# int = exactly this number of arguments
# tuple = between n1 and n2 args, accept as numbered params
# empty list = accept any number of arguments, accept as 1 tuple/list


def select_expr(eval, cols, frm, js, where, group, order):
    q = f"SELECT {eval(cols)} FROM {eval(frm)} {eval(js)} "
    if where:
        q = f"{q} {eval(where)} "
    if group:
        q = f"{q} {eval(group)} "
    if order:
        q = f"{q} {eval(order)} "
    return q


elements = {
    'TABLE': (1, lambda r, out: out),
    'ALIAS': (2, lambda r, out1, out2: f"({r(out1)}) AS {out2} "),
    'SELECT': (6, select_expr),
    'JOINS': ("*", lambda r, js: " ".join([f"{r(j)} " for j in js]))
}


def element_count(element):
    return elements[element][0]

def substitution_rule(element):
    return elements[element][1]


def cls_mth_maker(key, n_elements):
    if isinstance(n_elements, int):
        @classmethod
        def cm(cls, *args):
            assert len(args) == n_elements
            return key.upper(), args[0] if len(args) == 1 else args
    elif isinstance(n_elements, list):
        @classmethod
        def cm(cls, *args):
            assert len(n_elements) == 0 \
                   or ((n_elements[0] == "*" or len(args) >= n_elements[0])
                       and n_elements[-1] == "*" or len(args) <= n_elements[-1])
            return key.upper(), args
    elif isinstance(n_elements, tuple):
        @classmethod
        def cm(cls, *args):
            assert len(n_elements) == 0 \
                   or ((n_elements[0] == "*" or len(args) >= n_elements[0])
                       and n_elements[-1] == "*" or len(args) <= n_elements[-1])
            return (key.upper(), *args)
    else:
        raise ValueError()
    return cm


class SQL:
    pass


for x in elements:
    setattr(SQL, x, cls_mth_maker(x, elements[x]))