from cs4102lib import Graph, Queue

def dfs0(graph, start):
    visited = {}
    dfs_recurs0(graph, start, visited)

def dfs_recurs0(graph, curnode, visited):
    visited[curnode] = True
    alist = graph.get_adjlist(curnode)
    for v in alist:
        #if not visited.has_key(v):  # same as next line
        if v not in visited:
            print "  dfs_recurs0 traversing edge:", curnode, v
            dfs_recurs0(graph, v, visited)
        else:
            print "backedge", curnode, v
    # end for-all adj vertices
    return

def dfs1(graph, start):
    color = {}
    dfs_nums = {}
    edge_info = []
    for v in graph:
        color[v] = "white"
        dfs_nums[v] = None
    dfs_recurs1(graph, start, color, dfs_nums, 0,
                None, edge_info)
    print "\ndfs1 results:"
    print "\tvertex\t(disc,fin)"
    for v in graph:
        print "\t", v, "\t", dfs_nums[v]
    print "Classification of edges:"
    print "Tree:", map(lambda t: t[1:],
                       filter(lambda t: t[0]=="tree", edge_info))
    print "Back:", map(lambda t: t[1:],
                       filter(lambda t: t[0]=="back", edge_info))
    print "Other:", map(lambda t: t[1:],
                        filter(lambda t: t[0]=="other", edge_info))
    

def dfs_recurs1(graph, curnode, color, dfs_nums, ctr,
                parent, edge_info):
    color[curnode] = "gray"
    ctr = ctr + 1
    discovered = ctr
    alist = graph.get_adjlist(curnode)
    for v in alist:
        if color[v] == "white":
            edge_info.append( ("tree", curnode, v) )
            ctr = dfs_recurs1(graph, v, color, dfs_nums, ctr,
                              curnode, edge_info)
        elif color[v] == "gray" and v != parent:
            edge_info.append( ("back", curnode, v) )
        elif color[v] == "black":
            edge_info.append( ("other", curnode, v) )
    # end for-all adj vertices
    ctr = ctr + 1
    finished = ctr
    color[curnode] = "black"
    dfs_nums[curnode] = (discovered, finished)
    print "  dfs_recurs1 assigning (disc,fin) for: ", curnode, discovered, finished
    return ctr

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":[] }
    gr1 = Graph(g1)
    print gr1.num_nodes(), gr1.num_edge_items()/2
    print gr1
    print "\nCalling basic dfs:"
    dfs0(gr1, "a")
    #print "\nCalling more complex dfs:"
    #dfs1(gr1, "a")

main()