using AsbCloudApp.Data;
using AsbCloudApp.Services;
using AsbCloudDb.Model;
using AsbCloudInfrastructure.Services.Cache;
using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace AsbCloudInfrastructure.Services
{
    public abstract class TelemetryDataService<TDto, TModel> : ITelemetryDataService<TDto>, IConverter<TDto, TModel>
        where TDto : AsbCloudApp.Data.ITelemetryData
        where TModel : class, AsbCloudDb.Model.ITelemetryData
    {
        private readonly IAsbCloudDbContext db;
        private readonly ITelemetryService telemetryService;

        protected readonly CacheTable<Telemetry> cacheTelemetry;
        protected readonly CacheTable<TelemetryUser> cacheTelemetryUsers;
        protected readonly CacheTable<Well> cacheWells;

        public TelemetryDataService(
            IAsbCloudDbContext db,
            ITelemetryService telemetryService,
            CacheDb cacheDb)
        {
            this.db = db;
            this.telemetryService = telemetryService;

            cacheTelemetry = cacheDb.GetCachedTable<Telemetry>((AsbCloudDbContext)db);
            cacheTelemetryUsers = cacheDb.GetCachedTable<TelemetryUser>((AsbCloudDbContext)db);
            cacheWells = cacheDb.GetCachedTable<Well>((AsbCloudDbContext)db);
        }

        public virtual async Task<int> UpdateDataAsync(string uid, IEnumerable<TDto> dtos,
            CancellationToken token = default)
        {
            if (dtos == default || !dtos.Any())
                return 0;

            var idTelemetry = telemetryService.GetOrCreateTemetryIdByUid(uid);
            var dtoMinDate = dtos.Min(d => d.Date);
            var dtoMaxDate = dtos.Max(d => d.Date);
            var dataSet = db.Set<TModel>();

            var oldData = await (from d in dataSet
                                 where d.IdTelemetry == idTelemetry
                                        && d.Date > dtoMinDate
                                        && d.Date < dtoMaxDate
                                 select d)
                                .AsNoTracking()
                                .ToListAsync(token)
                                .ConfigureAwait(false);

            if (oldData.Any())
            { 
                dataSet.RemoveRange(oldData);
                await db.SaveChangesAsync(token).ConfigureAwait(false);
            }

            foreach (var dto in dtos)
            {
                dto.IdTelemetry = idTelemetry;
                var data = Convert(dto);
                data.Id = 0;
                dataSet.Add(data);
            }

            return await db.SaveChangesAsync(token).ConfigureAwait(false);
        }

        public virtual async Task<IEnumerable<TDto>> GetAsync(int idWell,
            DateTime dateBegin = default, double intervalSec = 600d,
            int approxPointsCount = 1024, CancellationToken token = default)
        {
            var well = cacheWells.FirstOrDefault(w => w.Id == idWell);
            if (well is null)
                return default;

            var telemetry = cacheTelemetry.FirstOrDefault(t => t.Id == well.IdTelemetry);
            if (telemetry is null)
                return default;

            if (dateBegin == default)
                dateBegin = DateTime.Now.AddSeconds(-intervalSec);

            var datEnd = dateBegin.AddSeconds(intervalSec);
            var dbSet = db.Set<TModel>();

            var query = from data in dbSet
                        where data.IdTelemetry == telemetry.Id
                        && data.Date >= dateBegin && data.Date < datEnd
                        select data;

            var fullDataCount = await query.CountAsync(token)
                .ConfigureAwait(false);

            if (fullDataCount == 0)
                return default;

            if (fullDataCount > 1.75 * approxPointsCount)
            {
                var m = (int)Math.Round(1d * fullDataCount / approxPointsCount);
                if (m > 1)
                    query = query.Where(d => d.Id % m == 0);
            }

            var entities = await query.AsNoTracking()
                .ToListAsync(token).ConfigureAwait(false);

            var dtos = entities.Select(e => Convert(e));

            return dtos;
        }

        public virtual async Task<DatesRangeDto> GetDataDatesRangeAsync(int idWell,
            CancellationToken token = default)
        {
            var telemetryId = telemetryService.GetIdTelemetryByIdWell(idWell);
            if (telemetryId is null)
                return null;

            var (From, To) = await db.GetDatesRangeAsync<TModel>((int)telemetryId, token)
                .ConfigureAwait(false);

            return new DatesRangeDto { From = From, To = To };
        }

        public abstract TDto Convert(TModel src);

        public abstract TModel Convert(TDto src);
    }
}