#!/usr/bin/python
#
# Copyright 2013.  Cumulus Networks, Inc.
# Author: Roopa Prabhu, roopa@cumulusnetworks.com
#
# graph --
#    graph helper module for ifupdown
#

import logging
from collections import deque
try:
    from gvgen import *
except ImportError, e:
    pass

class graph():

    def __init__(self):
        self.logger = logging.getLogger('ifupdown.' +
                    self.__class__.__name__)

    @classmethod
    def topological_sort(cls, dependency_graph, indegrees=None):
        S = []
        Q = deque()

        for ifname,indegree in indegrees.items():
            if indegree == 0:
                Q.append(ifname)

        while len(Q) != 0:
            # initialize queue
            x = Q.popleft()

            # Get dependents of x
            dlist = dependency_graph.get(x)
            if dlist == None or len(dlist) == 0:
                S.append(x)
                continue

            for y in dlist:
                indegrees[y] = indegrees.get(y) - 1
                if indegrees.get(y) == 0:
                    Q.append(y)

            S.append(x)

        # If some indegrees are non zero, we have a cycle
        for ifname,indegree in indegrees.items():
            if indegree != 0:
                raise Exception('cycle found involving iface %s' %ifname +
                                ' (indegree %d)' %indegree)

        return S

    @classmethod
    def add_to_dot_old(cls, dependency_graph, gvgraph, v, parentgvitem):
        dependents = dependency_graph.get(v, [])
        if dependents is None:
            return
        if len(dependents) > 1:
            # if more than one dependents .., add them to a box
            box = gvgraph.newItem(v)
            for d in dependents:
                dnode = gvgraph.newItem(d, box)
                cls.add_to_dot(dependency_graph, gvgraph, d, dnode)
                if parentgvitem is not None: gvgraph.newLink(parentgvitem,
                                                             dnode)
        else:
            for d in dependents:
                dnode = gvgraph.newItem(d)
                cls.add_to_dot(dependency_graph, gvgraph, d, dnode)
                if parentgvitem is not None: gvgraph.newLink(parentgvitem,
                                                             dnode)

    @classmethod
    def add_to_dot(cls, dependency_graph, gvgraph, v, parentgvitem):
        vnode = gvgraph.newItem(v)
        if parentgvitem is not None: gvgraph.newLink(parentgvitem, vnode)
        dependents = dependency_graph.get(v, [])
        if dependents is None:
            return
        for d in dependents:
            cls.add_to_dot(dependency_graph, gvgraph, d, vnode)

    @classmethod
    def generate_dot(cls, dependency_graph, v):
        gvgraph = GvGen()
        cls.add_to_dot(dependency_graph, gvgraph, v, None)
        gvgraph.dot(name=v)

    @classmethod
    def generate_dots(cls, dependency_graph, indegrees):
        roots = [k for k, v in indegrees.items() if v == 0]
        if roots is None:
            return
        print roots
        map(lambda r: cls.generate_dot(dependency_graph, r), roots)