Chunk a long message into chunks of max length n with the page numbers like (1/10)

chunk_message.py

def chunk(msg, n):
    words = msg.split(" ")
    totalPages = 1
    prevTotalPages = 0
    while totalPages != prevTotalPages:
        chunks = []
        chunk = []
        for word in words:
            page = "(%d/%d)" % (len(chunks) + 1, totalPages)
            if len(" ".join(chunk + [page])) > n:
                raise Exception("n is too small!")
            if len(" ".join(chunk + [word, page])) <= n:
                chunk.append(word)
            else:
                if not chunk:
                    raise Exception("n is too small!")
                chunks.append(" ".join(chunk + [page]))
                chunk = [word]
        if chunk:
            page = "(%d/%d)" % (len(chunks) + 1, totalPages)
            if len(" ".join(chunk + [page])) > n:
                raise Exception("n is too small!")
            chunks.append(" ".join(chunk + [page]))

        prevTotalPages = totalPages
        totalPages = len(chunks)

    return chunks