/// <summary>
/// Contains endpoints that use different enums.
/// </summary>
[Route("api/data")]
[ApiController]
public class EnumsController : ControllerBase
{
    /// <summary>
    /// Executes operation of requested type and returns result status.
    /// </summary>
    /// <param name="id">Operation id.</param>
    /// <param name="type">Operation type.</param>
    /// <returns>Result status.</returns>
    [HttpGet]
    public Task<Result> ExecuteOperation(int id, OperationType type)
    {
        return Task.FromResult(Result.Success);
    }
    /// <summary>
    /// Changes data
    /// </summary>
    [HttpPost]
    public Task<IActionResult> Change(DataChange change)
    {
        return Task.FromResult<IActionResult>(Ok());
    }
}

/// <summary>
/// Operation types.
/// </summary>
public enum OperationType
{
    /// <summary>
    /// Do operation.
    /// </summary>
    Do,
    /// <summary>
    /// Undo operation.
    /// </summary>
    Undo
}
/// <summary>
/// Operation results.
/// </summary>
public enum Result
{
    /// <summary>
    /// Operations was completed successfully.
    /// </summary>
    Success,
    /// <summary>
    /// Operation failed.
    /// </summary>
    Failure
}
/// <summary>
/// Data change information.
/// </summary>
public class DataChange
{
    /// <summary>
    /// Data id.
    /// </summary>
    public int Id { get; set; }
    /// <summary>
    /// Source type.
    /// </summary>
    public Sources Source { get; set; }
    /// <summary>
    /// Operation type.
    /// </summary>
    public OperationType Operation { get; set; }
}
/// <summary>
/// Types of sources.
/// </summary>
public enum Sources
{
    /// <summary>
    /// In-memory data source.
    /// </summary>
    Memory,
    /// <summary>
    /// Database data source.
    /// </summary>
    Database
}

public class Startup
{
    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddControllers();
        services.AddSwaggerGen(c => {
            // Set the comments path for the Swagger JSON and UI.
            var xmlFile = $"{Assembly.GetExecutingAssembly().GetName().Name}.xml";
            var xmlPath = Path.Combine(AppContext.BaseDirectory, xmlFile);
            c.IncludeXmlComments(xmlPath);
        });
    }
    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        app.UseSwagger();
        app.UseSwaggerUI();
        app.UseRouting();
        ...
    }
}

services.AddControllers();

services.AddControllers().AddNewtonsoftJson(o =>
{
    o.SerializerSettings.Converters.Add(new StringEnumConverter
    {
        CamelCaseText = true
    });
});

public class EnumTypesSchemaFilter : ISchemaFilter
{
    private readonly XDocument _xmlComments;
    public EnumTypesSchemaFilter(string xmlPath)
    {
        if(File.Exists(xmlPath))
        {
            _xmlComments = XDocument.Load(xmlPath);
        }
    }
    public void Apply(OpenApiSchema schema, SchemaFilterContext context)
    {
        if (_xmlComments == null) return;
        if(schema.Enum != null && schema.Enum.Count > 0 &&
            context.Type != null && context.Type.IsEnum)
        {
            schema.Description += "<p>Members:</p><ul>";
            var fullTypeName = context.Type.FullName;
            foreach (var enumMemberName in schema.Enum.OfType<OpenApiString>().Select(v => v.Value))
            {
                var fullEnumMemberName = $"F:{fullTypeName}.{enumMemberName}";
                var enumMemberComments = _xmlComments.Descendants("member")
                    .FirstOrDefault(m => m.Attribute("name").Value.Equals(fullEnumMemberName, StringComparison.OrdinalIgnoreCase));
                if (enumMemberComments == null) continue;
                var summary = enumMemberComments.Descendants("summary").FirstOrDefault();
                if (summary == null) continue;
                schema.Description += $"<li><i>{enumMemberName}</i> - {summary.Value.Trim()}</li>";
            }
            schema.Description += "</ul>";
        }
    }
}

services.AddSwaggerGen(c => {
    // Set the comments path for the Swagger JSON and UI.
    var xmlFile = $"{Assembly.GetExecutingAssembly().GetName().Name}.xml";
    var xmlPath = Path.Combine(AppContext.BaseDirectory, xmlFile);
    c.IncludeXmlComments(xmlPath);
    c.SchemaFilter<EnumTypesSchemaFilter>(xmlPath);
});

public Task<Result> ExecuteOperation(int id, OperationType type)

public class EnumTypesDocumentFilter : IDocumentFilter
{
    public void Apply(OpenApiDocument swaggerDoc, DocumentFilterContext context)
    {
        foreach (var path in swaggerDoc.Paths.Values)
        {
            foreach(var operation in path.Operations.Values)
            {
                foreach(var parameter in operation.Parameters)
                {
                    var schemaReferenceId = parameter.Schema.Reference?.Id;
                    if (string.IsNullOrEmpty(schemaReferenceId)) continue;
                    var schema = context.SchemaRepository.Schemas[schemaReferenceId];
                    if (schema.Enum == null || schema.Enum.Count == 0) continue;
                    parameter.Description += "<p>Variants:</p>";
                    int cutStart = schema.Description.IndexOf("<ul>");
                    int cutEnd = schema.Description.IndexOf("</ul>") + 5;
                    parameter.Description += schema.Description
                        .Substring(cutStart, cutEnd - cutStart);
                }
            }
        }
    }
}

services.AddSwaggerGen(c => {
    // Set the comments path for the Swagger JSON and UI.
    var xmlFile = $"{Assembly.GetExecutingAssembly().GetName().Name}.xml";
    var xmlPath = Path.Combine(AppContext.BaseDirectory, xmlFile);
    c.IncludeXmlComments(xmlPath);
    c.SchemaFilter<EnumTypesSchemaFilter>(xmlPath);
    c.DocumentFilter<EnumTypesDocumentFilter>();
});