using Microsoft.Extensions.Hosting;

namespace Service;

/// <summary>
/// 周期性账单后台服务
/// </summary>
public class PeriodicBillBackgroundService(
    IServiceProvider serviceProvider,
    ILogger<PeriodicBillBackgroundService> logger
) : BackgroundService
{
    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        logger.LogInformation("周期性账单后台服务已启动");

        while (!stoppingToken.IsCancellationRequested)
        {
            try
            {
                var now = DateTime.Now;
            
                // 计算下次执行时间（每天早上6点）
                var nextRun = now.Date.AddHours(6);
                if (now >= nextRun)
                {
                    nextRun = nextRun.AddDays(1);
                }

                var delay = nextRun - now;
                logger.LogInformation("下次执行周期性账单检查时间: {NextRun}, 延迟: {Delay}", 
                    nextRun.ToString("yyyy-MM-dd HH:mm:ss"), delay);

                await Task.Delay(delay, stoppingToken);

                if (stoppingToken.IsCancellationRequested)
                    break;

                // 执行周期性账单检查
                using (var scope = serviceProvider.CreateScope())
                {
                    var periodicService = scope.ServiceProvider.GetRequiredService<ITransactionPeriodicService>();
                    await periodicService.ExecutePeriodicBillsAsync();
                }
            }
            catch (OperationCanceledException)
            {
                logger.LogInformation("周期性账单后台服务已取消");
                break;
            }
            catch (Exception ex)
            {
                logger.LogError(ex, "周期性账单后台服务执行出错");
                // 出错后等待1小时再重试
                await Task.Delay(TimeSpan.FromHours(1), stoppingToken);
            }
        }

        logger.LogInformation("周期性账单后台服务已停止");
    }
}