using Laservall.Solidworks.Server.Dto;
using Newtonsoft.Json;
using System.IO;
using System.Net;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace Laservall.Solidworks.Server.Handlers
{
    internal sealed class SaveHandler
    {
        private readonly IBomDataProvider _dataProvider;

        public SaveHandler(IBomDataProvider dataProvider)
        {
            _dataProvider = dataProvider;
        }

        public async Task HandleSave(HttpListenerContext context, CancellationToken ct)
        {
            string body;
            using (var reader = new StreamReader(context.Request.InputStream, Encoding.UTF8))
            {
                body = await reader.ReadToEndAsync();
            }

            var request = JsonConvert.DeserializeObject<SaveRequest>(body);
            if (request?.Changes == null || request.Changes.Count == 0)
            {
                await WriteJson(context.Response, new SaveResponse { Success = true, SavedCount = 0 }, ct);
                return;
            }

            var changes = new System.Collections.Generic.List<ChangeItem>();
            foreach (var c in request.Changes)
            {
                changes.Add(new ChangeItem
                {
                    DocPath = c.DocPath,
                    Key = c.Key,
                    Value = c.Value
                });
            }

            var result = _dataProvider.SaveChanges(changes);
            var response = new SaveResponse
            {
                Success = result.Success,
                SavedCount = result.SavedCount,
                Error = result.Error
            };

            context.Response.StatusCode = result.Success ? 200 : 500;
            await WriteJson(context.Response, response, ct);
        }

        private static async Task WriteJson(HttpListenerResponse response, object data, CancellationToken ct)
        {
            response.ContentType = "application/json; charset=utf-8";
            string json = JsonConvert.SerializeObject(data);
            byte[] bytes = Encoding.UTF8.GetBytes(json);
            response.ContentLength64 = bytes.Length;
            await response.OutputStream.WriteAsync(bytes, 0, bytes.Length, ct);
            response.Close();
        }
    }
}