use std::env::args;
use std::fs::File;
use std::io::Read;

struct CharIterator {
    reader: File,
    buffer: [u8; 256],
    size: usize,
    pos: usize,
}

impl CharIterator {
    fn new(reader: File) -> CharIterator {
        CharIterator {
            reader: reader,
            buffer: [0; 256],
            size: 0,
            pos: 0,
        }
    }
}

impl Iterator for CharIterator {
    type Item = char;

    fn next(&mut self) -> Option<Self::Item> {
        if self.pos == self.size {
            self.size = self.reader.read(&mut self.buffer).ok()?;
            self.pos = 0;
        }
        if self.size == 0 {
            return None;
        }
        let byte = self.buffer[self.pos];
        self.pos += 1;
        return Some(char::from(byte));
    }
}


fn main() {
    let path = args().nth(1).unwrap();
    let file = File::open(path).unwrap();

    let mut v1 = 0;
    let mut v2 = 0;
    let mut state = 0;
    let mut enabled = true;

    let mut sum1 = 0;
    let mut sum2 = 0;

    for c in CharIterator::new(file) {
        state = match (state, c) {
            (0, 'm') => 1,
            (1, 'u') => 2,
            (2, 'l') => 3,
            (3, '(') => 4,
            (4, c) if c.is_ascii_digit() => { v1 = v1 * 10 + c.to_digit(10).unwrap(); 4 },
            (4, ',') => 5,
            (5, c) if c.is_ascii_digit() => { v2 = v2 * 10 + c.to_digit(10).unwrap(); 5 },
            (5, ')') => {
                sum1 += v1 * v2;
                if enabled {
                    sum2 += v1 * v2;
                }
                v1 = 0;
                v2 = 0;
                0
            },
            (0, 'd') => 6,
            (6, 'o') => 7,
            (7, '(') => 8,
            (8, ')') => { enabled = true; 0 },
            (7, 'n') => 9,
            (9, '\'') => 10,
            (10, 't') => 11,
            (11, '(') => 12,
            (12, ')') => { enabled = false; 0 },
            _ => { v1 = 0; v2 = 0; 0 },
        };
    }

    println!("part1: {}", sum1);
    println!("part2: {}", sum2);
}