RUST: EC number validation checker

use regex::Regex;
use std::io;

fn is_valid_ec_number(ec: &str) -> bool {
    // Check if the EC number matches the format
    let ec_pattern = Regex::new(r"^\d{3}-\d{3}-\d$").unwrap();
    if !ec_pattern.is_match(ec) {
        return false;
    }

    // Remove hyphens and convert to a vector of digits
    let digits: Vec<u32> = ec
        .replace("-", "")
        .chars()
        .filter_map(|c| c.to_digit(10))
        .collect();

    // Ensure there are exactly 7 digits (6 for the number, 1 for the checksum)
    if digits.len() != 7 {
        return false;
    }

    // Separate the checksum from the rest of the digits
    let checksum = digits[digits.len() - 1];
    let number_digits = &digits[..digits.len() - 1];

    // Calculate the weighted sum
    let sum: u32 = number_digits
        .iter()
        .enumerate()
        .map(|(i, &digit)| digit * (i as u32 + 1))
        .sum();

    // Calculate the expected checksum
    let expected_checksum = sum % 11;

    // Compare the expected checksum to the actual checksum
    expected_checksum == checksum
}

fn main() {
    // Prompt the user for input
    println!("Enter an EC number to validate:");

    let mut input = String::new();
    io::stdin()
        .read_line(&mut input)
        .expect("Failed to read input");

    // Trim whitespace from the input
    let ec_number = input.trim();

    // Validate the EC number
    if is_valid_ec_number(ec_number) {
        println!("'{}' is a valid EC number.", ec_number);
    } else {
        println!("'{}' is NOT a valid EC number.", ec_number);
    }
}