pub(crate) fn percent_encode(message: &str) -> String {
    let mut encoded = String::with_capacity(message.len() + 16);
    message.as_bytes().iter().for_each(|b| {
        match b {
            b if (b >= &b'a' && b <= &b'z')
                || (b >= &b'A' && b <= &b'Z')
                || (b >= &b'0' && b <= &b'9') => encoded.push(*b as char),
            b'~' | b'_' | b'-' | b'.' => encoded.push(*b as char),
            _ => encoded.push_str(&format!("%{:X}", b)),
        }
    });
    encoded
}

#[inline]
pub(crate) fn join_slices(part1: &[u8], part2: &[u8]) -> Vec<u8> {
    let mut joined = part1.to_vec();
    joined.extend_from_slice(part2);
    joined
}

#[test]
fn test_percent_encode() {
    assert_eq!("0123456789", percent_encode("0123456789"));
    assert_eq!("abcdefghijklmnopqrstuvwxyz", percent_encode("abcdefghijklmnopqrstuvwxyz"));
    assert_eq!("ABCDEFGHIJKLMNOPQRSTUVWXYZ", percent_encode("ABCDEFGHIJKLMNOPQRSTUVWXYZ"));
    assert_eq!("Hello%20World%21", percent_encode("Hello World!"));
    assert_eq!("~%21%40%23%24%25%5E%26%2A%28%29_%2B-%3D", percent_encode("~!@#$%^&*()_+-="));
    assert_eq!("%E8%BF%99%E6%98%AF%E4%B8%80%E4%B8%AA%E6%B5%8B%E8%AF%95", percent_encode("这是一个测试"));
    assert_eq!("%F0%9F%98%84", percent_encode("😄"));
    assert_eq!("%2C.%2F%3C%3E%3F%3B%27%3A%22%5B%5D%5C%7B%7D%7C", percent_encode(",./<>?;':\"[]\\{}|"));
    assert_eq!("%21%27%28%29%2A-._~", percent_encode("!'()*-._~"));
    assert_eq!("%21%23%24%26%27%28%29%2A%2B%2C-.%2F%3A%3B%3D%3F%40_~", percent_encode("!#$&'()*+,-./:;=?@_~"));
}

#[test]
fn test_join_slices() {
    assert_eq!(&b"Hello World"[..], &join_slices(b"Hello", b" World")[..])
}