package Advent2018;

import graph.DGraph;
import graph.Graph;
import graph.SearchType;
import util.AdventOfCode;
import util.Direction;
import util.Node;

import java.util.*;

public class Day20 extends AdventOfCode {

    Graph<Node> graph;
    String in;
    Node root = new Node(0, 0);
    long part2;

    static Map<Character, Direction> dirs = new HashMap<>();

    static {
        dirs.put('N', Direction.NORTH);
        dirs.put('E', Direction.EAST);
        dirs.put('S', Direction.SOUTH);
        dirs.put('W', Direction.WEST);
    }

    public Day20(List<String> input) {
        super(input);
        title = "A Regular Map";
        part1Description = "Longest shortest path: ";
        part2Description = "Paths >= 1000 doors: ";
    }

    @Override
    public Object part1() {
        buildGraph(0, root);
        List<List<Node>> paths = new ArrayList<>();
        for (Node node : graph.getVertices()) {
            if (!node.equals(root)) {
                paths.add(graph.search(root, node, SearchType.BFS));
            }
        }
        part2 = paths.stream().mapToInt(List::size).filter(x -> x > 1000).count();
        return paths.stream().mapToInt(List::size).max().getAsInt() - 1;
    }

    @Override
    public Object part2() {
        return part2;
    }

    int buildGraph(int pos, Node n) {
        Node next = n;
        while (pos < in.length() - 1) {
            char c = in.charAt(pos);
            switch (c) {
                case 'N':
                case 'E':
                case 'S':
                case 'W':
                    next = dirs.get(c).move(n);
                    graph.addEdge(n, next);
                    break;
                case '(':
                    pos = buildGraph(pos + 1, n);
                    while (in.charAt(pos) == '|') {
                        pos = buildGraph(pos + 1, n);
                    }
                    break;
                case '|':
                case ')':
                    return pos;
            }
            pos++;
            n = next;
        }
        return pos;
    }

    @Override
    public void parse() {
        graph = new DGraph<>();
        in = input.get(0).substring(1, input.get(0).length() - 1);
    }

}