from functools import wraps
from flask import flash, request, render_template, url_for
from flask import redirect as _redirect

from .login import current_user

import datetime
today = datetime.date.today

def _gen_tpl(endpoint):
    return endpoint.replace('.', '/') + '.jinja'

def templated(template=None):
    fun = None
    if template is not None and callable(template):
        # a function was passed in
        fun = template
        template = None

    def decorator(f):
        @wraps(f)
        def decorated_function(*args, **kwargs):
            if template is None:
                template_name = _gen_tpl(request.endpoint)
            elif template[0] == '.' and request.blueprint is not None:
                template_name = _gen_tpl(request.blueprint + template)
            else:
                template_name = template

            ctx = f(*args, **kwargs)
            if ctx is None:
                ctx = {}
            elif not isinstance(ctx, dict):
                return ctx
            return render_template(template_name, **ctx)
        return decorated_function

    if fun is None:
        return decorator
    else:
        return decorator(fun)

def redirect (target, **kwargs):
    code = kwargs.pop('_code', None)
    url = url_for(target, **kwargs)

    if code is None:
        return _redirect(url)
    else:
        return _redirect(url, code)

def assert_authorisation(constructor, param):
    def decorator(f):
        @wraps(f)
        def decorated_function(*args, **kwargs):
            p = kwargs.get(param, None)

            if p is None:
                raise TypeError("Keyword %s expected but not received." % param)

            obj = constructor(p)
            if obj is None:
                flash(u"Eintrag existiert nicht!", u'error')
                return redirect('index')

            if not hasattr(obj, 'user_id'):
                return f(*args, **kwargs)

            # explicitly use user_id to avoid having to load the user object
            if obj.user_id != current_user.id:
                flash(u"Nicht erlaubte Operation!", u'error')
                return redirect('index')
            else:
                return f(*args, **kwargs)
        return decorated_function
    return decorator