import re
from functools import wraps

from inspect import getcallargs
from .error import ValidateException

def boolean(value, field):
    t=[True,"true",1]
    f=[False,"false",0]
    if value in t:
        return True
    elif value in f:
        return False
    else:
        raise ValidateException(field=field, msg='%s is not boolean' % field)


def validateHash(value,field,minlength=None,maxlength=None):
    if not re.match(r'^[a-f0-9]*$', value.lower()):
        raise ValidateException(field=field)
    if minlength and len(value)<minlength:
        raise ValidateException(field=field)
    if maxlength and len(value)>maxlength:
        raise ValidateException(field=field)
    return value

def vuserhash(value,field):
    '''vailidate function for userhash'''
    return validateHash(value,field,minlength=15,maxlength=15)

def validate(kwd,func, need=True,*args,**kargs):
    '''validate decorator
    use it like this:
        @validate(kwd=userhash, func=vuserhash)
        f(userhash)
    that will validate usrhash with the function vuserhash.
    Every validate function should raise an Exception, if the the value is not valid'''
    def v(f):
        @wraps(f)
        def new_f(*a,**k):
            kp=getcallargs(new_f.original,*a,**k)
            try:
                if need or kp[kwd] is not None:
                    kp[kwd] = func(kp[kwd],kwd,*args,**kargs)
                else:
                    kp[kwd] = None
            except KeyError:
                if need:
                    raise ValidateException(field=kwd,msg="%s is nessasary"%kwd)
            return f(**kp)
        try:
            new_f.original=f.original
        except AttributeError:
            new_f.original=f
        return new_f
    return v