using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.Hosting;
using MongoDB.Driver;
using PolyTrader.Core.Persistence;
using PolyTraderSharp.Models;

namespace PolyTraderSharp.Services
{
    /// <summary>
    /// Hydriert den TradingState (Accounts, Demo-Positionen, Trader) EINMALIG beim App-Start.
    /// Registriert als erster IHostedService, damit die Hydration abgeschlossen ist, bevor die
    /// Trading-BackgroundServices (TraderMonitor, CopyTradingEngine, ...) ihre ExecuteAsync
    /// starten. Behebt den Startup-Race, bei dem Services gegen einen leeren State anliefen
    /// (früher lag diese Logik in frm_main.LoadDatabaseAndState und lief erst NACH AppHost.Start()).
    /// </summary>
    public class StartupHydrationService : IHostedService
    {
        private readonly TradingState _state;
        private readonly CopyTradingState _copyState;
        private readonly IAccountRepository _accountRepo;
        private readonly IPositionRepository _positionRepo;
        private readonly IMongoDatabase _db;
        private readonly TerminalLogger _logger;

        public StartupHydrationService(
            TradingState state,
            CopyTradingState copyState,
            IAccountRepository accountRepo,
            IPositionRepository positionRepo,
            IMongoDatabase db,
            TerminalLogger logger)
        {
            _state = state;
            _copyState = copyState;
            _accountRepo = accountRepo;
            _positionRepo = positionRepo;
            _db = db;
            _logger = logger;
        }

        public Task StartAsync(CancellationToken cancellationToken)
        {
            try
            {
                foreach (var acc in _accountRepo.GetAll())
                {
                    if (acc.IsDemo)
                    {
                        foreach (var pos in _positionRepo.GetDemo(acc.AccountId))
                        {
                            acc.OpenPositions.TryAdd(pos.TokenId, pos);
                        }
                    }
                    _state.Accounts[acc.AccountId] = acc;
                }

                // Trader (TrackedTrader) sind aktuell noch modulnah; bis zum Trader-Repo in
                // Phase 5 direkt aus der "trackers"-Collection geladen.
                var tradersCol = _db.GetCollection<TrackedTrader>("trackers");
                foreach (var trd in tradersCol.Find(_ => true).ToList())
                {
                    _copyState.Traders[trd.Id] = trd;
                }

                _logger.Info($"Startup-Hydration abgeschlossen: {_state.Accounts.Count} Accounts, {_copyState.Traders.Count} Trader geladen.");
            }
            catch (System.Exception ex)
            {
                _logger.Error($"Startup-Hydration fehlgeschlagen: {ex.Message}");
            }

            return Task.CompletedTask;
        }

        public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
    }
}