from . import VALID, INVALID

def mac_addr(addr):

    VALID_MAC_CHARS = "0123456789abcdefABCDEF"

    if len(addr) != 17:
        return INVALID
        
    COLON_START_IDX = 2
    COLON_STEP = 3
    for idx in range(COLON_START_IDX, len(addr), COLON_STEP):
        if addr[idx] != ":":
            return INVALID
    
    mac_sections = addr.split(":")
    if len(mac_sections) != 6:
        return INVALID
    
    for mac_byte in mac_sections:
        
        if len(mac_byte) != 2:
            return INVALID

        for char in mac_byte:
            if not char in VALID_MAC_CHARS:
                return INVALID
    
    return VALID



def password_strength(password):

    PW_MIN_LEN = 8

    if not isinstance(password, str):
        return "Not a string"

    if len(password) < PW_MIN_LEN:
        return f"Password too short. {PW_MIN_LEN} character minimum"



def text_numeric_only(text, extra_chars=""):
    WHITELIST_CHARS = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"

    for char in text:
        if not (char in WHITELIST_CHARS or char in extra_chars):
            return INVALID

    return VALID



def username(username):
    return text_numeric_only(username, extra_chars=" _-")


def email(email):
    return text_numeric_only(email, extra_chars=" _-@+.")