// src/Services/WhipClient.h
#pragma once
#define CPPHTTPLIB_OPENSSL_SUPPORT
#include <memory>
#include <string>
#include <string_view>
#include <atomic>
#include <mutex>
#include <optional>
#include <filesystem>
#include <vector>
#include <regex>
#include <array>
#include <random>
#include <cstdint>
#include <cstring>

#include <spdlog/spdlog.h>
#include <nlohmann/json.hpp>
#include <httplib.h> // build with CPPHTTPLIB_OPENSSL_SUPPORT

#include <rtc/rtc.hpp>
#include <rtc/peerconnection.hpp>
#include <rtc/description.hpp>
#include <rtc/track.hpp>

namespace snoop
{

    class WhipClient
    {
    public:
        struct Params
        {
            std::string whipUrl; // full WHIP endpoint (may include ?token=...)
            std::string caPath;  // CA chain
            std::string crtPath; // client cert
            std::string keyPath; // client key (temp extracted from keyctl)
            int sampleRate = 48000;
            int channels = 1; // 1 or 2; timestamp advance uses PCM frames per channel
        };

        explicit WhipClient(Params p) : m_p(std::move(p)) {}

        ~WhipClient() { Stop(); }

        void Start()
        {
            std::lock_guard lk(m_mtx);
            if (m_started)
                return;

            rtc::Configuration cfg;
            m_pc = std::make_shared<rtc::PeerConnection>(cfg);

            m_pc->onStateChange([this](rtc::PeerConnection::State s)
                                { spdlog::info("WHIP pc state: {}", (int)s); });
            m_pc->onGatheringStateChange([this](rtc::PeerConnection::GatheringState s)
                                         { spdlog::info("WHIP gathering state: {}", (int)s); });
            m_pc->onLocalDescription([this](rtc::Description desc)
                                     {
            try {
                const std::string offer = std::string(desc);
                auto [answer, resourceUrl] = PostOfferWHIP(offer);
                m_resourceUrl = resourceUrl;
                m_pc->setRemoteDescription(rtc::Description(answer, "answer"));
                spdlog::info("WHIP remote description set");
            } catch (const std::exception& e) {
                spdlog::error("WHIP POST offer failed: {}", e.what());
            } });
            m_pc->onLocalCandidate([this](rtc::Candidate c)
                                   {
            if (!m_resourceUrl) return;
            try { PatchCandidateWHIP(c); }
            catch (const std::exception& e) { spdlog::warn("WHIP PATCH candidate failed: {}", e.what()); } });

            // Create a sendonly audio track
            rtc::Description::Audio audioDesc("audio", rtc::Description::Direction::SendOnly);
            // Opus PT typically negotiated to 111 by browsers; we'll use 111 in RTP header
            m_track = m_pc->addTrack(audioDesc);

            // Initialize RTP state (random SSRC/seq)
            std::mt19937 rng{std::random_device{}()};
            m_ssrc = std::uniform_int_distribution<uint32_t>()(rng);
            m_seq = std::uniform_int_distribution<uint16_t>()(rng);
            m_ts = 0; // RTP clock for Opus is 48kHz

            // Create SDP offer (triggers onLocalDescription)
            m_pc->setLocalDescription();

            m_started = true;
        }

        void Stop()
        {
            std::lock_guard lk(m_mtx);
            if (!m_started)
                return;

            m_track.reset();
            m_pc.reset();

            m_resourceUrl.reset();
            m_started = false;
        }

        // Call this from your Opus encoder callback.
        // opusData: encoded Opus frame bytes
        // opusBytes: length
        // pcmFramesPerChannel: number of PCM samples per channel represented by this Opus frame (e.g., 960 for 20ms @48k).
        void PushOpus(const unsigned char *opusData, size_t opusBytes, int pcmFramesPerChannel)
        {
            std::lock_guard lk(m_mtx);
            if (!m_track || !m_started)
                return;

            // Build RTP header (12 bytes)
            std::array<uint8_t, 12> rtp{};
            rtp[0] = 0x80;                 // V=2, P=0, X=0, CC=0
            rtp[1] = 0x80 | (m_pt & 0x7F); // M=1 (end of frame), PT
            rtp[2] = uint8_t(m_seq >> 8);
            rtp[3] = uint8_t(m_seq & 0xFF);
            rtp[4] = uint8_t(m_ts >> 24);
            rtp[5] = uint8_t((m_ts >> 16) & 0xFF);
            rtp[6] = uint8_t((m_ts >> 8) & 0xFF);
            rtp[7] = uint8_t(m_ts & 0xFF);
            rtp[8] = uint8_t(m_ssrc >> 24);
            rtp[9] = uint8_t((m_ssrc >> 16) & 0xFF);
            rtp[10] = uint8_t((m_ssrc >> 8) & 0xFF);
            rtp[11] = uint8_t(m_ssrc & 0xFF);

            // Concatenate header + payload
            rtc::binary packet;
            packet.resize(rtp.size() + opusBytes);
            std::memcpy(packet.data(), rtp.data(), rtp.size());
            std::memcpy(packet.data() + rtp.size(), opusData, opusBytes);

            // Send RTP on the media track
            m_track->send(packet); // libdatachannel expects RTP bytes on tracks

            // Advance RTP state
            ++m_seq;
            // For Opus @ 48k clock, timestamp increments by the PCM frame count per channel
            // (do not multiply by channels)
            m_ts += static_cast<uint32_t>(pcmFramesPerChannel);
        }

    private:
        Params m_p;
        std::shared_ptr<rtc::PeerConnection> m_pc;
        std::shared_ptr<rtc::Track> m_track;
        std::optional<std::string> m_resourceUrl;
        std::mutex m_mtx;
        std::atomic<bool> m_started{false};

        // RTP state
        uint32_t m_ssrc = 0;
        uint16_t m_seq = 0;
        uint32_t m_ts = 0;
        uint8_t m_pt = 111; // dynamic payload type commonly used for Opus

        // --- WHIP HTTP helpers (mTLS-capable) ---

        static std::tuple<std::string, std::string> ExtractAnswerAndLocation(const httplib::Result &r)
        {
            if (!r)
                throw std::runtime_error("No HTTP result");
            if (r->status != 201 && r->status != 200)
                throw std::runtime_error("Unexpected WHIP status: " + std::to_string(r->status));
            std::string answer = r->body;
            std::string resourceUrl;
            if (r->has_header("Location"))
                resourceUrl = r->get_header_value("Location");
            return {answer, resourceUrl};
        }

        std::pair<std::string, std::string> PostOfferWHIP(const std::string &sdpOffer)
        {
            auto [cli, path] = MakeClientForUrl(sdpOffer, m_p.whipUrl);
            auto res = cli->Post(path.c_str(), sdpOffer, "application/sdp");
            auto [answer, resUrl] = ExtractAnswerAndLocation(res);
            return {answer, resUrl};
        }

        void PatchCandidateWHIP(const rtc::Candidate &cand)
        {
            if (!m_resourceUrl)
                return;
            auto [cli, path] = MakeClientForUrl(std::string(""), *m_resourceUrl);
            std::string frag = "a=" + std::string(cand);
            auto res = cli->Patch(path.c_str(), frag, "application/trickle-ice-sdpfrag");
            if (!res || (res->status < 200 || res->status >= 300))
            {
                spdlog::warn("WHIP PATCH {} -> {}", path, res ? res->status : -1);
            }
        }

        // Build client + path for URL; uses mTLS when https
        std::pair<std::unique_ptr<httplib::SSLClient>, std::string>
        MakeClientForUrl(const std::string &body, const std::string &url)
        {
            (void)body;
            static const std::regex re(R"(^(https?)://([^/:]+)(?::(\d+))?(/.*)?$)");
            std::smatch m;
            if (!std::regex_match(url, m, re))
                throw std::runtime_error("Invalid URL: " + url);
            std::string scheme = m[1].str();
            std::string host = m[2].str();
            int port = m[3].matched ? std::stoi(m[3].str()) : (scheme == "https" ? 443 : 80);
            std::string path = m[4].matched ? m[4].str() : "/";

            if (scheme == "https")
            {
#ifndef CPPHTTPLIB_OPENSSL_SUPPORT
                throw std::runtime_error("https URL but CPPHTTPLIB_OPENSSL_SUPPORT not enabled");
#else
                auto cli = std::make_unique<httplib::SSLClient>(host.c_str(), port, m_p.crtPath, m_p.keyPath, std::string());
                cli->enable_server_certificate_verification(true);
                cli->set_ca_cert_path(m_p.caPath.c_str());
                cli->set_connection_timeout(10);
                cli->set_read_timeout(60);
                cli->set_write_timeout(60);
                return {std::move(cli), path};
#endif
            }
            // else
            // {
            //     auto cli = std::make_unique<httplib::Client>(host.c_str(), port);
            //     cli->set_connection_timeout(10);
            //     cli->set_read_timeout(60);
            //     cli->set_write_timeout(60);
            //     return {std::move(cli), path};
            // }
        }
    };

} // namespace snoop