using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Tango.BL;
using Tango.Telemetry.Mappers;
using Tango.Telemetry.Telemetries;

namespace Tango.Telemetry.Sources
{
    public class TelemetryEventsHistorySource : ITelemetryHistorySource
    {
        private bool _isBusy;

        public TelemetryHistorySourceDirection Direction { get; } = TelemetryHistorySourceDirection.Descending;
        public string Name { get; } = "Events History";
        public bool RequiresTelemetryDuplicationTracking { get; } = true;

        public async Task<bool> CanRequestHistory(DateTime from)
        {
            if (_isBusy)
            {
                return false;
            }
            else
            {
                try
                {
                    using (ObservablesContext db = ObservablesContext.CreateDefault())
                    {
                        return await db.MachinesEvents.CountAsync(x => x.LastUpdated < from) > 0;
                    }
                }
                catch
                {
                    return false;
                }
            }
        }

        public async Task<IEnumerable<ITelemetry>> RequestHistory(DateTime from)
        {
            try
            {
                _isBusy = true;

                using (ObservablesContext db = ObservablesContext.CreateDefault())
                {
                    var events = await db.MachinesEvents
                        .OrderByDescending(x => x.LastUpdated)
                        .Where(x => x.LastUpdated < from)
                        .Take(10)
                        .ToListAsync();

                    List<TelemetryEvent> tRuns = new List<TelemetryEvent>();

                    foreach (var ev in events)
                    {
                        var tEvent = EventMapper.MapEvent(ev);
                        tRuns.Add(tEvent);
                    }

                    return tRuns;
                }
            }
            finally
            {
                _isBusy = false;
            }
        }

        public void Dispose()
        {
            
        }
    }
}