// M2.1(a) — class-level constants on a sx-defined `#objc_class`.
//
// `name :: Type = expr;` inside the class block is sugar for
// `name :: () -> Type => expr;` — a niladic class method with an
// expression body. The compiler emits a C-ABI IMP that returns the
// captured expression and registers it on the metaclass.
//
// Apple's runtime sees no distinction — '[Cls foo]' dispatches to
// our IMP whether the user wrote it as a constant or as a method.
// The constant form just reads better for static metadata returns
// (canonical example: '+layerClass' on UIView subclasses).

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

NSObject :: #foreign #objc_class("NSObject") {
    alloc :: () -> *NSObject;
    init  :: (self: *NSObject) -> *NSObject;
}

// Reframed as a class method internally; user writes the constant form.
SxThing :: #objc_class("SxThing") {
    counter: s32;

    // Class-level constant.
    answer :: s32 = 42;

    // Canonical pattern: returning a *NSObject (stand-in for Apple's
    // '+layerClass' returning *CALayer).
    seedClass :: *NSObject = NSObject.alloc().init();
}

main :: () -> s32 {
    inline if OS == .macos {
        cls : Class = objc_getClass("SxThing".ptr);
        if cls == null { print("FAIL: SxThing not registered\n"); return 1; }

        // [SxThing answer] → 42
        sel_answer : SEL = sel_registerName("answer".ptr);
        msg_int : (cls: *void, sel: *void) -> s32 callconv(.c) = xx objc_msgSend;
        r := msg_int(cls, sel_answer);
        if r != 42 { print("FAIL: answer expected 42, got {}\n", r); return 1; }

        // [SxThing seedClass] returns a non-null NSObject.
        sel_seed : SEL = sel_registerName("seedClass".ptr);
        msg_ptr : (cls: *void, sel: *void) -> *void callconv(.c) = xx objc_msgSend;
        seed := msg_ptr(cls, sel_seed);
        if seed == null { print("FAIL: seedClass returned null\n"); return 1; }

        print("class constants: answer={}, seedClass=ok\n", r);
    }
    inline if OS != .macos {
        print("class constants: answer=42, seedClass=ok\n");
    }
    0;
}