use thiserror::Error;

pub fn parse_mac_address(mac: &str) -> Result<[u8; 6], MacAddressError> {
    if mac.len() != 12 {
        return Err(MacAddressError::Length(mac.len()));
    }

    let mut mac_bytes = [0u8; 6];
    for i in 0..6 {
        let hex_part = &mac[i * 2..i * 2 + 2];
        mac_bytes[i] = u8::from_str_radix(hex_part, 16)?;
    }

    Ok(mac_bytes)
}

#[derive(Error, Debug)]
pub enum MacAddressError {
    #[error("Error converting MAC Address")]
    Conversion(#[from] std::num::ParseIntError),
    #[error("MAC Address length mismatch")]
    Length(usize),
}

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

    #[test]
    fn test_valid_mac_address_plain() {
        let mac_str = "001A2B3C4D5E";
        let expected = [0x00, 0x1A, 0x2B, 0x3C, 0x4D, 0x5E];
        assert_eq!(parse_mac_address(mac_str).unwrap(), expected);
    }

    #[test]
    fn test_valid_lowercase_mac_address() {
        let mac_str = "001a2b3c4d5e";
        let expected = [0x00, 0x1A, 0x2B, 0x3C, 0x4D, 0x5E];
        assert_eq!(parse_mac_address(mac_str).unwrap(), expected);
    }

    #[test]
    fn test_invalid_mac_address_wrong_length() {
        let mac_str = "001A2B3C4D";
        assert!(parse_mac_address(mac_str).is_err());
    }

    #[test]
    fn test_invalid_mac_address_invalid_characters() {
        let mac_str = "001A2B3C4DZZ";
        assert!(parse_mac_address(mac_str).is_err());
    }

    #[test]
    fn test_empty_mac_address() {
        let mac_str = "";
        assert!(parse_mac_address(mac_str).is_err());
    }

    #[test]
    fn test_mac_address_with_extra_spaces() {
        let mac_str = "001A2B3C 4D5E";
        assert!(parse_mac_address(mac_str).is_err());
    }
}