class Namespace

static VALUE
rb_namespace_current(VALUE klass)
{
    const rb_namespace_t *ns = rb_current_namespace();
    if (NAMESPACE_USER_P(ns)) {
        return ns->ns_object;
    }
    if (NAMESPACE_BUILTIN_P(ns)) {
        return Qnil;
    }
    return Qfalse;
}

static VALUE
rb_namespace_s_getenabled(VALUE namespace)
{
    return RBOOL(rb_namespace_available());
}

static VALUE
rb_namespace_s_is_builtin_p(VALUE namespace, VALUE klass)
{
    if (RCLASS_PRIME_CLASSEXT_READABLE_P(klass) && !RCLASS_PRIME_CLASSEXT_WRITABLE_P(klass))
        return Qtrue;
    return Qfalse;
}

static VALUE
namespace_initialize(VALUE namespace)
{
    rb_namespace_t *ns;
    rb_classext_t *object_classext;
    VALUE entry;
    ID id_namespace_entry;
    CONST_ID(id_namespace_entry, "__namespace_entry__");

    if (!rb_namespace_available()) {
        rb_raise(rb_eRuntimeError, "Namespace is disabled. Set RUBY_NAMESPACE=1 environment variable to use Namespace.");
    }

    entry = rb_class_new_instance_pass_kw(0, NULL, rb_cNamespaceEntry);
    ns = get_namespace_struct_internal(entry);

    ns->ns_object = namespace;
    ns->ns_id = namespace_generate_id();
    ns->load_path = rb_ary_dup(GET_VM()->load_path);
    ns->is_user = true;
    rb_define_singleton_method(ns->load_path, "resolve_feature_path", rb_resolve_feature_path, 1);

    // Set the Namespace object unique/consistent from any namespaces to have just single
    // constant table from any view of every (including main) namespace.
    // If a code in the namespace adds a constant, the constant will be visible even from root/main.
    RCLASS_SET_PRIME_CLASSEXT_WRITABLE(namespace, true);

    // fallback to ivptr for ivars from shapes to manipulate the constant table
    rb_evict_ivars_to_hash(namespace);

    // Get a clean constant table of Object even by writable one
    // because ns was just created, so it has not touched any constants yet.
    object_classext = RCLASS_EXT_WRITABLE_IN_NS(rb_cObject, ns);
    RCLASS_SET_CONST_TBL(namespace, RCLASSEXT_CONST_TBL(object_classext), true);

    rb_ivar_set(namespace, id_namespace_entry, entry);

    setup_pushing_loading_namespace(ns);

    return namespace;
}

static VALUE
rb_namespace_inspect(VALUE obj)
{
    rb_namespace_t *ns;
    VALUE r;
    if (obj == Qfalse) {
        r = rb_str_new_cstr("#<Namespace:root>");
        return r;
    }
    ns = rb_get_namespace_t(obj);
    r = rb_str_new_cstr("#<Namespace:");
    rb_str_concat(r, rb_funcall(LONG2NUM(ns->ns_id), rb_intern("to_s"), 0));
    if (NAMESPACE_BUILTIN_P(ns)) {
        rb_str_cat_cstr(r, ",builtin");
    }
    if (NAMESPACE_USER_P(ns)) {
        rb_str_cat_cstr(r, ",user");
    }
    if (NAMESPACE_MAIN_P(ns)) {
        rb_str_cat_cstr(r, ",main");
    }
    else if (NAMESPACE_OPTIONAL_P(ns)) {
        rb_str_cat_cstr(r, ",optional");
    }
    rb_str_cat_cstr(r, ">");
    return r;
}

static VALUE
rb_namespace_load(int argc, VALUE *argv, VALUE namespace)
{
    VALUE fname, wrap;
    rb_thread_t *th = GET_THREAD();
    rb_namespace_t *ns = rb_get_namespace_t(namespace);

    rb_scan_args(argc, argv, "11", &fname, &wrap);

    VALUE args = rb_ary_new_from_args(2, fname, wrap);
    namespace_push(th, namespace);
    rb_namespace_push_loading_namespace(ns);
    struct namespace_pop2_arg arg = {
        .th = th,
        .ns = ns
    };
    return rb_ensure(rb_load_entrypoint, args, namespace_both_pop, (VALUE)&arg);
}

static VALUE
rb_namespace_load_path(VALUE namespace)
{
    return rb_get_namespace_t(namespace)->load_path;
}

static VALUE
rb_namespace_require(VALUE namespace, VALUE fname)
{
    rb_thread_t *th = GET_THREAD();
    rb_namespace_t *ns = rb_get_namespace_t(namespace);
    namespace_push(th, namespace);
    rb_namespace_push_loading_namespace(ns);
    struct namespace_pop2_arg arg = {
        .th = th,
        .ns = ns
    };
    return rb_ensure(rb_require_string, fname, namespace_both_pop, (VALUE)&arg);
}

static VALUE
rb_namespace_require_relative(VALUE namespace, VALUE fname)
{
    rb_thread_t *th = GET_THREAD();
    rb_namespace_t *ns = rb_get_namespace_t(namespace);
    namespace_push(th, namespace);
    rb_namespace_push_loading_namespace(ns);
    struct namespace_pop2_arg arg = {
        .th = th,
        .ns = ns
    };
    return rb_ensure(rb_require_relative_entrypoint, fname, namespace_both_pop, (VALUE)&arg);
}