using Backend.Interface;

namespace Backend.ServiceHander
{
	public sealed class NewsSentimentRefreshService : BackgroundService
	{
		private static readonly TimeSpan PollInterval = TimeSpan.FromMinutes(15);
		private static readonly TimeZoneInfo Pacific = TimeZoneInfo.FindSystemTimeZoneById("America/Los_Angeles");

		private readonly IServiceProvider _services;
		private readonly ILogger<NewsSentimentRefreshService> _logger;

		public NewsSentimentRefreshService(
			IServiceProvider services,
			ILogger<NewsSentimentRefreshService> logger)
		{
			_services = services;
			_logger = logger;
		}

		protected override async Task ExecuteAsync(CancellationToken stoppingToken)
		{
			while (!stoppingToken.IsCancellationRequested)
			{
				if (IsWithinActiveWindow())
				{
					await RefreshAsync(stoppingToken);
				}
				else
				{
					_logger.LogDebug("Outside active window (weekdays 07:00-20:00 PST), skipping refresh.");
				}

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

		private static bool IsWithinActiveWindow()
		{
			var pacificNow = TimeZoneInfo.ConvertTimeFromUtc(DateTime.UtcNow, Pacific);

			if (pacificNow.DayOfWeek is DayOfWeek.Saturday or DayOfWeek.Sunday)
				return false;

			var hour = pacificNow.Hour;
			return hour >= 7 && hour < 20;
		}

		private async Task RefreshAsync(CancellationToken cancellationToken)
		{
			try
			{
				var interests = _services.GetRequiredService<IUserInterestStore>();
				var sentiment = _services.GetRequiredService<NewsSentimentService>();

				var keywords = await interests.FetchAllDistinctValuesAsync(cancellationToken);

				_logger.LogInformation("Refreshing news for {Count} keywords.", keywords.Count);

				foreach (var keyword in keywords)
				{
					try
					{
						await sentiment.AnalyzeAsync(keyword, cancellationToken);
					}
					catch (Exception ex)
					{
						_logger.LogWarning(ex, "Failed to refresh news for keyword '{Keyword}'.", keyword);
					}
				}
			}
			catch (Exception ex)
			{
				_logger.LogError(ex, "News sentiment refresh cycle failed.");
			}
		}
	}
}