PolyTraderSharp/services/SnapshotService.cs

using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json;
using PolyTraderSharp.Models;

namespace PolyTraderSharp.Services
{
    public class SnapshotService : BackgroundService
    {
        private readonly TradingState _state;
        private readonly CopyTradingState _copyState;
        private readonly ILogger<SnapshotService> _logger;
        private readonly string _snapshotPath = "snapshot.json";
        private readonly TimeSpan _interval = TimeSpan.FromSeconds(30);

        private readonly JobStatusRow _jobStatus;

        public SnapshotService(TradingState state, CopyTradingState copyState, ILogger<SnapshotService> logger, JobManager jobManager)
        {
            _state = state;
            _copyState = copyState;
            _logger = logger;

            _jobStatus = new JobStatusRow
            {
                JobName = "LiteDB State Snapshot",
                Description = "Saves active application state (balances, open pos) to snapshot.json.",
                StatusText = "Pending Initial Delay..."
            };

            _jobStatus.ManualTriggerAction = async () => 
            {
                string oldStatus = _jobStatus.StatusText;
                _jobStatus.StatusText = "Running (Manual)...";
                await SaveSnapshotAsync();
                _jobStatus.StatusText = "Idle";
            };

            jobManager.RegisterJob(_jobStatus);
        }

        public override async Task StartAsync(CancellationToken cancellationToken)
        {
            // Load state on startup
            if (File.Exists(_snapshotPath))
            {
                try
                {
                    string json = await File.ReadAllTextAsync(_snapshotPath, cancellationToken);
                    var snapshot = JsonConvert.DeserializeObject<StateSnapshot>(json);
                    
                    if (snapshot != null)
                    {
                        _state.LiveTradingMode = snapshot.LiveMode;
                        _state.DemoTradingMode = snapshot.DemoMode;
                        _copyState.TotalCopyTrades = snapshot.CopyTrades;
                        _state.GlobalPnl = snapshot.GlobalPnl;
                        
                        int restoredPositions = 0;
                        // Restore OpenPositions to matching accounts
                        foreach (var kvp in snapshot.OpenPositions)
                        {
                            if (_state.Accounts.TryGetValue(kvp.Key, out var acc))
                            {
                                foreach (var pos in kvp.Value)
                                {
                                    acc.OpenPositions.TryAdd(pos.Key, pos.Value);
                                    restoredPositions++;
                                }
                            }
                        }
                        
                        _logger.LogInformation($"Snapshot loaded. Restored {restoredPositions} positions. Modes: Live={snapshot.LiveMode}, Demo={snapshot.DemoMode}");
                    }
                }
                catch (Exception ex)
                {
                    _logger.LogError(ex, "Failed to load snapshot on startup");
                }
            }

            await base.StartAsync(cancellationToken);
        }

        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            _jobStatus.StatusText = "Idle";

            while (!stoppingToken.IsCancellationRequested)
            {
                if (_jobStatus.IsEnabled)
                {
                    try
                    {
                        _jobStatus.StatusText = "Running (Scheduled)...";
                        await SaveSnapshotAsync();
                        _jobStatus.LastRun = DateTime.Now;
                    }
                    catch (TaskCanceledException)
                    {
                        break;
                    }
                    catch (Exception ex)
                    {
                        _logger.LogError(ex, "Error saving TradingState snapshot");
                        _jobStatus.StatusText = "Error!";
                    }
                    finally
                    {
                        if (_jobStatus.StatusText != "Error!") _jobStatus.StatusText = "Idle";
                    }
                }
                else
                {
                    _jobStatus.StatusText = "Paused";
                }

                _jobStatus.NextRun = DateTime.Now.Add(_interval);
                await Task.Delay(_interval, stoppingToken);
            }
        }

        private async Task SaveSnapshotAsync()
        {
            var snapshot = new StateSnapshot
            {
                LiveMode = _state.LiveTradingMode,
                DemoMode = _state.DemoTradingMode,
                CopyTrades = _copyState.TotalCopyTrades,
                GlobalPnl = _state.GlobalPnl,
                OpenPositions = _state.Accounts.ToDictionary(
                    a => a.Key, 
                    a => a.Value.OpenPositions.ToDictionary(p => p.Key, p => p.Value)
                )
            };

            string json = JsonConvert.SerializeObject(snapshot, Formatting.Indented);
            await File.WriteAllTextAsync(_snapshotPath, json);

            _logger.LogTrace("TradingState snapshot saved.");
        }

        private class StateSnapshot
        {
            public TradingMode LiveMode { get; set; }
            public TradingMode DemoMode { get; set; }
            public int CopyTrades { get; set; }
            public decimal GlobalPnl { get; set; }
            public Dictionary<int, Dictionary<string, Position>> OpenPositions { get; set; } = new();
        }
    }
}