From 17ec89d88635f63f9fbacd600531fd35295d40fe Mon Sep 17 00:00:00 2001
From: Joshua Seigler <joshua@seigler.net>
Date: Mon, 10 Oct 2022 02:15:34 -0400
Subject: [PATCH] useSignal demo, wow

---
 package-lock.json            |  38 +++++++++++++
 package.json                 |   1 +
 src/strategies/index.ts      |   2 +
 src/strategies/useSignal.tsx | 103 +++++++++++++++++++++++++++++++++++
 4 files changed, 144 insertions(+)
 create mode 100644 src/strategies/useSignal.tsx

diff --git a/package-lock.json b/package-lock.json
index ae6e889..d8d5131 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -8,6 +8,7 @@
       "version": "1.0.0",
       "license": "MIT",
       "dependencies": {
+        "@preact/signals-react": "^1.1.1",
         "@types/react": "^18.0.21",
         "@types/react-dom": "^18.0.6",
         "@types/react-router-dom": "^5.3.3",
@@ -1429,6 +1430,30 @@
         "@parcel/core": "^2.7.0"
       }
     },
+    "node_modules/@preact/signals-core": {
+      "version": "1.2.1",
+      "resolved": "https://registry.npmjs.org/@preact/signals-core/-/signals-core-1.2.1.tgz",
+      "integrity": "sha512-aqzRMNFU1hoQyP4Kb1ldJrUTCnA9vqPDa7qHEQzHJ3upnBOcC2pjmvjAuTqGuY4AVTtUkCQV0FvOCuIQQ2hSdA==",
+      "funding": {
+        "type": "opencollective",
+        "url": "https://opencollective.com/preact"
+      }
+    },
+    "node_modules/@preact/signals-react": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/@preact/signals-react/-/signals-react-1.1.1.tgz",
+      "integrity": "sha512-U5HNWBt4q5pmsZjDOuVcz3OXLQtaBMMSErnTHFohOFQClBqHlVD/hmhayEEO38I9iU71kofhw2ngeWso/GsVMw==",
+      "dependencies": {
+        "@preact/signals-core": "^1.2.1"
+      },
+      "funding": {
+        "type": "opencollective",
+        "url": "https://opencollective.com/preact"
+      },
+      "peerDependencies": {
+        "react": "17.x || 18.x"
+      }
+    },
     "node_modules/@remix-run/router": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/@remix-run/router/-/router-1.0.2.tgz",
@@ -3758,6 +3783,19 @@
         "nullthrows": "^1.1.1"
       }
     },
+    "@preact/signals-core": {
+      "version": "1.2.1",
+      "resolved": "https://registry.npmjs.org/@preact/signals-core/-/signals-core-1.2.1.tgz",
+      "integrity": "sha512-aqzRMNFU1hoQyP4Kb1ldJrUTCnA9vqPDa7qHEQzHJ3upnBOcC2pjmvjAuTqGuY4AVTtUkCQV0FvOCuIQQ2hSdA=="
+    },
+    "@preact/signals-react": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/@preact/signals-react/-/signals-react-1.1.1.tgz",
+      "integrity": "sha512-U5HNWBt4q5pmsZjDOuVcz3OXLQtaBMMSErnTHFohOFQClBqHlVD/hmhayEEO38I9iU71kofhw2ngeWso/GsVMw==",
+      "requires": {
+        "@preact/signals-core": "^1.2.1"
+      }
+    },
     "@remix-run/router": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/@remix-run/router/-/router-1.0.2.tgz",
diff --git a/package.json b/package.json
index b0ecc07..42ae765 100644
--- a/package.json
+++ b/package.json
@@ -20,6 +20,7 @@
   "author": "Joshua Seigler",
   "license": "MIT",
   "dependencies": {
+    "@preact/signals-react": "^1.1.1",
     "@types/react": "^18.0.21",
     "@types/react-dom": "^18.0.6",
     "@types/react-router-dom": "^5.3.3",
diff --git a/src/strategies/index.ts b/src/strategies/index.ts
index c6a5992..b415bd6 100644
--- a/src/strategies/index.ts
+++ b/src/strategies/index.ts
@@ -1,7 +1,9 @@
 import { UseReducer } from "./useReducer";
+import { UseSignal } from "./useSignal";
 import { UseState } from "./useState";
 
 export const strategies = [
   { name: 'useState', component: UseState },
   { name: 'useReducer', component: UseReducer },
+  { name: 'useSignal', component: UseSignal },
 ]
diff --git a/src/strategies/useSignal.tsx b/src/strategies/useSignal.tsx
new file mode 100644
index 0000000..137f75d
--- /dev/null
+++ b/src/strategies/useSignal.tsx
@@ -0,0 +1,103 @@
+import React, { useEffect } from 'react'
+import localforage from 'localforage'
+import { effect, signal, useSignalEffect } from '@preact/signals-react'
+
+type Todo = {
+  id: string
+  text: string
+  status: 'incomplete' | 'complete'
+}
+
+const isLoading = signal(true)
+const todos = signal<Todo[]>([])
+effect(() => {
+  if (!isLoading.value) {
+    localforage.setItem('react-state-management/todos', todos.value)
+  }
+})
+const newTodoText = signal('')
+
+function addTodo() {
+  const newTodo = {
+    id: crypto.randomUUID(),
+    text: newTodoText.value,
+    status: 'incomplete' as const
+  }
+  todos.value = todos.value.concat([newTodo])
+  newTodoText.value = ''
+}
+
+function removeTodo(id: string) {
+  todos.value = todos.value.filter((t) => t.id !== id)
+}
+
+function updateTodo(value: Todo) {
+  todos.value = todos.value.map((t) => (t.id === value.id ? value : t))
+}
+
+export function UseSignal() {
+  useEffect(() => {
+    // run once when mounted
+    localforage.getItem('react-state-management/todos', (_err, value) => {
+      isLoading.value = false
+      if (value) {
+        todos.value = value as Todo[] // validation first would be better
+      }
+    })
+  }, [])
+
+  return (
+    <main
+      style={isLoading.value ? { pointerEvents: 'none', cursor: 'wait' } : {}}>
+      <TodoList />
+      <form
+        onSubmit={(e) => {
+          e.preventDefault()
+          addTodo()
+        }}>
+        <label>
+          New todo:{' '}
+          <input
+            type="text"
+            value={newTodoText.value}
+            onChange={(e) => (newTodoText.value = e.target.value)}
+          />
+        </label>
+      </form>
+    </main>
+  )
+}
+
+function TodoList() {
+  return (
+    <>
+      {todos.value.map((todo) => (
+        <TodoItem key={todo.id} todo={todo} />
+      ))}
+    </>
+  )
+}
+
+function TodoItem({ todo }: { todo: Todo }) {
+  return (
+    <label
+      style={
+        todo.status === 'complete' ? { textDecoration: 'line-through' } : {}
+      }>
+      <a style={{ float: 'right' }} onClick={() => removeTodo(todo.id)}>
+        x
+      </a>
+      <input
+        type="checkbox"
+        onChange={(e) => {
+          updateTodo({
+            ...todo,
+            status: e.target.checked ? 'complete' : 'incomplete'
+          })
+        }}
+        checked={todo.status === 'complete'}
+      />{' '}
+      {todo.text}
+    </label>
+  )
+}