//Java/JavaClasses/Mattrixwv/Stopwatch.java
//Matthew Ellison (Mattrixwv)
// Created: 03-01-19
//Modified: 03-01-19
//This file contains a class that is used to time the execution time of other programs


package mattrixwv;


public class Stopwatch{
	private Long startTime;
	private Long stopTime;
	//Constructor makes sure all values are set to defaults
	public Stopwatch(){
		//Make sure both values are null so it is easier to detect incorrect function calling order
		startTime = null;
		stopTime = null;
	}
	//Returns a long with the elapsed time in nanoseconds. Used by other functions to get the time before converting it to the correct resolution
	private Long getTime(){
		if(startTime == null){
			///This should throw an exception instead of returning 0
			return 0L;
		}
		else if(stopTime == null){
			return System.nanoTime() - startTime;
		}
		else{
			return stopTime - startTime;
		}
	}
	//An enum that helps keep track of how many times the time has been reduced in the getStr function
	private enum TIME_RESOLUTION{ NANOSECOND, MICROSECOND, MILLISECOND, SECOND, MINUTE, HOUR, ERROR }
	//Simulates starting a stopwatch by saving the time
	public void start(){
		//Get the time as close to calling the function as possible
		startTime = System.nanoTime();
		//Make sure the stop time is reset to 0
		stopTime = null;
	}
	//SImulates stoping a stopwatch by saving the time
	public void stop(){
		//Set the stopTime as close to call time as possible
		stopTime = System.nanoTime();
		//If the startTime has not been set then reset stopTime
		if(startTime == null){
			stopTime = null;
		}
	}
	//Resets all variables in the stopwatch
	public void reset(){
		//Make sure all variables are reset correctly
		startTime = null;
		stopTime = null;
	}
	//Returns the time in nanoseconds
	public double getNano(){
		return getTime().doubleValue();
	}
	//Returns the time in microseconds
	public double getMicro(){
		return getTime().doubleValue() / 1000D;
	}
	//Returns the time in milliseconds
	public double getMilli(){
		return getTime().doubleValue() / 1000000D;
	}
	//Returns the time in seconds
	public double getSecond(){
		return getTime().doubleValue() / 1000000000D;
	}
	//Returns the time in minutes
	public double getMinute(){
		return getTime().doubleValue() / 60000000000D;
	}
	//Returns the time in hours
	public double getHour(){
		return getTime().doubleValue() / 3600000000000D;
	}
	//Returns the time as a string at the 'best' resolution. (Goal is xxx.xxx)
	public String getStr(){
		//Get the current duration from time
		Double duration = getTime().doubleValue();
		//Reduce the number to the appropriate number of digits. (xxx.x). This loop works down to seconds
		TIME_RESOLUTION resolution;
		for(resolution = TIME_RESOLUTION.NANOSECOND;(resolution.ordinal() < TIME_RESOLUTION.SECOND.ordinal()) && (duration >= 1000);resolution = TIME_RESOLUTION.values()[resolution.ordinal() + 1]){
			duration /= 1000;
		}
		//Check if the duration needs reduced to minutes
		if(duration >= 1000){
			//Reduce to minutes
			duration /= 60;
			resolution = TIME_RESOLUTION.values()[resolution.ordinal() + 1];
		}
		//Check if the duration needs reduced to hours
		if(duration >= 1000){
			//Reduce to hours
			duration /= 60;
			resolution = TIME_RESOLUTION.values()[resolution.ordinal() + 1];
		}

		//Turn the number into a string
		Double durationFraction = ((duration % 1) * 1000);
		String time = String.format("%d.%03d", duration.intValue(), durationFraction.intValue());

		//Tack on the appropriate suffix for resolution
		switch(resolution){
			case NANOSECOND: time += " nanoseconds"; break;
			case MICROSECOND: time += " microseconds"; break;
			case MILLISECOND: time += " milliseconds"; break;
			case SECOND: time += " seconds"; break;
			case MINUTE: time += " minutes"; break;
			case HOUR: time += " hours"; break;
			case ERROR:
			default: time = "There was an error computing the time"; break;	///This should throw an error instead
		}
		//Return the string
		return time;
	}
}