use xmpp_parsers::Error;

/// Codec for colon-separated bytes of uppercase hexadecimal.
pub struct ColonSeparatedHex;

impl ColonSeparatedHex {
    pub fn decode(s: &str) -> Result<Vec<u8>, Error> {
        let mut bytes = vec![];
        for i in 0..(1 + s.len()) / 3 {
            let byte = u8::from_str_radix(&s[3 * i..3 * i + 2], 16)?;
            if 3 * i + 2 < s.len() {
                assert_eq!(&s[3 * i + 2..3 * i + 3], ":");
            }
            bytes.push(byte);
        }
        Ok(bytes)
    }

    pub fn encode(b: &[u8]) -> Option<String> {
        let mut bytes = vec![];
        for byte in b {
            bytes.push(format!("{:02X}", byte));
        }
        Some(bytes.join(":"))
    }
}