use std::collections::HashSet;
use std::error::Error;
use std::fs::File;
use std::io::{self, BufRead};
use std::vec::Vec;

enum Instruction {
    Nop(i32),
    Acc(i32),
    Jmp(i32),
}

fn line_to_instruction(line: String) -> Instruction {
    let mut parts = line.split(" ");
    let opcode = parts.nth(0).unwrap();
    let arg: i32 = parts.nth(0).unwrap().parse().unwrap();

    match opcode {
        "nop" => Instruction::Nop(arg),
        "acc" => Instruction::Acc(arg),
        "jmp" => Instruction::Jmp(arg),
        _ => panic!("Unsupported Instruction: {}", opcode),
    }
}

fn main() -> Result<(), Box<dyn Error>> {
    let file = File::open("inputs/day8.txt")?;
    let lines = io::BufReader::new(file).lines().map(|l| l.unwrap());

    let programm: Vec<Instruction> = lines.map(line_to_instruction).collect();

    let mut pc = 0usize;
    let mut visted: HashSet<usize> = HashSet::new();
    let mut acc = 0i32;

    while !visted.contains(&pc) {
        visted.insert(pc);
        match programm.get(pc) {
            Some(Instruction::Nop(_)) => pc += 1,
            Some(Instruction::Acc(arg)) => {
                pc += 1;
                acc += arg
            }
            Some(Instruction::Jmp(arg)) => {
                pc = (pc as i32 + arg) as usize;
            }
            None => panic!("PC {} is beyond the programm", pc),
        }
        println!("PC: {}, Acc: {}", pc, acc);
    }

    println!("Final PC: {}, Final Acc: {}", pc, acc);

    Ok(())
}