/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

parcel Lucy;

__C__
#define CFISH_HOST_ARGTYPE_I32    (int32_t)0x00000001
#define CFISH_HOST_ARGTYPE_I64    (int32_t)0x00000002
#define CFISH_HOST_ARGTYPE_F32    (int32_t)0x00000003
#define CFISH_HOST_ARGTYPE_F64    (int32_t)0x00000004
#define CFISH_HOST_ARGTYPE_STR    (int32_t)0x00000006
#define CFISH_HOST_ARGTYPE_OBJ    (int32_t)0x00000007
#define CFISH_HOST_ARGTYPE_MASK            0x00000007

#define CFISH_ARG_I32(_label, _value) \
    CFISH_HOST_ARGTYPE_I32, (_label), ((int32_t)_value)
#define CFISH_ARG_I64(_label, _value) \
    CFISH_HOST_ARGTYPE_I64, (_label), ((int64_t)_value)
#define CFISH_ARG_I(_type, _label, _value) \
    (sizeof(_type) <= 4 ? CFISH_HOST_ARGTYPE_I32 : CFISH_HOST_ARGTYPE_I64), \
    (_label), (sizeof(_type) <= 4 ? (int32_t)_value : (int64_t)_value)
#define CFISH_ARG_F32(_label, _value) \
    CFISH_HOST_ARGTYPE_F32, (_label), ((double)_value)
#define CFISH_ARG_F64(_label, _value) \
    CFISH_HOST_ARGTYPE_F64, (_label), ((double)_value)
#define CFISH_ARG_STR(_label, _value) \
    CFISH_HOST_ARGTYPE_STR, (_label), ((lucy_CharBuf*)_value)
#define CFISH_ARG_OBJ(_label, _value) \
    CFISH_HOST_ARGTYPE_OBJ, (_label), ((lucy_Obj*)_value)

#ifdef LUCY_USE_SHORT_NAMES
  #define ARG_I32                 CFISH_ARG_I32
  #define ARG_I64                 CFISH_ARG_I64
  #define ARG_F32                 CFISH_ARG_F32
  #define ARG_F64                 CFISH_ARG_F64
  #define ARG_STR                 CFISH_ARG_STR
  #define ARG_OBJ                 CFISH_ARG_OBJ
#endif

__END_C__

/** Callbacks to the host environment.
 *
 * All the callback functions are variadic, and all are designed to take a
 * series of arguments using the ARG_XXX macros.
 *
 *   int32_t area = (int32_t)Host_callback_i64(self, "calc_area", 2,
 *        ARG_I32("length", len),  ARG_I32("width", width));
 *
 * The first argument is void* to avoid the need for tiresome casting to Obj*,
 * but must always be a Clownfish object.
 *
 * If the invoker is a VTable, it will be used to make a class
 * callback rather than an object callback.
 */
inert class Lucy::Object::Host {

    /** Invoke an object method in a void context.
     */
    inert void
    callback(void *self, char *method, uint32_t num_args, ...);

    /** Invoke an object method, expecting an integer.
     */
    inert int64_t
    callback_i64(void *self, char *method, uint32_t num_args, ...);

    /** Invoke an object method, expecting a 64-bit floating point return
     * value.
     */
    inert double
    callback_f64(void *self, char *method, uint32_t num_args, ...);

    /** Invoke an object method, expecting a Obj-derived object back, or
     * possibly NULL.  In order to ensure that the host environment doesn't
     * reclaim the return value, it's refcount is increased by one, which the
     * caller will have to deal with.
     */
    inert incremented nullable Obj*
    callback_obj(void *self, char *method, uint32_t num_args, ...);

    /** Invoke an object method, expecting a host string of some kind back,
     * which will be converted into a newly allocated CharBuf.
     */
    inert incremented nullable CharBuf*
    callback_str(void *self, char *method, uint32_t num_args, ...);

    /** Invoke an object method, expecting a host data structure back.  It's
     * up to the caller to know how to process it.
     */
    inert nullable void*
    callback_host(void *self, char *method, uint32_t num_args, ...);
}