# -*- coding: utf-8 -*-
"""
Day_5 参考解答
=============
主题：面向对象（二）—— 继承。
建议：先自己写，写不出来再看；看完后关掉文件自己默写一遍。
"""

import time

class BaseModel:
    objects = []            # 类属性：模拟数据库表（所有子类共用）

    def save(self):
        BaseModel.objects.append(self)
        print(f"[DB] 已保存 {type(self).__name__}: {self}")

    def delete(self):
        BaseModel.objects.remove(self)
        print(f"[DB] 已删除 {self}")

    def to_dict(self):
        return dict(self.__dict__)           # 实例的所有属性 => 字典

    def __str__(self):
        return f"<{type(self).__name__}#{id(self)}>"


class Article(BaseModel):
    def __init__(self, title, content, author):
        self.title = title
        self.content = content
        self.author = author
        self.created_at = time.strftime("%Y-%m-%d %H:%M:%S")

    # 进阶：重写 save，先打日志，再调用父类逻辑
    def save(self):
        print(f"[LOG] 正在保存文章《{self.title}》...")
        super().save()                       # 父类的 save 负责真正"入库"

    def __str__(self):
        return f"<Article: {self.title}>"


class Comment(BaseModel):
    def __init__(self, content, author):
        self.content = content
        self.author = author

    def __str__(self):
        return f"<Comment: {self.content[:10]}...>"


if __name__ == '__main__':
    a1 = Article("Django 入门", "从 Hello World 开始", "zhangsan")
    a1.save()                                # 触发重写后的 save（带日志 + super）
    c1 = Comment("写得太好了！", "lisi")
    c1.save()

    for obj in BaseModel.objects:
        print(obj.to_dict())

    print(issubclass(Article, BaseModel))    # True
    print(isinstance(a1, BaseModel))         # True

    a1.delete()
    print(len(BaseModel.objects))            # 1（只剩评论）