第三天作业

import json
#查询函数
def fetch(backend):
    backend_title = "backend %s" %backend
    record_list = []

    with open("data.txt", "r") as obj:
        flag = False
        for line in obj:
            line = line.strip()
            if line == backend_title:
                flag = True
                continue
            if flag and line.startswith("backend"):
                #匹配到第二个backend开头的字符串则退出循环
                flag = False
                break
            if flag and line:
                #把第一个backend开头的字符串后的不为空的数据存入列表
                record_list.append(line)
    return record_list

#添加函数
def add(dict_info):
    backend = dict_info.get("backend")
    record_list = fetch(backend)
    backend_title = "backend %s" % backend
    current_record = "server %s %s weight %d maxconn %d" %(dict_info["record"]["server"], dict_info["record"]["server"], dict_info["record"]["weight"], dict_info["record"]["maxconn"])
    if not record_list:
        #如果列表为空（配置表中没有这个数据），则添加到列表中
        record_list.append(backend_title)
        record_list.append(current_record)

        with open("data,txt", "r") as read_file, open("new_data.txt", "w") as write_file:
            flag = False
            for line in read_file:
                write_file.write(line)
            for i in record_list:
                if i.startswith("backend"):
                    write_file.write(i+"
")
                else:
                    write_file.write("%s%s
" %(8*" ", i))
    else:
        record_list.insert(0, backend_title)
        if current_record not in record_list:
            record_list.append(current_record)

        with open("data.txt", "r") as read_file, open("new_data.txt", "w") as write_file:
            flag = False
            has_write = False
            for line in read_file:
                line = line.strip()
                if line == backend_title:
                    flag = True
                    continue
                if flag and line.startswith("backend"):
                    flag = False

                if not flag:
                    write_file.write(line+"
")
                else:
                    if not has_write:
                        for i in record_list:
                            if i.startswith("backend"):
                                write_file.write(i+"
")
                            else:
                                write_file.write("%s%s
" %(8*" ", i))
                    has_write = True

#删除函数
def remove(dict_info):
    backend = dict_info.get("backend")
    record_list = fetch(backend)
    backend_title = "backend %s" % backend
    current_record = "server %s %s weight %d maxconn %d" % (
    dict_info["record"]["server"], dict_info["record"]["server"], dict_info["record"]["weight"],
    dict_info["record"]["maxconn"])
    if not record_list:
        return
    else:
        if current_record not in record_list:
            return
        else:
            del record_list[record_list.index(current_record)]
            if len(record_list) > 0:
                record_list.insert(0, backend_title)
        with open("data.txt", "r") as read_file, open("new_data.txt", "w") as write_file:
            flag = False
            has_write = False
            for line in read_file:
                line = line.strip()
                if line == backend_title:
                    flag = True
                    continue
                if flag and line.startswith("backend"):
                    flag = False

                if not flag:
                    write_file.write(line + "
")
                else:
                    if not has_write:
                        for i in record_list:
                            if i.startswith("backend"):
                                write_file.write(i + "
")
                            else:
                                write_file.write("%s%s
" % (8 * " ", i))
                    has_write = True


#主函数
if __name__ == "__main__":
    flag = True
    print("1:查询, 2:添加, 3:删除")

    while flag:
        #确保输入为：1、2、3
        num = input("请输入序号:")
        if num in ["1", "2", "3"]:
            flag = False

    data = input("请输入内容:")

    if num == "1":
        #输入1调用查询函数
        list_data = fetch(data)
        for i in list_data:
            print(i)
    else:
        #输入为2、3调用添加和删除函数
        dict_data = json.loads(data)   #把输入的数据转换为字典
        if num == "2":
            #调用添加函数
            add(dict_data)
        else:
            #调用删除函数
            remove(dict_data)