:organization: Logilab

:copyright: 2001-2009 LOGILAB S.A. (Paris, FRANCE), all rights reserved.

:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr

"""

__docformat__ = "restructuredtext en"

from rql import nodes

def need_table_view(rset, schema):

    """return True if we think that a table view is more appropriate than a

    list or primary view to display the given result set

    """

    rqlst = rset.syntax_tree()

    if len(rqlst.children) > 1:

        # UNION query, use a table

        return True

    selected = rqlst.children[0].selection

    try:

        mainvar = selected[0]

    except AttributeError:

        # not a variable ref, using table view is probably a good option

        return True

    if not (isinstance(mainvar, nodes.VariableRef) or

            (isinstance(mainvar, nodes.Constant) and mainvar.uid)):

        return True

    for i, etype in enumerate(rset.description[0][1:]):

        # etype may be None on outer join

        if etype is None:

            return True

        # check the selected index node is a VariableRef (else we

        # won't detect aggregate function

        if not isinstance(selected[i+1], nodes.VariableRef):

            return True

        # if this is not a final entity

        if not schema.eschema(etype).is_final():

            return True

        # if this is a final entity not linked to the main variable

        var = selected[i+1].variable

        for vref in var.references():

            rel = vref.relation()

            if rel is None:

                continue

            if mainvar.is_equivalent(rel.children[0]):

                break

        else:

            return True

    return False

def vid_from_rset(req, rset, schema):

    """given a result set, return a view id"""

    if rset is None:

        return 'index'

    nb_rows = len(rset)

    # empty resultset

    if nb_rows == 0 :

        return 'noresult'

    # entity result set

    if not schema.eschema(rset.description[0][0]).is_final():

        if need_table_view(rset, schema):

            return 'table'

        if nb_rows == 1:

            if req.search_state[0] == 'normal':

                return 'primary'

            return 'outofcontext-search'

        return 'list'

    return 'table'

def linksearch_select_url(req, rset):

    """when searching an entity to create a relation, return an url to select

    entities in the given rset

    """

    req.add_js( ('cubicweb.ajax.js', 'cubicweb.edition.js') )

    target, eid, r_type, searchedtype = req.search_state[1]

    if target == 'subject':

        id_fmt = '%s:%s:%%s' % (eid, r_type)

    else:

        id_fmt = '%%s:%s:%s' % (r_type, eid)

    triplets = '-'.join(id_fmt % row[0] for row in rset.rows)

    return "javascript: selectForAssociation('%s', '%s');" % (triplets, eid)