//typescriptClasses/Stopwatch.ts
//Matthew Ellison
// Created: 10-18-20
//Modified: 10-18-20
//This file contains a class that is used to time the execution time of other programs
/*
Copyright (C) 2020  Matthew Ellison

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU Lesser General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU Lesser General Public License for more details.

	You should have received a copy of the GNU Lesser General Public License
	along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/


import {InvalidResult} from "./InvalidResult";
import {performance} from "perf_hooks";


//An enum that helps keep track of how many times the time has been reduced in the getStr function
enum TIME_RESOLUTION{ NANOSECOND, MICROSECOND, MILLISECOND, SECOND, MINUTE, HOUR, ERROR };

export class Stopwatch{
	private startTime: number;
	private stopTime: number;
	//Constructor makes sure all values are set to defaults
	public constructor(){
		//Make sure both values are null so it is easier to detect incorrect function calling order
		this.startTime = null;
		this.stopTime = null;
	}
	//Returns a long with the elapsed time in milliseconds. Used by other functions to get the time before converting it to the correct resolution
	private getTime(): number{
		if(this.startTime == null){
			return 0;
		}
		else if(this.stopTime == null){
			return performance.now() - this.startTime;
		}
		else{
			return this.stopTime - this.startTime;
		}
	}
	//Simultates starting a stopwatch by saving the time
	public start(): void{
		//Make sure the stop time is reset
		this.stopTime = null;
		//Get the time as close to returning from the function as possible
		this.startTime = performance.now();
	}
	//Simulates stopping a stopwatch by saving the time
	public stop(): void{
		//Set the stopTime as close to call time as possible
		this.stopTime = performance.now();
		//If the startTime has not been set then reset stopTime
		if(this.startTime == null){
			this.stopTime = null;
		}
	}
	//Resets all variables in the stopwatch
	public reset(): void{
		//Make sure all variables are reset correctly
		this.startTime = null;
		this.stopTime = null;
	}
	//Returns the time in nanoseconds
	public getNano(): number{
		return this.getTime() * 1000000;
	}
	//Returns the time in microseconds
	public getMicro(): number{
		return this.getTime() * 1000;
	}
	//Returns the time in milliseconds
	public getMilli(): number{
		return this.getTime();
	}
	//Returns the time in seconds
	public getSecond(): number{
		return this.getTime() / 1000;
	}
	//Returns the time in minutes
	public getMinute(): number{
		return this.getTime() / 60000;
	}
	//Returns the time in hours
	public getHour(): number{
		return this.getTime() / 3600000;
	}
	//Returns the time as a string at the 'best' resolution. (Goal is xxx.xxx)
	public getStr(): string{
		//Get the current duraction from time
		return Stopwatch.getStr(this.getNano());
	}

	public static getStr(nanoseconds: number): string{
		let duration: number = nanoseconds;
		//Reduce the num,ber to the appropriate number of digits. (xxx.x).
		//This loop works down to seconds
		let resolution: TIME_RESOLUTION;
		for(resolution = TIME_RESOLUTION.NANOSECOND;(resolution < TIME_RESOLUTION.SECOND) && (duration >= 1000);++resolution){
			duration /= 1000;
		}
		//Check if the duration needs reduced to minutes
		if((duration >= 120) && (resolution == TIME_RESOLUTION.SECOND)){
			//Reduce to minutes
			duration /= 60;
			++resolution;

			//Check if the duration needs reduced to hours
			if(duration >= 60){
				//Reduce to hours
				duration /= 60;
				++resolution;
			}
		}

		//Turn the number into a string
		let time: string = duration.toFixed(3);

		//Tack on the appropriate suffix for resolution
		switch(resolution){
			case TIME_RESOLUTION.NANOSECOND: time += " nanoseconds"; break;
			case TIME_RESOLUTION.MICROSECOND: time += " microseconds"; break;
			case TIME_RESOLUTION.MILLISECOND: time += " milliseconds"; break;
			case TIME_RESOLUTION.SECOND: time += " seconds"; break;
			case TIME_RESOLUTION.MINUTE: time += " minutes"; break;
			case TIME_RESOLUTION.HOUR: time += " hours"; break;
			case TIME_RESOLUTION.ERROR:
			default: throw new InvalidResult("timeResolution was invalid");
		}
		//Return the string
		return time;
	}
}