// Obj-C runtime FFI smoke test: round-trip a string through NSString.
//
// Demonstrates the typed-fn-pointer cast idiom for `objc_msgSend`. Each
// shape we invoke gets its own variable typed with the exact ABI:
//
//   msg_3 : (*void, *void, [*]u8) -> *void = xx objc_msgSend;
//   msg_2 : (*void, *void) -> [*]u8 = xx objc_msgSend;
//
// On ARM64 Apple, objc_msgSend doesn't take a varargs path — invoking it
// through a typed fn-pointer is the only correct way to land args in the
// right registers.

#import "modules/std.sx";
#import "modules/std/objc.sx";

main :: () -> s32 {
    ns_class      := objc_getClass("NSString".ptr);
    sel_with_utf8 := sel_registerName("stringWithUTF8String:".ptr);
    sel_utf8      := sel_registerName("UTF8String".ptr);

    msg_3 : (*void, *void, [*]u8) -> *void callconv(.c) = xx objc_msgSend;
    ns_str := msg_3(ns_class, sel_with_utf8, "hi".ptr);

    msg_2 : (*void, *void) -> [*]u8 callconv(.c) = xx objc_msgSend;
    back := msg_2(ns_str, sel_utf8);

    return xx (back[0] + back[1]); // 'h' + 'i' = 104 + 105 = 209
}
