package com.mattrixwv.adventOfCode24.days;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Scanner;
import java.util.Set;

import com.mattrixwv.Stopwatch;
import com.mattrixwv.Triple;

public class Problem19 extends Problem{
	private static final String inputFileName = "days/Problem19.txt";
	private List<List<Integer>> map;
	private List<Triple<Integer, Integer, Integer>> trailHeadScores;


	public Problem19(){
		super();
		description = "Find the sum of the trail head scores.";
		result = "Unresolved";
	}


	public String runSolution(){
		Stopwatch timer = new Stopwatch();
		timer.start();


		//Read the file
		map = new ArrayList<>();
		try(Scanner scanner = new Scanner(this.getClass().getClassLoader().getResourceAsStream(inputFileName))){
			scanner.useDelimiter("\n");
			while(scanner.hasNext()){
				String mapLine = scanner.next();
				if(!mapLine.isBlank()){
					List<Integer> mapArray = new ArrayList<>();
					for(char ch : mapLine.toCharArray()){
						mapArray.add(Integer.parseInt(Character.toString(ch)));
					}
					map.add(mapArray);
				}
			}
		}


		//Calculate the trail head scores
		trailHeadScores = new ArrayList<>();
		for(int rowCnt = 0;rowCnt < map.size();++rowCnt){
			for(int colCnt = 0;colCnt < map.get(rowCnt).size();++colCnt){
				if(map.get(rowCnt).get(colCnt) == 0){
					Set<Triple<Integer, Integer, Integer>> foundEndpoints = new HashSet<>();
					foundEndpoints.addAll(checkAllDirections(new Triple<Integer, Integer, Integer>(rowCnt, colCnt, 0)));
					trailHeadScores.add(new Triple<Integer, Integer, Integer>(rowCnt, colCnt, foundEndpoints.size()));
				}
			}
		}

		//Sum the trail head scores
		int sum = 0;
		for(Triple<Integer, Integer, Integer> trailHeadScore : trailHeadScores){
			sum += trailHeadScore.getC();
		}



		//Save the results
		timer.stop();
		result = "The sum of the trail head scores is " + sum + ".\nIt took " + timer.toString() + " to run this algorithm.";
		return result;
	}


	private Set<Triple<Integer, Integer, Integer>> checkAllDirections(Triple<Integer, Integer, Integer> loc){
		Set<Triple<Integer, Integer, Integer>> foundEndpoints = new HashSet<>();
		foundEndpoints.addAll(moveUp(loc));
		foundEndpoints.addAll(moveRight(loc));
		foundEndpoints.addAll(moveDown(loc));
		foundEndpoints.addAll(moveLeft(loc));
		return foundEndpoints;
	}

	private Set<Triple<Integer, Integer, Integer>> moveUp(Triple<Integer, Integer, Integer> loc){
		//Check the current and next elements are in bounds
		if((loc.getA() <= 0) || (loc.getA() >= map.size()) || (loc.getB() < 0) || (loc.getB() >= map.get(loc.getA()).size())){
			return new HashSet<>();
		}

		Set<Triple<Integer, Integer, Integer>> finishSet = new HashSet<>();
		//Check if we need to continue looking
		if(map.get(loc.getA() - 1).get(loc.getB()) == (loc.getC() + 1)){
			Triple<Integer, Integer, Integer> newLoc = new Triple<Integer, Integer, Integer>(loc.getA() - 1, loc.getB(), loc.getC() + 1);
			if(newLoc.getC() == 9){
				finishSet.add(newLoc);
			}
			else{
				finishSet.addAll(checkAllDirections(newLoc));
			}
		}
		//If the next value is not correct, then return an empty set
		//Return any values we found
		return finishSet;
	}

	private Set<Triple<Integer, Integer, Integer>> moveRight(Triple<Integer, Integer, Integer> loc){
		//Check the current and next elements are in bounds
		if((loc.getA() < 0) || (loc.getA() >= map.size()) || (loc.getB() < 0) || (loc.getB() >= (map.get(loc.getA()).size() - 1))){
			return new HashSet<>();
		}

		Set<Triple<Integer, Integer, Integer>> finishSet = new HashSet<>();
		//Check if we need to continue looking
		if(map.get(loc.getA()).get(loc.getB() + 1) == (loc.getC() + 1)){
			Triple<Integer, Integer, Integer> newLoc = new Triple<Integer, Integer, Integer>(loc.getA(), loc.getB() + 1, loc.getC() + 1);
			if(newLoc.getC() == 9){
				finishSet.add(newLoc);
			}
			else{
				finishSet.addAll(checkAllDirections(newLoc));
			}
		}
		//If the next value is not correct, then return an empty set
		//Return any values we found
		return finishSet;
	}

	private Set<Triple<Integer, Integer, Integer>> moveDown(Triple<Integer, Integer, Integer> loc){
		//Check the current and next elements are in bounds
		if((loc.getA() < 0) || (loc.getA() >= (map.size() - 1)) || (loc.getB() < 0) || (loc.getB() >= map.get(loc.getA()).size())){
			return new HashSet<>();
		}

		Set<Triple<Integer, Integer, Integer>> finishSet = new HashSet<>();
		//Check if we need to continue looking
		if(map.get(loc.getA() + 1).get(loc.getB()) == (loc.getC() + 1)){
			Triple<Integer, Integer, Integer> newLoc = new Triple<Integer, Integer, Integer>(loc.getA() + 1, loc.getB(), loc.getC() + 1);
			if(newLoc.getC() == 9){
				finishSet.add(newLoc);
			}
			else{
				finishSet.addAll(checkAllDirections(newLoc));
			}
		}
		//If the next value is not correct, then return an empty set
		//Return any values we found
		return finishSet;
	}

	private Set<Triple<Integer, Integer, Integer>> moveLeft(Triple<Integer, Integer, Integer> loc){
		//Check the current and next elements are in bounds
		if((loc.getA() < 0) || (loc.getA() >= map.size()) || (loc.getB() <= 0) || (loc.getB() >= map.get(loc.getA()).size())){
			return new HashSet<>();
		}

		Set<Triple<Integer, Integer, Integer>> finishSet = new HashSet<>();
		//Check if we need to continue looking
		if(map.get(loc.getA()).get(loc.getB() - 1) == (loc.getC() + 1)){
			Triple<Integer, Integer, Integer> newLoc = new Triple<Integer, Integer, Integer>(loc.getA(), loc.getB() - 1, loc.getC() + 1);
			if(newLoc.getC() == 9){
				finishSet.add(newLoc);
			}
			else{
				finishSet.addAll(checkAllDirections(newLoc));
			}
		}
		//If the next value is not correct, then return an empty set
		//Return any values we found
		return finishSet;
	}
}


/*
Find the sum of the trail head scores.
The sum of the trail head scores is 510.
It took 16.725 milliseconds to run this algorithm.
*/