Initial support for converting the mappings to a Pact(flow) json file (#748)

* WithDescription

* WithConsumer / WithProvider

* x

* .

* .

* .

* .

* fix

* pact

* nullable

* ficx

* .

* fix

src/WireMock.Net/Server/WireMockServer.Pact.cs

@@ -0,0 +1,167 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using WireMock.Admin.Mappings;
+using WireMock.Pact.Models.V2;
+using WireMock.Util;
+
+namespace WireMock.Server;
+
+public partial class WireMockServer
+{
+    private const string DefaultPath = "/";
+    private const string DefaultMethod = "GET";
+    private const int DefaultStatus = 200;
+    private const string DefaultConsumer = "Default Consumer";
+    private const string DefaultProvider = "Default Provider";
+
+    /// <summary>
+    /// Save the mappings as a Pact Json file V2.
+    /// </summary>
+    /// <param name="folder">The folder to save the pact file.</param>
+    /// <param name="filename">The filename for the .json file [optional].</param>
+    public void SavePact(string folder, string? filename = null)
+    {
+        var consumer = Consumer ?? DefaultConsumer;
+        var provider = Provider ?? DefaultProvider;
+
+        filename ??= $"{consumer} - {provider}.json";
+
+        var pact = new Pact.Models.V2.Pact
+        {
+            Consumer = new Pacticipant { Name = consumer },
+            Provider = new Pacticipant { Name = provider }
+        };
+
+        foreach (var mapping in MappingModels)
+        {
+            var interaction = new Interaction
+            {
+                Description = mapping.Description,
+                ProviderState = mapping.Title,
+                Request = MapRequest(mapping.Request),
+                Response = MapResponse(mapping.Response)
+            };
+
+            pact.Interactions.Add(interaction);
+        }
+
+        var bytes = JsonUtils.SerializeAsPactFile(pact);
+        _settings.FileSystemHandler.WriteFile(folder, filename, bytes);
+    }
+
+    private static Request MapRequest(RequestModel request)
+    {
+        string path;
+        switch (request.Path)
+        {
+            case string pathAsString:
+                path = pathAsString;
+                break;
+
+            case PathModel pathModel:
+                path = GetPatternAsStringFromMatchers(pathModel.Matchers, DefaultPath);
+                break;
+
+            default:
+                path = DefaultPath;
+                break;
+        }
+
+        return new Request
+        {
+            Method = request.Methods?.FirstOrDefault() ?? DefaultMethod,
+            Path = path,
+            Query = MapQueryParameters(request.Params),
+            Headers = MapRequestHeaders(request.Headers),
+            Body = MapBody(request.Body)
+        };
+    }
+
+    private static Response MapResponse(ResponseModel? response)
+    {
+        if (response == null)
+        {
+            return new Response();
+        }
+
+        return new Response
+        {
+            Status = MapStatusCode(response.StatusCode),
+            Headers = MapResponseHeaders(response.Headers),
+            Body = response.BodyAsJson
+        };
+    }
+
+    private static int MapStatusCode(object? statusCode)
+    {
+        if (statusCode is string statusCodeAsString)
+        {
+            return int.TryParse(statusCodeAsString, out var statusCodeAsInt) ? statusCodeAsInt : DefaultStatus;
+        }
+
+        if (statusCode != null)
+        {
+            // Convert to Int32 because Newtonsoft deserializes an 'object' with a number value to a long.
+            return Convert.ToInt32(statusCode);
+        }
+
+        return DefaultStatus;
+    }
+
+    private static string? MapQueryParameters(IList<ParamModel>? queryParameters)
+    {
+        if (queryParameters == null)
+        {
+            return null;
+        }
+
+        var values = queryParameters
+            .Where(qp => qp.Matchers != null && qp.Matchers.Any() && qp.Matchers[0].Pattern is string)
+            .Select(param => $"{Uri.EscapeDataString(param.Name)}={Uri.EscapeDataString((string)param.Matchers![0].Pattern)}");
+
+        return string.Join("&", values);
+    }
+
+    private static IDictionary<string, string>? MapRequestHeaders(IList<HeaderModel>? headers)
+    {
+        if (headers == null)
+        {
+            return null;
+        }
+
+        var validHeaders = headers.Where(h => h.Matchers != null && h.Matchers.Any() && h.Matchers[0].Pattern is string);
+        return validHeaders.ToDictionary(x => x.Name, y => (string)y.Matchers![0].Pattern);
+    }
+
+    private static IDictionary<string, string>? MapResponseHeaders(IDictionary<string, object>? headers)
+    {
+        if (headers == null)
+        {
+            return null;
+        }
+
+        var validHeaders = headers.Where(h => h.Value is string);
+        return validHeaders.ToDictionary(x => x.Key, y => (string)y.Value);
+    }
+
+    private static object? MapBody(BodyModel? body)
+    {
+        if (body == null || body.Matcher.Name != "JsonMatcher")
+        {
+            return null;
+        }
+
+        return body.Matcher.Pattern;
+    }
+
+    private static string GetPatternAsStringFromMatchers(MatcherModel[]? matchers, string defaultValue)
+    {
+        if (matchers != null && matchers.Any() && matchers[0].Pattern is string patternAsString)
+        {
+            return patternAsString;
+        }
+
+        return defaultValue;
+    }
+}