/* ObjectWindows base object destruction protocol. */

#include "tdkpin_object_lifecycle.h"

enum {
    OBJECT_PARENT_OFFSET = 6,
    OBJECT_BOUND_THUNK_OFFSET = 0x12,
    OBJECT_TEARDOWN_SLOT = 0x24,
    DISPOSE_CHILD_CALLBACK_OFFSET = 0x03e9,
};

static void write_far(
    Win16FarPtr object, uint16_t offset, Win16FarPtr value)
{
    win16_write_u16(object, offset, win16_far_offset(value));
    win16_write_u16(
        object, (uint16_t)(offset + 2), win16_far_selector(value));
}

/*
 * 1018:0341 — construct the ObjectWindows base object and its bound thunk.
 * The object joins its parent's circular child ring before publishing its own
 * empty child tail and callback thunk.
 */
Win16FarPtr object_windows_object_construct(
    Win16FarPtr object, uint16_t vmt, Win16FarPtr parent)
{
    BorlandObjectCallFrame frame = {object, vmt};
    if (!borland_enter_object_constructor(&frame, 0)) {
        return frame.object;
    }
    frame.object = borland_default_object_constructor(frame.object, 0);
    win16_write_u16(frame.object, 2, 0);
    win16_write_u16(frame.object, 4, 0);
    win16_write_u16(frame.object, 0x17, 0);
    write_far(frame.object, OBJECT_PARENT_OFFSET, parent);
    if (parent == 0) {
        write_far(frame.object, 0x19, 0);
    } else {
        object_windows_append_child(parent, frame.object);
    }
    write_far(frame.object, 0x0a, 0);
    write_far(frame.object, 0x0e, 0);
    write_far(
        frame.object,
        OBJECT_BOUND_THUNK_OFFSET,
        object_windows_allocate_bound_thunk(frame.object));
    win16_write_u8(win16_far_add_offset(frame.object, 0x16), 0);
    object_windows_set_flag_4(frame.object);
    return frame.object;
}

/*
 * 1018:03ff — destroy one ObjectWindows object.
 * Ordering is binary-significant: virtual teardown, child disposal, parent
 * unlink, bound-thunk release, root destruction, then owned-allocation free.
 */
void object_windows_object_destruct(
    Win16FarPtr object, uint16_t vmt)
{
    uint16_t installed_vmt = win16_read_u16(object);
    Win16FarPtr teardown = win16_read_far_pointer(
        win16_dgroup_pointer(installed_vmt), OBJECT_TEARDOWN_SLOT);
    win16_call_object_method(teardown, object);

    object_windows_for_each_child(
        object,
        win16_relocated_code_pointer(4, DISPOSE_CHILD_CALLBACK_OFFSET));
    Win16FarPtr parent =
        win16_read_far_pointer(object, OBJECT_PARENT_OFFSET);
    if (parent != 0) {
        object_windows_remove_child(parent, object);
    }
    object_windows_release_bound_thunk(
        win16_read_far_pointer(object, OBJECT_BOUND_THUNK_OFFSET));
    borland_default_object_destructor(object, 0);
    BorlandObjectCallFrame frame = {object, vmt};
    borland_finish_object_destructor(&frame, 0);
}