#include <libraries/commodities.h>
#include <string.h>
#include <stdio.h>

#include <proto/exec.h>

typedef CxObj * (*CREATECXOBJ_FUNC)(register ULONG type asm("d0"),
                 register ULONG arg1 asm("a0"),
                 register ULONG arg2 asm("a1"),
                 register struct Library *lib asm("a6"));
             

CREATECXOBJ_FUNC old_createcxobj;


#define LVO_CreateCxObj (-6 * 5)

CxObj * New_CreateCxObj(register ULONG type asm("d0"),
                        register ULONG arg1 asm("a0"),
                        register ULONG arg2 asm("a1"),
                        register struct Library *lib asm("a6"))
{
    if (type == CX_FILTER)
    {
             if (!strcasecmp((STRPTR)arg1, "f1")) arg1 = (ULONG)"alt f1";
        else if (!strcasecmp((STRPTR)arg1, "f2")) arg1 = (ULONG)"alt f2";
        else if (!strcasecmp((STRPTR)arg1, "f3")) arg1 = (ULONG)"alt f3";
        /* ... */
        
    }    
    return old_createcxobj(type, arg1, arg2, lib);
}


int main(void)
{
    struct Library * lib = OpenLibrary("commodities.library", 0);
    
    if (lib)    
    {
        Forbid();
        old_createcxobj = (CREATECXOBJ_FUNC)SetFunction(lib, LVO_CreateCxObj, (APTR)New_CreateCxObj);
        Permit();
    
        printf("Patch installedn");
        
        for(;;)
        {
            CREATECXOBJ_FUNC act_CreateCxObj;

            Wait(SIGBREAKF_CTRL_C);

            Forbid();
            act_CreateCxObj = (CREATECXOBJ_FUNC)SetFunction(lib, LVO_CreateCxObj, (APTR)old_createcxobj);
            if (act_CreateCxObj == New_CreateCxObj)
            {
                Permit();
                break;
            }

            SetFunction(lib, LVO_CreateCxObj, (APTR)act_CreateCxObj);
            Permit();

            printf("Cannot remove patch!n");
        }
        
        CloseLibrary(lib);
    }
    else
    {
        printf("Cannot open commodities.library!n");
    }
        
}