from functools import wraps
from functools import reduce
import time


def timeit(func):
    '''A function wrapper that measures execution time and prints it.'''
    @wraps(func)
    def wrapper(*args, **kwargs):
        timer = time.time()
        rslt = func(*args, **kwargs)
        print(f'Elapsed time: {time.time() - timer:0.2f}s')
        return rslt
    return wrapper


def read_words(path):
    '''Read bags of words from a file'''
    with open(path, 'r') as f:
        return [line.strip().split(' ') for line in f]


def match(documents, topics):
    '''For each topic, find documents containing all the words from that topic'''
    word_docs = {}
    for i, d in enumerate(documents):
        for w in d:
            word_docs.setdefault(w, []).append(i)

    rslt = []
    for t in topics:
        iterator = (word_docs.get(w, []) for w in t)
        ds = reduce(lambda x, y: x.intersection(y), iterator, set(next(iterator)))
        rslt.append(ds)

    return rslt


# Load and match
documents = read_words('documents.txt')
topics = read_words('topics.txt')
rslt = timeit(match)(documents, topics)

# Print a few summary statistics
print(sum(len(d) > 0 for d in rslt))
print(max(len(d) for d in rslt))