#    Copyright (C) 2004-2019 by
#    Aric Hagberg <hagberg@lanl.gov>
#    Dan Schult <dschult@colgate.edu>
#    Pieter Swart <swart@lanl.gov>
#    All rights reserved.
#    BSD license.
#
# Author:  Aric Hagberg (hagberg@lanl.gov),
#          Pieter Swart (swart@lanl.gov),
#          Dan Schult(dschult@colgate.edu)
"""Filter factories to hide or show sets of nodes and edges.

These filters return the function used when creating `SubGraph`.
"""
__all__ = ['no_filter', 'hide_nodes',
           'hide_edges', 'hide_multiedges',
           'hide_diedges', 'hide_multidiedges',
           'show_nodes',
           'show_edges', 'show_multiedges',
           'show_diedges', 'show_multidiedges',
           ]


def no_filter(*items):
    return True


def hide_nodes(nodes):
    nodes = set(nodes)
    return lambda node: node not in nodes


def hide_diedges(edges):
    edges = {(u, v) for u, v in edges}
    return lambda u, v: (u, v) not in edges


def hide_edges(edges):
    alledges = set(edges) | {(v, u) for (u, v) in edges}
    return lambda u, v: (u, v) not in alledges


def hide_multidiedges(edges):
    edges = {(u, v, k) for u, v, k in edges}
    return lambda u, v, k: (u, v, k) not in edges


def hide_multiedges(edges):
    alledges = set(edges) | {(v, u, k) for (u, v, k) in edges}
    return lambda u, v, k: (u, v, k) not in alledges


# write show_nodes as a class to make SubGraph pickleable
class show_nodes(object):
    def __init__(self, nodes):
        self.nodes = set(nodes)

    def __call__(self, node):
        return node in self.nodes


def show_diedges(edges):
    edges = {(u, v) for u, v in edges}
    return lambda u, v: (u, v) in edges


def show_edges(edges):
    alledges = set(edges) | {(v, u) for (u, v) in edges}
    return lambda u, v: (u, v) in alledges


def show_multidiedges(edges):
    edges = {(u, v, k) for u, v, k in edges}
    return lambda u, v, k: (u, v, k) in edges


def show_multiedges(edges):
    alledges = set(edges) | {(v, u, k) for (u, v, k) in edges}
    return lambda u, v, k: (u, v, k) in alledges
