const VALID = true;
const INVALID = false;


class validation {

    static mac_addr(addr) {

        const VALID_MAC_CHARS = "0123456789abcdefABCDEF";

        if (addr.length !== 17) {
            return INVALID;
        }

        const COLON_START_IDX = 2;
        const COLON_STEP = 3;
        for (let idx = COLON_START_IDX; idx < addr.length; idx += COLON_STEP) {
            if (addr[idx] != ":") {
                return INVALID;
            }
        }

        const mac_sections = addr.split(":");
        if (mac_sections.length !== 6) {
            return INVALID;
        }

        for (const mac_byte of mac_sections) {

            if (mac_byte.length !== 2) {
                return INVALID;
            }

            for (const char of mac_byte) {
                if (!VALID_MAC_CHARS.includes(char)) {
                    return INVALID;
                }
            }
        }

        return VALID;

    }

}