using Microsoft.AspNetCore.Http;
using System.Linq;

namespace NDB.Extensions.Swagger.ReverseProxy
{
    public static class ReverseProxyHelper
    {
        public static (string host, string basePath, string scheme) GetUrlComponents(HttpRequest request)
        {
            var host = ExtractHost(request);
            var basePath = ExtractBasePath(request);
            var scheme = ExtractScheme(request);

            return (host, basePath, scheme);
        }

        private static string ExtractHost(HttpRequest request)
        {
            if (request.Headers.ContainsKey("X-Forwarded-Host"))
                return request.Headers["X-Forwarded-Host"].First();

            return request.Host.Value;
        }

        private static string ExtractBasePath(HttpRequest request)
        {
            if (request.Headers.ContainsKey("X-Forwarded-PathBase"))
                return request.Headers["X-Forwarded-PathBase"].First();

            return string.Empty;
        }

        private static string ExtractScheme(HttpRequest request)
        {
            return request.Headers["X-Forwarded-Proto"].FirstOrDefault() ?? request.Scheme;
        }
    }
}