using AsbCloudApp.Services;
using System;
using System.Collections.Generic;
using System.Linq;
using AsbCloudDb.Model;
using AsbCloudInfrastructure.Services.Cache;
using Microsoft.EntityFrameworkCore;

namespace AsbCloudInfrastructure.Services
{
    public class TelemetryTracker : ITelemetryTracker
    {
        class TrackerStat
        {
            //public int Id { get; set; }

            public string RemoteUid { get; set; }

            /// <summary>
            /// Время последнего запроса (по времени сервера)
            /// </summary>
            public DateTime LastTimeServer { get; set; }

            /// <summary>
            /// Время указанное в данных последнего запроса (из удаленного источника)
            /// </summary>
            public DateTime LastTimeRemote { get; set; }
        }

        private readonly Dictionary<string, TrackerStat> requests;

        public TelemetryTracker(CacheDb cacheDb)
        {
            var options = new DbContextOptionsBuilder<AsbCloudDbContext>()
                .UseNpgsql("Host=localhost;Database=postgres;Username=postgres;Password=q;Persist Security Info=True")
                .Options;
            using var db = new AsbCloudDbContext(options);

            var cacheTelemetry = cacheDb.GetCachedTable<Telemetry>(db);
            
            var lastTelemetriesDates = (from d in db.TelemetryDataSaub
                                        group d by d.IdTelemetry into g
                                        select new
                                        {
                                            IdTelemetry = g.Key,
                                            Date = g.Max(t => t.Date)
                                        })
                                        .AsNoTracking()
                                        .ToList();

            requests = lastTelemetriesDates.Select(t => new
            {
                //Id = t.IdTelemetry,
                RemoteUid = cacheTelemetry.FirstOrDefault(c => c.Id == t.IdTelemetry).RemoteUid,
                LastTimeRemote = t.Date,

            }).ToDictionary(t => t.RemoteUid, t => new TrackerStat {
                //Id = t.Id,
                RemoteUid = t.RemoteUid,
                LastTimeRemote = t.LastTimeRemote,
                LastTimeServer = t.LastTimeRemote,
            });
        }

        public void SaveRequestDate(string uid, DateTime remoteDate)
        {
            var stat = requests.GetValueOrDefault(uid);
            if(stat is null)
            {
                stat = new TrackerStat{ RemoteUid = uid };
                requests[uid] = stat;
            }
            stat.LastTimeServer = DateTime.Now;
            stat.LastTimeRemote = remoteDate;
        }

        public DateTime GetLastTelemetryDateByUid(string uid) =>
            requests.GetValueOrDefault(uid)?.LastTimeRemote ?? default;

        public IEnumerable<string> GetTransmittingTelemetriesUids() =>
            requests.Keys;
    }
}