From 1a6e8d3cc0e61511661da4867b0e0f91f5842456 Mon Sep 17 00:00:00 2001
From: Westin Newell <westin@squareup.com>
Date: Thu, 12 Jan 2023 16:05:53 -0800
Subject: [PATCH] Add support for observing AnyWorkflowConvertible to
 WorkflowHost

---
 Workflow/Sources/WorkflowHost.swift           | 37 +++++++++++++++++++
 .../Hosting/WorkflowHostingController.swift   | 25 +------------
 2 files changed, 39 insertions(+), 23 deletions(-)

diff --git a/Workflow/Sources/WorkflowHost.swift b/Workflow/Sources/WorkflowHost.swift
index 2cab79e41..5b9ee43e0 100644
--- a/Workflow/Sources/WorkflowHost.swift
+++ b/Workflow/Sources/WorkflowHost.swift
@@ -100,3 +100,40 @@ public final class WorkflowHost<WorkflowType: Workflow> {
         return outputEvent
     }
 }
+
+extension WorkflowHost {
+    /// Initializes a new host with the given workflow at the root.
+    ///
+    /// - Parameter workflow: The root workflow in the hierarchy
+    /// - Parameter debugger: An optional debugger. If provided, the host will notify the debugger of updates
+    ///
+    @_disfavoredOverload
+    public convenience init<AnyWorkflowType: AnyWorkflowConvertible>(
+        workflow: AnyWorkflowType,
+        debugger: WorkflowDebugger? = nil
+    ) where WorkflowType == AnyWorkflowWrapper<AnyWorkflowType.Rendering, AnyWorkflowType.Output> {
+        self.init(workflow: AnyWorkflowWrapper(workflow), debugger: debugger)
+    }
+}
+
+public typealias AnyWorkflowHost<Rendering, Output> = WorkflowHost<AnyWorkflowWrapper<Rendering, Output>>
+
+/// A wrapper around an AnyWorkflow that allows consumers to create a WorkflowHost from an
+/// `AnyWorkflowConvertible`.
+public struct AnyWorkflowWrapper<Rendering, Output>: Workflow {
+    public typealias State = Void
+    public typealias Output = Output
+    public typealias Rendering = Rendering
+
+    var wrapped: AnyWorkflow<Rendering, Output>
+
+    public init<W: AnyWorkflowConvertible>(_ wrapped: W) where W.Rendering == Rendering, W.Output == Output {
+        self.wrapped = wrapped.asAnyWorkflow()
+    }
+
+    public func render(state: State, context: RenderContext<Self>) -> Rendering {
+        return wrapped
+            .mapOutput { AnyWorkflowAction(sendingOutput: $0) }
+            .rendered(in: context)
+    }
+}
diff --git a/WorkflowUI/Sources/Hosting/WorkflowHostingController.swift b/WorkflowUI/Sources/Hosting/WorkflowHostingController.swift
index 761364796..ae1e75bfd 100644
--- a/WorkflowUI/Sources/Hosting/WorkflowHostingController.swift
+++ b/WorkflowUI/Sources/Hosting/WorkflowHostingController.swift
@@ -29,7 +29,7 @@
 
         private(set) var rootViewController: UIViewController
 
-        private let workflowHost: WorkflowHost<RootWorkflow<ScreenType, Output>>
+        private let workflowHost: AnyWorkflowHost<ScreenType, Output>
 
         private let (lifetime, token) = Lifetime.make()
 
@@ -40,7 +40,7 @@
         }
 
         public init<W: AnyWorkflowConvertible>(workflow: W, rootViewEnvironment: ViewEnvironment = .empty) where W.Rendering == ScreenType, W.Output == Output {
-            self.workflowHost = WorkflowHost(workflow: RootWorkflow(workflow))
+            self.workflowHost = WorkflowHost(workflow: workflow)
 
             self.rootViewController = workflowHost
                 .rendering
@@ -144,27 +144,6 @@
         }
     }
 
-    /// Wrapper around an AnyWorkflow that allows us to have a concrete
-    /// WorkflowHost without WorkflowHostingController itself being generic
-    /// around a Workflow.
-    fileprivate struct RootWorkflow<Rendering, Output>: Workflow {
-        typealias State = Void
-        typealias Output = Output
-        typealias Rendering = Rendering
-
-        var wrapped: AnyWorkflow<Rendering, Output>
-
-        init<W: AnyWorkflowConvertible>(_ wrapped: W) where W.Rendering == Rendering, W.Output == Output {
-            self.wrapped = wrapped.asAnyWorkflow()
-        }
-
-        func render(state: State, context: RenderContext<RootWorkflow>) -> Rendering {
-            return wrapped
-                .mapOutput { AnyWorkflowAction(sendingOutput: $0) }
-                .rendered(in: context)
-        }
-    }
-
     @available(*, deprecated, renamed: "WorkflowHostingController")
     public typealias ContainerViewController = WorkflowHostingController