Consolidates enums for Swagger file

SwaggerXTypeEnumConsolidator.cs

using System.Collections.Generic;
using System.Linq;
using Newtonsoft.Json.Linq;

namespace OpenApi.Extensions
{
    /// <summary>
    /// Consolidates enums based on <code>x-type-fullname</code> vendor extension.
    /// <example>
    /// {
    ///   "name": "enumA",
    ///   "in": "query",
    ///   "required": true,
    ///   "type": "string",
    ///   "enum": ["A", "B"],
    ///   "x-nullable": false,
    ///   "x-type-fullname": "Serko.Services.Swagger.WebTest.EnumA"
    /// }
    /// </example>
    /// </summary>
    public class SwaggerXTypeEnumConsolidator
    {
        /// <summary>
        /// Swagger spec file vendor extension name.
        /// </summary>
        public const string XTypeFullName = "x-type-fullname";

        /// <summary>
        /// Modifies input Swagger spec file.
        /// </summary>
        /// <param name="swaggerJObject"></param>
        /// <returns>Modified Swagger spec file.</returns>
        public string ModifySwaggerSpec(JObject swaggerJObject)
        {
            // get all enums
            var enums = swaggerJObject.Descendants().OfType<JProperty>()
                .Where(d => d.Name == "enum" && d.Parent[XTypeFullName] != null).ToList();

            var enumsHashSet = new HashSet<string>();

            var distinctEnums = enums
                .Select(e =>
                    new Enum(e.Parent[XTypeFullName].Value<string>())
                    {
                        Values = e.Value.Values<string>().ToList()
                    })
                .Where(i => enumsHashSet.Add(i.FullName)).ToList();

            // replace all enums with references
            foreach (var e in enums)
            {
                var p = (JObject)e.Parent;
                p.Remove("enum");
                p.Add(new JProperty("$ref", $"#/definitions/{p[XTypeFullName].Value<string>().Replace("+", string.Empty)}"));
            }

            var definitions = (JObject)swaggerJObject["definitions"];
            // add enum definitions into definitions section of Swagger spec file
            foreach (var enumParameter in distinctEnums)
            {
                // replacing "+" to prevent incorrect naming for nested enums
                definitions.Add(new JProperty(enumParameter.FullName.Replace("+", string.Empty),
                    new JObject(new JProperty("enum", enumParameter.Values), new JProperty("type", "string"))));
            }

            return swaggerJObject.ToString();
        }

        private class Enum
        {
            public Enum(string fullName)
            {
                FullName = fullName;
            }

            public string FullName { get; }

            public IList<string> Values { get; set; }
        }
    }
}