Refactor useHydratedStore hook. Remove mst-persist

- consolidate `useStore` and `useHydratedStore`, so that `useHydratedStore` calls `useStore` to create the new store.
- add a `persist` helper to manage store snapshots.
- remove `mst-persist`.

Move Classifier hooks to @hooks
Load hooks from `/src/hooks`, aliased to `@hooks`.

Test the useHydratedStore hook

Consolidate store hooks
Replace the store hooks with a single `useHydratedStore` hook. Use synchronous storage.

packages/lib-classifier/package.json

@@ -35,7 +35,6 @@
     "i18next": "~21.6.3",
     "lodash": "~4.17.11",
     "mobx-utils": "~6.0.4",
-    "mst-persist": "~0.1.3",
     "react-i18next": "~11.15.1",
     "react-player": "~2.9.0",
     "react-resize-detector": "~7.0.0",

packages/lib-classifier/src/components/Classifier/ClassifierContainer.js

@@ -11,7 +11,7 @@ import {
   tutorials as tutorialsClient
 } from '@zooniverse/panoptes-js'
 
-import { useHydratedStore, useStore, useWorkflowSnapshot } from './hooks'
+import { useHydratedStore, useWorkflowSnapshot } from '@hooks'
 import { unregisterWorkers } from '../../workers'
 import Classifier from './Classifier'
 
@@ -62,15 +62,12 @@ export default function ClassifierContainer({
   workflowID
 }) {
 
-  const classifierStore = useStore({
-    authClient,
-    client,
-    initialState: {}
-  })
+  const storeOptions = { authClient, client }
 
   const workflowSnapshot = useWorkflowSnapshot(workflowID)
 
-  const loaded = useHydratedStore(classifierStore, cachePanoptesData, `fem-classifier-${project.id}`)
+  const classifierStore = useHydratedStore(storeOptions, cachePanoptesData, `fem-classifier-${project.id}`)
+  const loaded = !!classifierStore
 
   useEffect(function onMount() {
     console.log('resetting stale user data')

packages/lib-classifier/src/helpers/index.js

@@ -1,5 +1,4 @@
 import * as featureDetection from './featureDetection'
-export { default as asyncSessionStorage } from './asyncSessionStorage'
 export { default as createLocationCounts } from './createLocationCounts'
 export { featureDetection }
 export { default as findLocationsByMediaType } from './findLocationsByMediaType'

packages/lib-classifier/src/hooks/Readme.md

@@ -0,0 +1,19 @@
+# Classifier hooks
+
+## useHydratedStore
+
+Create a `mobx-state-tree` store from an optional stored [snapshot](https://mobx-state-tree.js.org/concepts/snapshots). Adds an `onSnapshot` handler to keep the stored snapshot updated when the store changes.
+
+Returns the new store when hydration is complete. Snapshots are stored in session storage, so that they don't persist across tabs or windows.
+
+```js
+const classifierStore = useHydratedStore({ authClient, client }, cachePanoptesData = false, storageKey)
+```
+
+## useWorkflowSnapshot
+
+A wrapper for [`useSWR`](https://swr.vercel.app/), which fetches a workflow by ID, using the default SWR options. The workflow will refresh on visibility change (eg. waking from sleep), or when the classifier receives focus.
+
+```js
+const workflowSnapshot = useWorkflowSnapshot(workflowID)
+```

packages/lib-classifier/src/components/Classifier/hooks/index.js → packages/lib-classifier/src/hooks/index.js

@@ -1,3 +1,2 @@
 export { default as useHydratedStore } from './useHydratedStore'
-export { default as useStore } from './useStore'
 export { default as useWorkflowSnapshot } from './useWorkflowSnapshot'

packages/lib-classifier/src/hooks/useHydratedStore.js

@@ -0,0 +1,51 @@
+import makeInspectable from 'mobx-devtools-mst'
+import { addDisposer, onSnapshot } from 'mobx-state-tree'
+import { useMemo } from 'react'
+
+import RootStore from '@store'
+
+function loadSnapshot(storageKey, storage) {
+  const data = storage.getItem(storageKey)
+  return JSON.parse(data) || {}
+}
+
+function persist(storageKey, _store, storage) {
+  function _saveSnapshot(snapshot) {
+    const data = JSON.stringify(snapshot)
+    storage.setItem(storageKey, data)
+  }
+  const snapshotDisposer = onSnapshot(_store, _saveSnapshot)
+  return addDisposer(_store, snapshotDisposer)
+}
+
+let store = null
+
+function initStore({ authClient, cachePanoptesData, client, storageKey }) {
+  if (store === null) {
+    let initialState = {}
+
+    if (cachePanoptesData) {
+      initialState = loadSnapshot(storageKey, window.sessionStorage)
+    }
+
+    store = RootStore.create(initialState, {
+      authClient,
+      client
+    })
+
+    if (cachePanoptesData) {
+      persist(storageKey, store, window.sessionStorage)
+    }
+    makeInspectable(store)
+  }
+  return store
+}
+
+export function cleanStore() {
+  store = null
+}
+
+export default function useHydratedStore({ authClient, client }, cachePanoptesData = false, storageKey) {
+  const _store = useMemo(() => initStore({ authClient, cachePanoptesData, client, storageKey }), [authClient, cachePanoptesData, client, storageKey])
+  return _store
+}

packages/lib-classifier/src/hooks/useHydratedStore.spec.js

@@ -0,0 +1,98 @@
+import { applySnapshot, getSnapshot } from 'mobx-state-tree'
+import React from 'react'
+import { renderHook } from '@testing-library/react-hooks/pure'
+
+import mockStore from '@test/mockStore'
+import RootStore from '@store/RootStore'
+import { cleanStore } from './useHydratedStore'
+import { useHydratedStore } from '.'
+
+describe('Hooks > useHydratedStore', function () {
+  describe('without an existing store', function () {
+    let store
+
+    beforeEach(function () {
+      const { authClient, client } = mockStore()
+      const { result } = renderHook(() => useHydratedStore({ authClient, client }, false, 'test-key'))
+      store = result.current
+    })
+
+    afterEach(function () {
+      cleanStore()
+    })
+
+    it('should create a new store', function () {
+      const mockStore = getSnapshot(RootStore.create({}))
+      const snapshot = getSnapshot(store)
+      expect(snapshot).to.deep.equal(mockStore)
+    })
+  })
+
+  describe('with an existing store', function () {
+    let store
+    let newStore
+
+    beforeEach(function () {
+      const { authClient, client } = mockStore()
+      const { result: firstRun } = renderHook(() => useHydratedStore({ authClient, client }, false, 'test-key'))
+      store = firstRun.current
+      const { result: secondRun } = renderHook(() => useHydratedStore({ authClient, client }, false, 'test-key'))
+      newStore = secondRun.current
+    })
+
+    afterEach(function () {
+      cleanStore()
+    })
+
+    it('should use the existing store', function () {
+      expect(newStore).to.deep.equal(store)
+    })
+  })
+
+  describe('with session storage enabled', function () {
+    let store
+
+    beforeEach(function () {
+      const expectedStore = mockStore()
+      const { authClient, client } = expectedStore
+      const { result } = renderHook(() => useHydratedStore({ authClient, client }, true, 'test-key'))
+      store = result.current
+      const mockSnapshot = getSnapshot(expectedStore)
+      applySnapshot(store.projects, mockSnapshot.projects)
+    })
+
+    afterEach(function () {
+      cleanStore()
+    })
+
+    it('should save snapshots in session storage', function () {
+      const mockSnapshot = window.sessionStorage.getItem('test-key')
+      const snapshot = getSnapshot(store)
+      expect(JSON.stringify(snapshot)).to.equal(mockSnapshot)
+    })
+  })
+
+  describe('with a saved snapshot', function () {
+    let store
+    let mockSnapshot
+
+    beforeEach(function () {
+      const expectedStore = mockStore()
+      mockSnapshot = getSnapshot(expectedStore)
+      window.sessionStorage.setItem('test-key', JSON.stringify(mockSnapshot))
+
+      const { authClient, client } = expectedStore
+      const { result } = renderHook(() => useHydratedStore({ authClient, client }, true, 'test-key'))
+      store = result.current
+    })
+
+    afterEach(function () {
+      cleanStore()
+    })
+
+    it('should load the snapshot into the store', function () {
+      const snapshot = getSnapshot(store)
+      expect(snapshot.projects).to.deep.equal(mockSnapshot.projects)
+    })
+  })
+})

packages/lib-classifier/webpack.dev.js

@@ -44,6 +44,7 @@ module.exports = {
   resolve: {
     alias: {
       '@components': path.resolve(__dirname, 'src/components'),
+      '@hooks': path.resolve(__dirname, 'src/hooks'),
       '@helpers': path.resolve(__dirname, 'src/helpers'),
       '@plugins': path.resolve(__dirname, 'src/plugins'),
       '@store': path.resolve(__dirname, 'src/store'),

packages/lib-classifier/webpack.dist.js

@@ -37,6 +37,7 @@ module.exports = {
   resolve: {
     alias: {
       '@components': path.resolve(__dirname, 'src/components'),
+      '@hooks': path.resolve(__dirname, 'src/hooks'),
       '@helpers': path.resolve(__dirname, 'src/helpers'),
       '@plugins': path.resolve(__dirname, 'src/plugins'),
       '@store': path.resolve(__dirname, 'src/store'),

yarn.lock

@@ -12044,11 +12044,6 @@ mst-middlewares@~5.1.0:
   resolved "https://registry.yarnpkg.com/mst-middlewares/-/mst-middlewares-5.1.3.tgz#059a2cf4e44cdb44ae92eb4a4e8ce47f6c117c66"
   integrity sha512-zVPxLO6kQFMTU0S7xYoyiSml8nUP5Ekto3CY4Ra7cGwbuLOwIDBgCyNIEEtLpq95KFbhAEl9oIchg4RW13iCZg==
 
-mst-persist@~0.1.3:
-  version "0.1.3"
-  resolved "https://registry.yarnpkg.com/mst-persist/-/mst-persist-0.1.3.tgz#ac7203f3ab36085106c4293d4a9cd67dd5613708"
-  integrity sha512-G2IzmTvi2E8zOTTCiMENkli+KmANhpPNlkguOEJp0dioqfdETDQjLO6QKy5hXhDTRIQhu48IlDJeNdyeZ8NIaw==
-
 multicast-dns-service-types@^1.1.0:
   version "1.1.0"
   resolved "https://registry.yarnpkg.com/multicast-dns-service-types/-/multicast-dns-service-types-1.1.0.tgz#899f11d9686e5e05cb91b35d5f0e63b773cfc901"