From 766ab2f4e9d6be79e9171d38b87adac4f96e332c Mon Sep 17 00:00:00 2001
From: Ward Oosterlijnck <wardoosterlijnck@gmail.com>
Date: Tue, 16 Apr 2019 19:26:01 +1000
Subject: [PATCH] createReducer for redux middleware, related #164

---
 package.json                            |  2 +
 src/__stories__/createReducer.story.tsx | 56 +++++++++++++++++++++++++
 src/createReducer.ts                    | 35 ++++++++++++++++
 src/index.ts                            |  2 +
 yarn.lock                               | 17 ++++++++
 5 files changed, 112 insertions(+)
 create mode 100644 src/__stories__/createReducer.story.tsx
 create mode 100644 src/createReducer.ts

diff --git a/package.json b/package.json
index 9a24b26348..ad05cffdef 100644
--- a/package.json
+++ b/package.json
@@ -87,6 +87,8 @@
     "react-hooks-testing-library": "0.4.0",
     "react-spring": "6.1.10",
     "rebound": "0.1.0",
+    "redux-logger": "^3.0.6",
+    "redux-thunk": "^2.3.0",
     "rimraf": "2.6.3",
     "rxjs": "6.4.0",
     "semantic-release": "15.13.3",
diff --git a/src/__stories__/createReducer.story.tsx b/src/__stories__/createReducer.story.tsx
new file mode 100644
index 0000000000..1edaf91e1a
--- /dev/null
+++ b/src/__stories__/createReducer.story.tsx
@@ -0,0 +1,56 @@
+import { storiesOf } from '@storybook/react';
+import * as React from 'react';
+import logger from 'redux-logger';
+import thunk from 'redux-thunk';
+
+import { createReducer } from '..';
+// import ShowDocs from './util/ShowDocs';
+
+const useThunkReducer = createReducer(thunk, logger);
+
+// React useReducer lazy initialization example: https://reactjs.org/docs/hooks-reference.html#lazy-initialization
+function init(initialCount) {
+  return { count: initialCount };
+}
+
+function reducer(state, action) {
+  switch (action.type) {
+    case 'increment':
+      return { count: state.count + 1 };
+    case 'decrement':
+      return { count: state.count - 1 };
+    case 'reset':
+      return init(action.payload);
+    default:
+      throw new Error();
+  }
+}
+
+const Demo = ({ initialCount = 1 }) => {
+  // Action creator to increment count, wait a second and then reset
+  const addAndReset = React.useCallback(() => {
+    return dispatch => {
+      dispatch({ type: 'increment' });
+
+      setTimeout(() => {
+        dispatch({ type: 'reset', payload: initialCount });
+      }, 1000);
+    };
+  }, [initialCount]);
+
+  const [state, dispatch] = useThunkReducer(reducer, initialCount, init);
+
+  return (
+    <div>
+      <pre>{JSON.stringify(state, null, 2)}</pre>
+      <button onClick={() => dispatch(addAndReset())}>Add and reset</button>
+      <button onClick={() => dispatch({ type: 'reset', payload: initialCount })}>Reset</button>
+      <button onClick={() => dispatch({ type: 'increment' })}>+</button>
+      <button onClick={() => dispatch({ type: 'decrement' })}>-</button>
+    </div>
+  );
+};
+
+storiesOf('State|createReducer', module)
+  // .add('Docs', () => <ShowDocs md={require('../../docs/createMemo.md')} />)
+  .add('Demo', () => <Demo />);
diff --git a/src/createReducer.ts b/src/createReducer.ts
new file mode 100644
index 0000000000..7ff5fd3b83
--- /dev/null
+++ b/src/createReducer.ts
@@ -0,0 +1,35 @@
+import { useReducer } from 'react';
+
+function compose(...funcs) {
+  if (funcs.length === 0) {
+    return arg => arg;
+  }
+
+  if (funcs.length === 1) {
+    return funcs[0];
+  }
+
+  return funcs.reduce((a, b) => (...args) => a(b(...args)));
+}
+
+const createReducer = (...middlewares) => (...args) => {
+  const [state, dispatch] = useReducer(...args);
+
+  let middlewareDispatch = () => {
+    throw new Error(
+      'Dispatching while constructing your middleware is not allowed. ' +
+        'Other middleware would not be applied to this dispatch.'
+    );
+  };
+
+  const middlewareAPI = {
+    getState: () => state,
+    dispatch: (...args) => middlewareDispatch(...args),
+  };
+  const chain = middlewares.map(middleware => middleware(middlewareAPI));
+  middlewareDispatch = compose(...chain)(dispatch);
+
+  return [state, middlewareDispatch];
+};
+
+export default createReducer;
diff --git a/src/index.ts b/src/index.ts
index 3923f60cca..bd458171c1 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,4 +1,5 @@
 import createMemo from './createMemo';
+import createReducer from './createReducer';
 import useAsync from './useAsync';
 import useAsyncFn from './useAsyncFn';
 import useAsyncRetry from './useAsyncRetry';
@@ -72,6 +73,7 @@ import useWindowSize from './useWindowSize';
 
 export {
   createMemo,
+  createReducer,
   useAsync,
   useAsyncFn,
   useAsyncRetry,
diff --git a/yarn.lock b/yarn.lock
index 95ca898a8f..d71ee0ff7d 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -5007,6 +5007,11 @@ dedent@^0.7.0:
   resolved "https://registry.yarnpkg.com/dedent/-/dedent-0.7.0.tgz#2495ddbaf6eb874abb0e1be9df22d2e5a544326c"
   integrity sha1-JJXduvbrh0q7Dhvp3yLS5aVEMmw=
 
+deep-diff@^0.3.5:
+  version "0.3.8"
+  resolved "https://registry.yarnpkg.com/deep-diff/-/deep-diff-0.3.8.tgz#c01de63efb0eec9798801d40c7e0dae25b582c84"
+  integrity sha1-wB3mPvsO7JeYgB1Ax+Da4ltYLIQ=
+
 deep-extend@^0.6.0:
   version "0.6.0"
   resolved "https://registry.yarnpkg.com/deep-extend/-/deep-extend-0.6.0.tgz#c4fa7c95404a17a9c3e8ca7e1537312b736330ac"
@@ -11333,6 +11338,18 @@ redeyed@~2.1.0:
   dependencies:
     esprima "~4.0.0"
 
+redux-logger@^3.0.6:
+  version "3.0.6"
+  resolved "https://registry.yarnpkg.com/redux-logger/-/redux-logger-3.0.6.tgz#f7555966f3098f3c88604c449cf0baf5778274bf"
+  integrity sha1-91VZZvMJjzyIYExEnPC69XeCdL8=
+  dependencies:
+    deep-diff "^0.3.5"
+
+redux-thunk@^2.3.0:
+  version "2.3.0"
+  resolved "https://registry.yarnpkg.com/redux-thunk/-/redux-thunk-2.3.0.tgz#51c2c19a185ed5187aaa9a2d08b666d0d6467622"
+  integrity sha512-km6dclyFnmcvxhAcrQV2AkZmPQjzPDjgVlQtR0EQjxZPyJ0BnMf3in1ryuR8A2qU0HldVRfxYXbFSKlI3N7Slw==
+
 refractor@^2.4.1:
   version "2.7.0"
   resolved "https://registry.yarnpkg.com/refractor/-/refractor-2.7.0.tgz#3ed9a96a619e75326a429e644241dea51be070a3"