1 files changed, 117 insertions, 0 deletions
diff --git a/kosten/app/utils.py b/kosten/app/utils.py
new file mode 100644
index 0000000..73f2b51
--- /dev/null
+++ b/kosten/app/utils.py
@@ -0,0 +1,117 @@
+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):
+    """Marks a view as being rendered by a template. The view then shall
+    return a dictionary holding the parameters for the template. Ig this
+    is not the case, the response is returned unchanged. This is needed
+    to support `redirect` and similar.
+
+    The correct template is deducted as:
+        - when passed nothing: the name of the view
+        - when passed a string '.bla', the endpoint 'bla' in the current
+          blueprint
+        - when passed any other string: this string (VERBATIM!)
+
+    Except for the last case, the hierarchy of blueprint and view is taken
+    as directories in the template directory. And '.jinja' is appended.
+
+    If the first argument is a function, this is taken as 'None' to allow:
+        >>> @templated
+        ... def foo():
+        ...    ...
+
+    (else it would have to be ``@templated()``).
+    """
+
+    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):
+    """Convenience wrapper for `flask.redirect`. It applies `url_for`
+    on the target, which also gets passed all arguments.
+
+    Special argument '_code' to set the HTTP-Code.
+    """
+    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):
+    """Asserts that the current user has the right to load some specific data.
+
+    This is done by using the argument with keyword `param` and pass it
+    to `constructor`. If the resulting object has an attribute `user_id`,
+    this is checked to be equal to `current_user.id`.
+
+    Usage example::
+
+        @route('/job/<int:id>')
+        @assert_authorisation(Job, 'id')
+        def show_job(id):
+            # this is only executed if Job(id).user_id == current_user.id
+
+    """
+    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("Eintrag existiert nicht!", '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("Nicht erlaubte Operation!", 'error')
+                return redirect('index')
+            else:
+                return f(*args, **kwargs)
+        return decorated_function
+    return decorator