'''
本例的基本模式还是观察者
基类 Subject 提供注册和提醒注册上的对象提醒机制

因为函数和参数混杂在一起传递，使得各个模块的处理结构其实是 case by case
'''

from collections import Counter
from typing import List
from cppy.cp_util import *

class Subject:
    def register_handler(self, handler: callable, *args, **kwargs):
        self.handler = handler
        self.args = args
        self.kwargs = kwargs

    def notify(self, *args, **kwargs):
        self.handler( self.data, *self.args, **self.kwargs)
        


# 组件一：TextLoader - 负责读取文本并过滤停用词
class TextLoader(Subject):
    def load_text(self, filename: str) -> List[str]:
        return extract_file_words(filename)

    def notify(self, *args, **kwargs):
        filename = args[0]
        self.data = self.load_text(filename)
        super().notify(self.data, *args, **kwargs)        


# 组件二：WordCounter - 计算词频
class WordCounter(Subject):
    def count_words(self, words: List[str]) -> dict:
        return Counter(words)

    def notify(self, *args, **kwargs ):
        words = args[0] 
        self.data = self.count_words(words)        
        super().notify(self.data, *args, **kwargs)


# 组件三：TopWordsPresenter - 排序并输出前10个词
class TopWordsPresenter(Subject):    
    def notify(self, words,*args, **kwargs):                
        n = args[0]                   
        top_words = words.most_common(n)
        print_word_freqs( top_words )


# 主程序逻辑
def main():
    loader = TextLoader()
    counter = WordCounter()
    presenter = TopWordsPresenter()

    # 注册事件处理器
    loader.register_handler(counter.notify)
    counter.register_handler( presenter.notify,10 )

    # 触发加载文本并开始流程
    loader.notify(testfilepath)


if __name__ == "__main__":
    main()