using Microsoft.AspNetCore.Http;
using System;
using System.IO;
using System.Text;
using System.Threading.Tasks;

namespace Middleware
{
    /// <summary>
    /// Middleware used for logging HTTP requests and responses, their content and statuses
    /// </summary>
    public class LoggingMiddleware
    {
        private RequestDelegate _next;
        private readonly ILogger _logger;

        public LoggingMiddleware(ILogger logger, RequestDelegate next)
        {
            _logger = logger;
            _next = next;
        }

        public async Task InvokeAsync(HttpContext context)
        {
            StringBuilder log = new StringBuilder();

            // Request
            log.Append($"A {context.Request.Method} request arrived at {context.Request.Path} {context.Request.QueryString.ToString()}");
            log.Append($"\nRequest time (local): {DateTime.Now.ToString("r")}");

            if (context.Request.Method.Equals("POST", StringComparison.OrdinalIgnoreCase))
            {
                context.Request.EnableBuffering();

                using (var reader = new StreamReader(context.Request.Body, System.Text.Encoding.UTF8, true, 10240, true))
                {
                    string body = await reader.ReadToEndAsync();
                    string bodyLog = !string.IsNullOrEmpty(body) ? body : "EMPTY";

                    log.Append($"\nBody: {bodyLog}");
                    context.Request.Body.Seek(0, SeekOrigin.Begin);
                }
            }

            // Response
            var originalBodyStream = context.Response.Body;
            using (var responseBody = new MemoryStream())
            {
                context.Response.Body = responseBody;

                // Invoke next middleware
                await _next(context);

                var response = context.Response;

                response.Body.Seek(0, SeekOrigin.Begin);
                string responseText = await new StreamReader(response.Body).ReadToEndAsync();
                string bodyLog = !string.IsNullOrEmpty(responseText) ? responseText : "EMPTY";
                response.Body.Seek(0, SeekOrigin.Begin);

                log.Append($"\nResponse time (local): {DateTime.Now.ToString("r")}");
                log.Append($"\nResponse status: {context.Response.StatusCode}");
                log.Append($"\nBody: {bodyLog}");

                await responseBody.CopyToAsync(originalBodyStream);
            }

            await Task.Run(() =>
            {
                _logger.Log(log.ToString());
                return Task.CompletedTask;
            });
        }
    }
}