WIP

README.md

@@ -1 +1,95 @@
 # DIT.Workflower
+
+Workflower is a library based on .NET Standard, To handle Finite State Machines (FSM) and workflow management.
+
+## Getting Started
+
+### Nuget
+
+Install the latest nuget package into your ASP.NET Core application.
+
+    ```sh
+    dotnet add package DIT.Workflower
+    ```
+
+    You can also download support for Dependency Injection:
+
+    ```sh
+    dotnet add package DIT.Workflower.DependencyInjection
+    ```
+
+### Workflow Builder
+In the `Program.cs`, register the Swagger generator, defining one or more Swagger documents.
+
+```csharp
+using DIT.Workflower;
+```
+
+```csharp
+
+var builder = new WorkflowDefinitionBuilder<TState, TCommand, TContext>()
+                .From(TState.State_1)
+                    .On(TCommand.GoNext)
+                    .To(TState.State_2)
+
+                .From(TState.State_2)
+                    .On(TCommand.GoNext)
+                    .To(TState.State_3)
+                    .AndOn(TCommand.GoBack)
+                    .To(TState.State_1)
+
+var workflow = builder.Build();
+
+var allowedTransitions = workflow.GetAllowedTransitions(from: TState.State_2);
+
+// allowedTransitions will be 2 transitions
+// State_2 -> State_3 (GoNext)
+// State_2 -> State_1 (GoBack)
+
+```
+
+### Dependency Injection
+
+
+```csharp
+public record PhoneCall(bool Active);
+
+services.AddWorkflowDefinition<PhoneState, PhoneCommand, PhoneCall>(version: 1)
+        // Idle -> Ringing (Incoming)
+        .From(PhoneState.Idle)
+            .On(PhoneCommand.IncomingCall)
+            .To(PhoneState.Ringing)
+
+        // Ringing -> Connected (Accept & ctx.Active)
+        .From(PhoneState.Ringing)
+            .On(PhoneCommand.Accept)
+            .To(PhoneState.Connected)
+            .When(ctx => ctx.Active) // An instance of PhoneCall will become the ctx.
+
+        // Ringing -> Declined (Decline)
+        .From(PhoneState.Ringing)
+            .On(PhoneCommand.Decline)
+            .To(PhoneState.Declined)
+```
+```csharp
+[Route("[controller]")]
+public class SampleController : JsonApiControllerBase
+{
+
+    private readonly IWorkflow<PhoneState, PhoneCommand, PhoneCall> _workflow;
+
+    public SampleController(IWorkflowFactory<PhoneState, PhoneCommand, PhoneCall> factory)
+    {
+        _workflow = factory.CreateWorkflow(version: 1); // Optional version param to support versioning on workflows.
+    }
+
+    [HttpGet("{state}")]
+    [ProducesResponseType(typeof(JsonApiSingleDataResponse<InitiateRequest>), StatusCodes.Status200OK)]
+    public ActionResult GetRequest(PhoneState state, bool isActive)
+    {
+        var phoneCall = new PhoneCall(isActive)
+        var transitions = _workflow.GetAllowedTransitions(context: phoneCall, state);
+        return Ok(transitions)
+    }
+}
+```

src/DIT.Workflower.DependencyInjection/Extensions/IServiceCollectionExtensions.cs

@@ -5,25 +5,25 @@ namespace DIT.Workflower.DependencyInjection.Extensions;
 public static class IServiceCollectionExtensions
 {
 
-    public static WorkflowDefinitionBuilder<TState, TCommand, TContext> AddWorkflowDefinition<TState, TCommand, TContext>(this IServiceCollection services)
+    public static ITransitionOn<TState, TCommand, TContext> AddWorkflowDefinition<TState, TCommand, TContext>(this IServiceCollection services, TState initial)
         where TState : struct
         where TCommand : struct
     {
-        return AddWorkflowDefinition<TState, TCommand, TContext>(services, version: 1);
+        return AddWorkflowDefinition<TState, TCommand, TContext>(services, initial, version: 1);
     }
 
-    public static WorkflowDefinitionBuilder<TState, TCommand, TContext> AddWorkflowDefinition<TState, TCommand, TContext>(this IServiceCollection services, int version)
+    public static ITransitionOn<TState, TCommand, TContext> AddWorkflowDefinition<TState, TCommand, TContext>(this IServiceCollection services, TState initial, int version)
         where TState : struct
         where TCommand : struct
     {
-        var builder = new WorkflowDefinitionBuilder<TState, TCommand, TContext>();
+        var builder = WorkflowDefinitionBuilder<TState, TCommand, TContext>.Initial(initial);
 
         services.TryAddSingleton<IWorkflowFactory<TState, TCommand, TContext>, DefaultWorkflowFactory<TState, TCommand, TContext>>();
 
         services.AddSingleton<IWorkflow<TState, TCommand, TContext>, WorkflowDefinitionWrapper<TState, TCommand, TContext>>(sp =>
         {
-            var workflow = builder.Build();
+            var definition = ((WorkflowDefinitionBuilder<TState, TCommand, TContext>)builder);
-            var wrapper = new WorkflowDefinitionWrapper<TState, TCommand, TContext>(builder, version);
+            var wrapper = new WorkflowDefinitionWrapper<TState, TCommand, TContext>(definition, version);
             return wrapper;
         });
 

src/DIT.Workflower.DependencyInjection/Usings.cs

@@ -1,2 +1,3 @@
-global using DIT.Workflower.DependencyInjection.Abstractions;
+global using Microsoft.Extensions.DependencyInjection;
-global using Microsoft.Extensions.DependencyInjection;
+global using DIT.Workflower.Abstractions;
+global using DIT.Workflower.DependencyInjection.Abstractions;

src/DIT.Workflower/Abstractions.cs

@@ -0,0 +1,35 @@
+namespace DIT.Workflower.Abstractions;
+
+public interface ITransitionOn<TState, TCommand, TContext>
+    where TState : struct
+    where TCommand : struct
+{
+    ITransitionCondition<TState, TCommand, TContext> On(in TCommand command);
+}
+
+public interface ITransitionExit<TState, TCommand, TContext>
+    where TState : struct
+    where TCommand : struct
+{
+    ITransitionDone<TState, TCommand, TContext> To(in TState command);
+}
+
+public interface ITransitionCondition<TState, TCommand, TContext> : ITransitionExit<TState, TCommand, TContext>
+    where TState : struct
+    where TCommand : struct
+{
+    ITransitionCondition<TState, TCommand, TContext> WithMeta(in object meta);
+
+    ITransitionCondition<TState, TCommand, TContext> When(Func<TContext, bool> condition);
+
+}
+
+public interface ITransitionDone<TState, TCommand, TContext> : ITransitionOn<TState, TCommand, TContext>
+    where TState : struct
+    where TCommand : struct
+{
+
+    ITransitionOn<TState, TCommand, TContext> From(in TState state);
+
+    WorkflowDefinition<TState, TCommand, TContext> Build();
+}

src/DIT.Workflower/Transition.cs

@@ -4,11 +4,11 @@ public record Transition<TState, TCommand>
     where TState : struct
     where TCommand : struct
 {
-    public TState From { get; set; }
+    public TState From { get; set; } = default!;
 
-    public TState To { get; set; }
+    public TState To { get; set; } = default!;
 
-    public TCommand Command { get; set; }
+    public TCommand Command { get; set; } = default!;
 
     public object? Meta { get; set; }
 }

src/DIT.Workflower/WorkflowDefinitionBuilder.cs

@@ -1,59 +1,64 @@
-namespace DIT.Workflower;
+using DIT.Workflower.Abstractions;
+
+namespace DIT.Workflower;
+
+public sealed class WorkflowDefinitionBuilder<TState, TCommand, TContext> : 
+    ITransitionOn<TState, TCommand, TContext>,
+    ITransitionExit<TState, TCommand, TContext>,
+    ITransitionCondition<TState, TCommand, TContext>,
+    ITransitionDone<TState, TCommand, TContext>
 
-public class WorkflowDefinitionBuilder<TState, TCommand, TContext>
     where TState : struct
     where TCommand : struct
 {
-    private TransitionDefinition<TState, TCommand, TContext>? _current;
+    private TransitionDefinition<TState, TCommand, TContext> _current;
 
     public List<TransitionDefinition<TState, TCommand, TContext>> Transitions { get; } = new();
 
+    #region Constructor 
 
-    public WorkflowDefinitionBuilder<TState, TCommand, TContext> From(in TState state)
+    private WorkflowDefinitionBuilder(TState initialState)
+        => _current = new() { From = initialState };
+    
+    public static ITransitionOn<TState, TCommand, TContext> Initial(TState initialState)
+        => new WorkflowDefinitionBuilder<TState, TCommand, TContext>(initialState);
+
+    #endregion
+
+    #region Methods
+
+    public ITransitionOn<TState, TCommand, TContext> From(in TState state)
     {
-        if (_current != null)
-            Transitions.Add(_current);
-
         _current = new() { From = state };
 
         return this;
     }
 
-    public WorkflowDefinitionBuilder<TState, TCommand, TContext> To(in TState state)
+    public ITransitionDone<TState, TCommand, TContext> To(in TState state)
     {
-        if (_current == null)
-            throw new InvalidOperationException($"From needs to be called first");
-
         _current = _current with { To = state };
 
+        Transitions.Add(_current);
+
         return this;
     }
 
-    public WorkflowDefinitionBuilder<TState, TCommand, TContext> On(in TCommand command)
+    public ITransitionCondition<TState, TCommand, TContext> On(in TCommand command)
     {
-        if (_current == null)
-            throw new InvalidOperationException($"From needs to be called first");
-
         _current = _current with { Command = command };
 
         return this;
     }
 
-    public WorkflowDefinitionBuilder<TState, TCommand, TContext> WithMeta(in object meta)
+    public ITransitionCondition<TState, TCommand, TContext> WithMeta(in object meta)
     {
-        if (_current == null)
-            throw new InvalidOperationException($"From needs to be called first");
-
         _current.Meta = meta;
 
         return this;
     }
 
-    public WorkflowDefinitionBuilder<TState, TCommand, TContext> When(Func<TContext, bool> condition)
+    public ITransitionCondition<TState, TCommand, TContext> When(Func<TContext, bool> condition)
     {
-        if (_current == null)
-            throw new InvalidOperationException($"From needs to be called first");
-
         if (_current.Conditions is null)
             _current.Conditions = new();
 
@@ -64,7 +69,6 @@ public class WorkflowDefinitionBuilder<TState, TCommand, TContext>
 
     public WorkflowDefinition<TState, TCommand, TContext> Build()
     {
-        if (_current != null)
         Transitions.Add(_current);
 
         if (!Transitions.Any())
@@ -72,4 +76,6 @@ public class WorkflowDefinitionBuilder<TState, TCommand, TContext>
 
         return new(Transitions);
     }
+
+    #endregion
 }

tests/DIT.Workflower.Tests/DependencyInjection/DependencyInjectionTests.cs

@@ -18,9 +18,7 @@ public class DependencyInjectionTests
 
         var sc = new ServiceCollection();
 
-        sc.AddWorkflowDefinition<PhoneState, PhoneCommand, PhoneCall>(version: 1)
+        sc.AddWorkflowDefinition<PhoneState, PhoneCommand, PhoneCall>(initial: PhoneState.Idle, version: 1)
-
-            .From(PhoneState.Idle)
                 .On(PhoneCommand.IncomingCall)
                 .To(PhoneState.Ringing)
 
@@ -29,9 +27,7 @@ public class DependencyInjectionTests
                 .To(PhoneState.Connected)
             ;
 
-        sc.AddWorkflowDefinition<PhoneState, PhoneCommand, PhoneCall>(version: 2)
+        sc.AddWorkflowDefinition<PhoneState, PhoneCommand, PhoneCall>(initial: PhoneState.Idle, version: 2)
-
-            .From(PhoneState.Idle)
                 .On(PhoneCommand.IncomingCall)
                 .To(PhoneState.Ringing)
 

tests/DIT.Workflower.Tests/Usings.cs

@@ -1,2 +1,3 @@
 global using DIT.Workflower;
+global using DIT.Workflower.Abstractions;
 global using Xunit;

tests/DIT.Workflower.Tests/WorkflowConditionTests.cs

@@ -2,27 +2,27 @@ namespace DIT.Workflower.Tests;
 
 public class WorkflowConditionTests
 {
-    private WorkflowDefinitionBuilder<PhoneState, PhoneCommand, PhoneCall> GetDefaultBuilder()
+    private ITransitionOn<PhoneState, PhoneCommand, PhoneCall> GetDefaultBuilder()
     {
-        return new();
+        return WorkflowDefinitionBuilder<PhoneState, PhoneCommand, PhoneCall>.Initial(PhoneState.Idle);
     }
 
     [Fact]
     public void SingleConditionTests()
     {
         var phone = new PhoneCall(Active: false);
-        var builder1 = GetDefaultBuilder();
-        var builder2 = GetDefaultBuilder();
 
         var a = "b";
 
-        builder1
+        var builder1 = GetDefaultBuilder()
-            .From(PhoneState.Idle)
+            .On(PhoneCommand.Decline)
-            .When((res) => a == "n");
+            .When((res) => a == "n")
+            .To(PhoneState.Declined);
 
-        builder2
+        var builder2 = GetDefaultBuilder()
-            .From(PhoneState.Idle)
+            .On(PhoneCommand.Decline)
-            .When((res) => a == "b" && res.Active is false);
+            .When((res) => a == "b" && res.Active is false)
+            .To(PhoneState.OnHold);
 
         Assert.Empty(builder1.Build().GetAllowedTransitions(phone, PhoneState.Idle));
         Assert.Single(builder2.Build().GetAllowedTransitions(phone, PhoneState.Idle));
@@ -32,21 +32,21 @@ public class WorkflowConditionTests
     public void MultiConditionTests()
     {
         var phone = new PhoneCall();
-        var builder1 = GetDefaultBuilder();
-        var builder2 = GetDefaultBuilder();
 
         var a = "b";
         var other = a;
 
-        builder1
+        var builder1 = GetDefaultBuilder()
-            .From(PhoneState.Idle)
+            .On(PhoneCommand.Resume)
             .When((res) => a == "c")
-            .When((res) => other == a);
+            .When((res) => other == a)
+            .To(PhoneState.Connected);
 
-        builder2
+        var builder2 = GetDefaultBuilder()
-            .From(PhoneState.Idle)
+            .On(PhoneCommand.Resume)
             .When((res) => a == "b")
-            .When((res) => other == a);
+            .When((res) => other == a)
+            .To(PhoneState.Connected);
 
         Assert.Empty(builder1.Build().GetAllowedTransitions(phone, PhoneState.Idle));
         Assert.Single(builder2.Build().GetAllowedTransitions(phone, PhoneState.Idle));

tests/DIT.Workflower.Tests/WorkflowMetaTests.cs

@@ -1,14 +0,0 @@
-namespace DIT.Workflower.Tests;
-
-public class WorkflowMetaTests
-{
-
-    [Fact]
-    public void WorkflowNeedsAtLeastOneTransition()
-    {
-        var builder = new WorkflowDefinitionBuilder<PhoneState, PhoneCommand, PhoneCall>();
-
-        Assert.Throws<InvalidOperationException>(builder.Build);
-    }
-
-}