/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 hivemall.utils.datetime;

import java.util.concurrent.TimeUnit;

import javax.annotation.Nonnull;

/**
 * StopWatch provides a API for timings.
 */
public final class StopWatch {

    private final String label;
    private long begin = 0;
    private long end = 0;
    private boolean showInSec = false;

    public StopWatch() {
        this(null, false);
    }

    public StopWatch(String label) {
        this(label, false);
    }

    public StopWatch(String label, boolean showInSec) {
        this.label = label;
        this.showInSec = showInSec;
        start();
    }

    public void setShowInSec(boolean showInSec) {
        this.showInSec = showInSec;
    }

    public void start() {
        begin = System.currentTimeMillis();
    }

    public long stop() {
        end = System.currentTimeMillis();
        return end - begin;
    }

    public void suspend() {
        end = System.currentTimeMillis();
    }

    public void resume() {
        begin += (System.currentTimeMillis() - end);
    }

    public StopWatch reset() {
        begin = 0;
        end = 0;
        return this;
    }

    public long elapsed() {
        if (end != 0) {
            return end - begin;
        } else {
            return System.currentTimeMillis() - begin;
        }
    }

    public long elapsed(@Nonnull TimeUnit unit) {
        return unit.convert(elapsed(), TimeUnit.MILLISECONDS);
    }

    @Override
    public String toString() {
        final StringBuilder buf = new StringBuilder();
        if (label != null) {
            buf.append(label + ": ");
        }
        long t = elapsed();
        if (showInSec) {
            buf.append(DateTimeFormatter.formatTimeInSec(t));
            buf.append("sec");
        } else {
            buf.append(DateTimeFormatter.formatTime(t));
        }
        return buf.toString();
    }

}