),
                        CreateGenerationEntry("Template", null, 1, "NamedEntry"),
                        CreateGenerationEntry("TEMPLATE", null, 2, "NamedEntry")
                });

                data.Add(new[]
                {
                        CreateGenerationEntry("template/{parameter=0}", null, 0, "NamedEntry"),
                        CreateGenerationEntry("template/{parameter=0}", null, 1, "NamedEntry"),
                        CreateGenerationEntry("template/{parameter=0}", null, 2, "NamedEntry")
                });

                return data;
            }
        }

        [Theory]
        [MemberData(nameof(TreeRouterTest.NamedEntriesWithTheSameTemplate))]
        public void TreeRouter_GeneratesLink_ForMultipleNamedEntriesWithTheSameTemplate(
            IEnumerable<TreeRouteLinkGenerationEntry> namedEntries)
        {
            // Arrange
            var expectedLink = 
                namedEntries.First().Template.Parameters.Any() ? "/template/5" : "/template";

            var matchingEntries = Enumerable.Empty<TreeRouteMatchingEntry>();

            var route = CreateAttributeRoute(matchingEntries, namedEntries);

            var ambientValues = namedEntries.First().Template.Parameters.Any() ? new { parameter = 5 } : null;

            var context = CreateVirtualPathContext(values: null, ambientValues: ambientValues, name: "NamedEntry");

            // Act
            var result = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(result);
            Assert.Equal(expectedLink, result.VirtualPath);
            Assert.Same(route, result.Router);
            Assert.Empty(result.DataTokens);
        }

        [Fact]
        public void TreeRouter_GenerateLink_WithName()
        {
            // Arrange
            var namedEntry = CreateGenerationEntry("named", requiredValues: null, order: 1, name: "NamedRoute");
            var unnamedEntry = CreateGenerationEntry("unnamed", requiredValues: null, order: 0);

            // The named route has a lower order which will ensure that we aren't trying the route as
            // if it were an unnamed route.
            var linkGenerationEntries = new[] { namedEntry, unnamedEntry };

            var matchingEntries = Enumerable.Empty<TreeRouteMatchingEntry>();

            var route = CreateAttributeRoute(matchingEntries, linkGenerationEntries);

            var context = CreateVirtualPathContext(values: null, ambientValues: null, name: "NamedRoute");

            // Act
            var result = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(result);
            Assert.Equal("/named", result.VirtualPath);
            Assert.Same(route, result.Router);
            Assert.Empty(result.DataTokens);
        }

        [Fact]
        public void TreeRouter_DoesNotGenerateLink_IfThereIsNoRouteForAGivenName()
        {
            // Arrange
            var namedEntry = CreateGenerationEntry("named", requiredValues: null, order: 1, name: "NamedRoute");

            // Add an unnamed entry to ensure we don't fall back to generating a link for an unnamed route.
            var unnamedEntry = CreateGenerationEntry("unnamed", requiredValues: null, order: 0);

            // The named route has a lower order which will ensure that we aren't trying the route as
            // if it were an unnamed route.
            var linkGenerationEntries = new[] { namedEntry, unnamedEntry };

            var matchingEntries = Enumerable.Empty<TreeRouteMatchingEntry>();

            var route = CreateAttributeRoute(matchingEntries, linkGenerationEntries);

            var context = CreateVirtualPathContext(values: null, ambientValues: null, name: "NonExistingNamedRoute");

            // Act
            var result = route.GetVirtualPath(context);

            // Assert
            Assert.Null(result);
        }

        [Theory]
        [InlineData("template/{parameter:int}", null)]
        [InlineData("template/{parameter:int}", "NaN")]
        [InlineData("template/{parameter}", null)]
        [InlineData("template/{*parameter:int}", null)]
        [InlineData("template/{*parameter:int}", "NaN")]
        public void TreeRouter_DoesNotGenerateLink_IfValuesDoNotMatchNamedEntry(string template, string value)
        {
            // Arrange
            var namedEntry = CreateGenerationEntry(template, requiredValues: null, order: 1, name: "NamedRoute");

            // Add an unnamed entry to ensure we don't fall back to generating a link for an unnamed route.
            var unnamedEntry = CreateGenerationEntry("unnamed", requiredValues: null, order: 0);

            // The named route has a lower order which will ensure that we aren't trying the route as
            // if it were an unnamed route.
            var linkGenerationEntries = new[] { namedEntry, unnamedEntry };

            var matchingEntries = Enumerable.Empty<TreeRouteMatchingEntry>();

            var route = CreateAttributeRoute(matchingEntries, linkGenerationEntries);

            var ambientValues = value == null ? null : new { parameter = value };

            var context = CreateVirtualPathContext(values: null, ambientValues: ambientValues, name: "NamedRoute");

            // Act
            var result = route.GetVirtualPath(context);

            // Assert
            Assert.Null(result);
        }

        [Theory]
        [InlineData("template/{parameter:int}", "5")]
        [InlineData("template/{parameter}", "5")]
        [InlineData("template/{*parameter:int}", "5")]
        [InlineData("template/{*parameter}", "5")]
        public void TreeRouter_GeneratesLink_IfValuesMatchNamedEntry(string template, string value)
        {
            // Arrange
            var next = new Mock<IRouter>();
            next
                .Setup(s => s.GetVirtualPath(It.IsAny<VirtualPathContext>()))
                .Returns((VirtualPathData)null);

            var namedEntry = CreateGenerationEntry(template, requiredValues: null, order: 1, name: "NamedRoute");

            // Add an unnamed entry to ensure we don't fall back to generating a link for an unnamed route.
            var unnamedEntry = CreateGenerationEntry("unnamed", requiredValues: null, order: 0);

            // The named route has a lower order which will ensure that we aren't trying the route as
            // if it were an unnamed route.
            var linkGenerationEntries = new[] { namedEntry, unnamedEntry };

            var matchingEntries = Enumerable.Empty<TreeRouteMatchingEntry>();

            var route = CreateAttributeRoute(next.Object, matchingEntries, linkGenerationEntries);

            var ambientValues = value == null ? null : new { parameter = value };

            var context = CreateVirtualPathContext(values: null, ambientValues: ambientValues, name: "NamedRoute");

            // Act
            var result = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(result);
            Assert.Equal("/template/5", result.VirtualPath);
            Assert.Same(route, result.Router);
            Assert.Empty(result.DataTokens);
        }

        [Fact]
        public void TreeRouter_GenerateLink_NoRequiredValues()
        {
            // Arrange
            var entry = CreateGenerationEntry("api/Store", new { });
            var route = CreateAttributeRoute(entry);

            var context = CreateVirtualPathContext(new { });

            // Act
            var pathData = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(pathData);
            Assert.Equal("/api/Store", pathData.VirtualPath);
            Assert.Same(route, pathData.Router);
            Assert.Empty(pathData.DataTokens);
        }

        [Fact]
        public void TreeRouter_GenerateLink_Match()
        {
            // Arrange
            var entry = CreateGenerationEntry("api/Store", new { action = "Index", controller = "Store" });
            var route = CreateAttributeRoute(entry);

            var context = CreateVirtualPathContext(new { action = "Index", controller = "Store" });

            // Act
            var pathData = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(pathData);
            Assert.Equal("/api/Store", pathData.VirtualPath);
            Assert.Same(route, pathData.Router);
            Assert.Empty(pathData.DataTokens);
        }

        [Fact]
        public void TreeRouter_GenerateLink_NoMatch()
        {
            // Arrange
            var entry = CreateGenerationEntry("api/Store", new { action = "Details", controller = "Store" });
            var route = CreateAttributeRoute(entry);

            var context = CreateVirtualPathContext(new { action = "Index", controller = "Store" });

            // Act
            var path = route.GetVirtualPath(context);

            // Assert
            Assert.Null(path);
        }

        [Fact]
        public void TreeRouter_GenerateLink_Match_WithAmbientValues()
        {
            // Arrange
            var entry = CreateGenerationEntry("api/Store", new { action = "Index", controller = "Store" });
            var route = CreateAttributeRoute(entry);

            var context = CreateVirtualPathContext(new { }, new { action = "Index", controller = "Store" });

            // Act
            var pathData = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(pathData);
            Assert.Equal("/api/Store", pathData.VirtualPath);
            Assert.Same(route, pathData.Router);
            Assert.Empty(pathData.DataTokens);
        }

        [Fact]
        public void TreeRouter_GenerateLink_Match_WithParameters()
        {
            // Arrange
            var entry = CreateGenerationEntry("api/Store/{action}", new { action = "Index", controller = "Store" });
            var route = CreateAttributeRoute(entry);

            var context = CreateVirtualPathContext(new { action = "Index", controller = "Store" });

            // Act
            var pathData = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(pathData);
            Assert.Equal("/api/Store/Index", pathData.VirtualPath);
            Assert.Same(route, pathData.Router);
            Assert.Empty(pathData.DataTokens);
        }

        [Fact]
        public void TreeRouter_GenerateLink_Match_WithMoreParameters()
        {
            // Arrange
            var entry = CreateGenerationEntry(
                "api/{area}/dosomething/{controller}/{action}",
                new { action = "Index", controller = "Store", area = "AwesomeCo" });

            var next = new StubRouter();
            var route = CreateAttributeRoute(next, entry);

            var context = CreateVirtualPathContext(
                new { action = "Index", controller = "Store" },
                new { area = "AwesomeCo" });

            // Act
            var pathData = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(pathData);
            Assert.Equal("/api/AwesomeCo/dosomething/Store/Index", pathData.VirtualPath);
            Assert.Same(route, pathData.Router);
            Assert.Empty(pathData.DataTokens);
        }

        [Fact]
        public void TreeRouter_GenerateLink_Match_WithDefault()
        {
            // Arrange
            var entry = CreateGenerationEntry("api/Store/{action=Index}", new { action = "Index", controller = "Store" });
            var route = CreateAttributeRoute(entry);

            var context = CreateVirtualPathContext(new { action = "Index", controller = "Store" });

            // Act
            var pathData = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(pathData);
            Assert.Equal("/api/Store", pathData.VirtualPath);
            Assert.Same(route, pathData.Router);
            Assert.Empty(pathData.DataTokens);
        }

        [Fact]
        public void TreeRouter_GenerateLink_Match_WithConstraint()
        {
            // Arrange
            var entry = CreateGenerationEntry("api/Store/{action}/{id:int}", new { action = "Index", controller = "Store" });

            var next = new StubRouter();
            var route = CreateAttributeRoute(next, entry);

            var context = CreateVirtualPathContext(new { action = "Index", controller = "Store", id = 5 });

            // Act
            var pathData = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(pathData);
            Assert.Equal("/api/Store/Index/5", pathData.VirtualPath);
            Assert.Same(route, pathData.Router);
            Assert.Empty(pathData.DataTokens);
        }

        [Fact]
        public void TreeRouter_GenerateLink_NoMatch_WithConstraint()
        {
            // Arrange
            var entry = CreateGenerationEntry("api/Store/{action}/{id:int}", new { action = "Index", controller = "Store" });
            var route = CreateAttributeRoute(entry);

            var next = new StubRouter();
            var context = CreateVirtualPathContext(new { action = "Index", controller = "Store", id = "heyyyy" });

            // Act
            var path = route.GetVirtualPath(context);

            // Assert
            Assert.Null(path);
        }

        [Fact]
        public void TreeRouter_GenerateLink_Match_WithMixedAmbientValues()
        {
            // Arrange
            var entry = CreateGenerationEntry("api/Store", new { action = "Index", controller = "Store" });
            var route = CreateAttributeRoute(entry);

            var context = CreateVirtualPathContext(new { action = "Index" }, new { controller = "Store" });

            // Act
            var pathData = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(pathData);
            Assert.Equal("/api/Store", pathData.VirtualPath);
            Assert.Same(route, pathData.Router);
            Assert.Empty(pathData.DataTokens);
        }

        [Fact]
        public void TreeRouter_GenerateLink_Match_WithQueryString()
        {
            // Arrange
            var entry = CreateGenerationEntry("api/Store", new { action = "Index", controller = "Store" });
            var route = CreateAttributeRoute(entry);

            var context = CreateVirtualPathContext(new { action = "Index", id = 5 }, new { controller = "Store" });

            // Act
            var pathData = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(pathData);
            Assert.Equal("/api/Store?id=5", pathData.VirtualPath);
            Assert.Same(route, pathData.Router);
            Assert.Empty(pathData.DataTokens);
        }

        [Fact]
        public void TreeRouter_GenerateLink_RejectedByFirstRoute()
        {
            // Arrange
            var entry1 = CreateGenerationEntry("api/Store", new { action = "Index", controller = "Store" });
            var entry2 = CreateGenerationEntry("api2/{controller}", new { action = "Index", controller = "Blog" });

            var route = CreateAttributeRoute(entry1, entry2);

            var context = CreateVirtualPathContext(new { action = "Index", controller = "Blog" });

            // Act
            var pathData = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(pathData);
            Assert.Equal("/api2/Blog", pathData.VirtualPath);
            Assert.Same(route, pathData.Router);
            Assert.Empty(pathData.DataTokens);
        }

        [Fact]
        public void TreeRouter_GenerateLink_ToArea()
        {
            // Arrange
            var entry1 = CreateGenerationEntry("Help/Store", new { area = "Help", action = "Edit", controller = "Store" });
            entry1.GenerationPrecedence = 2;

            var entry2 = CreateGenerationEntry("Store", new { area = (string)null, action = "Edit", controller = "Store" });
            entry2.GenerationPrecedence = 1;

            var next = new StubRouter();

            var route = CreateAttributeRoute(next, entry1, entry2);

            var context = CreateVirtualPathContext(new { area = "Help", action = "Edit", controller = "Store" });

            // Act
            var pathData = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(pathData);
            Assert.Equal("/Help/Store", pathData.VirtualPath);
            Assert.Same(route, pathData.Router);
            Assert.Empty(pathData.DataTokens);
        }

        [Fact]
        public void TreeRouter_GenerateLink_ToArea_PredecedenceReversed()
        {
            // Arrange
            var entry1 = CreateGenerationEntry("Help/Store", new { area = "Help", action = "Edit", controller = "Store" });
            entry1.GenerationPrecedence = 1;

            var entry2 = CreateGenerationEntry("Store", new { area = (string)null, action = "Edit", controller = "Store" });
            entry2.GenerationPrecedence = 2;

            var next = new StubRouter();

            var route = CreateAttributeRoute(next, entry1, entry2);

            var context = CreateVirtualPathContext(new { area = "Help", action = "Edit", controller = "Store" });

            // Act
            var pathData = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(pathData);
            Assert.Equal("/Help/Store", pathData.VirtualPath);
            Assert.Same(route, pathData.Router);
            Assert.Empty(pathData.DataTokens);
        }

        [Fact]
        public void TreeRouter_GenerateLink_ToArea_WithAmbientValues()
        {
            // Arrange
            var entry1 = CreateGenerationEntry("Help/Store", new { area = "Help", action = "Edit", controller = "Store" });
            entry1.GenerationPrecedence = 2;

            var entry2 = CreateGenerationEntry("Store", new { area = (string)null, action = "Edit", controller = "Store" });
            entry2.GenerationPrecedence = 1;

            var next = new StubRouter();

            var route = CreateAttributeRoute(next, entry1, entry2);

            var context = CreateVirtualPathContext(
                values: new { action = "Edit", controller = "Store" },
                ambientValues: new { area = "Help" });

            // Act
            var pathData = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(pathData);
            Assert.Equal("/Help/Store", pathData.VirtualPath);
            Assert.Same(route, pathData.Router);
            Assert.Empty(pathData.DataTokens);
        }

        [Fact]
        public void TreeRouter_GenerateLink_OutOfArea_IgnoresAmbientValue()
        {
            // Arrange
            var entry1 = CreateGenerationEntry("Help/Store", new { area = "Help", action = "Edit", controller = "Store" });
            entry1.GenerationPrecedence = 2;

            var entry2 = CreateGenerationEntry("Store", new { area = (string)null, action = "Edit", controller = "Store" });
            entry2.GenerationPrecedence = 1;

            var next = new StubRouter();

            var route = CreateAttributeRoute(next, entry1, entry2);

            var context = CreateVirtualPathContext(
                values: new { action = "Edit", controller = "Store" },
                ambientValues: new { area = "Blog" });

            // Act
            var pathData = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(pathData);
            Assert.Equal("/Store", pathData.VirtualPath);
            Assert.Same(route, pathData.Router);
            Assert.Empty(pathData.DataTokens);
        }

        public static IEnumerable<object[]> OptionalParamValues
        {
            get
            {
                return new object[][]
                {
                    // defaults
                    // ambient values
                    // values
                    new object[]
                    {
                        "Test/{val1}/{val2}.{val3?}",
                        new {val1 = "someval1", val2 = "someval2", val3 = "someval3a"},
                        new {val3 = "someval3v"},
                        "/Test/someval1/someval2.someval3v",
                    },
                    new object[]
                    {
                        "Test/{val1}/{val2}.{val3?}",
                        new {val3 = "someval3a"},
                        new {val1 = "someval1", val2 = "someval2", val3 = "someval3v" },
                        "/Test/someval1/someval2.someval3v",
                    },
                    new object[]
                    {
                        "Test/{val1}/{val2}.{val3?}",
                        null,
                        new {val1 = "someval1", val2 = "someval2" },
                        "/Test/someval1/someval2",
                    },
                    new object[]
                    {
                        "Test/{val1}.{val2}.{val3}.{val4?}",
                        new {val1 = "someval1", val2 = "someval2" },
                        new {val4 = "someval4", val3 = "someval3" },
                        "/Test/someval1.someval2.someval3.someval4",
                    },
                    new object[]
                    {
                        "Test/{val1}.{val2}.{val3}.{val4?}",
                        new {val1 = "someval1", val2 = "someval2" },
                        new {val3 = "someval3" },
                        "/Test/someval1.someval2.someval3",
                    },
                    new object[]
                    {
                        "Test/.{val2?}",
                        null,
                        new {val2 = "someval2" },
                        "/Test/.someval2",
                    },
                    new object[]
                    {
                        "Test/.{val2?}",
                        null,
                        null,
                        "/Test/",
                    },
                    new object[]
                    {
                        "Test/{val1}.{val2}",
                        new {val1 = "someval1", val2 = "someval2" },
                        new {val3 = "someval3" },
                        "/Test/someval1.someval2?val3=someval3",
                    },
                };
            }
        }

        [Theory]
        [MemberData("OptionalParamValues")]
        public void TreeRouter_GenerateLink_Match_WithOptionalParameters(
            string template,
            object ambientValues,
            object values,
            string expected)
        {
            // Arrange
            var entry = CreateGenerationEntry(template, null);
            var route = CreateAttributeRoute(entry);

            var context = CreateVirtualPathContext(values, ambientValues);

            // Act
            var pathData = route.GetVirtualPath(context);

            // Assert
            Assert.NotNull(pathData);
            Assert.Equal(expected, pathData.VirtualPath);
            Assert.Same(route, pathData.Router);
            Assert.Empty(pathData.DataTokens);
        }

        [Fact]
        public async Task TreeRouter_CreatesNewRouteData()
        {
            // Arrange
            RouteData nestedRouteData = null;

            var next = new Mock<IRouter>();
            next
                .Setup(r => r.RouteAsync(It.IsAny<RouteContext>()))
                .Callback<RouteContext>(c =>
                {
                    nestedRouteData = c.RouteData;
                    c.Handler = NullHandler;
                })
                .Returns(Task.FromResult(true))
                .Verifiable();

            var entry = CreateMatchingEntry(next.Object, "api/Store", order: 0);
            var route = CreateAttributeRoute(next.Object, entry);

            var context = CreateRouteContext("/api/Store");

            var originalRouteData = context.RouteData;
            originalRouteData.Values.Add("action", "Index");

            // Act
            await route.RouteAsync(context);

            // Assert
            Assert.NotSame(originalRouteData, context.RouteData);
            Assert.NotSame(originalRouteData, nestedRouteData);
            Assert.Same(nestedRouteData, context.RouteData);

            // The new routedata is a copy
            Assert.Equal("Index", context.RouteData.Values["action"]);
            Assert.Single(context.RouteData.Values, kvp => kvp.Key == "test_route_group");

            Assert.Equal(1, context.RouteData.Routers.Count);
            Assert.Equal(next.Object.GetType(), context.RouteData.Routers[0].GetType());
        }

        [Fact]
        public async Task TreeRouter_ReplacesExistingRouteValues_IfNotNull()
        {
            // Arrange
            var router = new Mock<IRouter>();
            router
                .Setup(r => r.RouteAsync(It.IsAny<RouteContext>()))
                .Callback<RouteContext>(c => c.Handler = NullHandler)
                .Returns(Task.FromResult(true))
                .Verifiable();

            var entry = CreateMatchingEntry(router.Object, "Foo/{*path}", order: 0);
            var route = CreateAttributeRoute(router.Object, entry);

            var context = CreateRouteContext("/Foo/Bar");

            var originalRouteData = context.RouteData;
            originalRouteData.Values.Add("path", "default");

            // Act
            await route.RouteAsync(context);

            // Assert
            Assert.Equal("Bar", context.RouteData.Values["path"]);
        }

        [Fact]
        public async Task TreeRouter_DoesNotReplaceExistingRouteValues_IfNull()
        {
            // Arrange
            var router = new Mock<IRouter>();
            router
                .Setup(r => r.RouteAsync(It.IsAny<RouteContext>()))
                .Callback<RouteContext>(c => c.Handler = NullHandler)
                .Returns(Task.FromResult(true))
                .Verifiable();

            var entry = CreateMatchingEntry(router.Object, "Foo/{*path}", order: 0);
            var route = CreateAttributeRoute(router.Object, entry);

            var context = CreateRouteContext("/Foo/");

            var originalRouteData = context.RouteData;
            originalRouteData.Values.Add("path", "default");

            // Act
            await route.RouteAsync(context);

            // Assert
            Assert.Equal("default", context.RouteData.Values["path"]);
        }

        [Fact]
        public async Task TreeRouter_CreatesNewRouteData_ResetsWhenNotMatched()
        {
            // Arrange
            RouteData nestedRouteData = null;
            var next = new Mock<IRouter>();
            next
                .Setup(r => r.RouteAsync(It.IsAny<RouteContext>()))
                .Callback<RouteContext>(c =>
                {
                    nestedRouteData = c.RouteData;
                })
                .Returns(Task.FromResult(true))
                .Verifiable();

            var entry = CreateMatchingEntry(next.Object, "api/Store", order: 0);
            var route = CreateAttributeRoute(next.Object, entry);

            var context = CreateRouteContext("/api/Store");

            var originalRouteData = context.RouteData;
            originalRouteData.Values.Add("action", "Index");

            // Act
            await route.RouteAsync(context);

            // Assert
            Assert.Same(originalRouteData, context.RouteData);
            Assert.NotSame(originalRouteData, nestedRouteData);
            Assert.NotSame(nestedRouteData, context.RouteData);

            // The new routedata is a copy
            Assert.Equal("Index", context.RouteData.Values["action"]);
            Assert.Equal("Index", nestedRouteData.Values["action"]);
            Assert.DoesNotContain(context.RouteData.Values, kvp => kvp.Key == "test_route_group");
            Assert.Single(nestedRouteData.Values, kvp => kvp.Key == "test_route_group");

            Assert.Empty(context.RouteData.Routers);

            Assert.Equal(1, nestedRouteData.Routers.Count);
            Assert.Equal(next.Object.GetType(), nestedRouteData.Routers[0].GetType());
        }

        [Fact]
        public async Task TreeRouter_CreatesNewRouteData_ResetsWhenThrows()
        {
            // Arrange
            RouteData nestedRouteData = null;
            var next = new Mock<IRouter>();
            next
                .Setup(r => r.RouteAsync(It.IsAny<RouteContext>()))
                .Callback<RouteContext>(c =>
                {
                    nestedRouteData = c.RouteData;
                })
                .Throws(new Exception());

            var entry = CreateMatchingEntry(next.Object, "api/Store", order: 0);
            var route = CreateAttributeRoute(next.Object, entry);

            var context = CreateRouteContext("/api/Store");

            var originalRouteData = context.RouteData;
            originalRouteData.Values.Add("action", "Index");

            // Act
            await Assert.ThrowsAsync<Exception>(() => route.RouteAsync(context));

            // Assert
            Assert.Same(originalRouteData, context.RouteData);
            Assert.NotSame(originalRouteData, nestedRouteData);
            Assert.NotSame(nestedRouteData, context.RouteData);

            // The new routedata is a copy
            Assert.Equal("Index", context.RouteData.Values["action"]);
            Assert.Equal("Index", nestedRouteData.Values["action"]);
            Assert.DoesNotContain(context.RouteData.Values, kvp => kvp.Key == "test_route_group");
            Assert.Single(nestedRouteData.Values, kvp => kvp.Key == "test_route_group");

            Assert.Empty(context.RouteData.Routers);

            Assert.Equal(1, nestedRouteData.Routers.Count);
            Assert.Equal(next.Object.GetType(), nestedRouteData.Routers[0].GetType());
        }

        private static RouteContext CreateRouteContext(string requestPath)
        {
            var request = new Mock<HttpRequest>(MockBehavior.Strict);
            request.SetupGet(r => r.Path).Returns(new PathString(requestPath));

            var context = new Mock<HttpContext>(MockBehavior.Strict);
            context.Setup(m => m.RequestServices.GetService(typeof(ILoggerFactory)))
                .Returns(NullLoggerFactory.Instance);

            context.SetupGet(c => c.Request).Returns(request.Object);

            return new RouteContext(context.Object);
        }

        private static VirtualPathContext CreateVirtualPathContext(
            object values,
            object ambientValues = null,
            string name = null)
        {
            var mockHttpContext = new Mock<HttpContext>();
            mockHttpContext.Setup(h => h.RequestServices.GetService(typeof(ILoggerFactory)))
                .Returns(NullLoggerFactory.Instance);

            return new VirtualPathContext(
                mockHttpContext.Object,
                new RouteValueDictionary(ambientValues),
                new RouteValueDictionary(values),
                name);
        }

        private static TreeRouteMatchingEntry CreateMatchingEntry(IRouter router, string template, int order)
        {
            var routeGroup = string.Format("{0}&&{1}", order, template);
            var entry = new TreeRouteMatchingEntry();
            entry.Target = router;
            entry.RouteTemplate = TemplateParser.Parse(template);
            var parsedRouteTemplate = TemplateParser.Parse(template);
            entry.TemplateMatcher = new TemplateMatcher(
                parsedRouteTemplate,
                new RouteValueDictionary(new { test_route_group = routeGroup }));
            entry.Precedence = RoutePrecedence.ComputeMatched(parsedRouteTemplate);
            entry.Order = order;
            entry.Constraints = GetRouteConstriants(CreateConstraintResolver(), template, parsedRouteTemplate);
            return entry;
        }

        private static TreeRouteLinkGenerationEntry CreateGenerationEntry(
            string template,
            object requiredValues,
            int order = 0,
            string name = null)
        {
            var constraintResolver = CreateConstraintResolver();

            var entry = new TreeRouteLinkGenerationEntry();
            entry.Template = TemplateParser.Parse(template);

            var defaults = new RouteValueDictionary();
            foreach (var parameter in entry.Template.Parameters)
            {
                if (parameter.DefaultValue != null)
                {
                    defaults.Add(parameter.Name, parameter.DefaultValue);
                }
            }

            var constraintBuilder = new RouteConstraintBuilder(CreateConstraintResolver(), template);
            foreach (var parameter in entry.Template.Parameters)
            {
                if (parameter.InlineConstraints != null)
                {
                    if (parameter.IsOptional)
                    {
                        constraintBuilder.SetOptional(parameter.Name);
                    }

                    foreach (var constraint in parameter.InlineConstraints)
                    {
                        constraintBuilder.AddResolvedConstraint(parameter.Name, constraint.Constraint);
                    }
                }
            }

            var constraints = constraintBuilder.Build();

            entry.Constraints = constraints;
            entry.Defaults = defaults;
            entry.Binder = new TemplateBinder(Encoder, Pool, entry.Template, defaults);
            entry.Order = order;
            entry.GenerationPrecedence = RoutePrecedence.ComputeGenerated(entry.Template);
            entry.RequiredLinkValues = new RouteValueDictionary(requiredValues);
            entry.RouteGroup = CreateRouteGroup(order, template);
            entry.Name = name;
            return entry;
        }

        private TreeRouteMatchingEntry CreateMatchingEntry(string template)
        {
            var mockConstraint = new Mock<IRouteConstraint>();
            mockConstraint.Setup(c => c.Match(
                It.IsAny<HttpContext>(),
                It.IsAny<IRouter>(),
                It.IsAny<string>(),
                It.IsAny<RouteValueDictionary>(),
                It.IsAny<RouteDirection>()))
            .Returns(true);

            var mockConstraintResolver = new Mock<IInlineConstraintResolver>();
            mockConstraintResolver.Setup(r => r.ResolveConstraint(
                It.IsAny<string>()))
            .Returns(mockConstraint.Object);

            var entry = new TreeRouteMatchingEntry();
            entry.Target = new StubRouter();
            entry.RouteTemplate = TemplateParser.Parse(template);

            return entry;
        }

        private static string CreateRouteGroup(int order, string template)
        {
            return string.Format("{0}&{1}", order, template);
        }

        private static DefaultInlineConstraintResolver CreateConstraintResolver()
        {
            var options = new RouteOptions();
            var optionsMock = new Mock<IOptions<RouteOptions>>();
            optionsMock.SetupGet(o => o.Value).Returns(options);

            return new DefaultInlineConstraintResolver(optionsMock.Object);
        }

        private static TreeRouter CreateAttributeRoute(TreeRouteLinkGenerationEntry entry)
        {
            return CreateAttributeRoute(new StubRouter(), entry);
        }

        private static TreeRouter CreateAttributeRoute(IRouter next, TreeRouteLinkGenerationEntry entry)
        {
            return CreateAttributeRoute(next, new[] { entry });
        }

        private static TreeRouter CreateAttributeRoute(params TreeRouteLinkGenerationEntry[] entries)
        {
            return CreateAttributeRoute(new StubRouter(), entries);
        }

        private static TreeRouter CreateAttributeRoute(IRouter next, params TreeRouteLinkGenerationEntry[] entries)
        {
            return CreateAttributeRoute(
                next,
                Enumerable.Empty<TreeRouteMatchingEntry>(),
                entries);
        }

        private static TreeRouter CreateAttributeRoute(IRouter next, params TreeRouteMatchingEntry[] entries)
        {
            return CreateAttributeRoute(
                next,
                entries,
                Enumerable.Empty<TreeRouteLinkGenerationEntry>());
        }

        private static TreeRouter CreateAttributeRoute(
            IEnumerable<TreeRouteMatchingEntry> matchingEntries,
            IEnumerable<TreeRouteLinkGenerationEntry> generationEntries)
        {
            return CreateAttributeRoute(new StubRouter(), matchingEntries, generationEntries);
        }

        private static TreeRouter CreateAttributeRoute(
            IRouter next,
            IEnumerable<TreeRouteMatchingEntry> matchingEntries,
            IEnumerable<TreeRouteLinkGenerationEntry> generationEntries)
        {
            var builder = new TreeRouteBuilder(next, NullLoggerFactory.Instance);

            foreach (var entry in matchingEntries)
            {
                builder.Add(entry);
            }

            foreach (var entry in generationEntries)
            {
                builder.Add(entry);
            }

            return builder.Build(version: 1);
        }

        private static TreeRouter CreateAttributeRoute(
            string firstTemplate,
            string secondTemplate)
        {
            var next = new Mock<IRouter>();
            next
                .Setup(n => n.GetVirtualPath(It.IsAny<VirtualPathContext>()))
                .Returns((VirtualPathData)null);

            var matchingRoutes = Enumerable.Empty<TreeRouteMatchingEntry>();
            var firstEntry = CreateGenerationEntry(firstTemplate, requiredValues: null);
            var secondEntry = CreateGenerationEntry(secondTemplate, requiredValues: null);

            return CreateAttributeRoute(
                next.Object,
                matchingRoutes,
                new[] { secondEntry, firstEntry });
        }

        private static TreeRouter CreateRoutingAttributeRoute(
            ILoggerFactory loggerFactory = null,
            params TreeRouteMatchingEntry[] entries)
        {
            loggerFactory = loggerFactory ?? NullLoggerFactory.Instance;

            var builder = new TreeRouteBuilder(new StubRouter(), loggerFactory);

            foreach (var entry in entries)
            {
                builder.Add(entry);
            }

            return builder.Build(version: 1);
        }

        private static IDictionary<string, IRouteConstraint> GetRouteConstriants(
            IInlineConstraintResolver inlineConstraintResolver,
            string template,
            RouteTemplate parsedRouteTemplate)
        {
            var constraintBuilder = new RouteConstraintBuilder(inlineConstraintResolver, template);
            foreach (var parameter in parsedRouteTemplate.Parameters)
            {
                if (parameter.InlineConstraints != null)
                {
                    if (parameter.IsOptional)
                    {
                        constraintBuilder.SetOptional(parameter.Name);
                    }

                    foreach (var constraint in parameter.InlineConstraints)
                    {
                        constraintBuilder.AddResolvedConstraint(parameter.Name, constraint.Constraint);
                    }
                }
            }

            return constraintBuilder.Build();
        }
        private class StubRouter : IRouter
        {
            public VirtualPathContext GenerationContext { get; set; }

            public RouteContext MatchingContext { get; set; }

            public Func<RouteContext, bool> MatchingDelegate { get; set; }

            public VirtualPathData GetVirtualPath(VirtualPathContext context)
            {
                GenerationContext = context;
                return null;
            }

            public Task RouteAsync(RouteContext context)
            {
                if (MatchingDelegate == null)
                {
                    context.Handler = NullHandler;
                }
                else
                {
                    context.Handler = MatchingDelegate(context) ? NullHandler : null;
                }

                return Task.FromResult(true);
            }
        }
    }
}