import re

from inspect import getcallargs

from .error import ValidateException

def vuserhash(hash,field):

    '''vailidate function for userhash'''

    if not re.match(r'^[a-f0-9]{15,}$', hash.lower()):

        raise ValidateException(field=field)

    return True

def validate(**kargs):

    '''validate decorator

    use it like this:

        @validate(userhash=vuserhash)

        f(userhash)

    that will validate usrhah with the function vuserhash.

    Every validate function should raise an Exception, if the the value is not valid'''

    def v(f):

        def new_f(*a,**k):

            kp=getcallargs(f,*a,**k)

            for i in kargs:

                kargs[i](kp[i],i)

            return f(*a,**k)

        new_f.__name__ = f.__name__

        return new_f

    return v