/*
 * Copyright (C) 2022 The Android Open Source Project
 *
 * 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.
 */
package com.android.app.viewcapture;

import android.os.Handler;
import android.os.Looper;

import java.util.concurrent.Callable;
import java.util.concurrent.Executor;
import java.util.concurrent.Future;
import java.util.concurrent.FutureTask;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.RunnableFuture;

/**
 * Implementation of {@link Executor} which executes on a provided looper.
 */
public class LooperExecutor implements Executor {

    private final Handler mHandler;

    public LooperExecutor(Looper looper) {
        mHandler = new Handler(looper);
    }

    @Override
    public void execute(Runnable runnable) {
        if (mHandler.getLooper() == Looper.myLooper()) {
            runnable.run();
        } else {
            mHandler.post(runnable);
        }
    }

    /**
     * @throws RejectedExecutionException {@inheritDoc}
     * @throws NullPointerException       {@inheritDoc}
     */
    public <T> Future<T> submit(Callable<T> task) {
        if (task == null) throw new NullPointerException();
        RunnableFuture<T> ftask = new FutureTask<T>(task);
        execute(ftask);
        return ftask;
    }

}