from netlib.http import url


def parse_headers(headers):
    authority = headers.get(':authority', b'')
    method = headers.get(':method', b'GET')
    scheme = headers.get(':scheme', b'https')
    path = headers.get(':path', b'/')

    headers.clear(":method")
    headers.clear(":scheme")
    headers.clear(":path")

    host = None
    port = None

    if path == b'*' or path.startswith(b"/"):
        first_line_format = "relative"
    elif method == b'CONNECT':  # pragma: no cover
        raise NotImplementedError("CONNECT over HTTP/2 is not implemented.")
    else:  # pragma: no cover
        first_line_format = "absolute"
        # FIXME: verify if path or :host contains what we need
        scheme, host, port, _ = url.parse(path)

    if authority:
        host, _, port = authority.partition(b':')

    if not host:
        host = b'localhost'

    if not port:
        port = 443 if scheme == b'https' else 80

    port = int(port)

    return first_line_format, method, scheme, host, port, path