// (C) Copyright 2015 Moodle Pty Ltd.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

/**
 * Singleton with helper functions for time operations.
 */
export class CoreTime {

    /**
     * Wrap a function so that it is called only once.
     *
     * @param fn Function.
     * @return Wrapper that will call the underlying function only once.
     */
    static once<T extends unknown[]>(fn: (...args: T) => unknown): (...args: T) => void {
        let called = false;

        return (...args: T) => {
            if (called) {
                return;
            }

            called = true;
            fn.apply(null, args);
        };
    }

}