package adventofcode;

import adventofcode.utils.Utils;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

public class Day2 {
    public static void solve() {
        String input = Utils.getInput(2).get(0);

        List<Integer> program = Arrays.stream(input.split(","))
                .map(Integer::valueOf).collect(Collectors.toList());

        System.out.println(part1(program));
        System.out.println(part2(program, 19690720));
    }

    private static int part1(List<Integer> originalProgram) {
        List<Integer> program = new ArrayList<>(originalProgram);

        run(program, 12, 2);

        return program.get(0);
    }

    private static int part2(List<Integer> originalProgram, int expectedOutput) {
        for(int noun = 0 ; noun <= 99 ; noun++) {
            for(int verb = 0 ; verb <= 99 ; verb++) {
                List<Integer> program = new ArrayList<>(originalProgram);

                run(program, noun, verb);

                if(program.get(0) == expectedOutput) {
                    return 100 * noun + verb;
                }
            }
        }

        throw new IllegalStateException("HCF");
    }

    private static void run(List<Integer> program, int noun, int verb) {
        program.set(1, noun);
        program.set(2, verb);

        for(int i = 0 ; i < program.size() ; i += 4) {
            if(program.get(i) == 99) {
                break;
            }

            int opcode = program.get(i);
            int addr1 = program.get(i + 1);
            int addr2 = program.get(i + 2);
            int addr3 = program.get(i + 3);
            int result = instruction(opcode, program.get(addr1), program.get(addr2));

            program.set(addr3, result);
        }
    }

    private static int instruction(int opcode, int operand1, int operand2) {
        switch(opcode) {
            case 1:
                return operand1 + operand2;
            case 2:
                return operand1 * operand2;
            default:
                throw new IllegalStateException("HCF");
        }
    }
}