using iTextSharp.text.log;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Extensions;
using Microsoft.IO;

namespace DealerSelection.Common.Logging;

public class LoggingMiddleware
{
    public const string Key = "LoggingMiddlewareCfg";
    private const int ReadChunkBufferLength = 4096;
    private const int MaxContentLength = 10 * 1024 * 1024; //10MB 
    private RecyclableMemoryStreamManager MemoryStreamManager { get; set; } = null;
    private readonly RequestDelegate RequestDelegate;
    enum ErrorTypes
    {
        Validation,
        Error
    };

    public LoggingMiddleware(RequestDelegate requestDelegate)
    {
        RequestDelegate = requestDelegate;

        MemoryStreamManager = new RecyclableMemoryStreamManager();
    }

    public async Task Invoke(HttpContext context, ILogger logger)
    {
        try 
        {
            ApiInfo loggingInfo = await ExtractInfoFromRequest(context.Request);

            Stream originalBodyStream = context.Request.Body;
            using MemoryStream responseBody = MemoryStreamManager.GetStream();
            context.Response.Body = responseBody;

            await RequestDelegate(context);

            ExtractMessageHeaderIntoInfo(loggingInfo, context.Request);

            if(await ExtractResponseInfo(loggingInfo, context.Response, originalBodyStream, logger))
            {
                //logger.Info(loggingInfo.ToString());
                AzureLogHelper.LogMessage($"Api Incoming: {loggingInfo.ToString()}");
            }
        }
        catch { }
    }

    private async Task<ApiInfo> ExtractInfoFromRequest(HttpRequest request)
    {
        ApiInfo info = new ApiInfo(request.Method, request.GetDisplayUrl(),Environment.MachineName,DateTime.Now);

        if(request.ContentLength.GetValueOrDefault() > 0)
        {
            request.EnableBuffering();

            using MemoryStream requestStream = MemoryStreamManager.GetStream();
            await request.Body.CopyToAsync(requestStream);
            info.RequestInfo.ContentBody = await ReadStreamInChunks(requestStream);

            request.Body.Position = 0;
        }
        return info;
    }

    private async Task<string> ReadStreamInChunks(Stream stream)
    {
        stream.Seek(0, SeekOrigin.Begin);
        await using StringWriter textWriter = new StringWriter();
        using StreamReader reader = new StreamReader(stream);
        char[] readChunk = new char[ReadChunkBufferLength];
        int readChunkLength;
        do
        {
            readChunkLength = await reader.ReadBlockAsync(readChunk, 0, ReadChunkBufferLength);
            await textWriter.WriteAsync(readChunk, 0, readChunkLength);
        } while (readChunkLength > 0);
        return textWriter.ToString();
    }

    private async Task<bool> ExtractResponseInfo(ApiInfo loggingInfo, HttpResponse response, Stream originalBodyStream, ILogger logger)
    {
        //loggingInfo.CustomInfo = new CustomInfo(response);
        if(loggingInfo.IsValid())
        {
            try
            {
                loggingInfo.ResponseInfo = new ResponseInfo(response);
                response.Body.Seek(0, SeekOrigin.Begin);

                if(response.Body.Length < MaxContentLength) 
                    loggingInfo.ResponseInfo.ContentBody = await new StreamReader(response.Body).ReadToEndAsync();
                else
                    loggingInfo.ResponseInfo.ContentBody = $"Size {response.Body.Length} too large to retrieve";
            }
            catch (Exception ex)
            {
                logger.Error($"Exception logging request {@loggingInfo}, error {@ex}");
                return false;
            }

            loggingInfo.ResponseInfo.ContentType = response.Headers.ContentType.Any() ? string.Join(",", response.Headers.ContentType) : null;
        }
        response.Body.Seek(0, SeekOrigin.Begin);

        await response.Body.CopyToAsync(originalBodyStream);
        return loggingInfo.IsValid();
    }
    
    
    private void ExtractMessageHeaderIntoInfo(ApiInfo apiInfo, HttpRequest request)
    {
        //List<KeyValuePair<string, StringValues>> headers = request.Headers.ToList();
        //apiInfo.RequestInfo.BuId = HttpHeaderHelper.ExtractInt(CustomInfo.BuId, headers);
        //apiInfo.RequestInfo.RecordId = HttpHeaderHelper.ExtractInt(CustomInfo.RecordId, headers);
        //apiInfo.RequestInfo.SecurityContext = HttpHeaderHelper.ExtractInt(CustomInfo.SecurityContext, headers);
        //apiInfo.RequestInfo.InnerException = HttpHeaderHelper.ExtractInt(CustomInfo.InnerException, headers);
        //apiInfo.RequestInfo.ExceptionStack = HttpHeaderHelper.ExtractInt(CustomInfo.ExceptionStack, headers);
        //apiInfo.RequestInfo.RealException = HttpHeaderHelper.ExtractInt(CustomInfo.RealException, headers);
        //apiInfo.RequestInfo.BuId = HttpHeaderHelper.ExtractInt(CustomInfo.BuId, headers);
        //apiInfo.RequestInfo.BuId = HttpHeaderHelper.ExtractInt(CustomInfo.BuId, headers);

    }
}