Credit Trader

//https://rathena.org/board/topic/108845-can-anyone-give-me-the-mvp-npc-script-and-help-me-unknown-item-3/
prontera,184,177,5  script  Credit Trader   851,{
    .@zeny_worth = 1000000;
    query_sql ( "SELECT `balance` FROM `cp_credits` WHERE `account_id` = "+getcharid(3)+";", .@credits );

    mes "What would you like to do?";
    next;
    .@select = select("Credits -> Zeny?:Zeny -> Credits?") -1;

    mes "How "+( .@select ? "much zeny" : "many credits" )+" would you like to convert?";
    mes .@select ? "Zeny: ^0000FF"+Zeny+"^000000" : "Credits: ^0000FF"+.@credits+"^000000";
    next;
    if( input( .@withdraw, 1, .@select ? Zeny : .@credits ) != 0 ) {
        mes "Please input a number between 1 and ^0000FF"+(.@select ? Zeny : .@credits)+"^000000.";
        close;
    }
    if( .@select && .@withdraw < .@zeny_worth ) {
        mes "Each credit costs at least ^0000FF"+.@zeny_worth+"^000000 Zeny.";
        close;
    }
    mes "Are you sure?";
    mes .@select ?
        "^0000FF"+.@withdraw+"^000000 Zeny -> ^00FF00"+( .@withdraw / .@zeny_worth )+"^000000 Credits.";
    :
        "^0000FF"+.@withdraw+"^000000 Credits -> ^00FF00"+( .@withdraw * .@zeny_worth )+"^000000 Zeny.";
    next;
    if( select("Yes:No") == 2 ) {
        mes "Alright come again!";
        close;
    }

    Zeny = .@select ? ( ( Zeny - .@withdraw ) + ( .@withdraw % .@zeny_worth ) ) : Zeny + ( .@withdraw * .@zeny_worth );
    query_sql ( "UPDATE `cp_credits` SET `balance` = "+( .@select ? .@credits + ( .@withdraw / .@zeny_worth ) : .@credits - .@withdraw )+" WHERE `account_id` = "+getcharid(3)+";" );
    mes "Thanks for using our service have a nice day.";
    close;
}