feat: create extendable sync states (#1854)

Author: tonai

Diff for: packages/client/index.ts

@@ -9,5 +9,11 @@ export { useNav } from './composables/useNav'
 export { useSlideContext } from './context'
 export * from './env'
 
+export { createSyncState, disableSlidevSync, addSyncMethod } from './state/syncState'
+export { onDrawingUpdate, drawingState } from './state/drawings'
+export { onSharedUpdate, sharedState } from './state/shared'
+export type { DrawingsState } from './state/drawings'
+export type { SharedState } from './state/shared'
+
 export * from './layoutHelper'
 export { onSlideEnter, onSlideLeave, useIsSlideActive } from './logic/slides'

Diff for: packages/client/state/drawings.ts

@@ -6,6 +6,7 @@ export type DrawingsState = Record<number, string | undefined>
 export const {
   init: initDrawingState,
   onPatch: onPatchDrawingState,
+  onUpdate: onDrawingUpdate,
   patch: patchDrawingState,
   state: drawingState,
 } = createSyncState<DrawingsState>(serverDrawingState, serverDrawingState, __SLIDEV_FEATURE_DRAWINGS_PERSIST__)

Diff for: packages/client/state/shared.ts

@@ -22,7 +22,7 @@ export interface SharedState {
   }
 }
 
-const { init, onPatch, patch, state } = createSyncState<SharedState>(serverState, {
+const { init, onPatch, onUpdate, patch, state } = createSyncState<SharedState>(serverState, {
   page: 1,
   clicks: 0,
   clicksTotal: 0,
@@ -34,6 +34,7 @@ const { init, onPatch, patch, state } = createSyncState<SharedState>(serverState
 export {
   init as initSharedState,
   onPatch,
+  onUpdate as onSharedUpdate,
   patch,
   state as sharedState,
 }

Diff for: packages/client/state/syncState.ts

@@ -1,4 +1,72 @@
-import { reactive, toRaw, watch } from 'vue'
+import { reactive, ref, toRaw, watch } from 'vue'
+
+export type SyncWrite<State extends object> = (state: State, updating?: boolean) => void
+
+export interface Sync {
+  enabled?: boolean
+  init: <State extends object>(channelKey: string, onUpdate: (data: Partial<State>) => void, state: State, persist?: boolean) => SyncWrite<State> | undefined
+}
+
+interface SlidevSync extends Sync {
+  channels: BroadcastChannel[]
+  disable: () => void
+  listener?: (event: StorageEvent) => void
+}
+
+const slidevSync: SlidevSync = {
+  channels: [],
+  enabled: true,
+  init<State extends object>(channelKey: string, onUpdate: (data: Partial<State>) => void, state: State, persist = false) {
+    let stateChannel: BroadcastChannel
+    if (!__SLIDEV_HAS_SERVER__ && !persist) {
+      stateChannel = new BroadcastChannel(channelKey)
+      stateChannel.addEventListener('message', (event: MessageEvent<Partial<State>>) => onUpdate(event.data))
+      this.channels.push(stateChannel)
+    }
+    else if (!__SLIDEV_HAS_SERVER__ && persist) {
+      this.listener = function (event: StorageEvent) {
+        if (event && event.key === channelKey && event.newValue)
+          onUpdate(JSON.parse(event.newValue) as Partial<State>)
+      }
+      window.addEventListener('storage', this.listener)
+      const serializedState = window.localStorage.getItem(channelKey)
+      if (serializedState)
+        onUpdate(JSON.parse(serializedState) as Partial<State>)
+    }
+    return (state: State, updating = false) => {
+      if (this.enabled) {
+        if (!persist && stateChannel && !updating)
+          stateChannel.postMessage(toRaw(state))
+        if (persist && !updating)
+          window.localStorage.setItem(channelKey, JSON.stringify(state))
+      }
+    }
+  },
+  disable() {
+    this.enabled = false
+    this.channels.forEach(channel => channel.close())
+    if (this.listener) {
+      window.removeEventListener('storage', this.listener)
+    }
+  },
+}
+const syncInterfaces: Sync[] = reactive([slidevSync])
+const channels: Map<string, { onUpdate: (data: Partial<object>) => void, persist?: boolean, state: object }> = new Map()
+const syncWrites = ref<Record<string, SyncWrite<object>[]>>({})
+
+export function disableSlidevSync() {
+  slidevSync.disable()
+}
+
+export function addSyncMethod(sync: Sync) {
+  syncInterfaces.push(sync)
+  for (const [channelKey, { onUpdate, persist, state }] of channels.entries()) {
+    const write = sync.init(channelKey, onUpdate, state, persist)
+    if (write) {
+      syncWrites.value[channelKey].push(write)
+    }
+  }
+}
 
 export function createSyncState<State extends object>(serverState: State, defaultState: State, persist = false) {
   const onPatchCallbacks: ((state: State) => void)[] = []
@@ -36,35 +104,19 @@ export function createSyncState<State extends object>(serverState: State, defaul
   }
 
   function init(channelKey: string) {
-    let stateChannel: BroadcastChannel
-    if (!__SLIDEV_HAS_SERVER__ && !persist) {
-      stateChannel = new BroadcastChannel(channelKey)
-      stateChannel.addEventListener('message', (event: MessageEvent<Partial<State>>) => onUpdate(event.data))
-    }
-    else if (!__SLIDEV_HAS_SERVER__ && persist) {
-      window.addEventListener('storage', (event) => {
-        if (event && event.key === channelKey && event.newValue)
-          onUpdate(JSON.parse(event.newValue) as Partial<State>)
-      })
-    }
+    channels.set(channelKey, { onUpdate, persist, state })
+    syncWrites.value[channelKey] = syncInterfaces
+      .map(sync => sync.init<State>(channelKey, onUpdate, state, persist))
+      .filter((x): x is SyncWrite<object> => Boolean(x))
 
     function onStateChanged() {
-      if (!persist && stateChannel && !updating)
-        stateChannel.postMessage(toRaw(state))
-      else if (persist && !updating)
-        window.localStorage.setItem(channelKey, JSON.stringify(state))
+      syncWrites.value[channelKey].forEach(write => write?.(toRaw(state), updating))
       if (!patching)
         onPatchCallbacks.forEach((fn: (state: State) => void) => fn(state))
     }
 
-    watch(state, onStateChanged, { deep: true, flush: 'sync' })
-
-    if (!__SLIDEV_HAS_SERVER__ && persist) {
-      const serialzedState = window.localStorage.getItem(channelKey)
-      if (serialzedState)
-        onUpdate(JSON.parse(serialzedState) as Partial<State>)
-    }
+    watch(state, onStateChanged, { deep: true })
   }
 
-  return { init, onPatch, patch, state }
+  return { init, onPatch, onUpdate, patch, state }
 }