"""Views/forms and actions for the CubicWeb web client

:organization: Logilab
:copyright: 2001-2008 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_match(req, rset):
    """when searching an entity to create a relation, return True if entities in
    the given rset may be used as relation end
    """
    try:
        searchedtype = req.search_state[1][-1]
    except IndexError:
        return 0 # no searching for association
    for etype in rset.column_types(0):
        if etype != searchedtype:
            return 0
    return 1
    
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, link_eid, r_type, searchedtype = req.search_state[1]
    if target == 'subject':
        id_fmt = '%s:%s:%%s' % (link_eid, r_type)
    else:
        id_fmt = '%%s:%s:%s' % (r_type, link_eid)
    triplets = '-'.join(id_fmt % row[0] for row in rset.rows)
    return "javascript: selectForAssociation('%s', '%s');" % (triplets,
                                                              link_eid)