[kratoss1812]

You don't need to code anything ^.^

Add The following in csgo/cfg/gamemode_casual_server.cfg or in your server.cfg!

mp_match_restart_delay 20

//mp_endmatch_votenextmap_keepcurrent 0
mp_endmatch_votenextmap 0 // keep this to 0
mp_endmatch_votenextleveltime 20

EDIT: I did't read your problem well.. but you can keep these convars in your server.cfg and use Map chooser and for chat messages you can use my plugin ( not released.. too simply)

PHP Code:

#define PLUGIN_AUTHOR "kRatoss"
#define PLUGIN_VERSION "1.00"

#include <sourcemod>
#include <colors>

public Plugin myinfo = 
{
    name = "Map Commands",
    author = PLUGIN_AUTHOR,
    description = "",
    version = PLUGIN_VERSION,
    url = ""
};

public void OnPluginStart()
{
    RegConsoleCmd("sm_nextmap", Cmd_Next);
    RegAdminCmd("sm_setnextmap", Cmd_Set, ADMFLAG_CHANGEMAP);
}

public Action Cmd_Next(int client, int args)
{
    char sMap[64];
    GetNextMap(sMap, sizeof(sMap));
    
    PrintToChat(client, "\x04 Next map: \x03 %s", sMap);
}

public Action Cmd_Set(int client, int args)
{
    if(args != 1)
    {
        PrintToChat(client, "Usage: sm_setnextmap <map>");
        return Plugin_Handled;
    }
    
    char sArgs[64];
    GetCmdArg(1, sArgs, sizeof(sArgs));
    
    char sMap[62];
    GetCmdArgString(sMap, sizeof(sMap));
    
    SetNextMap(sMap);
    
    char sName[MAX_NAME_LENGTH];
    GetClientName(client, sName, MAX_NAME_LENGTH);
    
    PrintToChatAll("\x04 Admin %s set the next map to: %s", sName, sMap);
    
    return Plugin_Handled;
}