Analyze rsyncd log with state-machine style python script

analyze.py

from sys import stdin
from collections import defaultdict

def analyze(line):
    state = 0
    for idx, c in enumerate(line):
        if state == 0:
            if c == ']':
                if line[idx + 2:idx + 6] == "send":
                    state = 1
                else:
                    return None
        elif state == 1:
            if c == ']':
                if line[idx + 2:idx + 6] == "repo":
                    state = 2
                else:
                    pos = line[idx:].find("(")
                    return line[idx + 2:idx + pos - 1]
        elif state == 2:
            if c == ')':
                pos = line[idx:].find("/")
                if pos < 0:
                    raise ValueError
                return line[idx + 2:idx + pos]

def main():
    counters = defaultdict(int)
    for line in stdin:
        line = line.strip()
        result = analyze(line)
        if result is None:
            continue
        counters[result] += 1
    print(counters)

if __name__ == "__main__":
    main()