//ProjectEulerTS/Problems/Problem25.ts
//Matthew Ellison
// Created: 04-08-21
//Modified: 04-08-21
//What is the index of the first term in the Fibonacci sequence to contain 1000 digits?
//Unless otherwise listed all non-standard includes are my own creation and available from https://bibucket.org/Mattrixwv/typescriptClasses
/*
	Copyright (C) 2021  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 { getFibBig } from "../../../Typescript/typescriptClasses/Algorithms";
import { Unsolved } from "../Unsolved";
import { Problem } from "./Problem";


export class Problem25 extends Problem{
	//Variables
	//Static variables
	private static NUM_DIGITS: number = 1000;	//The number of digits to calculate up to
	//Instance variables
	private number: bigint;	//The current Fibonacci number
	private index: bigint;	//The index of the current Fibonacci number just calculated

	//Functions
	//Constructor
	public constructor(){
		super(`What is the index of the first term in the Fibonacci sequence to contains ${Problem25.NUM_DIGITS} digits?`);
		this.number = 0n;
		this.index = 2n;
	}
	//Operational functions
	//Solve the problem
	public solve(): void{
		//If the problem has already been solved do nothing and end the function
		if(this.solved){
			return;
		}

		//Start the timer
		this.timer.start();

		//Move through all Fibonacci numbers until you reach the one with at least NUM_DIGITS digits
		while(this.number.toString().length < Problem25.NUM_DIGITS){
			this.index += 1n;	//Increase the index number. Doing this at the beginning keeps the index correct at the end of the loop
			this.number = getFibBig(this.index);	//Calculate the number
		}

		//Stop the timer
		this.timer.stop();

		//Throw a flag to show the problem is solved
		this.solved = true;
	}
	//Reset the problem so it can be run again
	public reset(): void{
		super.reset();
		this.number = 0n;
		this.index = 2n;
	}
	//Gets
	//Returns the result of solving the problem
	public getResult(): string{
		if(!this.solved){
			throw new Unsolved();
		}
		return `The first Fibonacci number with ${Problem25.NUM_DIGITS} digits is ${this.number}\nIts index is ${this.index}`;
	}
	//Returns the Fibonacci number asked for
	public getNumber(): bigint{
		if(!this.solved){
			throw new Unsolved();
		}
		return this.number;
	}
	//Returns the Fibonacci number asked for as a string
	public getNumberString(): string{
		if(!this.solved){
			throw new Unsolved();
		}
		return this.number.toString();
	}
	//Returns the index of the requested Fibonacci number
	public getIndex(): bigint{
		if(!this.solved){
			throw new Unsolved();
		}
		return this.index;
	}
	//Returns the index of the requested Fibonacci number as a string
	public getIndexString(): string{
		if(!this.solved){
			throw new Unsolved();
		}
		return this.index.toString();
	}
	//Returns the index of the requested Fibonacci number as a number
	public getIndexInt(): number{
		if(!this.solved){
			throw new Unsolved();
		}
		return Number(this.index);
	}
}

/* Results:
The first Fibonacci number with 1000 digits is 1070066266382758936764980584457396885083683896632151665013235203375314520604694040621889147582489792657804694888177591957484336466672569959512996030461262748092482186144069433051234774442750273781753087579391666192149259186759553966422837148943113074699503439547001985432609723067290192870526447243726117715821825548491120525013201478612965931381792235559657452039506137551467837543229119602129934048260706175397706847068202895486902666185435124521900369480641357447470911707619766945691070098024393439617474103736912503231365532164773697023167755051595173518460579954919410967778373229665796581646513903488154256310184224190259846088000110186255550245493937113651657039447629584714548523425950428582425306083544435428212611008992863795048006894330309773217834864543113205765659868456288616808718693835297350643986297640660000723562917905207051164077614812491885830945940566688339109350944456576357666151619317753792891661581327159616877487983821820492520348473874384736771934512787029218636250627816
Its index is 4782
It took an average of 4.112 seconds to run this problem through 100 iterations
*/