using System;

using System.Collections.Generic;

using Jint.Native;

using Raven.Client;

using Raven.Server.ServerWide.Context;

using Sparrow.Json;

using Sparrow.Logging;



namespace Raven.Server.Documents.Patch

{

    public class PatchConflict

    {

        private readonly DocumentDatabase _database;

        private readonly List<object> _docs = new List<object>();

        private readonly DocumentConflict _fstDocumentConflict;

        private readonly bool _hasTombstone;

        private static readonly string TombstoneResolverValue = Guid.NewGuid().ToString();

        private readonly Logger _logger;



        public PatchConflict(DocumentDatabase database, IReadOnlyList<DocumentConflict> docs)

        {

            _logger = LoggingSource.Instance.GetLogger<PatchConflict>(database.Name);

            _database = database;



            foreach (var doc in docs)

            {

                if (doc.Doc != null)

                {

                    _docs.Add(doc);

                }

                else

                {

                    _hasTombstone = true;

                }

            }

            _fstDocumentConflict = docs[0];

        }



        public bool TryResolveConflict(DocumentsOperationContext context, PatchRequest patch, out BlittableJsonReaderObject resolved)

        {

            using (_database.Scripts.GetScriptRunner(patch, false, out var run))

            using (var result = run.Run(context, context, "resolve", new object[] { _docs, _hasTombstone, TombstoneResolverValue }))

            {

                if (result.IsNull)

                {

                    resolved = null;

                    if (_logger.IsInfoEnabled)

                    {

                        _logger.Info(

                            $"Conflict resolution script for {_fstDocumentConflict.Collection} collection declined to resolve the conflict for {_fstDocumentConflict.LowerId}");

                    }

                    return false;

                }

                if (result.StringValue == TombstoneResolverValue)

                {

                    resolved = null;

                    return true;

                }

                var instance = result.GetOrCreate(Constants.Documents.Metadata.Key);

                // if user didn't specify it, we'll take it from the first doc

                // we cannot change collections here anyway, anything else, the 

                // user need to merge on their own

                instance.Put(Constants.Documents.Metadata.Collection, new JsValue(_fstDocumentConflict.Collection), false);

                resolved = result.TranslateToObject(context, usageMode: BlittableJsonDocumentBuilder.UsageMode.ToDisk);

                return true;

            }

        }

    }

}