/**
 * WebRTC implementation for tiny devices
 *
 * Copyright (c) 2022 Chris Hiszpanski. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 */

#ifndef TINYRTC_H
#define TINYRTC_H

///  CUSTOMIZABLE PARAMETERS  ////////////////////////////////////////////////

#define TINYRTC_MAX_ICE_CANDIDATE_SIZE                     256
#define TINYRTC_MAX_ICE_SERVER_CREDENTIAL_SIZE             128
#define TINYRTC_MAX_ICE_SERVERS                            2
#define TINYRTC_MAX_ICE_SERVER_URL_SIZE                    128
#define TINYRTC_MAX_ICE_SERVER_URLS                        3
#define TINYRTC_MAX_ICE_SERVER_USERNAME_SIZE               128
#define TINYRTC_MAX_ICE_CANDIDATE_USERNAME_FRAGMENT_SIZE   8
#define TINYRTC_MAX_ICE_CANDIDATE_SDP_MID_SIZE             32
#define TINYRTC_MAX_PEER_CONNECTIONS                       5
#define TINYRTC_MAX_SDP_SIZE                               4096
#define TINYRTC_MAX_ICE_UFRAG_SIZE                         5
#define TINYRTC_MAX_ICE_PWD_SIZE                           32


///  PUBLIC ENUMS  ///////////////////////////////////////////////////////////

enum rtc_session_description_type {
    RTC_SESSION_DESCRIPTION_TYPE_NONE = 0,
    RTC_SESSION_DESCRIPTION_TYPE_OFFER,
    RTC_SESSION_DESCRIPTION_TYPE_ANSWER
};


///  PUBLIC STRUCTS  /////////////////////////////////////////////////////////

struct rtc_peer_connection;

struct rtc_ice_server {
    char credential[TINYRTC_MAX_ICE_SERVER_CREDENTIAL_SIZE];
    char urls[TINYRTC_MAX_ICE_SERVER_URLS][TINYRTC_MAX_ICE_SERVER_URL_SIZE];
    char username[TINYRTC_MAX_ICE_SERVER_USERNAME_SIZE];
};

struct rtc_configuration {
    struct rtc_ice_server ice_servers[TINYRTC_MAX_ICE_SERVERS];
};

struct rtc_ice_candidate {
    char candidate[TINYRTC_MAX_ICE_CANDIDATE_SIZE];
    int  sdp_mline_index;
    char sdp_mid[TINYRTC_MAX_ICE_CANDIDATE_SDP_MID_SIZE];
    char username_fragment[TINYRTC_MAX_ICE_CANDIDATE_USERNAME_FRAGMENT_SIZE];
};

struct rtc_session_description {
    char sdp[TINYRTC_MAX_SDP_SIZE];
    enum rtc_session_description_type type;
};


///  CALLBACKS  //////////////////////////////////////////////////////////////

typedef void (rtc_on_ice_candidate)(const struct rtc_ice_candidate c,
        void *arg);


///  RTC PEER CONNECTION API  ////////////////////////////////////////////////

/**
 * Initialize library. Must call once before calling other functions.
 */
void rtc_init();

/**
 * Create new peer connection
 *
 * \param cfg[in] Configuration.
 *
 * \return Peer connection. NULL if all peer connections are already in use.
 */
struct rtc_peer_connection* rtc_peer_connection_create(
        struct rtc_configuration cfg);

void rtc_peer_connection_destroy(struct rtc_peer_connection* pc);

/**
 * Adds remote ICE candidate to local ICE agent
 *
 * \param pc[in] Peer connection.
 * \param c[in] ICE candidate from remote peer.
 *
 * \return 0 on success. -1 on error.
 */
int rtc_add_ice_candidate(
    struct rtc_peer_connection* pc, const struct rtc_ice_candidate c);

/**
 * Create SDP answer in response to a received SDP offer.
 *
 * \param pc[in] Peer connection.
 *
 * \return SDP answer. NULL on error.
 */
const char* rtc_create_answer(struct rtc_peer_connection* pc);

/**
 * Sets callback to call for each discovered local ICE candidate
 *
 * \param pc[in] Peer connection.
 * \param cb[in] Callback function.
 * \param arg[in] User-specified argument to pass to callback function.
 *
 * \return 0 on success. -1 on error.
 */
int rtc_set_on_ice_candidate(
    struct rtc_peer_connection* pc, rtc_on_ice_candidate* cb, void* arg);

int rtc_set_local_description(struct rtc_peer_connection* pc, const char* sdp);
int rtc_set_remote_description(struct rtc_peer_connection* pc, const char* sdp);

#endif

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