using System;
using System.Collections.Generic;
using System.Linq;

namespace ET.Server
{
    [EnableClass]
    public sealed class MemoryDBComponent : IDBComponent
    {
        private readonly Dictionary<string, Dictionary<long, byte[]>> data = new();

        public async ETTask Save<T>(long entityId, T entity) where T : class
        {
            Dictionary<long, byte[]> map = this.GetBucket<T>();
            map[entityId] = MongoHelper.Serialize(entity);
            await ETTask.CompletedTask;
        }

        public async ETTask<T> QueryByEntityId<T>(long entityId) where T : class
        {
            await ETTask.CompletedTask;
            Dictionary<long, byte[]> map = this.GetBucket<T>();
            if (!map.TryGetValue(entityId, out byte[] bytes))
            {
                return null;
            }

            return MongoHelper.Deserialize<T>(bytes);
        }

        public async ETTask<List<T>> Query<T>(Func<T, bool> predicate = null) where T : class
        {
            await ETTask.CompletedTask;
            Dictionary<long, byte[]> map = this.GetBucket<T>();
            IEnumerable<T> entities = map.Values.Select(MongoHelper.Deserialize<T>);
            if (predicate != null)
            {
                entities = entities.Where(predicate);
            }

            return entities.ToList();
        }

        public ETTask Update<T>(long entityId, T entity) where T : class
        {
            return this.Save(entityId, entity);
        }

        public async ETTask Delete<T>(long entityId) where T : class
        {
            Dictionary<long, byte[]> map = this.GetBucket<T>();
            map.Remove(entityId);
            await ETTask.CompletedTask;
        }

        private Dictionary<long, byte[]> GetBucket<T>() where T : class
        {
            string key = typeof(T).Name;
            if (!this.data.TryGetValue(key, out Dictionary<long, byte[]> bucket))
            {
                bucket = new Dictionary<long, byte[]>();
                this.data[key] = bucket;
            }

            return bucket;
        }
    }
}