/*
 * 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 org.apache.jena.atlas.lib ;

import org.apache.jena.atlas.AtlasException ;

/** A Timer of operations */ 
public class Timer {

    protected long    timeFinish = -1 ;
    protected boolean inTimer    = false ;
    protected long    timeStart  = 0 ;

    public Timer() {}

    public void startTimer() {
        if ( inTimer )
            throw new AtlasException("Already in timer") ;

        timeStart = System.currentTimeMillis() ;
        timeFinish = -1 ;
        inTimer = true ;
    }

    /** Return time in millisecods */
    public long endTimer() {
        if ( !inTimer )
            throw new AtlasException("Not in timer") ;
        timeFinish = System.currentTimeMillis() ;
        inTimer = false ;
        return getTimeInterval() ;
    }

    public long readTimer() {
        if ( !inTimer )
            throw new AtlasException("Not in timer") ;
        return System.currentTimeMillis() - timeStart ;
    }

    public long getTimeInterval() {
        if ( inTimer )
            throw new AtlasException("Still timing") ;
        if ( timeFinish == -1 )
            throw new AtlasException("No valid interval") ;

        return timeFinish - timeStart ;
    }

    static public String timeStr(long timeInterval) {
        return String.format("%.3f", timeInterval / 1000.0) ;
    }

    protected String timeStr(long timePoint, long startTimePoint) {
        return timeStr(timePoint - startTimePoint) ;
    }
}