using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.DependencyInjection;
using Predictalytics.Infrastructure.Data;
using Predictalytics.Application.Interfaces;

namespace Predictalytics.Worker.Services;

public class TraderAnalyticsWorker : BackgroundService
{
    private readonly IServiceProvider _services;
    private readonly ILogger<TraderAnalyticsWorker> _logger;

    public TraderAnalyticsWorker(IServiceProvider services, ILogger<TraderAnalyticsWorker> _logger)
    {
        _services = services;
        this._logger = _logger;
    }

    protected override async Task ExecuteAsync(CancellationToken ct)
    {
        _logger.LogInformation("TraderAnalyticsWorker starting...");

        while (!ct.IsCancellationRequested)
        {
            try
            {
                await RunAnalyticsAsync(ct);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error in TraderAnalyticsWorker");
            }

            _logger.LogInformation("TraderAnalyticsWorker sleeping for 12 hours...");
            await Task.Delay(TimeSpan.FromHours(12), ct);
        }
    }

    private async Task RunAnalyticsAsync(CancellationToken ct)
    {
        using var scope = _services.CreateScope();
        var db = scope.ServiceProvider.GetRequiredService<AppDbContext>();
        var pnlEngine = scope.ServiceProvider.GetRequiredService<IPositionPnLEngine>();

        var cutoff30d = DateTime.UtcNow.AddDays(-30);
        
        // Find traders active in the last 30 days
        var traderIds = await db.Trades
            .Where(t => t.ExecutedAt >= cutoff30d)
            .Select(t => t.TraderId)
            .Distinct()
            .ToListAsync(ct);

        _logger.LogInformation("Found {Count} active traders to analyze", traderIds.Count);

        foreach (var id in traderIds)
        {
            try
            {
                await pnlEngine.RecalculateTraderPositionsAsync(id, ct);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error recalculating positions/PnL for trader {TraderId}", id);
            }
        }

        _logger.LogInformation("Trader analytics update complete.");
    }
}