#include "bs_util.h"
using namespace std;

int main()
{
    Request req;
    Session se(req);
    Response res;
    json j;

    auto jsonfail=[&](int errcode,const std::string& dtl="")
    {
        jsonfail_func(j,errcode,dtl);
    };

    do
    {
        if(!se.isReady())
        {
            jsonfail(err_session);
            break;
        }

        if(se.getUser().empty())
        {
            jsonfail(err_need_login);
            break;
        }

        if(req.requestMethod!="POST")
        {
            jsonfail(err_method_not_supported);
            break;
        }

        postval(startid);
        postval(amount);

        int startid_real=ParseInt(startid);
        if(startid_real<0)
        {
            jsonfail(err_parameter,"Failed to parse startid");
            break;
        }

        int amount_real=ParseInt(amount);
        if(amount_real<0)
        {
            jsonfail(err_parameter,"Failed to parse amount");
            break;
        }

        /// Limit to 50.
        if(amount_real>50) amount_real=50;

        startdb();

        if(conn.exec(make_str("select class_id,name,book_type from bs_book where class_id>=",
                              startid_real,
                              " order by class_id limit ",
                              amount_real),
                     [&](MySQLResult& res)
                     {
                         res.stepRow([&](char** val,unsigned long* len)
                                     {
                                         json s;
                                         s["class_id"]=string(val[0]);
                                         s["book_name"]=string(val[1]);
                                         s["book_type"]=string(val[2]);
                                         j["result"].push_back(s);
                                     });
                     })<0)
        {
            jsonfail(err_sql,"Step 1");
            break;
        }

        j["success"]=1;
    }
    while(0);

    se.writeToResponse(res);
    res.content.append(j.dump());

    return 0;
}