jellyfin-server/Jellyfin.Server/Extensions/ApiApplicationBuilderExtensions.cs

using System.Collections.Generic;
using MediaBrowser.Controller.Configuration;
using Microsoft.AspNetCore.Builder;
using Microsoft.OpenApi.Models;

namespace Jellyfin.Server.Extensions
{
    /// <summary>
    /// Extensions for adding API specific functionality to the application pipeline.
    /// </summary>
    public static class ApiApplicationBuilderExtensions
    {
        /// <summary>
        /// Adds swagger and swagger UI to the application pipeline.
        /// </summary>
        /// <param name="applicationBuilder">The application builder.</param>
        /// <param name="serverConfigurationManager">The server configuration.</param>
        /// <returns>The updated application builder.</returns>
        public static IApplicationBuilder UseJellyfinApiSwagger(
            this IApplicationBuilder applicationBuilder,
            IServerConfigurationManager serverConfigurationManager)
        {
            // Enable middleware to serve swagger-ui (HTML, JS, CSS, etc.),
            // specifying the Swagger JSON endpoint.

            var baseUrl = serverConfigurationManager.Configuration.BaseUrl.Trim('/');
            var apiDocBaseUrl = serverConfigurationManager.Configuration.BaseUrl;
            if (!string.IsNullOrEmpty(baseUrl))
            {
                baseUrl += '/';
            }

            return applicationBuilder
                .UseSwagger(c =>
                {
                    // Custom path requires {documentName}, SwaggerDoc documentName is 'api-docs'
                    c.RouteTemplate = $"/{baseUrl}{{documentName}}/openapi.json";
                    c.PreSerializeFilters.Add((swagger, httpReq) =>
                    {
                        swagger.Servers = new List<OpenApiServer> { new OpenApiServer { Url = $"{httpReq.Scheme}://{httpReq.Host.Value}{apiDocBaseUrl}" } };

                        // BaseUrl is empty, ignore
                        if (apiDocBaseUrl.Length != 0)
                        {
                            // Update all relative paths to remove baseUrl.
                            var updatedPaths = new OpenApiPaths();
                            foreach (var (key, value) in swagger.Paths)
                            {
                                var relativePath = key;
                                relativePath = relativePath.Remove(0, apiDocBaseUrl.Length);
                                updatedPaths.Add(relativePath, value);
                            }

                            swagger.Paths = updatedPaths;
                        }
                    });
                })
                .UseSwaggerUI(c =>
                {
                    c.DocumentTitle = "Jellyfin API";
                    c.SwaggerEndpoint($"/{baseUrl}api-docs/openapi.json", "Jellyfin API");
                    c.RoutePrefix = $"{baseUrl}api-docs/swagger";
                })
                .UseReDoc(c =>
                {
                    c.DocumentTitle = "Jellyfin API";
                    c.SpecUrl($"/{baseUrl}api-docs/openapi.json");
                    c.RoutePrefix = $"{baseUrl}api-docs/redoc";
                });
        }
    }
}