Add WireMock.Net.AspNetCore.Middleware (#1175)

* Add WireMock.Net.AspNetCore.Middleware

* .

* WireMock.Net.Middleware.Tests

* .

* X-WireMock-Response-Delay

src/WireMock.Net.AspNetCore.Middleware/HttpDelegatingHandler/WireMockDelegationHandler.cs

@@ -0,0 +1,72 @@
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Logging;
+using Stef.Validation;
+using WireMock.Server;
+
+namespace WireMock.Net.AspNetCore.Middleware.HttpDelegatingHandler;
+
+/// <summary>
+/// DelegatingHandler that takes requests made via the <see cref="HttpClient"/>
+/// and routes them to the <see cref="WireMockServer"/>.
+/// </summary>
+internal class WireMockDelegationHandler : DelegatingHandler
+{
+    private readonly ILogger<WireMockDelegationHandler> _logger;
+    private readonly WireMockServerInstance _server;
+    private readonly IHttpContextAccessor _httpContextAccessor;
+    private readonly WireMockDelegationHandlerSettings _settings;
+
+    /// <summary>
+    /// Creates a new instance of <see cref="WireMockDelegationHandler"/>
+    /// </summary>
+    public WireMockDelegationHandler(
+        ILogger<WireMockDelegationHandler> logger,
+        WireMockServerInstance server,
+        IHttpContextAccessor httpContextAccessor,
+        WireMockDelegationHandlerSettings settings
+    )
+    {
+        _server = Guard.NotNull(server);
+        _httpContextAccessor = Guard.NotNull(httpContextAccessor);
+        _logger = Guard.NotNull(logger);
+        _settings = Guard.NotNull(settings);
+    }
+
+    /// <inheritdoc />
+    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+    {
+        Guard.NotNull(request);
+        Guard.NotNull(_httpContextAccessor.HttpContext);
+
+        if (_settings.AlwaysRedirect || IsWireMockRedirectHeaderSetToTrue())
+        {
+            _logger.LogDebug("Redirecting request to WireMock server");
+            if (_server.Instance?.Url != null)
+            {
+                request.RequestUri = new Uri(_server.Instance.Url + request.RequestUri!.PathAndQuery);
+            }
+        }
+
+        if (TryGetDelayHeaderValue(out var delayInMs))
+        {
+            await Task.Delay(delayInMs, cancellationToken);
+        }
+
+        return await base.SendAsync(request, cancellationToken);
+    }
+
+    private bool IsWireMockRedirectHeaderSetToTrue()
+    {
+        return
+            _httpContextAccessor.HttpContext!.Request.Headers.TryGetValue(AppConstants.HEADER_REDIRECT, out var values) &&
+            bool.TryParse(values.ToString(), out var shouldRedirectToWireMock) && shouldRedirectToWireMock;
+    }
+
+    private bool TryGetDelayHeaderValue(out int delayInMs)
+    {
+        delayInMs = 0;
+        return
+            _httpContextAccessor.HttpContext!.Request.Headers.TryGetValue(AppConstants.HEADER_RESPONSE_DELAY, out var values) &&
+            int.TryParse(values.ToString(), out delayInMs);
+    }
+}