from cs4102lib import Graph, Queue

def bfs0(graph, start):
    parent = {}
    color = {}
    for v in graph:
        color[v] = "white"
    pending = Queue()
    parent[start] = None
    color[start] = "gray"
    pending.add(start)

    while len(pending) > 0:
        v = pending.remove()
        alist = graph.get_adjlist(v)
        for w in alist:
            if color[w] == "white":
                color[w] = "gray"
                pending.add(w)
                parent[w] = v
            elif color[w] != "white" and parent[v] != w:
                print "cycle", v, w, color[w]
        color[v] = "black"
    return parent

def bfs1(graph, start):
    # store this 3-tuple for each node: (parent, discovery, dist)
    # NOTE: for now this code is MISSING code to store these things
    nodeinfo = {}  
    color = {}
    for v in graph:
        color[v] = "white"
    pending = Queue()
    color[start] = "gray"
    pending.add(start)
    ctr = 1
    nodeinfo[start] = (None,1,0) # Hmm, what should be here?

    while len(pending) > 0:
        v = pending.remove()
        alist = graph.get_adjlist(v)
        for w in alist:
            if color[w] == "white":
                color[w] = "gray"
                pending.add(w)
                ctr = ctr + 1
                parentinfo = nodeinfo[v] # (p, ctr, d)
                parentdist = parentinfo[2] # d
                nodeinfo[w] = (v,ctr, parentdist+1)
        color[v] = "black"

    return nodeinfo



def main():
    g1 = { "a": ["b", "f", "g"], "b": ["a", "c", "d", "e"],
            "c": ["b", "e"], "d": ["b", "e", "f"],
            "e": ["b", "c", "d", "f", "g"], "f": ["a", "d", "e"],
            "g": ["a", "e"], "h":[] }
    # print g1
    gr1 = Graph(g1)
    print gr1 
    par = bfs0(gr1,"a")
    print "bfs0 return data:", par
    ninfo = bfs1(gr1,"a")
    #print "bfs1 return data:", ninfo
    
## Some code to test/explore the Graph object
##    print len(gr1)
##    print "Adj to d:", gr1.get_adjlist("d")
##    print "Adj to h:", gr1.get_adjlist("h")
##    print "Adj to x:", gr1.get_adjlist("x")
##
##    print "a adj b? ", gr1.is_adjacent("a", "b")
##    print "a adj d? ", gr1.is_adjacent("a", "d")
##    print "a adj x? ", gr1.is_adjacent("a", "x")
##
##    for v in gr1:
##        print "vertex:", v, "  alist:", gr1.get_adjlist(v)


## Some code to test/explore the Queue object
##    l = [ 7, 9, 3, -1 ]
##    q1 = Queue(l)
##    print l
##    print len(q1)
##    q1.add(20)
##    print "About to remove", q1.front()
##    print q1.remove()
##    print q1
##    print q1.remove()
##    print len(q1)
##    print q1


main()