/*
streamer-tools OBS Camera Plugin - session wrapper tests
Copyright (C) 2026 CyberCoveLLC <jknapp85@gmail.com>

Licensed 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
*/

// What is and is not covered here, stated plainly because it matters:
//
//   COVERED headlessly -- the session's own decision-making: the state
//   machine's transitions (including the publisher-swap and reconnect paths
//   that motivated this plugin), track selection, frame geometry validation,
//   the stall-recovery watchdog's timing/backoff decisions (StallWatchdog,
//   driven with a fake clock -- see its own section below), and the real
//   connect() failure paths against the real SDK (bad URL, unreachable
//   host, garbage token).
//
//   NOT COVERED here -- anything that needs a LiveKit server to answer:
//   a successful connect, actual subscription, and actual decoded frames
//   reaching the handlers. Those can only be verified against a real room,
//   and the design doc's Testing section puts that in the integration-test /
//   manual-sign-off bucket.

#include <atomic>
#include <chrono>
#include <string>
#include <thread>

#include "stplugin/session.h"
#include "stplugin/session_types.h"
#include "test_util.h"

using namespace stplugin;

namespace {

// ---------------------------------------------------------------------------
// Pure logic
// ---------------------------------------------------------------------------

void testFrameGeometry()
{
    ST_ASSERT_EQ(planeCount(PixelFormat::I420), 3);
    ST_ASSERT_EQ(planeCount(PixelFormat::NV12), 2);
    ST_ASSERT_EQ(planeCount(PixelFormat::BGRA), 1);

    // 1280x720 I420: 921600 luma + 2 * 230400 chroma.
    ST_ASSERT_EQ(expectedFrameBytes(PixelFormat::I420, 1280, 720), std::size_t(1382400));
    ST_ASSERT_EQ(expectedFrameBytes(PixelFormat::NV12, 1280, 720), std::size_t(1382400));
    ST_ASSERT_EQ(expectedFrameBytes(PixelFormat::BGRA, 1280, 720), std::size_t(3686400));

    // Odd dimensions round the chroma planes up, the way libyuv does.
    ST_ASSERT_EQ(expectedFrameBytes(PixelFormat::I420, 3, 3), std::size_t(9 + 2 * 4));
    ST_ASSERT_EQ(expectedFrameBytes(PixelFormat::I420, 1, 1), std::size_t(1 + 2));

    // Degenerate geometry is 0, which the reader treats as "drop the frame".
    ST_ASSERT_EQ(expectedFrameBytes(PixelFormat::I420, 0, 720), std::size_t(0));
    ST_ASSERT_EQ(expectedFrameBytes(PixelFormat::I420, 1280, 0), std::size_t(0));
    ST_ASSERT_EQ(expectedFrameBytes(PixelFormat::I420, -1, -1), std::size_t(0));

    ST_ASSERT_EQ(std::string(describePixelFormat(PixelFormat::I420)), std::string("I420"));
}

void testTrackSelection()
{
    const std::string want = "cam1";

    // The camera we asked for.
    ST_ASSERT(isWantedVideoTrack(want, "cam1", MediaKind::Video, MediaSource::Camera));
    // A video track with no declared source is taken on kind alone.
    ST_ASSERT(isWantedVideoTrack(want, "cam1", MediaKind::Video, MediaSource::Unknown));

    // Someone else's camera.
    ST_ASSERT(!isWantedVideoTrack(want, "cam2", MediaKind::Video, MediaSource::Camera));
    // The right participant's screenshare is explicitly NOT the camera --
    // streamer-tools publishes those as separate sources.
    ST_ASSERT(!isWantedVideoTrack(want, "cam1", MediaKind::Video, MediaSource::Screenshare));
    // Their microphone is not a video track.
    ST_ASSERT(!isWantedVideoTrack(want, "cam1", MediaKind::Audio, MediaSource::Microphone));
    // No selection means nothing matches -- never "the first thing we see".
    ST_ASSERT(!isWantedVideoTrack("", "cam1", MediaKind::Video, MediaSource::Camera));
    ST_ASSERT(!isWantedVideoTrack("", "", MediaKind::Video, MediaSource::Camera));

    ST_ASSERT(isWantedAudioTrack(want, "cam1", MediaKind::Audio, MediaSource::Microphone));
    ST_ASSERT(isWantedAudioTrack(want, "cam1", MediaKind::Audio, MediaSource::Unknown));
    ST_ASSERT(!isWantedAudioTrack(want, "cam1", MediaKind::Audio, MediaSource::ScreenshareAudio));
    ST_ASSERT(!isWantedAudioTrack(want, "cam1", MediaKind::Video, MediaSource::Camera));
    ST_ASSERT(!isWantedAudioTrack(want, "other", MediaKind::Audio, MediaSource::Microphone));
}

void testStateMachineHappyPath()
{
    SessionStateMachine m;
    ST_ASSERT(m.state() == SessionState::Idle);
    ST_ASSERT(!m.hasVideo());
    ST_ASSERT(!m.waitingForCamera());

    m.onConnectRequested();
    ST_ASSERT(m.state() == SessionState::Connecting);
    // Connecting is not "waiting for camera": the placeholder belongs to a
    // live connection with a dark slot, not to a connection in progress.
    ST_ASSERT(!m.waitingForCamera());

    m.onConnectSucceeded();
    ST_ASSERT(m.state() == SessionState::Connected);
    ST_ASSERT(m.waitingForCamera());

    m.onVideoAttached();
    ST_ASSERT(m.hasVideo());
    ST_ASSERT(!m.waitingForCamera());

    m.onAudioAttached();
    ST_ASSERT(m.hasAudio());

    m.onLocalDisconnect();
    ST_ASSERT(m.state() == SessionState::Disconnected);
    ST_ASSERT(!m.hasVideo());
    ST_ASSERT(!m.hasAudio());
}

void testPublisherSwapIsNotAnError()
{
    // The motivating bug: a slot's publisher restarts mid-show. That must
    // read as "waiting for camera", never as a failure, and the connection
    // state must not move at all.
    SessionStateMachine m;
    m.onConnectRequested();
    m.onConnectSucceeded();
    m.onVideoAttached();

    m.onVideoDetached();
    ST_ASSERT(m.state() == SessionState::Connected);
    ST_ASSERT(!m.hasVideo());
    ST_ASSERT(m.waitingForCamera());
    ST_ASSERT(m.detail().empty());

    m.onVideoAttached();
    ST_ASSERT(m.state() == SessionState::Connected);
    ST_ASSERT(m.hasVideo());
    ST_ASSERT(!m.waitingForCamera());
}

void testReconnect()
{
    SessionStateMachine m;
    m.onConnectRequested();
    m.onConnectSucceeded();
    m.onVideoAttached();

    m.onReconnecting();
    ST_ASSERT(m.state() == SessionState::Reconnecting);
    // Tracks are re-subscribed on the far side, so video is not live yet.
    ST_ASSERT(!m.hasVideo());
    ST_ASSERT(m.waitingForCamera());
    ST_ASSERT_EQ(m.detail(), std::string("reconnecting"));

    m.onReconnected();
    ST_ASSERT(m.state() == SessionState::Connected);
    ST_ASSERT(m.detail().empty());

    // A stray reconnect notification after a hard failure must not resurrect
    // the session.
    SessionStateMachine dead;
    dead.onConnectRequested();
    dead.onConnectFailed("token rejected");
    dead.onReconnecting();
    ST_ASSERT(dead.state() == SessionState::Failed);
    dead.onReconnected();
    ST_ASSERT(dead.state() == SessionState::Failed);
}

void testFailureAndRecovery()
{
    SessionStateMachine m;
    m.onConnectRequested();
    m.onConnectFailed("token rejected");
    ST_ASSERT(m.state() == SessionState::Failed);
    ST_ASSERT_EQ(m.detail(), std::string("token rejected"));
    ST_ASSERT(!m.waitingForCamera());

    // A fresh attempt clears the stale reason, so a healthy connection can
    // never be shown next to the previous failure's message.
    m.onConnectRequested();
    ST_ASSERT(m.detail().empty());
    m.onConnectSucceeded();
    ST_ASSERT(m.state() == SessionState::Connected);
    ST_ASSERT(m.detail().empty());

    // A fatal room end (duplicate identity, token rejected) is Failed; an
    // ordinary drop is Disconnected.
    SessionStateMachine fatal;
    fatal.onConnectRequested();
    fatal.onConnectSucceeded();
    fatal.onRoomEnded("another client joined with the same identity", true);
    ST_ASSERT(fatal.state() == SessionState::Failed);

    SessionStateMachine dropped;
    dropped.onConnectRequested();
    dropped.onConnectSucceeded();
    dropped.onRoomEnded("the signalling connection closed", false);
    ST_ASSERT(dropped.state() == SessionState::Disconnected);

    // Room-ended events after we are already down are ignored, so a late
    // event cannot overwrite the reason the operator needs to see.
    SessionStateMachine idle;
    idle.onRoomEnded("stray", true);
    ST_ASSERT(idle.state() == SessionState::Idle);
}

// ---------------------------------------------------------------------------
// StallWatchdog -- the stall-recovery watchdog's pure timing/decision logic.
//
// This is deliberately driven with an explicit, fake clock (arbitrary
// steady_clock::time_points built by hand, never std::chrono::...::now())
// rather than real sleeps: every case below needs to be exact about
// "1999ms in" vs "2001ms in" and about backoff boundaries, and a test that
// actually slept for 30+ seconds to exercise the backoff ceiling would be
// exactly the kind of slow, flaky test this project's whole headless-test
// philosophy exists to avoid. See StallWatchdog's own comment
// (session_types.h) for the measured server evidence this exists to fix.
// ---------------------------------------------------------------------------

void testStallWatchdogFiresAfterThreshold()
{
    const auto t0 = std::chrono::steady_clock::now();
    StallWatchdog w(std::chrono::milliseconds(2000), std::chrono::milliseconds(30000));

    // Nothing subscribed yet: polling is a no-op, no matter how much time
    // has "passed" -- an audio-only source or a disconnected session must
    // never fire.
    ST_ASSERT(!w.poll(t0 + std::chrono::milliseconds(10000)));

    // A track becomes subscribed. Still well under the threshold: quiet.
    w.setExpectingFrames(true, t0);
    ST_ASSERT(!w.poll(t0 + std::chrono::milliseconds(500)));
    ST_ASSERT(!w.poll(t0 + std::chrono::milliseconds(1999)));

    // No frame ever arrived, and the threshold has now elapsed: fires
    // exactly once when asked right at/after the boundary.
    ST_ASSERT(w.poll(t0 + std::chrono::milliseconds(2000)));
    ST_ASSERT_EQ(w.attemptsThisStall(), 1);

    // A frame arriving resets the clock -- the far more common case in a
    // healthy stream, where onFrameDelivered() is called every ~33ms and
    // poll() (every kWatchdogPollInterval) never sees 2000ms of silence.
    StallWatchdog healthy(std::chrono::milliseconds(2000), std::chrono::milliseconds(30000));
    healthy.setExpectingFrames(true, t0);
    for (int ms = 0; ms <= 5000; ms += 33)
        healthy.onFrameDelivered(t0 + std::chrono::milliseconds(ms));
    ST_ASSERT(!healthy.poll(t0 + std::chrono::milliseconds(5010)));
    ST_ASSERT_EQ(healthy.attemptsThisStall(), 0);
}

void testStallWatchdogDoesNotFireWhenNotExpectingFrames()
{
    const auto t0 = std::chrono::steady_clock::now();
    StallWatchdog w(std::chrono::milliseconds(2000), std::chrono::milliseconds(30000));

    // A muted (or disabled/unsubscribed) track is expected silence, not a
    // stall -- setExpectingFrames(false, ...) is exactly what
    // LiveKitSession::Impl::handleMuteChange (and detachVideo()) call in
    // that case. It must not fire no matter how long it stays that way.
    w.setExpectingFrames(false, t0);
    ST_ASSERT(!w.poll(t0 + std::chrono::milliseconds(2000)));
    ST_ASSERT(!w.poll(t0 + std::chrono::milliseconds(60000)));
    ST_ASSERT(!w.poll(t0 + std::chrono::milliseconds(600000)));

    // Un-muting (setExpectingFrames(true, ...)) starts a BRAND NEW grace
    // period from that moment -- it must not read "was silent for ten
    // minutes" as "stalled for ten minutes" and fire immediately.
    const auto unmuted_at = t0 + std::chrono::milliseconds(600000);
    w.setExpectingFrames(true, unmuted_at);
    ST_ASSERT(!w.poll(unmuted_at + std::chrono::milliseconds(1999)));
    ST_ASSERT(w.poll(unmuted_at + std::chrono::milliseconds(2000)));
}

void testStallWatchdogBacksOffRatherThanLooping()
{
    const auto t0 = std::chrono::steady_clock::now();
    StallWatchdog w(std::chrono::milliseconds(2000), std::chrono::milliseconds(30000));
    w.setExpectingFrames(true, t0);

    // First attempt at the threshold.
    auto now = t0 + std::chrono::milliseconds(2000);
    ST_ASSERT(w.poll(now));
    ST_ASSERT_EQ(w.attemptsThisStall(), 1);

    // A genuinely gone publisher: no frame ever comes back. Immediately
    // asking again (the naive "retry every poll interval forever" a
    // watchdog without backoff would do) must NOT fire -- that is precisely
    // the "hammered every 2 seconds forever" this backoff exists to avoid.
    ST_ASSERT(!w.poll(now + std::chrono::milliseconds(250)));
    ST_ASSERT(!w.poll(now + std::chrono::milliseconds(1999)));

    // The backoff after attempt 1 is the base timeout (2000ms): the second
    // attempt is allowed at +2000ms from the first, not before.
    now += std::chrono::milliseconds(2000);
    ST_ASSERT(w.poll(now));
    ST_ASSERT_EQ(w.attemptsThisStall(), 2);

    // Backoff doubles: the third attempt needs a 4000ms gap, not 2000ms.
    ST_ASSERT(!w.poll(now + std::chrono::milliseconds(3999)));
    now += std::chrono::milliseconds(4000);
    ST_ASSERT(w.poll(now));
    ST_ASSERT_EQ(w.attemptsThisStall(), 3);

    // ... and again to 8000ms, and again to 16000ms.
    ST_ASSERT(!w.poll(now + std::chrono::milliseconds(7999)));
    now += std::chrono::milliseconds(8000);
    ST_ASSERT(w.poll(now));
    ST_ASSERT_EQ(w.attemptsThisStall(), 4);

    ST_ASSERT(!w.poll(now + std::chrono::milliseconds(15999)));
    now += std::chrono::milliseconds(16000);
    ST_ASSERT(w.poll(now));
    ST_ASSERT_EQ(w.attemptsThisStall(), 5);

    // The backoff is capped: doubling 16000ms would be 32000ms, but it
    // never exceeds max_backoff (30000ms) no matter how many attempts have
    // failed, so a publisher that comes back after an hour is still
    // retried at a bounded cadence, not abandoned.
    for (int i = 0; i < 6; ++i) {
        ST_ASSERT(!w.poll(now + std::chrono::milliseconds(29999)));
        now += std::chrono::milliseconds(30000);
        ST_ASSERT(w.poll(now));
    }

    // A frame finally arrives: the stall is over, and the NEXT one (a fresh
    // stall, not a continuation) starts back at the base cadence rather
    // than staying parked at the 30s ceiling forever.
    w.onFrameDelivered(now);
    ST_ASSERT_EQ(w.attemptsThisStall(), 0);
    ST_ASSERT(!w.poll(now + std::chrono::milliseconds(1999)));
    ST_ASSERT(w.poll(now + std::chrono::milliseconds(2000)));
    ST_ASSERT_EQ(w.attemptsThisStall(), 1);
}

// ---------------------------------------------------------------------------
// Real SDK, failure paths only (no LiveKit server available headlessly)
// ---------------------------------------------------------------------------

void testConnectRejectsIncompleteConfig()
{
    LiveKitSession session;
    std::atomic<int> state_calls{0};
    session.setStateHandler([&](SessionState, const std::string &) { state_calls.fetch_add(1); });

    SessionConfig config;
    config.ws_url = "";
    config.token = "t";
    config.participant_identity = "cam1";
    ST_ASSERT(!session.connect(config));
    ST_ASSERT(session.state() == SessionState::Failed);
    ST_ASSERT(!session.stateDetail().empty());

    config.ws_url = "ws://127.0.0.1:1";
    config.token = "";
    ST_ASSERT(!session.connect(config));
    ST_ASSERT(session.state() == SessionState::Failed);

    config.token = "t";
    config.participant_identity = "";
    ST_ASSERT(!session.connect(config));
    ST_ASSERT(session.state() == SessionState::Failed);

    // The state handler fired for each attempt (Connecting + Failed).
    ST_ASSERT(state_calls.load() >= 6);

    // Frame counters stay at zero and nothing crashes on teardown.
    ST_ASSERT_EQ(session.videoFrameCount(), std::uint64_t(0));
    ST_ASSERT_EQ(session.audioFrameCount(), std::uint64_t(0));
    session.disconnect();
    session.disconnect(); // idempotent
    ST_ASSERT(session.state() == SessionState::Failed || session.state() == SessionState::Disconnected);
}

void testConnectToUnreachableServerFailsCleanly()
{
    // Port 1 on loopback: nothing is listening, and the connection is
    // refused immediately rather than hanging. This exercises the real
    // livekit::Room::connect() failure path, with a real (garbage) token.
    LiveKitSession session;
    std::atomic<int> video_frames{0};
    session.setVideoHandler([&](const VideoFrameData &) { video_frames.fetch_add(1); });

    SessionConfig config;
    config.ws_url = "ws://127.0.0.1:1";
    config.token = "not.a.real.token";
    config.participant_identity = "cam1";
    config.connect_timeout_ms = 3000;

    const auto start = std::chrono::steady_clock::now();
    const bool ok = session.connect(config);
    const auto elapsed = std::chrono::steady_clock::now() - start;

    ST_ASSERT(!ok);
    ST_ASSERT(session.state() == SessionState::Failed);
    ST_ASSERT(!session.stateDetail().empty());
    ST_ASSERT_EQ(video_frames.load(), 0);
    // Must not sit on the caller's thread indefinitely -- this runs on an OBS
    // thread in the real adapter.
    ST_ASSERT(std::chrono::duration_cast<std::chrono::seconds>(elapsed).count() < 60);

    session.disconnect();
}

void testConnectToNonLiveKitServerFailsCleanly()
{
    // A URL that resolves and connects but is not a LiveKit signalling
    // endpoint. The realistic operator mistake: pasting the app URL.
    LiveKitSession session;
    SessionConfig config;
    config.ws_url = "ws://127.0.0.1:1/rtc";
    config.token = "eyJhbGciOiJIUzI1NiJ9.bm90YXRva2Vu.x";
    config.participant_identity = "cam1";
    config.connect_timeout_ms = 3000;
    ST_ASSERT(!session.connect(config));
    ST_ASSERT(session.state() == SessionState::Failed);
    session.disconnect();
}

void testDestroyWithoutDisconnect()
{
    // The OBS adapter destroys sources without necessarily having called
    // disconnect() first (an OBS shutdown mid-connect, say). The destructor
    // must join every thread it started rather than terminating.
    {
        LiveKitSession session;
        SessionConfig config;
        config.ws_url = "ws://127.0.0.1:1";
        config.token = "t";
        config.participant_identity = "cam1";
        config.connect_timeout_ms = 2000;
        (void)session.connect(config);
    }
    ST_ASSERT(true); // reaching here at all is the assertion
}

void testGlobalInitIsReferenceCounted()
{
    // Several OBS sources may each hold the SDK open; the last one out turns
    // the lights off, and an unbalanced extra shutdown must not underflow.
    LiveKitSession::globalInitialize();
    LiveKitSession::globalInitialize();
    LiveKitSession::globalShutdown();
    LiveKitSession::globalShutdown();
    LiveKitSession::globalShutdown(); // extra, must be harmless
    LiveKitSession::globalInitialize();
    LiveKitSession::globalShutdown();
    ST_ASSERT(true);
}

} // namespace

int main()
{
    testFrameGeometry();
    testTrackSelection();
    testStateMachineHappyPath();
    testPublisherSwapIsNotAnError();
    testReconnect();
    testFailureAndRecovery();

    testStallWatchdogFiresAfterThreshold();
    testStallWatchdogDoesNotFireWhenNotExpectingFrames();
    testStallWatchdogBacksOffRatherThanLooping();

    LiveKitSession::globalInitialize();
    testConnectRejectsIncompleteConfig();
    testConnectToUnreachableServerFailsCleanly();
    testConnectToNonLiveKitServerFailsCleanly();
    testDestroyWithoutDisconnect();
    LiveKitSession::globalShutdown();

    testGlobalInitIsReferenceCounted();

    return st_test_report("session");
}