use std::fs;
use std::io;
extern crate regex; // Add regex crate to your Cargo.toml
use regex::Regex;


fn main() -> io::Result<()> {
    let pattern = r"^mul\(\d{1,3},\d{1,3}\)$";
    let file_contents: String = fs::read_to_string("medium.txt")?;
    let length_of_string = file_contents.len(); 
    let re = Regex::new(pattern).unwrap();
    let mut total: u32 = 0;
    let mut total2: u32 = 0;
    let mut enabled: bool = true;

    for i in 0..length_of_string {
        let substring = &file_contents[i..i+1];
        if substring == "d" {
            //println!("{},{}",&file_contents[i..i+3],&file_contents[i..i+6]);
            if &file_contents[i..i+4] == "do()" {
                enabled = true;
            }
            else if &file_contents[i..i+7] == "don't()" {
                enabled = false;
            }
        }
        else if substring == "m" {
            let mut closed_bracket_position = 0;
            for j in i+3..length_of_string {
                let next_closed_bracket = &file_contents[j..j+1];
                if next_closed_bracket == ")" {
                    closed_bracket_position = j;
                    break;
                }
                // check it's reached the end of string
            }
            let string_to_check = &file_contents[i..closed_bracket_position+1];
            //println!("String to check is {}",&file_contents[i..closed_bracket_position+1]);
            if re.is_match(string_to_check) {
                //println!("{} is VALID!!!", string_to_check);
                let mut comma_position = 5;
                for j in 5..string_to_check.len() {
                    if &string_to_check[j..j+1] == "," {
                        comma_position = j;
                    }
                }
                let number1: &Result<u32, _> = &string_to_check[4..comma_position].parse();
                let number2: &Result<u32, _> = &string_to_check[comma_position+1..string_to_check.len()-1].parse();
                match (number1, number2) {
                    (Ok(n1), Ok(n2)) => {
                        let result = n1 * n2;
                        //println!("Multiplication result: {}", result);
                        total = total + result;
                        if enabled == true {
                            total2 = total2 + result;
                        }
                    },
                    _ => {
                        //println!("One or both of the values are invalid.");
                    }
                }
            }
        }
    }
    println!("Part 1 total is: {}", total);
    println!("Part 2 total is: {}", total2);
    Ok(())
}