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
    {
        private Dictionary<string, DateTime> requests;
        private readonly TimeSpan timeout;

        public TelemetryTracker(CacheDb cacheDb)
        {
            timeout = TimeSpan.FromDays(7);

            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.Max(t => t.IdTelemetry),
                                            Date = g.Max(t => t.Date)
                                        }).ToList();

            requests = lastTelemetriesDates.Select(t => new
            {
                Uid = cacheTelemetry.FirstOrDefault(c => c.Id == t.IdTelemetry).RemoteUid,
                t.Date
            }).ToDictionary(t => t.Uid, u => u.Date);
        }

        public void SaveRequestDate(string uid)
        {
            requests[uid] = DateTime.Now;
            DeleteOldRequestDates();
        }

        public DateTime GetLastTelemetryDateByUid(string uid) =>
            requests.GetValueOrDefault(uid, DateTime.MinValue);

        public IEnumerable<string> GetTransmittingTelemetryUids()
        {
            DeleteOldRequestDates();
            return requests.Keys;
        }
        
        private void DeleteOldRequestDates() // TODO: удалить этот метод
        {
            requests = requests.Where(dValue => (DateTime.Now - dValue.Value) < timeout)
                .ToDictionary(dValue => dValue.Key, dValue => dValue.Value);
        }
    }
}