Add hangfire implementations to the job scheduler and enqueuer

src/ContractImplementations.Hangfire/ContractImplementations.Hangfire.csproj

@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk">
+    <Import Project="../MSBuild/Base.props"/>
+    <Import Project="../MSBuild/Packable.props"/>
+
+    <ItemGroup>
+        <ProjectReference Include="..\Bootstrapping\Bootstrapping.csproj" />
+        <ProjectReference Include="..\Foundation\Foundation.csproj" />
+    </ItemGroup>
+
+    <ItemGroup>
+        <PackageReference Include="Hangfire.Core" Version="1.8.*" />
+    </ItemGroup>
+
+</Project>

src/ContractImplementations.Hangfire/Jobs/HangfireJobEnqueuer.cs

@@ -0,0 +1,38 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Hangfire;
+using IOKode.OpinionatedFramework.Jobs;
+
+namespace IOKode.OpinionatedFramework.ContractImplementations.Hangfire.Jobs;
+
+public class HangfireJobEnqueuer : IJobEnqueuer
+{
+    public Task EnqueueAsync(Queue queue, IJob job, CancellationToken cancellationToken)
+    {
+        BackgroundJob.Enqueue(queue.Name, () => InvokeJob(job));
+        return Task.CompletedTask;
+    }
+
+    public Task EnqueueWithDelayAsync(Queue queue, IJob job, TimeSpan delay, CancellationToken cancellationToken)
+    {
+        BackgroundJob.Schedule(queue.Name, () => InvokeJob(job), delay);
+        return Task.CompletedTask;
+    }
+
+    /// <summary>
+    /// This method is not intended to be called directly in application code.
+    /// Exists to allow Hangfire to serialize and deserialize the job object 
+    /// that it will receive as an argument. This ensures that the job 
+    /// can be processed correctly during execution.
+    /// </summary>
+    /// <remarks>
+    /// This method must be public because it is used by Hangfire during the deserialization 
+    /// and execution of enqueued tasks. Hangfire requires that methods to be invoked 
+    /// are publicly accessible to resolve them when deserializing the previously generated expression.
+    /// </remarks>
+    public async Task InvokeJob(IJob job)
+    {
+        await job.InvokeAsync(default);
+    }
+}

src/ContractImplementations.Hangfire/Jobs/HangfireJobScheduler.cs

@@ -0,0 +1,51 @@
+using System.Threading;
+using System.Threading.Tasks;
+using Cronos;
+using Hangfire;
+using IOKode.OpinionatedFramework.Ensuring;
+using IOKode.OpinionatedFramework.Jobs;
+
+namespace IOKode.OpinionatedFramework.ContractImplementations.Hangfire.Jobs;
+
+public class HangfireJobScheduler : IJobScheduler
+{
+    public Task<ScheduledJob> ScheduleAsync(IJob job, CronExpression interval, CancellationToken cancellationToken)
+    {
+        var scheduledJob = new HangfireMutableScheduledJob(interval, job);
+        RecurringJob.AddOrUpdate(scheduledJob.Identifier.ToString(), () => InvokeAsync(job), interval.ToString);
+        return Task.FromResult<ScheduledJob>(scheduledJob);
+    }
+
+    public Task RescheduleAsync(ScheduledJob scheduledJob, CronExpression interval, CancellationToken cancellationToken)
+    {
+        Ensure.Type.IsAssignableTo(scheduledJob.GetType(), typeof(MutableScheduledJob))
+            .ElseThrowsIllegalArgument($"Type must be assignable to {nameof(MutableScheduledJob)} type.", nameof(scheduledJob));
+
+        RecurringJob.AddOrUpdate(scheduledJob.Identifier.ToString(), () => InvokeAsync(scheduledJob.Job), interval.ToString);
+        ((MutableScheduledJob) scheduledJob).ChangeInterval(interval);
+
+        return Task.CompletedTask;
+    }
+
+    public Task UnscheduleAsync(ScheduledJob scheduledJob, CancellationToken cancellationToken)
+    {
+        RecurringJob.RemoveIfExists(scheduledJob.Identifier.ToString());
+        return Task.CompletedTask;
+    }
+
+    /// <summary>
+    /// This method is not intended to be called directly in application code.
+    /// Exists to allow Hangfire to serialize and deserialize the job object 
+    /// that it will receive as an argument. This ensures that the job 
+    /// can be processed correctly during execution.
+    /// </summary> 
+    /// <remarks>
+    /// This method must be public because it is used by Hangfire during the deserialization 
+    /// and execution of scheduled tasks. Hangfire requires that methods to be invoked 
+    /// are publicly accessible to resolve them when deserializing the previously generated expression.
+    /// </remarks>
+    public async Task InvokeAsync(IJob job)
+    {
+        await job.InvokeAsync(default);
+    }
+}

src/ContractImplementations.Hangfire/Jobs/HangfireMutableScheduledJob.cs

@@ -0,0 +1,16 @@
+using System;
+using Cronos;
+using IOKode.OpinionatedFramework.Jobs;
+
+namespace IOKode.OpinionatedFramework.ContractImplementations.Hangfire.Jobs;
+
+public class HangfireMutableScheduledJob : MutableScheduledJob
+{
+    public HangfireMutableScheduledJob(CronExpression interval, IJob job) : base(interval, job)
+    {
+    }
+
+    public HangfireMutableScheduledJob(CronExpression interval, IJob job, Guid id) : base(interval, job, id)
+    {
+    }
+}

src/ContractImplementations.Hangfire/Jobs/ServiceExtensions.cs

@@ -0,0 +1,18 @@
+using System;
+using Hangfire;
+using IOKode.OpinionatedFramework.Bootstrapping;
+using IOKode.OpinionatedFramework.Jobs;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace IOKode.OpinionatedFramework.ContractImplementations.Hangfire.Jobs;
+
+public static class ServiceExtensions
+{
+    public static void AddHangfireJobsImplementations(this IOpinionatedServiceCollection services, Action<IGlobalConfiguration> configuration)
+    {
+        services.AddSingleton<IJobEnqueuer, HangfireJobEnqueuer>();
+        services.AddSingleton<IJobScheduler, HangfireJobScheduler>();
+
+        configuration.Invoke(GlobalConfiguration.Configuration);
+    }
+}

src/Foundation/Jobs/ScheduledJob.cs

@@ -3,6 +3,16 @@
 
 namespace IOKode.OpinionatedFramework.Jobs;
 
+/// <summary>
+/// Represents the core details of a job that needs to be scheduled.
+/// </summary>
+/// <remarks>
+/// This abstract class is designed to encapsulate essential aspects of a job that is to be scheduled,
+/// its primary purpose is to serve as a foundational structure for managing metadata associated with
+/// scheduled jobs in scheduling frameworks.
+/// This class itself is not intended to represent the actual execution logic of the job, 
+/// but rather its scheduling details.
+/// </remarks>
 public abstract class ScheduledJob
 {
     public CronExpression Interval { get; protected set; }
@@ -24,6 +34,15 @@ protected void SetInterval(CronExpression interval)
     }
 }
 
+/// <summary>
+/// Extends <see cref="ScheduledJob"/> by allowing modifications to the execution interval.
+/// </summary>
+/// <remarks>
+/// It is designed to support scenarios where the scheduling 
+/// details of a job may need to change after it has been initially defined.
+/// Like its base class, this class focuses on managing the metadata and scheduling information for a job, 
+/// rather than its actual execution logic.
+/// </remarks>
 public abstract class MutableScheduledJob : ScheduledJob
 {
     public void ChangeInterval(CronExpression interval)

src/IOKode.OpinionatedFramework.sln

@@ -61,6 +61,10 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "DefaultBootstrapping", "Def
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "AspNetCoreIntegrations", "AspNetCoreIntegrations", "{038D9778-AA71-45A0-A33B-AFD50623285C}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ContractImplementations.Hangfire", "ContractImplementations.Hangfire\ContractImplementations.Hangfire.csproj", "{67CC3E42-1F98-439F-A83F-7F9B5B54CF86}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Tests.Hangfire", "Tests.Hangfire\Tests.Hangfire.csproj", "{4CFA733F-0697-47FF-831D-908530C40929}"
+EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ContractImplementations.TaskRunJobs", "ContractImplementations.TaskRunJobs\ContractImplementations.TaskRunJobs.csproj", "{9F7DB6F3-1AD9-4B31-9D02-1AD49224A4A6}"
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Tests.TaskRunJobs", "Tests.TaskRunJobs\Tests.TaskRunJobs.csproj", "{1F0291CD-0C3D-414F-B7D4-8062A8D62F41}"
@@ -149,6 +153,14 @@ Global
 		{4DFA2F5C-12DA-41F8-853F-3B6CF322C854}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{4DFA2F5C-12DA-41F8-853F-3B6CF322C854}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{4DFA2F5C-12DA-41F8-853F-3B6CF322C854}.Release|Any CPU.Build.0 = Release|Any CPU
+		{67CC3E42-1F98-439F-A83F-7F9B5B54CF86}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{67CC3E42-1F98-439F-A83F-7F9B5B54CF86}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{67CC3E42-1F98-439F-A83F-7F9B5B54CF86}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{67CC3E42-1F98-439F-A83F-7F9B5B54CF86}.Release|Any CPU.Build.0 = Release|Any CPU
+		{4CFA733F-0697-47FF-831D-908530C40929}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{4CFA733F-0697-47FF-831D-908530C40929}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{4CFA733F-0697-47FF-831D-908530C40929}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{4CFA733F-0697-47FF-831D-908530C40929}.Release|Any CPU.Build.0 = Release|Any CPU
 		{9F7DB6F3-1AD9-4B31-9D02-1AD49224A4A6}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{9F7DB6F3-1AD9-4B31-9D02-1AD49224A4A6}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{9F7DB6F3-1AD9-4B31-9D02-1AD49224A4A6}.Release|Any CPU.ActiveCfg = Release|Any CPU
@@ -211,6 +223,8 @@ Global
 		{A5A2C6D2-7069-4EF7-9391-0FA04924031A} = {C33ED8EA-76EF-4985-9055-12D9B668E210}
 		{AB7AE28D-9F0D-4528-B8FD-FCC4263F2227} = {C33ED8EA-76EF-4985-9055-12D9B668E210}
 		{F034D634-3141-4E98-97F1-BB9DF22C4917} = {756C3C1A-72CD-4CCE-BD8D-977F2980D1B6}
+		{67CC3E42-1F98-439F-A83F-7F9B5B54CF86} = {C33ED8EA-76EF-4985-9055-12D9B668E210}
+		{4CFA733F-0697-47FF-831D-908530C40929} = {756C3C1A-72CD-4CCE-BD8D-977F2980D1B6}
 		{9F7DB6F3-1AD9-4B31-9D02-1AD49224A4A6} = {C33ED8EA-76EF-4985-9055-12D9B668E210}
 		{1F0291CD-0C3D-414F-B7D4-8062A8D62F41} = {756C3C1A-72CD-4CCE-BD8D-977F2980D1B6}
 		{8E3B899D-50FA-4166-BD78-582E8E2BB16B} = {756C3C1A-72CD-4CCE-BD8D-977F2980D1B6}