// 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 Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Routing.Constraints;
using Microsoft.AspNetCore.Routing.TestObjects;
using Microsoft.Extensions.DependencyInjection;
using Moq;
using Xunit;

namespace Microsoft.AspNetCore.Routing
{
    // Detailed coverage for how DefaultLinkGenerator processes templates
    public class DefaultLinkGeneratorProcessTemplateTest : LinkGeneratorTestBase
    {
        [Fact]
        public void TryProcessTemplate_EncodesIntermediate_DefaultValues()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{p1}/{p2=a b}/{p3=foo}");
            var linkGenerator = CreateLinkGenerator(endpoint);

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: null,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { p1 = "Home", p3 = "bar", }),
                ambientValues: null,
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/a%20b/bar", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Theory]
        [InlineData("a/b/c", "/Home/Index/a%2Fb%2Fc")]
        [InlineData("a/b b1/c c1", "/Home/Index/a%2Fb%20b1%2Fc%20c1")]
        public void TryProcessTemplate_EncodesValue_OfSingleAsteriskCatchAllParameter(string routeValue, string expected)
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}/{*path}");
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { controller = "Home", action = "Index" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { path = routeValue, }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal(expected, result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Theory]
        [InlineData("/", "/Home/Index//")]
        [InlineData("a", "/Home/Index/a")]
        [InlineData("a/", "/Home/Index/a/")]
        [InlineData("a/b", "/Home/Index/a/b")]
        [InlineData("a/b/c", "/Home/Index/a/b/c")]
        [InlineData("a/b/cc", "/Home/Index/a/b/cc")]
        [InlineData("a/b/c/", "/Home/Index/a/b/c/")]
        [InlineData("a/b/c//", "/Home/Index/a/b/c//")]
        [InlineData("a//b//c", "/Home/Index/a//b//c")]
        public void TryProcessTemplate_DoesNotEncodeSlashes_OfDoubleAsteriskCatchAllParameter(string routeValue, string expected)
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}/{**path}");
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { controller = "Home", action = "Index" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { path = routeValue, }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal(expected, result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_EncodesContentOtherThanSlashes_OfDoubleAsteriskCatchAllParameter()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}/{**path}");
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { controller = "Home", action = "Index" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { path = "a/b b1/c c1" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index/a/b%20b1/c%20c1", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_EncodesValues()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}");
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { controller = "Home", action = "Index" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { name = "name with %special #characters" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index", result.path.ToUriComponent());
            Assert.Equal("?name=name%20with%20%25special%20%23characters", result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_ForListOfStrings()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}");
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { controller = "Home", action = "Index" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { color = new List<string> { "red", "green", "blue" } }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index", result.path.ToUriComponent());
            Assert.Equal("?color=red&color=green&color=blue", result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_ForListOfInts()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}");
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { controller = "Home", action = "Index" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { items = new List<int> { 10, 20, 30 } }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index", result.path.ToUriComponent());
            Assert.Equal("?items=10&items=20&items=30", result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_ForList_Empty()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}");
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { controller = "Home", action = "Index" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { color = new List<string> { } }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_ForList_StringWorkaround()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}");
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { controller = "Home", action = "Index" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { page = 1, color = new List<string> { "red", "green", "blue" }, message = "textfortest" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index", result.path.ToUriComponent());
            Assert.Equal("?page=1&color=red&color=green&color=blue&message=textfortest", result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_Success_AmbientValues()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}");
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { controller = "Home" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_GeneratesLowercaseUrl_SetOnRouteOptions()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}");
            Action<IServiceCollection> configure = (s) =>
            {
                s.Configure<RouteOptions>(o => o.LowercaseUrls = true);
            };

            var linkGenerator = CreateLinkGenerator(configure, endpoints: new[] { endpoint, });
            var httpContext = CreateHttpContext(ambientValues: new { controller = "Home" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/home/index", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        // Regression test for https://github.com/aspnet/Routing/issues/802
        [Fact]
        public void TryProcessTemplate_GeneratesLowercaseUrl_Includes_BufferedValues_SetOnRouteOptions()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("Foo/{bar=BAR}/{id?}");
            Action<IServiceCollection> configure = (s) =>
            {
                s.Configure<RouteOptions>(o => o.LowercaseUrls = true);
            };

            var linkGenerator = CreateLinkGenerator(configure, endpoints: new[] { endpoint, });
            var httpContext = CreateHttpContext();

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { id = "18" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/foo/bar/18", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        // Regression test for https://github.com/aspnet/Routing/issues/802
        [Fact]
        public void TryProcessTemplate_ParameterPolicy_Includes_BufferedValues()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("Foo/{bar=MyBar}/{id?}", policies: new { bar = new SlugifyParameterTransformer(), });
            var linkGenerator = CreateLinkGenerator(endpoints: new[] { endpoint, });
            var httpContext = CreateHttpContext();

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { id = "18" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Foo/my-bar/18", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        // Regression test for aspnet/Routing#435
        //
        // In this issue we used to lowercase URLs after parameters were encoded, meaning that if a character needed
        // encoding (such as a cyrillic character, it would not be encoded).
        [Fact]
        public void TryProcessTemplate_GeneratesLowercaseUrl_SetOnRouteOptions_CanLowercaseCharactersThatNeedEncoding()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}");
            Action<IServiceCollection> configure = (s) =>
            {
                s.Configure<RouteOptions>(o => o.LowercaseUrls = true);
            };

            var linkGenerator = CreateLinkGenerator(configure, endpoints: new[] { endpoint, });
            var httpContext = CreateHttpContext(ambientValues: new { controller = "Home" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "П" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext), // Cryillic uppercase Pe
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/home/%D0%BF", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());

            // Convert back to decoded.
            //
            // This is Cyrillic lowercase Pe (not an n).
            Assert.Equal("/home/п", PathString.FromUriComponent(result.path.ToUriComponent()).Value);
        }

        [Fact]
        public void TryProcessTemplate_GeneratesLowercaseQueryString_SetOnRouteOptions()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}");
            Action<IServiceCollection> configure = (s) =>
            {
                s.Configure<RouteOptions>(o =>
                {
                    o.LowercaseUrls = true;
                    o.LowercaseQueryStrings = true;
                });
            };

            var linkGenerator = CreateLinkGenerator(
                configure, 
                endpoints: new[] { endpoint, });
            var httpContext = CreateHttpContext(ambientValues: new { controller = "Home" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index", ShowStatus = "True", INFO = "DETAILED" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/home/index", result.path.ToUriComponent());
            Assert.Equal("?showstatus=true&info=detailed", result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_AppendsTrailingSlash_SetOnRouteOptions()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}");
            Action<IServiceCollection> configure = (s) =>
            {
                s.Configure<RouteOptions>(o => o.AppendTrailingSlash = true);
            };

            var linkGenerator = CreateLinkGenerator(
                configure,
                endpoints: new[] { endpoint });
            var httpContext = CreateHttpContext(ambientValues: new { controller = "Home" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index/", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_GeneratesLowercaseQueryStringAndTrailingSlash_SetOnRouteOptions()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}");
            Action<IServiceCollection> configure = (s) =>
            {
                s.Configure<RouteOptions>(o =>
                {
                    o.LowercaseUrls = true;
                    o.LowercaseQueryStrings = true;
                    o.AppendTrailingSlash = true;
                });
            };

            var linkGenerator = CreateLinkGenerator(
                configure,
                endpoints: new[] { endpoint });
            var httpContext = CreateHttpContext(ambientValues: new { controller = "Home" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index", ShowStatus = "True", INFO = "DETAILED" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/home/index/", result.path.ToUriComponent());
            Assert.Equal("?showstatus=true&info=detailed", result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_LowercaseUrlSetToTrue_OnRouteOptions_OverridenByCallsiteValue()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}");
            Action<IServiceCollection> configure = (s) =>
            {
                s.Configure<RouteOptions>(o => o.LowercaseUrls = true);
            };

            var linkGenerator = CreateLinkGenerator(
                configure,
                endpoints: new[] { endpoint });
            var httpContext = CreateHttpContext(ambientValues: new { controller = "HoMe" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "InDex" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: new LinkOptions
                {
                    LowercaseUrls = false
                },
                result: out var result);


            // Assert
            Assert.True(success);
            Assert.Equal("/HoMe/InDex", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_LowercaseUrlSetToFalse_OnRouteOptions_OverridenByCallsiteValue()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}");
            Action<IServiceCollection> configure = (s) =>
            {
                s.Configure<RouteOptions>(o => o.LowercaseUrls = false);
            };

            var linkGenerator = CreateLinkGenerator(
                configure,
                endpoints: new[] { endpoint });
            var httpContext = CreateHttpContext(ambientValues: new { controller = "HoMe" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "InDex" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: new LinkOptions()
                {
                    LowercaseUrls = true
                },
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/home/index", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_LowercaseUrlQueryStringsSetToTrue_OnRouteOptions_OverridenByCallsiteValue()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}");
            Action<IServiceCollection> configure = (s) =>
            {
                s.Configure<RouteOptions>(o =>
                {
                    o.LowercaseUrls = true;
                    o.LowercaseQueryStrings = true;
                });
            };

            var linkGenerator = CreateLinkGenerator(
                configure,
                endpoints: new[] { endpoint });
            var httpContext = CreateHttpContext(ambientValues: new { controller = "Home" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index", ShowStatus = "True", INFO = "DETAILED" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: new LinkOptions
                {
                    LowercaseUrls = false,
                    LowercaseQueryStrings = false
                },
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index", result.path.ToUriComponent());
            Assert.Equal("?ShowStatus=True&INFO=DETAILED", result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_LowercaseUrlQueryStringsSetToFalse_OnRouteOptions_OverridenByCallsiteValue()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}");
            Action<IServiceCollection> configure = (s) =>
            {
                s.Configure<RouteOptions>(o =>
                {
                    o.LowercaseUrls = false;
                    o.LowercaseQueryStrings = false;
                });
            };

            var linkGenerator = CreateLinkGenerator(
                configure,
                endpoints: new[] { endpoint });
            var httpContext = CreateHttpContext(ambientValues: new { controller = "Home" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index", ShowStatus = "True", INFO = "DETAILED" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: new LinkOptions()
                {
                    LowercaseUrls = true,
                    LowercaseQueryStrings = true,
                },
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/home/index", result.path.ToUriComponent());
            Assert.Equal("?showstatus=true&info=detailed", result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_AppendTrailingSlashSetToFalse_OnRouteOptions_OverridenByCallsiteValue()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}");
            Action<IServiceCollection> configure = (s) =>
            {
                s.Configure<RouteOptions>(o => o.AppendTrailingSlash = false);
            };

            var linkGenerator = CreateLinkGenerator(
                configure,
                endpoints: new[] { endpoint });
            var httpContext = CreateHttpContext(ambientValues: new { controller = "Home" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: new LinkOptions() { AppendTrailingSlash = true, },
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index/", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void RouteGenerationRejectsConstraints()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                "{p1}/{p2}",
                defaults: new { p2 = "catchall" },
                policies: new { p2 = "\\d{4}" });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { p1 = "abcd" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.False(success);
        }

        [Fact]
        public void RouteGenerationAcceptsConstraints()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                "{p1}/{p2}",
                defaults: new { p2 = "catchall" },
                policies: new { p2 = new RegexRouteConstraint("\\d{4}"), });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { p1 = "hello", p2 = "1234" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/hello/1234", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void RouteWithCatchAllRejectsConstraints()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                "{p1}/{*p2}",
                defaults: new { p2 = "catchall" },
                policies: new { p2 = new RegexRouteConstraint("\\d{4}") });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { p1 = "abcd" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.False(success);
        }

        [Fact]
        public void RouteWithCatchAllAcceptsConstraints()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                "{p1}/{*p2}",
                defaults: new { p2 = "catchall" },
                policies: new { p2 = new RegexRouteConstraint("\\d{4}") });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { p1 = "hello", p2 = "1234" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/hello/1234", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void GetLinkWithNonParameterConstraintReturnsUrlWithoutQueryString()
        {
            // Arrange
            var target = new Mock<IRouteConstraint>();
            target
                .Setup(
                    e => e.Match(
                        It.IsAny<HttpContext>(),
                        It.IsAny<IRouter>(),
                        It.IsAny<string>(),
                        It.IsAny<RouteValueDictionary>(),
                        It.IsAny<RouteDirection>()))
                .Returns(true)
                .Verifiable();
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                "{p1}/{p2}",
                defaults: new { p2 = "catchall" },
                policies: new { p2 = target.Object });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { p1 = "hello", p2 = "1234" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/hello/1234", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());

            target.VerifyAll();
        }


        // Any ambient values from the current request should be visible to constraint, even
        // if they have nothing to do with the route generating a link
        [Fact]
        public void TryProcessTemplate_ConstraintsSeeAmbientValues()
        {
            // Arrange
            var constraint = new CapturingConstraint();
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                template: "slug/Home/Store",
                defaults: new { controller = "Home", action = "Store" },
                policies: new { c = constraint });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(
                ambientValues: new { controller = "Home", action = "Blog", extra = "42" });
            var expectedValues = new RouteValueDictionary(
                new { controller = "Home", action = "Store", extra = "42" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Store" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/slug/Home/Store", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());

            Assert.Equal(expectedValues.OrderBy(kvp => kvp.Key), constraint.Values.OrderBy(kvp => kvp.Key));
        }

        // Non-parameter default values from the routing generating a link are not in the 'values'
        // collection when constraints are processed.
        [Fact]
        public void TryProcessTemplate_ConstraintsDontSeeDefaults_WhenTheyArentParameters()
        {
            // Arrange
            var constraint = new CapturingConstraint();
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                template: "slug/Home/Store",
                defaults: new { controller = "Home", action = "Store", otherthing = "17" },
                policies: new { c = constraint });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { controller = "Home", action = "Blog" });
            var expectedValues = new RouteValueDictionary(
                new { controller = "Home", action = "Store" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Store" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/slug/Home/Store", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());

            Assert.Equal(expectedValues.OrderBy(kvp => kvp.Key), constraint.Values.OrderBy(kvp => kvp.Key));
        }

        // Default values are visible to the constraint when they are used to fill a parameter.
        [Fact]
        public void TryProcessTemplate_ConstraintsSeesDefault_WhenThereItsAParamter()
        {
            // Arrange
            var constraint = new CapturingConstraint();
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                template: "slug/{controller}/{action}",
                defaults: new { action = "Index" },
                policies: new { c = constraint, });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { controller = "Home", action = "Blog" });
            var expectedValues = new RouteValueDictionary(
                new { controller = "Shopping", action = "Index" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { controller = "Shopping" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/slug/Shopping", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
            Assert.Equal(expectedValues, constraint.Values);
        }

        // Default values from the routing generating a link are in the 'values' collection when
        // constraints are processed - IFF they are specified as values or ambient values.
        [Fact]
        public void TryProcessTemplate_ConstraintsSeeDefaults_IfTheyAreSpecifiedOrAmbient()
        {
            // Arrange
            var constraint = new CapturingConstraint();
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                template: "slug/Home/Store",
                defaults: new { controller = "Home", action = "Store", otherthing = "17", thirdthing = "13" },
                policies: new { c = constraint, });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(
                ambientValues: new { controller = "Home", action = "Blog", otherthing = "17" });

            var expectedValues = new RouteValueDictionary(
                new { controller = "Home", action = "Store", otherthing = "17", thirdthing = "13" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Store", thirdthing = "13" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/slug/Home/Store", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());

            Assert.Equal(expectedValues.OrderBy(kvp => kvp.Key), constraint.Values.OrderBy(kvp => kvp.Key));
        }

        [Theory]
        [InlineData(true)]
        [InlineData(false)]
        public void TryProcessTemplate_InlineConstraints_Success(bool hasHttpContext)
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                template: "Home/Index/{id:int}",
                defaults: new { controller = "Home", action = "Index" },
                policies: new { });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = hasHttpContext ? CreateHttpContext(new { }) : null;

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index", controller = "Home", id = 4 }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index/4", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_InlineConstraints_NonMatchingvalue()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                template: "Home/Index/{id}",
                defaults: new { controller = "Home", action = "Index" },
                policies: new { id = "int" });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index", controller = "Home", id = "not-an-integer" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);
            
            // Assert
            Assert.False(success);
        }

        [Theory]
        [InlineData(true)]
        [InlineData(false)]
        public void TryProcessTemplate_InlineConstraints_OptionalParameter_ValuePresent(bool hasHttpContext)
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                template: "Home/Index/{id:int?}",
                defaults: new { controller = "Home", action = "Index" },
                policies: new { });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = hasHttpContext ? CreateHttpContext(new { }) : null;

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index", controller = "Home", id = 98 }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index/98", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_InlineConstraints_OptionalParameter_ValueNotPresent()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                template: "Home/Index/{id?}",
                defaults: new { controller = "Home", action = "Index" },
                policies: new { id = "int" });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index", controller = "Home" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_InlineConstraints_OptionalParameter_ValuePresent_ConstraintFails()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                template: "Home/Index/{id?}",
                defaults: new { controller = "Home", action = "Index" },
                policies: new { id = "int" });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index", controller = "Home", id = "not-an-integer" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.False(success);
        }

        [Theory]
        [InlineData(true)]
        [InlineData(false)]
        public void TryProcessTemplate_InlineConstraints_MultipleInlineConstraints(bool hasHttpContext)
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                template: "Home/Index/{id:int:range(1,20)}",
                defaults: new { controller = "Home", action = "Index" },
                policies: new { });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = hasHttpContext ? CreateHttpContext(new { }) : null;

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index", controller = "Home", id = 14 }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index/14", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Theory]
        [InlineData(true)]
        [InlineData(false)]
        public void TryProcessTemplate_InlineConstraints_CompositeInlineConstraint_Fails(bool hasHttpContext)
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                template: "Home/Index/{id:int:range(1,20)}",
                defaults: new { controller = "Home", action = "Index" },
                policies: new { });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = hasHttpContext ? CreateHttpContext(new { }) : null;

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index", controller = "Home", id = 50 }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.False(success);
        }

        [Fact]
        public void TryProcessTemplate_InlineConstraints_CompositeConstraint_FromConstructor()
        {
            // Arrange
            var constraint = new MaxLengthRouteConstraint(20);
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                template: "Home/Index/{name}",
                defaults: new { controller = "Home", action = "Index" },
                policies: new { name = constraint });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index", controller = "Home", name = "products" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index/products", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_OptionalParameter_ParameterPresentInValues()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}/{name?}");
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index", controller = "Home", name = "products" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index/products", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_OptionalParameter_ParameterNotPresentInValues()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}/{name?}");
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index", controller = "Home" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_OptionalParameter_ParameterPresentInValuesAndDefaults()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                template: "{controller}/{action}/{name}",
                defaults: new { name = "default-products" });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index", controller = "Home", name = "products" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index/products", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_OptionalParameter_ParameterNotPresentInValues_PresentInDefaults()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                template: "{controller}/{action}/{name}",
                defaults: new { name = "products" });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index", controller = "Home" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_ParameterNotPresentInTemplate_PresentInValues()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}/{name}");
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index", controller = "Home", name = "products", format = "json" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index/products", result.path.ToUriComponent());
            Assert.Equal("?format=json", result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_OptionalParameter_FollowedByDotAfterSlash_ParameterPresent()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                template: "{controller}/{action}/.{name?}");
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index", controller = "Home", name = "products" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index/.products", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_OptionalParameter_FollowedByDotAfterSlash_ParameterNotPresent()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}/.{name?}");
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index", controller = "Home" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);


            Assert.True(success);
            Assert.Equal("/Home/Index/", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_OptionalParameter_InSimpleSegment()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("{controller}/{action}/{name?}");
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { action = "Index", controller = "Home" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Home/Index", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_TwoOptionalParameters_OneValueFromAmbientValues()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("a/{b=15}/{c?}/{d?}");
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { c = "17" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/a/15/17", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_OptionalParameterAfterDefault_OneValueFromAmbientValues()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("a/{b=15}/{c?}");
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { c = "17" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/a/15/17", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_TwoOptionalParametersAfterDefault_LastValueFromAmbientValues()
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint("a/{b=15}/{c?}/{d?}");
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { d = "17" });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/a", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        public static TheoryData<object, object, object, object> DoesNotDiscardAmbientValuesData
        {
            get
            {
                // - ambient values
                // - explicit values
                // - required values
                // - defaults
                return new TheoryData<object, object, object, object>
                {
                    // link to same action on same controller
                    {
                        new { controller = "Products", action = "Edit", id = 10 },
                        new { controller = "Products", action = "Edit" },
                        new { area = (string)null, controller = "Products", action = "Edit", page = (string)null },
                        new { area = (string)null, controller = "Products", action = "Edit", page = (string)null }
                    },

                    // link to same action on same controller - ignoring case
                    {
                        new { controller = "ProDUcts", action = "EDit", id = 10 },
                        new { controller = "ProDUcts", action = "EDit" },
                        new { area = (string)null, controller = "Products", action = "Edit", page = (string)null },
                        new { area = (string)null, controller = "Products", action = "Edit", page = (string)null }
                    },

                    // link to same action and same controller on same area
                    {
                        new { area = "Admin", controller = "Products", action = "Edit", id = 10 },
                        new { area = "Admin", controller = "Products", action = "Edit" },
                        new { area = "Admin", controller = "Products", action = "Edit", page = (string)null },
                        new { area = "Admin", controller = "Products", action = "Edit", page = (string)null }
                    },

                    // link to same action and same controller on same area
                    {
                        new { area = "Admin", controller = "Products", action = "Edit", id = 10 },
                        new { controller = "Products", action = "Edit" },
                        new { area = "Admin", controller = "Products", action = "Edit", page = (string)null },
                        new { area = "Admin", controller = "Products", action = "Edit", page = (string)null }
                    },

                    // link to same action and same controller
                    {
                        new { controller = "Products", action = "Edit", id = 10 },
                        new { controller = "Products", action = "Edit" },
                        new { area = (string)null, controller = "Products", action = "Edit", page = (string)null },
                        new { area = (string)null, controller = "Products", action = "Edit", page = (string)null }
                    },
                    {
                        new { controller = "Products", action = "Edit", id = 10 },
                        new { controller = "Products", action = "Edit" },
                        new { area = (string)null, controller = "Products", action = "Edit", page = (string)null },
                        new { area = (string)null, controller = "Products", action = "Edit", page = (string)null }
                    },
                    {
                        new { controller = "Products", action = "Edit", id = 10 },
                        new { controller = "Products", action = "Edit" },
                        new { area = "", controller = "Products", action = "Edit", page = "" },
                        new { area = "", controller = "Products", action = "Edit", page = "" }
                    },

                    // link to same page
                    {
                        new { page = "Products/Edit", id = 10 },
                        new { page = "Products/Edit" },
                        new { area = (string)null, controller = (string)null, action = (string)null, page = "Products/Edit" },
                        new { area = (string)null, controller = (string)null, action = (string)null, page = "Products/Edit" }
                    },
                };
            }
        }

        [Theory]
        [MemberData(nameof(DoesNotDiscardAmbientValuesData))]
        public void TryProcessTemplate_DoesNotDiscardAmbientValues_IfAllRequiredKeysMatch(
            object ambientValues,
            object explicitValues,
            object requiredValues,
            object defaults)
        {
            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                "Products/Edit/{id}",
                requiredValues: requiredValues,
                defaults: defaults);
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues);

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(explicitValues),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Products/Edit/10", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_DoesNotDiscardAmbientValues_IfAllRequiredValuesMatch_ForGenericKeys()
        {
            // Verifying that discarding works in general usage case i.e when keys are not like controller, action etc.

            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                "Products/Edit/{id}",
                requiredValues: new { c = "Products", a = "Edit" },
                defaults: new { c = "Products", a = "Edit" });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { c = "Products", a = "Edit", id = 10 });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { c = "Products", a = "Edit" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.True(success);
            Assert.Equal("/Products/Edit/10", result.path.ToUriComponent());
            Assert.Equal(string.Empty, result.query.ToUriComponent());
        }

        [Fact]
        public void TryProcessTemplate_DiscardsAmbientValues_ForGenericKeys()
        {
            // Verifying that discarding works in general usage case i.e when keys are not like controller, action etc.

            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                "Products/Edit/{id}",
                requiredValues: new { c = "Products", a = "Edit" },
                defaults: new { c = "Products", a = "Edit" });
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues: new { c = "Products", a = "Edit", id = 10 });

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(new { c = "Products", a = "List" }),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.False(success);
        }

        public static TheoryData<object, object, object, object> DiscardAmbientValuesData
        {
            get
            {
                // - ambient values
                // - explicit values
                // - required values
                // - defaults
                return new TheoryData<object, object, object, object>
                {
                    // link to different action on same controller
                    {
                        new { controller = "Products", action = "Edit", id = 10 },
                        new { controller = "Products", action = "List" },
                        new { area = (string)null, controller = "Products", action = "List", page = (string)null },
                        new { area = (string)null, controller = "Products", action = "List", page = (string)null }
                    },

                    // link to different action on same controller and same area
                    {
                        new { area = "Customer", controller = "Products", action = "Edit", id = 10 },
                        new { area = "Customer", controller = "Products", action = "List" },
                        new { area = "Customer", controller = "Products", action = "List", page = (string)null },
                        new { area = "Customer", controller = "Products", action = "List", page = (string)null }
                    },

                    // link from one area to a different one
                    {
                        new { area = "Admin", controller = "Products", action = "Edit", id = 10 },
                        new { area = "Consumer", controller = "Products", action = "Edit" },
                        new { area = "Consumer", controller = "Products", action = "Edit", page = (string)null },
                        new { area = "Consumer", controller = "Products", action = "Edit", page = (string)null }
                    },

                    // link from non-area to a area one
                    {
                        new { controller = "Products", action = "Edit", id = 10 },
                        new { area = "Consumer", controller = "Products", action = "Edit" },
                        new { area = "Consumer", controller = "Products", action = "Edit", page = (string)null },
                        new { area = "Consumer", controller = "Products", action = "Edit", page = (string)null }
                    },

                    // link from area to a non-area based action
                    {
                        new { area = "Admin", controller = "Products", action = "Edit", id = 10 },
                        new { area = "", controller = "Products", action = "Edit" },
                        new { area = "", controller = "Products", action = "Edit", page = (string)null },
                        new { area = "", controller = "Products", action = "Edit", page = (string)null }
                    },

                    // link from controller-action to a page
                    {
                        new { controller = "Products", action = "Edit", id = 10 },
                        new { page = "Products/Edit" },
                        new { area = (string)null, controller = (string)null, action = (string)null, page = "Products/Edit"},
                        new { area = (string)null, controller = (string)null, action = (string)null, page = "Products/Edit"}
                    },

                    // link from a page to controller-action
                    {
                        new { page = "Products/Edit", id = 10 },
                        new { controller = "Products", action = "Edit" },
                        new { area = (string)null, controller = "Products", action = "Edit", page = (string)null },
                        new { area = (string)null, controller = "Products", action = "Edit", page = (string)null }
                    },

                    // link from one page to a different page
                    {
                        new { page = "Products/Details", id = 10 },
                        new { page = "Products/Edit" },
                        new { area = (string)null, controller = (string)null, action = (string)null, page = "Products/Edit" },
                        new { area = (string)null, controller = (string)null, action = (string)null, page = "Products/Edit" }
                    },
                };
            }
        }

        [Theory]
        [MemberData(nameof(DiscardAmbientValuesData))]
        public void TryProcessTemplate_DiscardsAmbientValues_IfAnyAmbientValue_IsDifferentThan_EndpointRequiredValues(
            object ambientValues,
            object explicitValues,
            object requiredValues,
            object defaults)
        {
            // Linking to a different action on the same controller

            // Arrange
            var endpoint = EndpointFactory.CreateRouteEndpoint(
                "Products/Edit/{id}",
                requiredValues: requiredValues,
                defaults: defaults);
            var linkGenerator = CreateLinkGenerator(endpoint);
            var httpContext = CreateHttpContext(ambientValues);

            // Act
            var success = linkGenerator.TryProcessTemplate(
                httpContext: httpContext,
                endpoint: endpoint,
                values: new RouteValueDictionary(explicitValues),
                ambientValues: DefaultLinkGenerator.GetAmbientValues(httpContext),
                options: null,
                result: out var result);

            // Assert
            Assert.False(success);
        }
    }
}