We reduce the number of options even more by treating link reach
and link role independently: link reach must be higher than its
ancestors' equivalent link reach and link role must be higher than
its ancestors' link role.
This reduces the number of possibilities but we decided to start
with the most restrictive and simple offer and extend it if we
realize it faces too many criticism instead of risking to offer
too many options that are too complex and must be reduced afterwards.
We were returning the list of roles a user has on a document (direct
and inherited). Now that we introduced priority on roles, we are able
to determine what is the max role and return only this one.
This commit also changes the role that is returned for the restricted
reach: we now return None because the role is not relevant in this
case.
This will allow us to simplify the get_abilities method. It is also
more efficient because we have computed this definitions dict and
the the get_select_options method was doing the conversion again.
We are going to need to compare choices to materialize the fact that
choices are ordered. For example an admin role is higer than an
editor role but lower than an owner role.
We will need this to compute the reach and role resulting from all
the document accesses (resp. link accesses) assigned on a document's
ancestors.
