/** @addtogroup Extensions
 *
 * @brief Various extensions including integration of libostd with other libs.
 *
 * @{
 */

/** @file sdl_rwops.hh
 *
 * @brief Integration of libostd streams with SDL RWops.
 *
 * This provides integration of libostd streams with SDL RWops so that
 * various APIs that provide a generic RWops interface to deal with
 * files can use libostd streams.
 *
 * Supports both SDL1 and SDL2, with SDL2 being default. If you want to
 * use SDL1 compatibility, define `OSTD_EXT_SDL_USE_SDL1` at build time
 * or before including this header.
 *
 * @copyright See COPYING.md in the project tree for further information.
 */

#ifndef OSTD_EXT_SDL_RWOPS_HH
#define OSTD_EXT_SDL_RWOPS_HH

#ifdef OSTD_EXT_SDL_USE_SDL1
#include <SDL/SDL.h>
#else
#include <SDL2/SDL.h>
#endif

#include "ostd/stream.hh"

namespace ostd {
namespace sdl {

/** @addtogroup Extensions
 * @{
 */

/** @brief Create an `SDL_RWops` using an libostd stream.
 *
 * The resulting RWops object is created using `SDL_AllocRW()`.
 *
 * The `size`, `seek`, `read`, `write` and `close` callbacks are set up,
 * but `close` will not actually close the stream, as the RWops object
 * does not take ownership.
 *
 * @returns The RWops object or `nullptr` on failure.
 */
inline SDL_RWops *stream_to_rwops(stream &s) noexcept {
#ifdef OSTD_EXT_SDL_USE_SDL1
    using sdl_rwops_off_t = int;
#else
    using sdl_rwops_off_t = int64_t;
#endif

    SDL_RWops *rwr = SDL_AllocRW();
    if (!rwr) {
        return nullptr;
    }

    rwr->hidden.unknown.data1 = &s;

    rwr->size = [](SDL_RWops *rw) -> sdl_rwops_off_t {
        auto &is = *static_cast<stream *>(rw->hidden.unknown.data1);
        try {
            return static_cast<sdl_rwops_off_t>(is.size());
        } catch (stream_error const &) {
            return -1;
        }
    };

    rwr->seek = [](SDL_RWops *rw, sdl_rwops_off_t pos, int whence) ->
        sdl_rwops_off_t
    {
        auto &is = *static_cast<stream *>(rw->hidden.unknown.data1);
        try {
            if (!pos && whence == SEEK_CUR) {
                return static_cast<sdl_rwops_off_t>(is.tell());
            }
            if (is->seek((stream_off_t(pos), stream_seek(whence)))) {
                return static_cast<sdl_rwops_off_t>(is.tell());
            }
        } catch (stream_error const &) {
            return -1;
        }
        return -1;
    };

    rwr->read = [](SDL_RWops *rw, void *buf, size_t size, size_t nb) ->
        size_t
    {
        auto &is = *static_cast<stream *>(rw->hidden.unknown.data1);
        try {
            return is.read_bytes(buf, size * nb) / size;
        } catch (stream_error const &) {
            return 0;
        }
    };

    rwr->write = [](SDL_RWops *rw, void const *buf, size_t size, size_t nb) ->
        size_t
    {
        stream &is = *static_cast<stream *>(rw->hidden.unknown.data1);
        try {
            return is->write_bytes(buf, size * nb) / size;
        } catch (stream_error const &) {
            return 0;
        }
    };

    rwr->close = [](SDL_RWops *) -> int {
        return 0;
    };

    return rwr;
}

}
}

/** @} */

#endif

/** @} */