fn main() -> Result<(), Box<dyn std::error::Error>> {
    let input_str = if let Some(string) = std::env::args().skip(1).next() {
        string
    } else {
        return Err("An input program is required.".into());
    };

    let input = tokenize(&input_str)?;

    let grammar_string = "brainfuck = *unit

unit = \">\" / \"<\" / \"+\" / \"-\" / \",\" / \";\" /
       \"[\" brainfuck \"]\"";

    let grammar: grammar::Grammar = grammar_string.parse().map_err(|err| format!("{err}"))?;

    println!("grammar = {grammar}");

    let atom: chain::atom::DefaultAtom =
        chain::atom::DefaultAtom::from_grammar(grammar).map_err(|err| format!("{err}"))?;

    // atom.print_viz("nfa.gv")?;

    use chain::Chain;

    let mut chain: chain::default::DefaultChain =
        chain::default::DefaultChain::unit(atom).map_err(|err| format!("{err}"))?;

    // let input = [0, 1, 6, 2, 6, 3, 4, 6, 5, 2, 7, 4, 7, 3, 2, 7, 2];

    for (index, token) in input.iter().copied().enumerate() {
        chain.chain(token, index, false)?;
        // if (5..=12).contains(&index) {
        //     chain.print_current(&format!("chain {index}.gv"))?;
        // }
    }

    let _extracted = chain.end_of_input(input.len(), input[input.len() - 1])?;

    // use graph::Graph;

    // extracted.print_viz("bf.gv")?;

    Ok(())
}

fn tokenize(input: &str) -> Result<Vec<usize>, String> {
    let mut result: Vec<usize> = Vec::with_capacity(input.len());

    for (index, c) in input.chars().enumerate() {
        match c {
            '>' => {
                result.push(0);
            }
            '<' => {
                result.push(1);
            }
            '+' => {
                result.push(2);
            }
            '-' => {
                result.push(3);
            }
            ',' => {
                result.push(4);
            }
            ';' => {
                result.push(5);
            }
            '[' => {
                result.push(6);
            }
            ']' => {
                result.push(7);
            }
            ' ' | '\t' | '\n' | '\r' => {}
            _ => {
                return Err(format!("Unknown character {c} at {index}"));
            }
        }
    }

    Ok(result)
}