/**
 * The MIT License (MIT)
 *
 * Copyright (c) 2013-2020 Winlin
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#ifndef SRS_APP_RTC_CONN_HPP
#define SRS_APP_RTC_CONN_HPP

#include <srs_core.hpp>
#include <srs_app_listener.hpp>
#include <srs_service_st.hpp>
#include <srs_kernel_utility.hpp>
#include <srs_rtmp_stack.hpp>
#include <srs_app_hybrid.hpp>
#include <srs_app_hourglass.hpp>
#include <srs_app_sdp.hpp>

#include <string>
#include <map>
#include <vector>

#include <openssl/ssl.h>
#include <srtp2/srtp.h>

class SrsUdpMuxSocket;
class SrsConsumer;
class SrsStunPacket;
class SrsRtcServer;
class SrsRtcSession;
class SrsSharedPtrMessage;
class SrsSource;

const uint8_t kSR   = 200;
const uint8_t kRR   = 201;
const uint8_t kSDES = 202;
const uint8_t kBye  = 203;
const uint8_t kApp  = 204;

// @see: https://tools.ietf.org/html/rfc4585#section-6.1
const uint8_t kRtpFb = 205;
const uint8_t kPsFb  = 206;

// @see: https://tools.ietf.org/html/rfc4585#section-6.3
const uint8_t kPLI  = 1;
const uint8_t kSLI  = 2;
const uint8_t kRPSI = 3;
const uint8_t kAFB  = 15;

const srs_utime_t kSrsRtcSessionStunTimeoutUs = 10*1000*1000LL;

enum SrsRtcSessionStateType
{
    // TODO: FIXME: Should prefixed by enum name.
    INIT = -1,
    WAITING_STUN = 1,
    DOING_DTLS_HANDSHAKE = 2,
    ESTABLISHED = 3,
    CLOSED = 4,
};

class SrsDtlsSession
{
private:
    SrsRtcSession* rtc_session;

	SSL* dtls;
    BIO* bio_in;
    BIO* bio_out;

    std::string client_key;
    std::string server_key;

    srtp_t srtp_send;
    srtp_t srtp_recv;

    bool handshake_done;

public:
    SrsDtlsSession(SrsRtcSession* s);
    virtual ~SrsDtlsSession();

    srs_error_t initialize();

    srs_error_t on_dtls(SrsUdpMuxSocket* udp_mux_skt);
    srs_error_t on_dtls_handshake_done(SrsUdpMuxSocket* udp_mux_skt);
    srs_error_t on_dtls_application_data(const char* data, const int len);
public:
    srs_error_t protect_rtp(char* protected_buf, const char* ori_buf, int& nb_protected_buf);
    srs_error_t unprotect_rtp(char* unprotected_buf, const char* ori_buf, int& nb_unprotected_buf);
    srs_error_t protect_rtcp(char* protected_buf, const char* ori_buf, int& nb_protected_buf);
    srs_error_t unprotect_rtcp(char* unprotected_buf, const char* ori_buf, int& nb_unprotected_buf);
private:
    srs_error_t handshake(SrsUdpMuxSocket* udp_mux_skt);
private:
    srs_error_t srtp_initialize();
    srs_error_t srtp_send_init();
    srs_error_t srtp_recv_init();
};

class SrsRtcSenderThread : public ISrsCoroutineHandler
{
protected:
    SrsCoroutine* trd;
    int _parent_cid;
private:
    SrsRtcSession* rtc_session;
    uint32_t video_ssrc;
    uint32_t audio_ssrc;
    uint16_t video_payload_type;
    uint16_t audio_payload_type;
public:
    SrsUdpMuxSocket* sendonly_ukt;
public:
    SrsRtcSenderThread(SrsRtcSession* s, SrsUdpMuxSocket* u, int parent_cid);
    virtual ~SrsRtcSenderThread();
public:
    srs_error_t initialize(const uint32_t& vssrc, const uint32_t& assrc, const uint16_t& v_pt, const uint16_t& a_pt);
public:
    virtual int cid();
public:
    virtual srs_error_t start();
    virtual void stop();
    virtual void stop_loop();
public:
    virtual srs_error_t cycle();
public:
    void update_sendonly_socket(SrsUdpMuxSocket* ukt);
private:
    void send_and_free_messages(SrsSharedPtrMessage** msgs, int nb_msgs, SrsUdpMuxSocket* udp_mux_skt);
};

class SrsRtcSession
{
    friend class SrsRtcSenderThread;
private:
    SrsRtcServer* rtc_server;
    SrsSdp  remote_sdp;
    SrsSdp  local_sdp;
    SrsRtcSessionStateType session_state;
    SrsDtlsSession* dtls_session;
    SrsRtcSenderThread* strd;
    std::string username;
    std::string peer_id;
    srs_utime_t last_stun_time;
private:
    // For each RTC session, we use a specified cid for debugging logs.
    int cid;
public:
    SrsRequest request;
    SrsSource* source;
public:
    SrsRtcSession(SrsRtcServer* rtc_svr, const SrsRequest& req, const std::string& un, int context_id);
    virtual ~SrsRtcSession();
public:
    SrsSdp* get_local_sdp() { return &local_sdp; }
    void set_local_sdp(const SrsSdp& sdp);

    SrsSdp* get_remote_sdp() { return &remote_sdp; }
    void set_remote_sdp(const SrsSdp& sdp) { remote_sdp = sdp; }

    SrsRtcSessionStateType get_session_state() { return session_state; }
    void set_session_state(SrsRtcSessionStateType state) { session_state = state; }

    std::string id() const { return peer_id + "_" + username; }

    std::string get_peer_id() const { return peer_id; }
    void set_peer_id(const std::string& id) { peer_id = id; }

    void switch_to_context();
public:
    srs_error_t on_stun(SrsUdpMuxSocket* udp_mux_skt, SrsStunPacket* stun_req);
    srs_error_t on_dtls(SrsUdpMuxSocket* udp_mux_skt);
    srs_error_t on_rtcp(SrsUdpMuxSocket* udp_mux_skt);
public:
    srs_error_t send_client_hello(SrsUdpMuxSocket* udp_mux_skt);
    srs_error_t on_connection_established(SrsUdpMuxSocket* udp_mux_skt);
    srs_error_t start_play(SrsUdpMuxSocket* udp_mux_skt);
public:
    bool is_stun_timeout() { return last_stun_time + kSrsRtcSessionStunTimeoutUs < srs_get_system_time(); }
private:
    srs_error_t check_source();
private:
    srs_error_t on_binding_request(SrsUdpMuxSocket* udp_mux_skt, SrsStunPacket* stun_req);
private:
    srs_error_t on_rtcp_feedback(char* buf, int nb_buf, SrsUdpMuxSocket* udp_mux_skt);
    srs_error_t on_rtcp_ps_feedback(char* buf, int nb_buf, SrsUdpMuxSocket* udp_mux_skt);
    srs_error_t on_rtcp_receiver_report(char* buf, int nb_buf, SrsUdpMuxSocket* udp_mux_skt);
};

class SrsRtcServer : virtual public ISrsUdpMuxHandler, virtual public ISrsHourGlass
{
private:
    SrsUdpMuxListener* listener;
    SrsHourGlass* timer;
private:
    std::map<std::string, SrsRtcSession*> map_username_session; // key: username(local_ufrag + ":" + remote_ufrag)
    std::map<std::string, SrsRtcSession*> map_id_session; // key: peerip(ip + ":" + port)
public:
    SrsRtcServer();
    virtual ~SrsRtcServer();
public:
    virtual srs_error_t initialize();
public:
    // TODO: FIXME: Support gracefully quit.
    // TODO: FIXME: Support reload.
    virtual srs_error_t listen_udp();
    virtual srs_error_t on_udp_packet(SrsUdpMuxSocket* udp_mux_skt);
public:
    virtual srs_error_t listen_api();
    SrsRtcSession* create_rtc_session(const SrsRequest& req, const SrsSdp& remote_sdp, SrsSdp& local_sdp);
    bool insert_into_id_sessions(const std::string& peer_id, SrsRtcSession* rtc_session);
    void check_and_clean_timeout_session();
private:
    srs_error_t on_stun(SrsUdpMuxSocket* udp_mux_skt);
    srs_error_t on_dtls(SrsUdpMuxSocket* udp_mux_skt);
    srs_error_t on_rtp_or_rtcp(SrsUdpMuxSocket* udp_mux_skt);
private:
    SrsRtcSession* find_rtc_session_by_username(const std::string& ufrag);
    SrsRtcSession* find_rtc_session_by_peer_id(const std::string& peer_id);
// interface ISrsHourGlass
public:
    virtual srs_error_t notify(int type, srs_utime_t interval, srs_utime_t tick);
};

// The RTC server adapter.
class RtcServerAdapter : public ISrsHybridServer
{
private:
    SrsRtcServer* rtc;
public:
    RtcServerAdapter();
    virtual ~RtcServerAdapter();
public:
    virtual srs_error_t initialize();
    virtual srs_error_t run();
    virtual void stop();
};

#endif