using AsbCloudDb.Model;
using AsbCloudDb.Model.Subsystems;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
using System;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace AsbCloudInfrastructure.Services.Subsystems
{
#nullable enable    
    internal class SubsystemOperationTimeBackgroundService : BackgroundService
    {
        private readonly string connectionString;
        private readonly TimeSpan period = TimeSpan.FromHours(1);
        private const int idSubsytemTorqueMaster = 65537;
        private const int idSubsytemSpinMaster = 65536; 
        public SubsystemOperationTimeBackgroundService(IConfiguration configuration)
        {
            connectionString = configuration.GetConnectionString("DefaultConnection");
        }
        protected override async Task ExecuteAsync(CancellationToken token)
        {
            var timeToStartAnalysis = DateTime.Now;
            var options = new DbContextOptionsBuilder<AsbCloudDbContext>()
                .UseNpgsql(connectionString)
                .Options;
            while (!token.IsCancellationRequested)
            {
                if (DateTime.Now > timeToStartAnalysis)
                {
                    timeToStartAnalysis = DateTime.Now + period;
                    try
                    {
                        using var context = new AsbCloudDbContext(options);
                        var added = await OperationTimeAllTelemetriesAsync(context, token);
                        Trace.TraceInformation($"Total subsystem operation time complete. Added {added} operations time.");
                    }
                    catch (Exception ex)
                    {
                        Trace.TraceError(ex.Message);
                    }
                    GC.Collect();
                }
                var ms = (int)(timeToStartAnalysis - DateTime.Now).TotalMilliseconds;
                ms = ms > 100 ? ms : 100;
                await Task.Delay(ms, token).ConfigureAwait(false);
            }
        }        

        public override async Task StopAsync(CancellationToken token)
        {
            await base.StopAsync(token).ConfigureAwait(false);
        }

        private static async Task<int> OperationTimeAllTelemetriesAsync(IAsbCloudDbContext db, CancellationToken token)
        {
            var lastDetectedDates = await db.SubsystemOperationTimes
                .GroupBy(o => o.IdTelemetry)
                .Select(g => new
                {
                    IdTelemetry = g.Key,
                    LastDate = g.Max(o => o.DateEnd)
                })
                .ToListAsync(token);

            var telemetryIds = await db.Telemetries
                .Where(t => t.Info != null && t.TimeZone != null)
                .Select(t => t.Id)
                .ToListAsync(token);

            var JounedlastDetectedDates = telemetryIds
                .GroupJoin(lastDetectedDates,
                    t => t,
                    o => o.IdTelemetry,
                    (outer, inner) => new
                    {
                        IdTelemetry = outer,
                        inner.SingleOrDefault()?.LastDate,
                    });
            var affected = 0;
            foreach (var item in JounedlastDetectedDates)
            {
                var newOperationsSaub = await OperationTimeSaubAsync(item.IdTelemetry, item.LastDate ?? DateTimeOffset.MinValue, db, token);
                if (newOperationsSaub?.Any() == true)
                {
                    db.SubsystemOperationTimes.AddRange(newOperationsSaub);
                    affected += await db.SaveChangesAsync(token);
                }
                var newOperationsSpin = await OperationTimeSpinAsync(item.IdTelemetry, item.LastDate ?? DateTimeOffset.MinValue, db, token);
                if (newOperationsSpin?.Any() == true)
                {
                    db.SubsystemOperationTimes.AddRange(newOperationsSpin);
                    affected += await db.SaveChangesAsync(token);
                }
            }
            return affected;
        }

        private static async Task<IEnumerable<SubsystemOperationTime>?> OperationTimeSaubAsync(int idTelemetry, DateTimeOffset begin, IAsbCloudDbContext db, CancellationToken token)
        {
            var query = db.TelemetryDataSaub
                .AsNoTracking()
                .Where(d => d.IdTelemetry == idTelemetry)
                .Select(d => new 
                {
                    DateTime = d.DateTime,                    
                    Mode = d.Mode,
                    Depth = d.WellDepth
                })
                .OrderBy(d => d.DateTime);
            var take = 4 * 86_400; // 4 дня
            var startDate = begin;            
            
            var resultSubsystemOperationTime = new List<SubsystemOperationTime>();
            while (true)
            {
                var data = await query
                .Where(d => d.DateTime > startDate)
                .Take(take)
                .ToArrayAsync(token);                
                var firstItem = data.FirstOrDefault();
                if (firstItem is null)
                    break;
                short? mode = firstItem.Mode;
                DateTimeOffset dateBegin = firstItem.DateTime;
                float? depthStart = firstItem.Depth;
                for (int i = 1; i < data.Length; i++)
                {
                    if (data[i].Mode != mode)
                    {
                        
                        var operationTimeItem = new SubsystemOperationTime()
                        {
                            IdTelemetry = idTelemetry,
                            DateStart = dateBegin,                            
                            DateEnd = data[i - 1].DateTime,
                            DepthStart = depthStart,
                            DepthEnd = data[i - 1].Depth
                        };
                        if (mode.HasValue)
                        {
                            operationTimeItem.IdSubsystem = (int)mode + 1;
                            resultSubsystemOperationTime.Add(operationTimeItem);
                        }
                        mode = data[i].Mode;
                        dateBegin = data[i].DateTime;
                        depthStart = data[i].Depth;
                    }
                }
                startDate = data.Last().DateTime;
            }
            return resultSubsystemOperationTime;
        }        
        private static async Task<IEnumerable<SubsystemOperationTime>?> OperationTimeSpinAsync(int idTelemetry, DateTimeOffset begin, IAsbCloudDbContext db, CancellationToken token)
        {
            Predicate<int> isSubsystemTorqueState = (int state) => state == 7;
            Predicate<short> isSubsystemTorqueMode = (short mode) => (mode & 2) > 0;
            Predicate<int> isSubsystemSpin = (int state) => state != 0 & state != 6 & state != 7;
            var operationTimeSpinWithDepth =
                $"select tspin.\"date\", tspin.\"mode\", tspin.\"state\", tsaub.\"well_depth\"" +
                $" from (select \"date\" ,\"mode\" ,lag(mode, 1) over (order by \"date\") as mode_pre, state , " +
                $"lag(state, 1) over (order by \"date\") as state_pre from t_telemetry_data_spin where id_telemetry = {idTelemetry} and date >= '{begin}') as tspin " +
                $"join (select \"date\", well_depth from t_telemetry_data_saub where id_telemetry = {idTelemetry} and date >= '{begin}') as tsaub " +
                $"on EXTRACT(EPOCH from tspin.date) = EXTRACT(EPOCH from tsaub.date) " +
                $"where mode!=mode_pre or state != state_pre order by \"date\";";            
            using var command =  db.Database.GetDbConnection().CreateCommand();
            command.CommandText = operationTimeSpinWithDepth;
            db.Database.OpenConnection();
            using var result = await command.ExecuteReaderAsync(token);            
            var telemetryOpearationSpinSubsystems = new List<SubsystemsSpinWithDepth>();            
            if (result.HasRows)
            {                
                while (result.Read())
                {
                    var itemEntity = new SubsystemsSpinWithDepth()
                    {
                        Date = result.GetFieldValue<DateTimeOffset>(0),
                        Mode = result.GetFieldValue<short>(1),
                        State = result.GetFieldValue<int>(2),
                        Depth = result.GetFieldValue<float>(3)
                    };
                    int? subsystemId = isSubsystemTorqueState(itemEntity.State) && isSubsystemTorqueMode(itemEntity.Mode)
                        ? idSubsytemTorqueMaster
                        : isSubsystemSpin(itemEntity.State)
                            ? idSubsytemSpinMaster
                            : 0;
                    if (subsystemId.HasValue)
                    {
                        itemEntity.IdSubsystem = subsystemId.Value;
                        telemetryOpearationSpinSubsystems.Add(itemEntity);
                    }         
                }
            }                
            var take = 4 * 86_400; // 4 дня
            var startDate = begin;            
            var resultSubsystemOperationTime = new List<SubsystemOperationTime>();
            while (true)
            {
                var data = telemetryOpearationSpinSubsystems
                    .Where(d => d.Date > startDate)
                    .Take(take)
                    .ToArray();
                var firstItem = data.FirstOrDefault();
                if (firstItem is null)
                    break;
                int idSubsystem = firstItem.IdSubsystem;
                DateTimeOffset dateBegin = firstItem.Date;
                float? depthStart = firstItem.Depth;
                for (int i = 1; i < data.Length; i++)
                {
                    if (data[i].IdSubsystem != idSubsystem)
                    {
                        var operationTimeItem = new SubsystemOperationTime()
                        {
                            IdTelemetry = idTelemetry,
                            DateStart = dateBegin,
                            IdSubsystem = data[i - 1].IdSubsystem,
                            DateEnd = data[i].Date,
                            DepthStart = depthStart,
                            DepthEnd = data[i].Depth

                        };
                        dateBegin = data[i].Date;
                        depthStart = data[i].Depth;
                        idSubsystem = data[i].IdSubsystem;
                        if (data[i - 1].IdSubsystem != 0)
                        {
                            resultSubsystemOperationTime.Add(operationTimeItem);
                        }
                    }
                }                
                startDate = data.LastOrDefault().Date;
            }
            return resultSubsystemOperationTime;
        }        
    }
#nullable disable
}