From 4a522e7a3934fdf2f3ae47ffde760755edd8d734 Mon Sep 17 00:00:00 2001
From: Taylor Lodge <taylor.lodge@koordinates.com>
Date: Tue, 9 Jan 2024 15:57:30 +1300
Subject: [PATCH] feat(builders): buildRoutingMachine

Utility function to reduce boilerplate for machines that solely consist of event -> state -> invoke machine states

Closes #50
---
 src/builders.spec.tsx             | 45 +++++++++++++++++++-
 src/{builders.ts => builders.tsx} | 70 ++++++++++++++++++++++++++++++-
 src/routing/Link.spec.tsx         |  4 +-
 xstate-tree.api.md                |  3 ++
 4 files changed, 116 insertions(+), 6 deletions(-)
 rename src/{builders.ts => builders.tsx} (82%)

diff --git a/src/builders.spec.tsx b/src/builders.spec.tsx
index c0be825..03b03c8 100644
--- a/src/builders.spec.tsx
+++ b/src/builders.spec.tsx
@@ -1,7 +1,10 @@
-import { render, waitFor } from "@testing-library/react";
+import { act, render, waitFor } from "@testing-library/react";
+import { createMemoryHistory } from "history";
 import React from "react";
 
-import { viewToMachine } from "./builders";
+import { buildRoutingMachine, viewToMachine } from "./builders";
+import { buildCreateRoute } from "./routing";
+import { XstateTreeHistory } from "./types";
 import { buildRootComponent } from "./xstateTree";
 
 describe("xstate-tree builders", () => {
@@ -15,4 +18,42 @@ describe("xstate-tree builders", () => {
       await waitFor(() => getByText("hello world"));
     });
   });
+
+  describe("buildRoutingMachine", () => {
+    const hist: XstateTreeHistory = createMemoryHistory();
+    const createRoute = buildCreateRoute(() => hist, "/");
+
+    const fooRoute = createRoute.simpleRoute()({
+      url: "/foo/",
+      event: "GO_TO_FOO",
+    });
+    const barRoute = createRoute.simpleRoute()({
+      url: "/bar/",
+      event: "GO_TO_BAR",
+    });
+
+    it("takes a mapping of routes to machines and returns a machine that invokes those machines when those routes events are broadcast", async () => {
+      const FooMachine = viewToMachine(() => <div>foo</div>);
+      const BarMachine = viewToMachine(() => <div>bar</div>);
+
+      const routingMachine = buildRoutingMachine([fooRoute, barRoute], {
+        GO_TO_FOO: FooMachine,
+        GO_TO_BAR: BarMachine,
+      });
+
+      const Root = buildRootComponent(routingMachine, {
+        history: hist,
+        basePath: "/",
+        routes: [fooRoute, barRoute],
+      });
+
+      const { getByText } = render(<Root />);
+
+      act(() => fooRoute.navigate());
+      await waitFor(() => getByText("foo"));
+
+      act(() => barRoute.navigate());
+      await waitFor(() => getByText("bar"));
+    });
+  });
 });
diff --git a/src/builders.ts b/src/builders.tsx
similarity index 82%
rename from src/builders.ts
rename to src/builders.tsx
index 319d44d..7ecdb9d 100644
--- a/src/builders.ts
+++ b/src/builders.tsx
@@ -8,9 +8,11 @@ import {
   type InterpreterFrom,
   type AnyFunction,
   createMachine,
+  StateNodeConfig,
 } from "xstate";
 
-import { Slot } from "./slots";
+import { AnyRoute } from "./routing";
+import { Slot, singleSlot } from "./slots";
 import {
   AnyActions,
   AnySelector,
@@ -274,9 +276,73 @@ export function createXStateTreeMachine<
  */
 export function viewToMachine(view: () => JSX.Element): AnyXstateTreeMachine {
   return createXStateTreeMachine(
-    createMachine({ initial: "idle", states: { idle: {} } }),
+    createMachine({
+      initial: "idle",
+      states: { idle: {} },
+    }),
     {
       View: view,
     }
   );
 }
+
+/**
+ * @public
+ *
+ * Utility to aid in reducing boilerplate of mapping route events to xstate-tree machines
+ *
+ * Takes a list of routes and a mapping of route events to xstate-tree machines and returns an xstate-tree machine
+ * that renders the machines based on the routing events
+ *
+ * @param _routes - the array of routes you wish to map to machines
+ * @param mappings - an object mapping the route events to the machine to invoke
+ * @returns an xstate-tree machine that will render the right machines based on the routing events
+ */
+export function buildRoutingMachine<TRoutes extends AnyRoute[]>(
+  _routes: TRoutes,
+  mappings: Record<TRoutes[number]["event"], AnyXstateTreeMachine>
+): AnyXstateTreeMachine {
+  const contentSlot = singleSlot("Content");
+  const mappingsToStates = Object.entries<AnyXstateTreeMachine>(
+    mappings
+  ).reduce((acc, [event, _machine]) => {
+    return {
+      ...acc,
+      [event]: {
+        invoke: {
+          src: (_ctx, e) => {
+            return mappings[e.type as TRoutes[number]["event"]];
+          },
+          id: contentSlot.getId(),
+        },
+      },
+    };
+  }, {} as Record<string, StateNodeConfig<any, any, any>>);
+
+  const mappingsToEvents = Object.keys(mappings).reduce(
+    (acc, event) => ({
+      ...acc,
+      [event]: {
+        target: `.${event}`,
+      },
+    }),
+    {}
+  );
+  const machine = createMachine({
+    on: {
+      ...mappingsToEvents,
+    },
+    initial: "idle",
+    states: {
+      idle: {},
+      ...mappingsToStates,
+    },
+  });
+
+  return createXStateTreeMachine(machine, {
+    slots: [contentSlot],
+    View: ({ slots }) => {
+      return <slots.Content />;
+    },
+  });
+}
diff --git a/src/routing/Link.spec.tsx b/src/routing/Link.spec.tsx
index 92b8c28..c7168a9 100644
--- a/src/routing/Link.spec.tsx
+++ b/src/routing/Link.spec.tsx
@@ -69,7 +69,7 @@ describe("Link", () => {
       route.preload = jest.fn();
 
       const { getByText } = render(
-        <Link to={route} params={{ param: "test" }} preloadOnHoverMs={15}>
+        <Link to={route} params={{ param: "test" }} preloadOnHoverMs={50}>
           Link
         </Link>
       );
@@ -78,7 +78,7 @@ describe("Link", () => {
       await delay(2);
       await userEvent.unhover(getByText("Link"));
 
-      await delay(15);
+      await delay(50);
       expect(route.preload).not.toHaveBeenCalled();
     });
 
diff --git a/xstate-tree.api.md b/xstate-tree.api.md
index 0a7aa3d..fffb35e 100644
--- a/xstate-tree.api.md
+++ b/xstate-tree.api.md
@@ -126,6 +126,9 @@ export function buildRootComponent(machine: AnyXstateTreeMachine, routing?: {
     rootMachine: AnyXstateTreeMachine;
 };
 
+// @public
+export function buildRoutingMachine<TRoutes extends AnyRoute[]>(_routes: TRoutes, mappings: Record<TRoutes[number]["event"], AnyXstateTreeMachine>): AnyXstateTreeMachine;
+
 // Warning: (ae-incompatible-release-tags) The symbol "buildSelectors" is marked as @public, but its signature references "CanHandleEvent" which is marked as @internal
 // Warning: (ae-incompatible-release-tags) The symbol "buildSelectors" is marked as @public, but its signature references "MatchesFrom" which is marked as @internal
 //