import itertools
import math

def get_circuit(a,circuits):
    if len(circuits) == 0:
        return None

    for circ in circuits:
        for pos in circ:
            if pos == a:
                return circ
    return None

def add_circuit(a,b,circuits):
    circ_a = get_circuit(a,circuits)
    circ_b = get_circuit(b,circuits)

    if circ_a is None and circ_b is None:
        circuits.append([a,b])
        return True

    if circ_a is None and not circ_b is None:
        circ_b.append(a)
        return True

    if not circ_a is None and circ_b is None:
        circ_a.append(b)
        return True

    if not circ_a is None and not circ_b is None:
        if circ_a == circ_b:
            # Already part of same circuit
            return True
        else:
            # Merge circuits...
            # Copy a to b
            for circ in circ_a:
                circ_b.append(circ)

            # Empty a
            for _ in range(0, len(circ_a)):
                circ_a.pop()
            return True

def get_lowest_distance(junctions_distance):
    a,b,_ = junctions_distance.pop()
    return a,b

def distance(a,b):
    # https://en.wikipedia.org/wiki/Euclidean_distance
    return math.sqrt( pow((a[0]-b[0]),2) + pow((a[1]-b[1]),2) + pow((a[2]-b[2]),2) )

def read_input(filename):
    space = []
    for line in open(filename).read().splitlines():
        x,y,z = line.split(",")
        space.append((int(x), int(y), int(z)))
    return space


filename = "day08/example_input" # 40
max_connections = 10

filename = "day08/input" # 115885
max_connections = 1000

junctions = read_input(filename)

# build list of (unique) combinations
junctions_comb = itertools.combinations(junctions,2)

print("Calculate distances")
# Add distance to the list
junctions_distance = []
for a,b in junctions_comb:
    dist = distance(a,b)
    junctions_distance.append((a,b,dist))

# Sort distance list, reversed so "pop()" will get/remove the shortest distance
def jd_sort(junc_dist):
    return junc_dist[2]
junctions_distance.sort(key=jd_sort, reverse=True)



circuits = []
connections = 0

print("Make connections")
while True:
    a,b = get_lowest_distance(junctions_distance)

    if add_circuit(a,b,circuits):
        connections += 1

    if connections == max_connections:
        break

    if connections % 100 == 0:
        print(f"Connections: {connections}")

sizes = [len(i) for i in circuits]
sizes.sort(reverse=True)


print(f"3 largest circuits multiplied: {sizes[0]*sizes[1]*sizes[2]}")