Principles_of_Database_System/Project/main.py

from flask import Flask, render_template, request, flash, redirect, url_for
import pymysql
from pymysql.cursors import Cursor
import os
from typing import Dict


app  = Flask(__name__)
app.secret_key = os.environ.get('SECRET_KEY', 'OPTIONALSECRETKEY')


def get_db():
    return pymysql.connect(
        host='localhost', user='kejingfan', 
        password='KJF2811879', database='TESTDB'
    )


@app.route("/")
def index():
    return render_template("index.html")


@app.route("/signup.html", methods=('GET', 'POST'))
def signup():
    if request.method == 'GET':
        return render_template('signup.html')
    
    if request.method == 'POST':
        id = request.form['cardCode']
        name = request.form['name']
        phone_number = request.form['mobileNo']
        password = request.form['encryptedPassword']

        db = get_db()
        cursor = db.cursor()

        # 检查已有用户
        sql = """
        SELECT COUNT(*) FROM passengers \
        WHERE ID = %s;
        """
        try:
            cursor.execute(sql, (id,))
            id_exist = cursor.fetchall()[0][0]
        except Exception as e:
            flash("数据库异常，查询失败")
            print(e)
            return redirect(url_for('signup'))
        if (id_exist != 0):
            flash("您已注册过，请勿重复注册")
            db.close()
            return redirect(url_for('index'))

        # 插入
        sql = '''
        INSERT INTO passengers (ID, `Name`, Phone_number, `Password`) \
        VALUES (%s, %s, %s, %s); \
        '''
        try:
            cursor.execute(sql, (id, name, phone_number, password))
            db.commit()
            flash("注册成功")
        except Exception as e:
            db.rollback()
            print(e)
            flash("数据库异常，注册失败")
        db.close()
        return redirect(url_for('index'))


def verify_user(cursor:Cursor, id:str, password:str) -> str:
    # 检查已有用户
        sql = """
        SELECT COUNT(*) FROM passengers \
        WHERE ID = %s;
        """
        try:
            cursor.execute(sql, (id,))
            id_exist = cursor.fetchall()[0][0]
        except Exception as e:
            flash("数据库异常，查询失败")
            print(e)
            return redirect(url_for('signup'))
        if (id_exist == 0):
            return "NO_USER"
        
        # 检查密码
        sql = """
        SELECT `Password` FROM passengers \
        WHERE ID = %s;
        """
        try:
            cursor.execute(sql, (id,))
            record_password = cursor.fetchall()[0][0]
        except Exception as e:
            flash("数据库异常，查询失败")
            print(e)
            return redirect(url_for('modify'))
        if (record_password != password):
            return "WRONG_PASSWORD"
        
        return "USER_VERIFIED"


class ModifyInfo:
    def __init__(self, form:Dict[str, str]):
        self.id = form['cardCode']
        modifyType = form['modifyType']
        self.new_password = form['encryptedNewPassword']
        self.phone_number = form['mobileNo']
        modifyType2command = {
            '1':'delete account',
            '2':'modify Password',
            '3':'modify Phone_Number'
        }
        self.sql_dict = {
            'delete account': 'DELETE FROM passengers WHERE ID = %s;',
            'modify Password': 'UPDATE passengers SET `Password` = %s WHERE ID = %s;',
            'modify Phone_Number': 'UPDATE passengers SET Phone_number = %s WHERE ID = %s;'
        }
        self.sql_args_dict = {
            'delete account': (self.id,),
            'modify Password': (self.new_password, self.id),
            'modify Phone_Number': (self.phone_number, self.id)
        }
        self.ok_message_dict = {
            'delete account': "删除账户成功",
            'modify Password': "修改密码成功",
            'modify Phone_Number': "修改手机号成功"
        }
        self.fail_message_dict = {
            'delete account': "数据库异常，删除账户失败",
            'modify Password': "数据库异常，修改密码失败",
            'modify Phone_Number': "数据库异常，修改手机号失败"
        }
        self.command = modifyType2command[modifyType]
    def get_sql(self):
        return self.sql_dict[self.command]
    def get_args(self):
        return self.sql_args_dict[self.command]
    def get_ok_message(self):
        return self.ok_message_dict[self.command]
    def get_fail_message(self):
        return self.fail_message_dict[self.command]


@app.route("/modify.html", methods=('GET', 'POST'))
def modify():
    if request.method == 'GET':
        return render_template('modify.html')
    
    if request.method == 'POST':
        id = request.form['cardCode']
        password = request.form['encryptedPassword']
        db = get_db()
        cursor = db.cursor()

        verify_info = verify_user(cursor, id, password)
        if (verify_info == "NO_USER"):
            flash("您未注册过，无法修改账号")
            db.close()
            return redirect(url_for('signup'))
        elif (verify_info == "WRONG_PASSWORD"):
            flash("密码错误")
            db.close()
            return redirect(url_for('modify'))

        modifyInfo = ModifyInfo(request.form)
        try:
            cursor.execute(modifyInfo.get_sql(), modifyInfo.get_args())
            db.commit()
            flash(modifyInfo.get_ok_message())
        except Exception as e:
            db.rollback()
            print(e)
            flash(modifyInfo.get_fail_message())
        db.close()
        return redirect(url_for('index'))