#pragma warning disable CS0618
using ServiceStack.Web;
using System;
using System.IO;
using System.Threading.Tasks;
using ServiceStack.Text;

namespace ServiceStack;

public class CompressResponseAttribute : ResponseFilterAsyncAttribute
{
    public override async Task ExecuteAsync(IRequest req, IResponse res, object response)
    {
        if (response is Exception)
            return;
        if (req.IsInProcessRequest())
            return;

        var httpResult = response as IHttpResult;
        var src = httpResult != null ? httpResult.Response : response;
        if (httpResult != null)
        {
            res.StatusCode = (int)httpResult.StatusCode;
        }
        if (src == null)
        {
            var concreteResult = response as HttpResult;
            src = concreteResult?.ResponseStream 
                  ?? (object) concreteResult?.ResponseText;
        }

        if (src is null or IPartialWriter or IPartialWriterAsync or IStreamWriter or IStreamWriterAsync)
            return;

        var encoding = req.GetCompressionType();
        if (encoding == null) //Client doesn't support compression
            return;

        var responseBytes = src as byte[];
        if (responseBytes == null)
        {
            if (src is string rawStr)
                responseBytes = rawStr.ToUtf8Bytes();
            else
            {
                if (src is Stream stream)
                    responseBytes = await stream.ReadFullyAsync().ConfigAwait();
            }
        }

        if (responseBytes != null || req.ResponseContentType.IsBinary())
        {
            if (responseBytes == null)
                responseBytes = HostContext.ContentTypes.SerializeToBytes(req, src);

            res.AddHeader(HttpHeaders.ContentEncoding, encoding);
            responseBytes = responseBytes.CompressBytes(encoding);
        }
        else
        {
            var serializedDto = req.SerializeToString(src);
            if (req.ResponseContentType.MatchesContentType(MimeTypes.Json))
            {
                var jsonp = req.GetJsonpCallback();
                if (jsonp != null)
                    serializedDto = jsonp + "(" + serializedDto + ")";
            }

            responseBytes = serializedDto.ToUtf8Bytes();

            res.AddHeader(HttpHeaders.ContentEncoding, encoding);
            responseBytes = responseBytes.CompressBytes(encoding);
        }

        if (httpResult != null)
        {
            foreach (var header in httpResult.Headers)
            {
                res.AddHeader(header.Key, header.Value);
            }
        }

        await res.WriteBytesToResponse(responseBytes, req.ResponseContentType).ConfigAwait();
        using (response as IDisposable) {}
    }
}