// 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.AspNetCore.Http;
using Microsoft.AspNetCore.Routing.Internal;
using Microsoft.AspNetCore.Routing.Template;
using Microsoft.Extensions.Internal;
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.AspNetCore.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 = CreateRouteGroup(0, firstTemplate);

            var builder = CreateBuilder();

            // 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.
            MapInboundEntry(builder, secondTemplate);
            MapInboundEntry(builder, firstTemplate);

            var route = builder.Build();

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

            // Act
            await route.RouteAsync(context);

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

        [Theory]
        [InlineData("/", "")]
        [InlineData("/Literal1", "Literal1")]
        [InlineData("/Literal1/Literal2", "Literal1/Literal2")]
        [InlineData("/Literal1/Literal2/Literal3", "Literal1/Literal2/Literal3")]
        [InlineData("/Literal1/Literal2/Literal3/4", "Literal1/Literal2/Literal3/{*constrainedCatchAll:int}")]
        [InlineData("/Literal1/Literal2/Literal3/Literal4", "Literal1/Literal2/Literal3/{*catchAll}")]
        [InlineData("/1", "{constrained1:int}")]
        [InlineData("/1/2", "{constrained1:int}/{constrained2:int}")]
        [InlineData("/1/2/3", "{constrained1:int}/{constrained2:int}/{constrained3:int}")]
        [InlineData("/1/2/3/4", "{constrained1:int}/{constrained2:int}/{constrained3:int}/{*constrainedCatchAll:int}")]
        [InlineData("/1/2/3/CatchAll4", "{constrained1:int}/{constrained2:int}/{constrained3:int}/{*catchAll}")]
        [InlineData("/parameter1", "{parameter1}")]
        [InlineData("/parameter1/parameter2", "{parameter1}/{parameter2}")]
        [InlineData("/parameter1/parameter2/parameter3", "{parameter1}/{parameter2}/{parameter3}")]
        [InlineData("/parameter1/parameter2/parameter3/4", "{parameter1}/{parameter2}/{parameter3}/{*constrainedCatchAll:int}")]
        [InlineData("/parameter1/parameter2/parameter3/CatchAll4", "{parameter1}/{parameter2}/{parameter3}/{*catchAll}")]
        public async Task TreeRouter_RouteAsync_MatchesRouteWithTheRightLength(string url, string expected)
        {
            // Arrange
            var routes = new[] {
                "",
                "Literal1",
                "Literal1/Literal2",
                "Literal1/Literal2/Literal3",
                "Literal1/Literal2/Literal3/{*constrainedCatchAll:int}",
                "Literal1/Literal2/Literal3/{*catchAll}",
                "{constrained1:int}",
                "{constrained1:int}/{constrained2:int}",
                "{constrained1:int}/{constrained2:int}/{constrained3:int}",
                "{constrained1:int}/{constrained2:int}/{constrained3:int}/{*constrainedCatchAll:int}",
                "{constrained1:int}/{constrained2:int}/{constrained3:int}/{*catchAll}",
                "{parameter1}",
                "{parameter1}/{parameter2}",
                "{parameter1}/{parameter2}/{parameter3}",
                "{parameter1}/{parameter2}/{parameter3}/{*constrainedCatchAll:int}",
                "{parameter1}/{parameter2}/{parameter3}/{*catchAll}",
            };

            var expectedRouteGroup = CreateRouteGroup(0, expected);

            var builder = CreateBuilder();

            // 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.
            foreach (var template in routes.Reverse())
            {
                MapInboundEntry(builder, template);
            }

            var route = builder.Build();

            var context = CreateRouteContext(url);

            // Act
            await route.RouteAsync(context);

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

        public static TheoryData<string, object[]> MatchesRoutesWithDefaultsData =>
            new TheoryData<string, object[]>
            {
                { "/", new object[] { "1", "2", "3", "4" } },
                { "/a", new object[] { "a", "2", "3", "4" } },
                { "/a/b", new object[] { "a", "b", "3", "4" } },
                { "/a/b/c", new object[] { "a", "b", "c", "4" } },
                { "/a/b/c/d", new object[] { "a", "b", "c", "d" } }
            };

        [Theory]
        [MemberData(nameof(MatchesRoutesWithDefaultsData))]
        public async Task TreeRouter_RouteAsync_MatchesRoutesWithDefaults(string url, object[] routeValues)
        {
            // Arrange
            var routes = new[] {
                "{parameter1=1}/{parameter2=2}/{parameter3=3}/{parameter4=4}",
            };

            var expectedRouteGroup = CreateRouteGroup(0, "{parameter1=1}/{parameter2=2}/{parameter3=3}/{parameter4=4}");
            var routeValueKeys = new[] { "parameter1", "parameter2", "parameter3", "parameter4" };
            var expectedRouteValues = new RouteValueDictionary();
            for (int i = 0; i < routeValueKeys.Length; i++)
            {
                expectedRouteValues.Add(routeValueKeys[i], routeValues[i]);
            }

            var builder = CreateBuilder();

            // 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.
            foreach (var template in routes.Reverse())
            {
                MapInboundEntry(builder, template);
            }

            var route = builder.Build();

            var context = CreateRouteContext(url);

            // Act
            await route.RouteAsync(context);

            // Assert
            Assert.Equal(expectedRouteGroup, context.RouteData.Values["test_route_group"]);
            foreach (var entry in expectedRouteValues)
            {
                var data = Assert.Single(context.RouteData.Values, v => v.Key == entry.Key);
                Assert.Equal(entry.Value, data.Value);
            }
        }

        public static TheoryData<string, object[]> MatchesConstrainedRoutesWithDefaultsData =>
            new TheoryData<string, object[]>
            {
                { "/", new object[] { "1", "2", "3", "4" } },
                { "/10", new object[] { "10", "2", "3", "4" } },
                { "/10/11", new object[] { "10", "11", "3", "4" } },
                { "/10/11/12", new object[] { "10", "11", "12", "4" } },
                { "/10/11/12/13", new object[] { "10", "11", "12", "13" } }
            };

        [Theory]
        [MemberData(nameof(MatchesConstrainedRoutesWithDefaultsData))]
        public async Task TreeRouter_RouteAsync_MatchesConstrainedRoutesWithDefaults(string url, object[] routeValues)
        {
            // Arrange
            var routes = new[] {
                "{parameter1:int=1}/{parameter2:int=2}/{parameter3:int=3}/{parameter4:int=4}",
            };

            var expectedRouteGroup = CreateRouteGroup(0, "{parameter1:int=1}/{parameter2:int=2}/{parameter3:int=3}/{parameter4:int=4}");
            var routeValueKeys = new[] { "parameter1", "parameter2", "parameter3", "parameter4" };
            var expectedRouteValues = new RouteValueDictionary();
            for (int i = 0; i < routeValueKeys.Length; i++)
            {
                expectedRouteValues.Add(routeValueKeys[i], routeValues[i]);
            }

            var builder = CreateBuilder();

            // 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.
            foreach (var template in routes.Reverse())
            {
                MapInboundEntry(builder, template);
            }

            var route = builder.Build();

            var context = CreateRouteContext(url);

            // Act
            await route.RouteAsync(context);

            // Assert
            Assert.Equal(expectedRouteGroup, context.RouteData.Values["test_route_group"]);
            foreach (var entry in expectedRouteValues)
            {
                var data = Assert.Single(context.RouteData.Values, v => v.Key == entry.Key);
                Assert.Equal(entry.Value, data.Value);
            }
        }

        [Fact]
        public async Task TreeRouter_RouteAsync_MatchesCatchAllRoutesWithDefaults()
        {
            // Arrange
            var routes = new[] {
                "{parameter1=1}/{parameter2=2}/{parameter3=3}/{*parameter4=4}",
            };
            var url = "/a/b/c";
            var routeValues = new[] { "a", "b", "c", "4" };

            var expectedRouteGroup = CreateRouteGroup(0, "{parameter1=1}/{parameter2=2}/{parameter3=3}/{*parameter4=4}");
            var routeValueKeys = new[] { "parameter1", "parameter2", "parameter3", "parameter4" };
            var expectedRouteValues = new RouteValueDictionary();
            for (int i = 0; i < routeValueKeys.Length; i++)
            {
                expectedRouteValues.Add(routeValueKeys[i], routeValues[i]);
            }

            var builder = CreateBuilder();

            // 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.
            foreach (var template in routes.Reverse())
            {
                MapInboundEntry(builder, template);
            }

            var route = builder.Build();

            var context = CreateRouteContext(url);

            // Act
            await route.RouteAsync(context);

            // Assert
            Assert.Equal(expectedRouteGroup, context.RouteData.Values["test_route_group"]);
            foreach (var entry in expectedRouteValues)
            {
                var data = Assert.Single(context.RouteData.Values, v => v.Key == entry.Key);
                Assert.Equal(entry.Value, data.Value);
            }
        }

        [Fact]
        public async Task TreeRouter_RouteAsync_DoesNotMatchRoutesWithIntermediateDefaultRouteValues()
        {
            // Arrange
            var url = "/a/b";

            var builder = CreateBuilder();

            MapInboundEntry(builder, "a/b/{parameter3=3}/d");

            var route = builder.Build();

            var context = CreateRouteContext(url);

            // Act
            await route.RouteAsync(context);

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

        [Theory]
        [InlineData("a/{b=3}/c/{d?}/e/{*f}", "/a")]
        [InlineData("a/{b=3}/c/{d?}/e/{*f}", "/a/b")]
        [InlineData("a/{b=3}/c/{d?}/e/{*f}", "/a/b/c")]
        [InlineData("a/{b=3}/c/{d?}/e/{*f}", "/a/b/c/d")]
        public async Task TreeRouter_RouteAsync_DoesNotMatchRoutesWithMultipleIntermediateDefaultOrOptionalRouteValues(string template, string url)
        {
            // Arrange
            var builder = CreateBuilder();

            MapInboundEntry(builder, template);

            var route = builder.Build();

            var context = CreateRouteContext(url);

            // Act
            await route.RouteAsync(context);

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

        [Theory]
        [InlineData("a/{b=3}/c/{d?}/e/{*f}", "/a/b/c/d/e")]
        [InlineData("a/{b=3}/c/{d?}/e/{*f}", "/a/b/c/d/e/f")]
        public async Task RouteAsync_MatchRoutesWithMultipleIntermediateDefaultOrOptionalRouteValues_WhenAllIntermediateValuesAreProvided(string template, string url)
        {
            // Arrange
            var builder = CreateBuilder();

            MapInboundEntry(builder, template);

            var route = builder.Build();

            var context = CreateRouteContext(url);

            // Act
            await route.RouteAsync(context);

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

        [Fact]
        public async Task TreeRouter_RouteAsync_DoesNotMatchShorterUrl()
        {
            // Arrange
            var routes = new[] {
                "Literal1/Literal2/Literal3",
            };

            var builder = CreateBuilder();

            // 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.
            foreach (var template in routes.Reverse())
            {
                MapInboundEntry(builder, template);
            }

            var route = builder.Build();

            var context = CreateRouteContext("/Literal1");

            // Act
            await route.RouteAsync(context);

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

        [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 = CreateRouteGroup(0, secondTemplate);

            var builder = CreateBuilder();

            // 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.
            MapInboundEntry(builder, firstTemplate, order: 1);
            MapInboundEntry(builder, secondTemplate, order: 0);

            var route = builder.Build();

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

            // Act
            await route.RouteAsync(context);

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

        [Theory]
        [InlineData("///")]
        [InlineData("/a//")]
        [InlineData("/a/b//")]
        [InlineData("//b//")]
        [InlineData("///c")]
        [InlineData("///c/")]
        public async Task TryMatch_MultipleOptionalParameters_WithEmptyIntermediateSegmentsDoesNotMatch(string url)
        {
            // Arrange
            var builder = CreateBuilder();

            MapInboundEntry(builder, "{controller?}/{action?}/{id?}");

            var route = builder.Build();

            var context = CreateRouteContext(url);

            // Act
            await route.RouteAsync(context);

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

        [Theory]
        [InlineData("")]
        [InlineData("/")]
        [InlineData("/a")]
        [InlineData("/a/")]
        [InlineData("/a/b")]
        [InlineData("/a/b/")]
        [InlineData("/a/b/c")]
        [InlineData("/a/b/c/")]
        public async Task TryMatch_MultipleOptionalParameters_WithIncrementalOptionalValues(string url)
        {
            // Arrange
            var builder = CreateBuilder();

            MapInboundEntry(builder, "{controller?}/{action?}/{id?}");

            var route = builder.Build();

            var context = CreateRouteContext(url);

            // Act
            await route.RouteAsync(context);

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

        [Theory]
        [InlineData("///")]
        [InlineData("////")]
        [InlineData("/a//")]
        [InlineData("/a///")]
        [InlineData("//b/")]
        [InlineData("//b//")]
        [InlineData("///c")]
        [InlineData("///c/")]
        public async Task TryMatch_MultipleParameters_WithEmptyValues(string url)
        {
            // Arrange
            var builder = CreateBuilder();

            MapInboundEntry(builder, "{controller}/{action}/{id}");

            var route = builder.Build();

            var context = CreateRouteContext(url);

            // Act
            await route.RouteAsync(context);

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

        [Theory]
        [InlineData("/a/b/c//")]
        [InlineData("/a/b/c/////")]
        public async Task TryMatch_CatchAllParameters_WithEmptyValuesAtTheEnd(string url)
        {
            // Arrange
            var builder = CreateBuilder();

            MapInboundEntry(builder, "{controller}/{action}/{*id}");

            var route = builder.Build();

            var context = CreateRouteContext(url);

            // Act
            await route.RouteAsync(context);

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

        [Theory]
        [InlineData("/a/b//")]
        [InlineData("/a/b///c")]
        public async Task TryMatch_CatchAllParameters_WithEmptyValues(string url)
        {
            // Arrange
            var builder = CreateBuilder();

            MapInboundEntry(builder, "{controller}/{action}/{*id}");

            var route = builder.Build();

            var context = CreateRouteContext(url);

            // Act
            await route.RouteAsync(context);

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

        [Theory]
        [InlineData("{*path}", "/a", "a")]
        [InlineData("{*path}", "/a/b/c", "a/b/c")]
        [InlineData("a/{*path}", "/a/b", "b")]
        [InlineData("a/{*path}", "/a/b/c/d", "b/c/d")]
        [InlineData("a/{*path:regex(10/20/30)}", "/a/10/20/30", "10/20/30")]
        public async Task TreeRouter_RouteAsync_MatchesWildCard_ForLargerPathSegments(
            string template,
            string requestPath,
            string expectedResult)
        {
            // Arrange
            var builder = CreateBuilder();
            MapInboundEntry(builder, template);
            var route = builder.Build();

            var context = CreateRouteContext(requestPath);

            // Act
            await route.RouteAsync(context);

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

        [Theory]
        [InlineData("a/{*path}", "/a")]
        [InlineData("a/{*path}", "/a/")]
        public async Task TreeRouter_RouteAsync_MatchesCatchAll_NullValue(
            string template,
            string requestPath)
        {
            // Arrange
            var builder = CreateBuilder();
            MapInboundEntry(builder, template);
            var route = builder.Build();

            var context = CreateRouteContext(requestPath);

            // Act
            await route.RouteAsync(context);

            // Assert
            Assert.NotNull(context.Handler);
            Assert.Null(context.RouteData.Values["path"]);
        }

        [Theory]
        [InlineData("a/{*path}", "/a")]
        [InlineData("a/{*path}", "/a/")]
        public async Task TreeRouter_RouteAsync_MatchesCatchAll_NullValue_DoesNotReplaceExistingValue(
            string template,
            string requestPath)
        {
            // Arrange
            var builder = CreateBuilder();
            MapInboundEntry(builder, template);
            var route = builder.Build();

            var context = CreateRouteContext(requestPath);
            context.RouteData.Values["path"] = "existing-value";

            // Act
            await route.RouteAsync(context);

            // Assert
            Assert.NotNull(context.Handler);
            Assert.Equal("existing-value", context.RouteData.Values["path"]);
        }

        [Theory]
        [InlineData("a/{*path=default}", "/a")]
        [InlineData("a/{*path=default}", "/a/")]
        public async Task TreeRouter_RouteAsync_MatchesCatchAll_UsesDefaultValue(
            string template,
            string requestPath)
        {
            // Arrange
            var builder = CreateBuilder();
            MapInboundEntry(builder, template);
            var route = builder.Build();

            var context = CreateRouteContext(requestPath);
            context.RouteData.Values["path"] = "existing-value";

            // Act
            await route.RouteAsync(context);

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

        [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 = CreateRouteGroup(0, template);

            var builder = CreateBuilder();

            // 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.
            MapInboundEntry(builder, template, order: 1);
            MapInboundEntry(builder, template, order: 0);

            var route = builder.Build();

            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 = CreateRouteGroup(0, first);

            var builder = CreateBuilder();

            // 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.
            MapInboundEntry(builder, first);
            MapInboundEntry(builder, second);

            var route = builder.Build();

            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 = CreateRouteGroup(0, template);

            var builder = CreateBuilder();
            MapInboundEntry(builder, template);
            var route = builder.Build();

            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 = CreateRouteGroup(0, template);

            var builder = CreateBuilder();
            MapInboundEntry(builder, template);
            var route = builder.Build();

            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 = CreateRouteGroup(0, template);

            var builder = CreateBuilder();
            MapInboundEntry(builder, template);
            var route = builder.Build();

            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 = CreateTreeRouter(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 = CreateTreeRouter(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 = CreateTreeRouter(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 = CreateTreeRouter(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 builder = CreateBuilder();

            // 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.
            MapOutboundEntry(builder, secondTemplate);
            MapOutboundEntry(builder, firstTemplate);

            var route = builder.Build();

            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 builder = CreateBuilder();
            MapOutboundEntry(builder, template);
            var route = builder.Build();

            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 builder = CreateBuilder();

            // 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.
            MapOutboundEntry(builder, firstTemplate, order: 1);
            MapOutboundEntry(builder, secondTemplate, order: 0);

            var route = builder.Build();

            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 builder = CreateBuilder();

            // 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.
            MapOutboundEntry(builder, firstTemplate, requiredValues: null, order: 1);
            MapOutboundEntry(builder, secondTemplate, requiredValues: null, order: 0);

            var route = builder.Build();

            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 builder = CreateBuilder();

            // 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.
            MapOutboundEntry(builder, secondTemplate, requiredValues: null, order: 0);
            MapOutboundEntry(builder, firstTemplate, requiredValues: null, order: 0);

            var route = builder.Build();

            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);
        }

        [Fact]
        public void TreeRouter_GenerateLink_CreatesLinksForRoutesWithIntermediateDefaultRouteValues()
        {
            // Arrange
            var builder = CreateBuilder();

            MapOutboundEntry(builder, template: "a/b/{parameter3=3}/d", requiredValues: null, order: 0);

            var route = builder.Build();

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

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

            // Assert
            Assert.NotNull(result);
            Assert.Equal("/a/b/3/d", result.VirtualPath);
        }


        [Fact]
        public void TreeRouter_GeneratesLink_ForMultipleNamedEntriesWithTheSameTemplate()
        {
            // Arrange
            var builder = CreateBuilder();

            MapOutboundEntry(builder, "Template", name: "NamedEntry", order: 1);
            MapOutboundEntry(builder, "TEMPLATE", name: "NamedEntry", order: 2);

            // Act & Assert (does not throw)
            builder.Build();
        }

        [Fact]
        public void TreeRouter_GenerateLink_WithName()
        {
            // Arrange
            var builder = CreateBuilder();

            // The named route has a lower order which will ensure that we aren't trying the route as
            // if it were an unnamed route.
            MapOutboundEntry(builder, "named", requiredValues: null, order: 1, name: "NamedRoute");
            MapOutboundEntry(builder, "unnamed", requiredValues: null, order: 0);

            var route = builder.Build();

            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 builder = CreateBuilder();

            // The named route has a lower order which will ensure that we aren't trying the route as
            // if it were an unnamed route.
            MapOutboundEntry(builder, "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.
            MapOutboundEntry(builder, "unnamed", requiredValues: null, order: 0);

            var route = builder.Build();

            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 builder = CreateBuilder();

            // The named route has a lower order which will ensure that we aren't trying the route as
            // if it were an unnamed route.
            MapOutboundEntry(builder, 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.
            MapOutboundEntry(builder, "unnamed", requiredValues: null, order: 0);

            var route = builder.Build();

            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 builder = CreateBuilder();

            // The named route has a lower order which will ensure that we aren't trying the route as
            // if it were an unnamed route.
            MapOutboundEntry(builder, 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.
            MapOutboundEntry(builder, "unnamed", requiredValues: null, order: 0);

            var route = builder.Build();

            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 builder = CreateBuilder();
            MapOutboundEntry(builder, "api/Store", new { });
            var route = builder.Build();

            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 builder = CreateBuilder();
            MapOutboundEntry(builder, "api/Store", new { action = "Index", controller = "Store" });
            var route = builder.Build();

            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 builder = CreateBuilder();
            MapOutboundEntry(builder, "api/Store", new { action = "Details", controller = "Store" });
            var route = builder.Build();

            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 builder = CreateBuilder();
            MapOutboundEntry(builder, "api/Store", new { action = "Index", controller = "Store" });
            var route = builder.Build();

            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 builder = CreateBuilder();
            MapOutboundEntry(builder, "api/Store/{action}", new { action = "Index", controller = "Store" });
            var route = builder.Build();

            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 builder = CreateBuilder();
            MapOutboundEntry(builder,
                "api/{area}/dosomething/{controller}/{action}",
                new { action = "Index", controller = "Store", area = "AwesomeCo" });

            var route = builder.Build();

            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 builder = CreateBuilder();
            MapOutboundEntry(builder, "api/Store/{action=Index}", new { action = "Index", controller = "Store" });
            var route = builder.Build();

            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 builder = CreateBuilder();
            MapOutboundEntry(builder, "api/Store/{action}/{id:int}", new { action = "Index", controller = "Store" });

            var route = builder.Build();

            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 builder = CreateBuilder();
            MapOutboundEntry(builder, "api/Store/{action}/{id:int}", new { action = "Index", controller = "Store" });
            var route = builder.Build();

            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 builder = CreateBuilder();
            MapOutboundEntry(builder, "api/Store", new { action = "Index", controller = "Store" });
            var route = builder.Build();

            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 builder = CreateBuilder();
            MapOutboundEntry(builder, "api/Store", new { action = "Index", controller = "Store" });
            var route = builder.Build();

            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 builder = CreateBuilder();
            MapOutboundEntry(builder, "api/Store", new { action = "Index", controller = "Store" });
            MapOutboundEntry(builder, "api2/{controller}", new { action = "Index", controller = "Blog" });

            var route = builder.Build();

            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 builder = CreateBuilder();
            var entry1 = MapOutboundEntry(builder, "Help/Store", new { area = "Help", action = "Edit", controller = "Store" });
            entry1.Precedence = 2;

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

            var route = builder.Build();

            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 builder = CreateBuilder();
            var entry1 = MapOutboundEntry(builder, "Help/Store", new { area = "Help", action = "Edit", controller = "Store" });
            entry1.Precedence = 1;

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

            var route = builder.Build();

            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 builder = CreateBuilder();
            var entry1 = MapOutboundEntry(builder, "Help/Store", new { area = "Help", action = "Edit", controller = "Store" });
            entry1.Precedence = 2;

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

            var route = builder.Build();

            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 builder = CreateBuilder();
            var entry1 = MapOutboundEntry(builder, "Help/Store", new { area = "Help", action = "Edit", controller = "Store" });
            entry1.Precedence = 2;

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

            var route = builder.Build();

            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 builder = CreateBuilder();
            MapOutboundEntry(builder, template);
            var route = builder.Build();

            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_ReplacesExistingRouteValues_IfNotNull()
        {
            // Arrange
            var builder = CreateBuilder();
            MapInboundEntry(builder, "Foo/{*path}");
            var route = builder.Build();

            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 builder = CreateBuilder();
            MapInboundEntry(builder, "Foo/{*path}");
            var route = builder.Build();

            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_SnapshotsRouteData()
        {
            // Arrange
            RouteValueDictionary nestedValues = null;
            List<IRouter> nestedRouters = null;

            var next = new Mock<IRouter>();
            next
                .Setup(r => r.RouteAsync(It.IsAny<RouteContext>()))
                .Callback<RouteContext>(c =>
                {
                    nestedValues = new RouteValueDictionary(c.RouteData.Values);
                    nestedRouters = new List<IRouter>(c.RouteData.Routers);
                    c.Handler = null; // Not a match
                })
                .Returns(Task.FromResult(0));

            var builder = CreateBuilder();
            MapInboundEntry(builder, "api/Store", handler: next.Object);
            var route = builder.Build();

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

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

            var originalValues = new RouteValueDictionary(context.RouteData.Values);

            // Act
            await route.RouteAsync(context);

            // Assert
            Assert.Equal(originalValues, context.RouteData.Values);
            Assert.NotEqual(nestedValues, context.RouteData.Values);
        }

        [Fact]
        public async Task TreeRouter_SnapshotsRouteData_ResetsWhenNotMatched()
        {
            // Arrange
            RouteValueDictionary nestedValues = null;
            List<IRouter> nestedRouters = null;

            var next = new Mock<IRouter>();
            next
                .Setup(r => r.RouteAsync(It.IsAny<RouteContext>()))
                .Callback<RouteContext>(c =>
                {
                    nestedValues = new RouteValueDictionary(c.RouteData.Values);
                    nestedRouters = new List<IRouter>(c.RouteData.Routers);
                    c.Handler = null; // Not a match
                })
                .Returns(Task.FromResult(0));

            var builder = CreateBuilder();
            MapInboundEntry(builder, "api/Store", handler: next.Object);
            var route = builder.Build();

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

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

            // Act
            await route.RouteAsync(context);

            // Assert
            Assert.NotEqual(nestedValues, context.RouteData.Values);

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

            Assert.Empty(context.RouteData.Routers);

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

        [Fact]
        public async Task TreeRouter_SnapshotsRouteData_ResetsWhenThrows()
        {
            // Arrange
            RouteValueDictionary nestedValues = null;
            List<IRouter> nestedRouters = null;

            var next = new Mock<IRouter>();
            next
                .Setup(r => r.RouteAsync(It.IsAny<RouteContext>()))
                .Callback<RouteContext>(c =>
                {
                    nestedValues = new RouteValueDictionary(c.RouteData.Values);
                    nestedRouters = new List<IRouter>(c.RouteData.Routers);
                    throw new Exception();
                })
                .Returns(Task.FromResult(0));

            var builder = CreateBuilder();
            MapInboundEntry(builder, "api/Store", handler: next.Object);
            var route = builder.Build();

            var context = CreateRouteContext("/api/Store");
            context.RouteData.Values.Add("action", "Index");

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

            // Assert
            Assert.NotEqual(nestedValues, context.RouteData.Values);

            Assert.Equal("Index", context.RouteData.Values["action"]);
            Assert.Equal("Index", nestedValues["action"]);
            Assert.DoesNotContain(context.RouteData.Values, kvp => kvp.Key == "test_route_group");
            Assert.Single(nestedValues, kvp => kvp.Key == "test_route_group");

            Assert.Empty(context.RouteData.Routers);

            Assert.Equal(1, nestedRouters.Count);
            Assert.Equal(next.Object.GetType(), nestedRouters[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 InboundRouteEntry MapInboundEntry(
            TreeRouteBuilder builder,
            string template,
            int order = 0,
            IRouter handler = null)
        {
            var entry = builder.MapInbound(
                handler ?? new StubRouter(),
                TemplateParser.Parse(template),
                routeName: null,
                order: order);

            // Add a generated 'route group' so we can identify later which entry matched.
            entry.Defaults["test_route_group"] = CreateRouteGroup(order, template);

            return entry;
        }

        private static OutboundRouteEntry MapOutboundEntry(
            TreeRouteBuilder builder,
            string template,
            object requiredValues = null,
            int order = 0,
            string name = null,
            IRouter handler = null)
        {
            var entry = builder.MapOutbound(
                handler ?? new StubRouter(),
                TemplateParser.Parse(template),
                requiredLinkValues: new RouteValueDictionary(requiredValues),
                routeName: name,
                order: order);

            // Add a generated 'route group' so we can identify later which entry matched.
            entry.Defaults["test_route_group"] = CreateRouteGroup(order, 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 TreeRouteBuilder CreateBuilder()
        {
            var objectPoolProvider = new DefaultObjectPoolProvider();
            var objectPolicy = new UriBuilderContextPooledObjectPolicy(UrlEncoder.Default);
            var objectPool = objectPoolProvider.Create<UriBuildingContext>(objectPolicy);

            var constraintResolver = CreateConstraintResolver();
            var builder = new TreeRouteBuilder(
                NullLoggerFactory.Instance,
                UrlEncoder.Default,
                objectPool,
                constraintResolver);
            return builder;
        }

        private static TreeRouter CreateTreeRouter(
            string firstTemplate,
            string secondTemplate)
        {
            var builder = CreateBuilder();
            MapOutboundEntry(builder, firstTemplate);
            MapOutboundEntry(builder, secondTemplate);
            return builder.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);
            }
        }
    }
}