#!/usr/bin/env python3

# Sample code from http://www.redblobgames.com/pathfinding/tower-defense/implementation.html
# This uses an internal reset

# Here's a sample graph node class:

class Node:
    def __init__(self, name):
        self.reached = False
        self.name = name
        self._neighbors = []

    def neighbors(self):
        return self._neighbors

    def __repr__(self):
        return "%s" % self.name

# and a sample graph:

A = Node("A")
B = Node("B")
C = Node("C")
D = Node("D")
E = Node("E")
A._neighbors = [B]
B._neighbors = [A, C]
C._neighbors = [D]
D._neighbors = [E]
E._neighbors = []



# Here's Breadth First Search from the article,
# modified to reset the "reached" field

from queue import Queue

def search_from(start, callback):
    open = Queue()
    open.put(start)
    start.reached = True
    reached_nodes = [start]

    while not open.empty():
        current = open.get()
        callback(current)
        for next in current.neighbors():
            if not next.reached:
                next.reached = True
                reached_nodes.append(next)
                open.put(next)

    # Reset "reached" for the next time we want to run search
    for node in reached_nodes:
        node.reached = False
    

results = []
search_from(A, results.append)
print("First search from A: ", results)

results = []
search_from(A, results.append)
print("Second search from A: ", results)  # succeeds, unlike sample-1.py