Finlytic/FinlyticBackend/Services/FavoritesPriceBackgroundService.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using FinlyticBackend.Database;
using FinlyticBackend.Entities;
using FinlyticBackend.Hubs;
using FinlyticBackend.Util;
using FinlyticCore.Dtos;
using FinlyticCore.Dtos.TechnicalAnalysis;
using Microsoft.AspNetCore.SignalR;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace FinlyticBackend.Services;

/// <summary>
/// Background service that periodically (every 10 seconds) queries FinlyticTechnicalAnalysis over MQTT RPC 
/// to retrieve current close prices and daily % growth for all favorited assets, and broadcasts the updates
/// via SignalR to connected clients.
/// </summary>
public class FavoritesPriceBackgroundService : BackgroundService
{
    private readonly IHubContext<FavoritesPriceHub> _hubContext;
    private readonly WebMqttClient _mqttClient;
    private readonly IServiceScopeFactory _scopeFactory;
    private readonly ILogger<FavoritesPriceBackgroundService> _logger;
    private readonly Random _random = new();

    public FavoritesPriceBackgroundService(
        IHubContext<FavoritesPriceHub> hubContext,
        WebMqttClient mqttClient,
        IServiceScopeFactory scopeFactory,
        ILogger<FavoritesPriceBackgroundService> logger)
    {
        _hubContext = hubContext;
        _mqttClient = mqttClient;
        _scopeFactory = scopeFactory;
        _logger = logger;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        _logger.LogInformation("[FavoritesPriceBackgroundService] Started 10-second periodic price & daily growth stream.");
        await Task.Delay(4000, stoppingToken);

        while (!stoppingToken.IsCancellationRequested)
        {
            try
            {
                var priceUpdates = await FetchFavoritePricesAsync(stoppingToken);
                if (priceUpdates.Count > 0)
                {
                    await _hubContext.Clients.All.SendAsync("ReceiveFavoritePrices", priceUpdates, cancellationToken: stoppingToken);
                }
            }
            catch (Exception ex)
            {
                _logger.LogWarning(ex, "[FavoritesPriceBackgroundService] Error broadcasting 10s favorite price updates.");
            }

            await Task.Delay(10000, stoppingToken);
        }
    }

    private async Task<Dictionary<string, object>> FetchFavoritePricesAsync(CancellationToken cancellationToken)
    {
        var priceMap = new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase);
        List<UserFavoriteAssetEntity> favorites = new();

        try
        {
            using var scope = _scopeFactory.CreateScope();
            var dbContext = scope.ServiceProvider.GetRequiredService<BackendDbContext>();
            favorites = await dbContext.UserFavoriteAssets
                .AsNoTracking()
                .ToListAsync(cancellationToken);
        }
        catch { }

        // De-duplicate by ISIN (preferring entries that have SelectedTicker)
        var dedupedFavorites = favorites
            .GroupBy(f => f.Isin.Trim().ToUpperInvariant())
            .Select(g => g.OrderByDescending(f => !string.IsNullOrEmpty(f.SelectedTicker)).First())
            .ToList();

        foreach (var fav in dedupedFavorites)
        {
            string cleanIsin = fav.Isin.Trim().ToUpperInvariant();
            if (string.IsNullOrWhiteSpace(cleanIsin)) continue;

            string querySymbol = !string.IsNullOrWhiteSpace(fav.SelectedTicker) ? fav.SelectedTicker.Trim().ToUpperInvariant() : cleanIsin;

            double currentPrice = 0.0;
            double dailyChangePercent = 0.0;
            bool resolvedFromTa = false;

            try
            {
                if (_mqttClient.IsConnected)
                {
                    var livePriceDto = await _mqttClient.SendRpcRequestAsync<LivePriceDto, IsinRequest>(
                        "tr_GetLivePrice",
                        new IsinRequest(querySymbol),
                        TimeSpan.FromSeconds(2)
                    );

                    if (livePriceDto != null)
                    {
                        currentPrice = (double)livePriceDto.CurrentPrice;
                        dailyChangePercent = (double)livePriceDto.DailyChangePercent;
                        resolvedFromTa = true;
                    }
                }
            }
            catch { }

            if (resolvedFromTa)
            {
                priceMap[cleanIsin] = new
                {
                    isin = cleanIsin,
                    symbol = querySymbol,
                    currentPrice = currentPrice,
                    dailyChangePercent = dailyChangePercent
                };
            }
        }

        return priceMap;
    }
}