#include "data_base.h"

QSqlDatabase database;
void Data_base::set_database()
{

    // 创建数据库，命名为Pet_project.db

        database = QSqlDatabase::addDatabase("QSQLITE");
        database.setDatabaseName("Pet_project.db");
        if (!database.open())
        {
            qDebug() << "Error: Failed to connect database." << database.lastError();
        }
        else
        {
            qDebug() << "Succeed to connect database." ;
        }
}

void Data_base::delete_table(){

            //删除表格
    QSqlQuery to_user;
    to_user.exec("drop table USER");
    if(to_user.exec())
                {
                    qDebug() << to_user.lastError();
                }
    else
                {
                    qDebug() << "Table cleared";
                }

}

void Data_base::creat_table()
{
    //在数据库中新建立一个表格，用于记录用户信息
        QSqlQuery to_user;
        QStringList table_list = database.tables();

        if(!table_list.contains("USER"))
        {
         //在数据库中新建立一个表格，用于记录用户信息
        if(!to_user.exec("create table USER(user_name varchar primary key,password varchar)"))
        {
            qDebug() << "Error: Fail to create table."<< to_user.lastError();
        }
        else{
            qDebug() << "Table user created!";
        }

        }
        else{
            qDebug()<<"USER already exist";
        }

        QString Username = "pet";
        QString s = QString("SELECT * FROM USER where user_name='%1' ").arg(Username);
        to_user.exec(s);

        int num=0;
        while(to_user.next())
        {
            num++;
        }
        if(num==0)
        {
        //给用户表中插入一个初始的用户,我的超级用户
        to_user.exec("insert into USER values('pet', '123456')");
        }



        if(!table_list.contains("COMMUNICATION"))
        {
         //在数据库中新建立一个表格，用于记录用户信息
        if(!to_user.exec("create table COMMUNICATION(the_content varchar,the_user varchar)"))
        {
            qDebug() << "Error: Fail to create Communication table."<< to_user.lastError();
        }
        else{
            qDebug() << "Table COMMUNICATION created!";
        }


        }

        else{
            qDebug()<<"COMMUNICATION already exist";
        }



}

bool Data_base::check_user(QString Username, QString Password)
{

    if(database.open())
    {
        QSqlQuery check(database);
        //查询是给返回一个满足条件的表，如果没有，表为空，check一开始指向的是返回的表之外
        QString s = QString("SELECT * FROM USER where user_name='%1' and password='%2' ").arg(Username).arg(Password);
        check.exec(s);

        int num=0;
        while(check.next())
        {
            num++;
        }

        if(num!=0) return true;
        else return false;

    }
}