from flask import Flask, render_template, request, redirect
import pymysql
import random
import string
from flask_bootstrap import Bootstrap

app = Flask(__name__)
Bootstrap(app)

# 配置 MySQL 数据库连接
app.config['MYSQL_DATABASE_USER'] = 'root'
app.config['MYSQL_DATABASE_PASSWORD'] = 'guo784512'
app.config['MYSQL_DATABASE_DB'] = 'short_url'
app.config['MYSQL_DATABASE_HOST'] = 'localhost'
app.config['MYSQL_DATABASE_PORT'] = 3306

# 初始化 MySQL 连接
db = pymysql.connect(
    user=app.config['MYSQL_DATABASE_USER'],
    password=app.config['MYSQL_DATABASE_PASSWORD'],
    database=app.config['MYSQL_DATABASE_DB'],
    host=app.config['MYSQL_DATABASE_HOST'],
    port=app.config['MYSQL_DATABASE_PORT']
)

def is_short_url_exists(short_url):
    with db.cursor() as cursor:
        cursor.execute("SELECT COUNT(*) FROM urls WHERE short_url = %s", (short_url,))
        result = cursor.fetchone()
        return result[0] > 0


"""旧"""
# def generate_unique_short_url():
#     current_length = 3
#     while True:
#         short_url = ''.join(random.choices(string.digits + string.ascii_letters, k=current_length))
#         if not is_short_url_exists(short_url):
#             yield short_url  # 使用 yield 生成迭代器
#             current_length = 4  # 在使用完当前长度后，设置下一次长度为4

def generate_unique_short_url():
    current_length = 3
    while True:
        short_url = ''.join(random.choices(string.digits + string.ascii_letters, k=current_length))
        if not is_short_url_exists(short_url):
            yield short_url
        else:
            current_length += 1  # 只有在使用完所有 3 位短链接后才递增长度


def check_and_reconnect_db(db_connection):
    try:
        db_connection.ping(reconnect=True)
    except Exception as e:
        print(f"Error: {e}")
        db_connection = pymysql.connect(
            user=app.config['MYSQL_DATABASE_USER'],
            password=app.config['MYSQL_DATABASE_PASSWORD'],
            database=app.config['MYSQL_DATABASE_DB'],
            host=app.config['MYSQL_DATABASE_HOST'],
            port=app.config['MYSQL_DATABASE_PORT']
        )


short_url_generator = generate_unique_short_url()

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

@app.route('/shorten', methods=['POST'])
def shorten():
    original_url = request.form['url']

    # 检查原始链接是否已经有对应的短链接
    with db.cursor() as cursor:
        cursor.execute("SELECT short_url FROM urls WHERE original_url = %s", (original_url,))
        result = cursor.fetchone()
        if result:
            existing_short_url = result[0]
            return render_template('result.html', original_url=original_url, short_url=existing_short_url)

    # 如果没有，生成新的短链接
    short_url = next(short_url_generator)

    # 将原始URL和短网址保存到数据库
    with db.cursor() as cursor:
        cursor.execute("INSERT INTO urls (original_url, short_url) VALUES (%s, %s)", (original_url, short_url))
        db.commit()
    check_and_reconnect_db(db)  # 在每次操作后检查并重新连接数据库

    return render_template('result.html', original_url=original_url, short_url=short_url)

@app.route('/<short_url>')
def redirect_to_original(short_url):
    check_and_reconnect_db(db)  # 在每次操作后检查并重新连接数据库
    # 从数据库中获取原始URL并重定向
    with db.cursor() as cursor:
        cursor.execute("SELECT original_url FROM urls WHERE short_url = %s", (short_url,))
        result = cursor.fetchone()
        if result:
            original_url = result[0]
            return redirect(original_url)
        else:
            return "Short URL not found."



if __name__ == '__main__':
    # 创建数据库表
    with app.app_context():
        check_and_reconnect_db(db)  # 在每次操作后检查并重新连接数据库
        with db.cursor() as cursor:
            cursor.execute("CREATE TABLE IF NOT EXISTS urls (id INT AUTO_INCREMENT PRIMARY KEY, original_url VARCHAR(255), short_url VARCHAR(255), UNIQUE KEY short_url_unique (short_url))")
            db.commit()

    app.run(debug=True, port=8082)  # 将端口号改为 8082