// Phase 1 step 1.8 (PLAN-FFI.md): >16 B non-HFA struct returns
// through `#objc_call`. AAPCS64 routes these through the indirect-
// return convention: caller allocates the result slot, passes its
// pointer in x8 with the `sret(<T>)` attribute, callee writes
// through it and returns void.
//
// Register a runtime-built Obj-C class with a method that returns
// a fixed `Triple`. The IMP is a plain sx fn (callconv .c) — its
// sret-shaped lowering already works (Phase 0.3 fix for plain
// `#foreign` returns). The `#objc_call` dispatch side now produces
// the matching call shape: `call void @objc_msgSend(ptr sret %slot,
// ...)` + load. The two halves must agree on the ABI for the
// round-trip to return the right bytes.

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

Triple :: struct { a: i64; b: i64; c: i64; }

// IMP for the runtime-installed method. Obj-C convention: implicit
// (self, _cmd) prefix, then declared args. Returns the value bytes.
triple_imp :: (self: *void, _cmd: *void) -> Triple callconv(.c) {
    Triple.{ a = 11, b = 22, c = 33 }
}

main :: () -> i32 {
    inline if OS == .macos {
        // Build the class:
        //   @interface SxTripleProbe : NSObject
        //     - (Triple)tripleValue;
        //   @end
        ns_object := objc_getClass("NSObject".ptr);
        my_cls := objc_allocateClassPair(ns_object, "SxTripleProbe".ptr, 0);
        sel := sel_registerName("tripleValue".ptr);
        // Type encoding: {Triple=qqq}@: → returns 24 B struct of 3 i64,
        // implicit (self: id, _cmd: SEL).
        ok := class_addMethod(my_cls, sel, xx triple_imp, "{Triple=qqq}@:".ptr);
        print("addMethod = {}\n", ok);
        objc_registerClassPair(my_cls);

        // Call through #objc_call — sret transform applies because
        // Triple is 24 B non-HFA.
        instance := class_createInstance(my_cls, 0);
        t := #objc_call(Triple)(instance, "tripleValue");
        print("triple = ({}, {}, {})\n", t.a, t.b, t.c);
    }
    inline if OS != .macos {
        print("skipped (not macos)\n");
    }
    0
}