dify

dify/web/hooks/use-mitt.ts

@@ -0,0 +1,74 @@
+import type { Emitter, EventType, Handler, WildcardHandler } from 'mitt'
+import create from 'mitt'
+import { useEffect, useRef } from 'react'
+
+const merge = <T extends Record<string, any>>(
+  ...args: Array<T | undefined>
+): T => {
+  return Object.assign({}, ...args)
+}
+
+export type _Events = Record<EventType, unknown>
+
+export type UseSubscribeOption = {
+  /**
+     * Whether the subscription is enabled.
+     * @default true
+     */
+  enabled: boolean;
+}
+
+export type ExtendedOn<Events extends _Events> = {
+  <Key extends keyof Events>(
+    type: Key,
+    handler: Handler<Events[Key]>,
+    options?: UseSubscribeOption,
+  ): void;
+  (
+    type: '*',
+    handler: WildcardHandler<Events>,
+    option?: UseSubscribeOption,
+  ): void;
+}
+
+export type UseMittReturn<Events extends _Events> = {
+  useSubscribe: ExtendedOn<Events>;
+  emit: Emitter<Events>['emit'];
+}
+
+const defaultSubscribeOption: UseSubscribeOption = {
+  enabled: true,
+}
+
+function useMitt<Events extends _Events>(
+  mitt?: Emitter<Events>,
+): UseMittReturn<Events> {
+  const emitterRef = useRef<Emitter<Events> | undefined>(undefined)
+  if (!emitterRef.current)
+    emitterRef.current = mitt ?? create<Events>()
+
+  if (mitt && emitterRef.current !== mitt) {
+    emitterRef.current.off('*')
+    emitterRef.current = mitt
+  }
+  const emitter = emitterRef.current
+  const useSubscribe: ExtendedOn<Events> = (
+    type: string,
+    handler: any,
+    option?: UseSubscribeOption,
+  ) => {
+    const { enabled } = merge(defaultSubscribeOption, option)
+    useEffect(() => {
+      if (enabled) {
+        emitter.on(type, handler)
+        return () => emitter.off(type, handler)
+      }
+    })
+  }
+  return {
+    emit: emitter.emit,
+    useSubscribe,
+  }
+}
+
+export { useMitt }