extern crate advent_of_code_2018;
use advent_of_code_2018::*;

use std::error::Error;
use std::path::PathBuf;

// cargo watch -cs "cargo run --release --bin day_19"

#[derive(Debug)]
struct Instruction {
    op: Op,
    a: i32,
    b: i32,
    c: i32
}

impl Instruction {
    fn execute(&self, counter_register: usize, registers: &mut [i32; 6]) -> i32{
        use Op::*;
        
        registers[self.c as usize] = match self.op {
            Addr => registers[self.a as usize] + registers[self.b as usize],
            Addi => registers[self.a as usize] + self.b,
            Mulr => registers[self.a as usize] * registers[self.b as usize],
            Muli => registers[self.a as usize] * self.b,
            Banr => registers[self.a as usize] & registers[self.b as usize],
            Bani => registers[self.a as usize] & self.b,
            Borr => registers[self.a as usize] | registers[self.b as usize],
            Bori => registers[self.a as usize] | self.b,
            Setr => registers[self.a as usize],
            Seti => self.a,
            Gtir => if self.a > registers[self.b as usize] { 1 } else { 0 },
            Gtri => if registers[self.a as usize] > self.b { 1 } else { 0 },
            Gtrr => if registers[self.a as usize] > registers[self.b as usize] { 1 } else { 0 },
            Eqir => if self.a == registers[self.b as usize] { 1 } else { 0 },
            Eqri => if registers[self.a as usize] == self.b { 1 } else { 0 },
            Eqrr => if registers[self.a as usize] == registers[self.b as usize] { 1 } else { 0 },
        };

        registers[counter_register]+1
    }
}

#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
enum Op {
    Addr,
    Addi,
    Mulr,
    Muli,
    Banr,
    Bani,
    Borr,
    Bori,
    Setr,
    Seti,
    Gtir,
    Gtri,
    Gtrr,
    Eqir,
    Eqri,
    Eqrr
}

fn main() -> Result<(), Box<Error>> {
    let input = read_file(&PathBuf::from("inputs/19.txt"))?;

    println!("Input: {:?}", input);

    let mut input_iter = input.iter();
    let counter_register: usize = input_iter.next()
        .map(|line| line.split_whitespace().nth(1).unwrap().parse().unwrap())
        .unwrap();

    let instructions: Vec<Instruction> = input_iter
        .map(|line| {
            let mut instruction_iter = line.split_whitespace();
            Instruction {
                op: match instruction_iter.next().unwrap() {
                    "addr" => Op::Addr,
                    "addi" => Op::Addi,
                    "mulr" => Op::Mulr,
                    "muli" => Op::Muli,
                    "banr" => Op::Banr,
                    "bani" => Op::Bani,
                    "borr" => Op::Borr,
                    "bori" => Op::Bori,
                    "setr" => Op::Setr,
                    "seti" => Op::Seti,
                    "gtir" => Op::Gtir,
                    "gtri" => Op::Gtri,
                    "gtrr" => Op::Gtrr,
                    "eqir" => Op::Eqir,
                    "eqri" => Op::Eqri,
                    "eqrr" => Op::Eqrr,
                    _ => panic!("unknown instruction")
                },
                a: instruction_iter.next().unwrap().parse().unwrap(),
                b: instruction_iter.next().unwrap().parse().unwrap(),
                c: instruction_iter.next().unwrap().parse().unwrap(),
            }
        })
        .collect();

    debug!(counter_register);
    debug!(instructions);

    let part1_registers = execute_program(&instructions, counter_register, [0; 6]);
    debug!(part1_registers);

    //let part2_registers = execute_program(&instructions, counter_register, [1, 0, 0, 0, 0, 0]);
    //debug!(part2_registers);
    part2();
    
    Ok(())
}

fn execute_program(instructions: &Vec<Instruction>, counter_register: usize, registers: [i32; 6]) -> [i32; 6] {
    let mut counter_val: i32 = 0;
    let mut registers = registers.clone();
    while counter_val >= 0 && counter_val < instructions.len() as i32 {
        registers[counter_register] = counter_val;
        counter_val = instructions[counter_val as usize].execute(counter_register, &mut registers);
    }

    registers
}



fn part2() {
    let r1 = ((27*28)+29)*30*14*32 + (11 * 19 * 2 * 2) + (3 * 22) + 9;
    let mut r0 = 0;
    for r5 in 1..r1+1 {
        if r1 % r5 == 0 {
            r0 += r1 / r5;
        }
    }
    debug!(r0);
}