from hashlib import sha1

from django.db import models
from django.db.models import PROTECT

# 高内聚 低耦合
# 面向对象七个设计原则
# 单一职责原则 / 开闭原则 / 依赖倒转原则 / 里氏替换原则 / 接口隔离原则 / 合成聚合复用原则 / 迪米特法则
# 1995年 - GoF - 23个设计模式
# 创建型模式中的原型模式
proto = sha1()


class User(models.Model):
    no = models.AutoField(primary_key=True, db_column='uno', verbose_name='编号')
    username = models.CharField(max_length=20, unique=True, verbose_name='用户名')
    password = models.CharField(max_length=40, verbose_name='口令')
    email = models.CharField(max_length=255, verbose_name='邮箱')

    def save(self, force_insert=False, force_update=False, using=None, update_fields=None):
        hasher = proto.copy()
        hasher.update(self.password.encode('utf-8'))
        self.password = hasher.hexdigest()
        super().save(force_insert, force_update, using, update_fields)

    class Meta(object):
        db_table = 'tb_user'
        verbose_name = '用户'
        verbose_name_plural = '用户'


class Subject(models.Model):
    no = models.AutoField(primary_key=True, db_column='sno', verbose_name='编号')
    name = models.CharField(max_length=50, db_column='sname', verbose_name='学科名称')
    intro = models.CharField(max_length=511, db_column='sintro', verbose_name='学科介绍')

    def __str__(self):
        return self.name

    class Meta(object):
        db_table = 'tb_subject'
        verbose_name = '学科'
        verbose_name_plural = '学科'


class Teacher(models.Model):
    no = models.AutoField(primary_key=True, db_column='tno', verbose_name='编号')
    name = models.CharField(max_length=20, db_column='tname', verbose_name='姓名')
    intro = models.CharField(max_length=1023, db_column='tintro', verbose_name='简介')
    motto = models.CharField(max_length=255, db_column='tmotto', verbose_name='教学理念')
    photo = models.CharField(max_length=511, db_column='tphoto', verbose_name='照片', null=True, blank=True)
    subject = models.ForeignKey(Subject, db_column='sno', on_delete=PROTECT, related_name='+', verbose_name='所属学科')
    manager = models.BooleanField(default=False, db_column='tmanager', verbose_name='是否主管')
    good_count = models.IntegerField(default=0, db_column='tgcount', verbose_name='好评数')
    bad_count = models.IntegerField(default=0, db_column='tbcount', verbose_name='差评数')

    @property
    def gcount(self):
        return f'{self.good_count}' \
            if self.good_count <= 999 else '999+'

    @property
    def bcount(self):
        return f'{self.bad_count}' \
            if self.bad_count <= 999 else '999+'

    class Meta(object):
        db_table = 'tb_teacher'
        verbose_name = '讲师'
        verbose_name_plural = '讲师'
        ordering = ('name', )