use crate::Stack;
use libloading::{Library, Symbol};

static mut STACKPTR: *mut Stack = 0 as *mut Stack;

#[no_mangle]
extern fn stack_pop_callback() -> u16  { 
    return unsafe {
        (*STACKPTR).memory.pop()
    }; 
}

#[no_mangle]
extern fn stack_push_callback(data: u16){ 
    unsafe { 
        (*STACKPTR).memory.push(data) 
    }; 
}

#[no_mangle]
extern fn stack_len_callback() -> usize { 
    return unsafe{
        (*STACKPTR).memory.len()
    }; 
}


pub fn native(stack: &mut Stack, arg: String) {
    unsafe {
        STACKPTR = stack as *mut Stack;
    }
    #[cfg(not(target_family = "windows"))]
    let libsuf: String = ".so".to_owned();

    #[cfg(target_family = "windows")]
    let libsuf: String = ".dll".to_owned();

    let libpref: String = "./".to_owned();

    unsafe {
        let module = Library::new([libpref, arg, libsuf].join("")).unwrap();
        // C libraries should use 
        // void (*labashka)(unsigned short (*pop)(void), void (*push)(unsigned short), size_t (*len)(void), size_t max_size);
        let func: Symbol<unsafe extern "C" fn(extern fn() -> u16, extern fn(u16), extern fn() -> usize, usize)> = module.get(b"labashka").unwrap();
        func(stack_pop_callback,stack_push_callback,stack_len_callback, stack.memory.size());
    }
}