iban_validator 0.2.2

#![doc=include_str!("../README.md")]

/// Removes whitespaces, and uppercases the string.
pub fn sanitise_iban(iban: &str) -> String {
    let uppercased = iban.to_uppercase();
    uppercased.split_whitespace().collect()
}

/// Checks if the string is at least 15, and not more than 34 characters long.
pub fn validate_length(iban: &str) -> bool {
    if iban.len() > 34 || iban.len() < 15 {
        return false;
    }
    true
}

/// Just a wrapper around format, to make it slightly more readable what we're doing.
fn rearrange(bban: &str, country_code: &str, check_digits: &str) -> String {
    format!("{bban}{country_code}{check_digits}")
}

/// Converts a rearranged IBAN to numbers. Character A = 10, B=11, and so on.
/// Don't ask me, that's how the standard works.
pub fn convert_to_numbers(rearranged_iban: &str) -> u128 {
    const NUMBER_OFFSET: u8 = 55;
    let chars = rearranged_iban.chars();
    let mut new_string = String::from("");
    for c in chars {
        if c.is_ascii_alphabetic() {
            // Yes this is extremely ugly. I'll probably chop this up in parts later.
            new_string += (c as u8 - NUMBER_OFFSET).to_string().as_str();
        } else {
            new_string += c.to_string().as_str();
        }
    }
    new_string.parse::<u128>().unwrap()
}

/// Checks whether the generated checksum is valid according to ISO 7064.
pub fn validate_checksum(checksum: u128) -> bool{
    checksum % 97 == 1
}

pub fn is_valid_checksum(country_code: &str, check_digits: &str, bban: &str) -> bool {
    let rearranged = rearrange(bban, country_code, check_digits);

    let checksum = convert_to_numbers(&rearranged);

    validate_checksum(checksum)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn remove_spaces_works() {
        let input = "GB82 WEST 1234 5698 7654 32";
        let result = sanitise_iban(input);
        assert_eq!(result, "GB82WEST12345698765432");
    }

    #[test]
    fn validate_length_works() {
        let input = "GB82 WEST 1234 5698 7654 32";
        let too_long = "GB82 WEST 1234 5698 7654 32 2222 222";
        let too_short = "GB82 WEST 1234";
        let result = validate_length(input);
        let result_long = validate_length(too_long);
        let result_short = validate_length(too_short);
        assert!(result);
        assert!(!result_long);
        assert!(!result_short);
    }

    #[test]
    fn validate_checksum_works() {
        let good = validate_checksum(3214282912345698765432161182);
        let bad= validate_checksum(3214282912345698765432161181);

        assert!(good);
        assert!(!bad);
    }

    #[test]
    fn convert_to_numbers_works() {
        let input = "WEST12345698765432GB82";

        let result = convert_to_numbers(input);

        assert_eq!(result, 3214282912345698765432161182)
    }
}