1/*
2 * Copyright (c) 2022 Huawei Device Co., Ltd.
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at
6 *
7 *     http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
14 */
15import {Log} from "../Log";
16
17export type Callback = (args: any) => void;
18const TAG = "EventBus";
19
20export interface EventBus<T> {
21    on(event: T | T[], cb: Callback): () => void;
22    once(event: T, cb: Callback): () => void;
23    off(event: T | T[] | undefined, cb: Callback): void;
24    emit(event: T, args: any): void;
25}
26
27export function createEventBus<T extends string>(): EventBus<T> {
28    let _cbs: { [key: string]: Set<Callback> } = {};
29
30    function on(events: T | T[], cb: Callback): () => void {
31        if (Array.isArray(events)) {
32            events.forEach((e) => on(e, cb));
33        } else {
34            (_cbs[events] || (_cbs[events] = new Set())).add(cb);
35            Log.showInfo(TAG, `add event[${events}] callback, size: ${_cbs[events]?.size}`);
36        }
37        return () => off(events, cb);
38    }
39
40    function once(event: T, cb: Callback): () => void {
41        let newCallback = (args: any) => {
42            cb(args);
43            removeSelf();
44        };
45        function removeSelf() {
46            off(event, newCallback);
47        }
48        return on(event, newCallback);
49    }
50
51    function off(event: T | T[] | undefined, cb: Callback) {
52        if (!event) {
53            _cbs = {};
54            Log.showInfo(TAG, `remove event[${event}] all callback`);
55            return;
56        }
57        if (Array.isArray(event)) {
58            event.forEach((e) => off(e, cb));
59            return;
60        }
61        _cbs[event]?.delete(cb);
62        Log.showInfo(TAG, `remove event[${event}] callback, size: ${_cbs[event]?.size}`);
63    }
64
65    function emit(event: T, args: any) {
66        _cbs[event]?.forEach((cb) => cb(args));
67    }
68
69    function stickyEmit(event: T, argument: any[]) {}
70    return {
71        on,
72        once,
73        off,
74        emit,
75    };
76}