dotnet-quartz-background-jobs

# Background Job Generator (Quartz)

## Overview

Quartz.NET is a full-featured job scheduling library:

- **Job scheduling** - Run tasks at specific times or intervals
- **Cron expressions** - Complex scheduling patterns
- **Persistence** - Jobs survive application restarts
- **Dependency injection** - Full DI support
- **Clustering** - Distributed job execution

## Quick Reference

| Component | Purpose |
|-----------|---------|
| `IJob` | Job interface to implement |
| `IConfigureOptions<QuartzOptions>` | Job registration |
| `JobKey` | Unique job identifier |
| `TriggerBuilder` | Defines when job runs |
| `CronScheduleBuilder` | Cron-based scheduling |
| `SimpleScheduleBuilder` | Interval-based scheduling |

---

## Job Structure

```
/Infrastructure/
├── BackgroundJobs/
│   ├── {JobName}Job.cs
│   ├── {JobName}JobSetup.cs
│   └── ...
└── DependencyInjection.cs
```

---

## Template: Simple Interval Job

```csharp
// src/{name}.infrastructure/BackgroundJobs/ProcessPendingOrdersJob.cs
using Microsoft.Extensions.Logging;
using Quartz;

namespace {name}.infrastructure.backgroundjobs;

/// <summary>
/// Processes pending orders every 5 minutes
/// </summary>
[DisallowConcurrentExecution]  // Prevent overlapping executions
public sealed class ProcessPendingOrdersJob : IJob
{
    private readonly IOrderRepository _orderRepository;
    private readonly IOrderProcessor _orderProcessor;
    private readonly ILogger<ProcessPendingOrdersJob> _logger;

    public ProcessPendingOrdersJob(
        IOrderRepository orderRepository,
        IOrderProcessor orderProcessor,
        ILogger<ProcessPendingOrdersJob> logger)
    {
        _orderRepository = orderRepository;
        _orderProcessor = orderProcessor;
        _logger = logger;
    }

    public async Task Execute(IJobExecutionContext context)
    {
        _logger.LogInformation("Starting pending orders processing...");

        try
        {
            var pendingOrders = await _orderRepository
                .GetPendingOrdersAsync(context.CancellationToken);

            _logger.LogInformation(
                "Found {Count} pending orders to process",
                pendingOrders.Count);

            foreach (var order in pendingOrders)
            {
                try
                {
                    await _orderProcessor.ProcessAsync(order, context.CancellationToken);
                    
                    _logger.LogInformation(
                        "Processed order {OrderId}",
                        order.Id);
                }
                catch (Exception ex)
                {
                    _logger.LogError(
                        ex,
                        "Failed to process order {OrderId}",
                        order.Id);
                }
            }

            _logger.LogInformation("Completed pending orders processing");
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error in pending orders processing job");
            throw;  // Quartz will handle retry based on configuration
        }
    }
}
```

---

## Template: Job Setup (IConfigureOptions)

```csharp
// src/{name}.infrastructure/BackgroundJobs/ProcessPendingOrdersJobSetup.cs
using Microsoft.Extensions.Options;
using Quartz;

namespace {name}.infrastructure.backgroundjobs;

internal sealed class ProcessPendingOrdersJobSetup 
    : IConfigureOptions<QuartzOptions>
{
    public void Configure(QuartzOptions options)
    {
        var jobKey = JobKey.Create(nameof(ProcessPendingOrdersJob));

        options
            .AddJob<ProcessPendingOrdersJob>(jobBuilder =>
                jobBuilder
                    .WithIdentity(jobKey)
                    .WithDescription("Processes pending orders"))
            .AddTrigger(triggerBuilder =>
                triggerBuilder
                    .ForJob(jobKey)
                    .WithIdentity($"{nameof(ProcessPendingOrdersJob)}-trigger")
                    .WithSimpleSchedule(schedule =>
                        schedule
                            .WithIntervalInMinutes(5)
                            .RepeatForever())
                    .StartNow());
    }
}
```

---

## Template: Cron Scheduled Job

```csharp
// src/{name}.infrastructure/BackgroundJobs/DailyReportJob.cs
using Microsoft.Extensions.Logging;
using Quartz;

namespace {name}.infrastructure.backgroundjobs;

/// <summary>
/// Generates daily reports at 6:00 AM every day
/// </summary>
[DisallowConcurrentExecution]
public sealed class DailyReportJob : IJob
{
    private readonly IReportService _reportService;
    private readonly IEmailService _emailService;
    private readonly ILogger<DailyReportJob> _logger;

    public DailyReportJob(
        IReportService reportService,
        IEmailService emailService,
        ILogger<DailyReportJob> logger)
    {
        _reportService = reportService;
        _emailService = emailService;
        _logger = logger;
    }

    public async Task Execute(IJobExecutionContext context)
    {
        _logger.LogInformation("Starting daily report generation...");

        var reportDate = DateTime.UtcNow.Date.AddDays(-1);

        var report = await _reportService.GenerateDailyReportAsync(
            reportDate,
            context.CancellationToken);

        await _emailService.SendReportAsync(
            report,
            context.CancellationToken);

        _logger.LogInformation(
            "Daily report for {Date} sent successfully",
            reportDate.ToShortDateString());
    }
}
```

```csharp
// src/{name}.infrastructure/BackgroundJobs/DailyReportJobSetup.cs
using Microsoft.Extensions.Options;
using Quartz;

namespace {name}.infrastructure.backgroundjobs;

internal sealed class DailyReportJobSetup : IConfigureOptions<QuartzOptions>
{
    public void Configure(QuartzOptions options)
    {
        var jobKey = JobKey.Create(nameof(DailyReportJob));

        options
            .AddJob<DailyReportJob>(jobBuilder =>
                jobBuilder