#pragma once

#include <QObject>
#include <QImage>
#include <QString>
#include <QTimer>
#include <QElapsedTimer>
#include <QAtomicInt>
#include <QAtomicInteger>
#include <deque>
#include <vector>
#include <memory>
#include <utility>
#include <cstdint>

class QThread;

/* Плеер видео на FFmpeg (GUI-процесс). Декод в отдельном потоке,
 * отрисовка кадров по мастер-часам (аудио-курсор или системный таймер). */
class VideoPlayerEngine : public QObject {
    Q_OBJECT
public:
    enum State { Stopped = 0, Playing = 1, Paused = 2, Finished = 3 };

    explicit VideoPlayerEngine(QObject* parent = nullptr);
    ~VideoPlayerEngine() override;

    void open(const QString& path);
    void play();
    void pause();
    void togglePlayPause();
    void seekMs(qint64 ms);
    void stop();
    void close();

    State state() const { return m_state; }
    qint64 durationMs() const { return m_durationMs; }
    qint64 positionMs() const { return m_positionMs; }
    bool hasAudio() const { return m_hasAudio; }
    int videoWidth() const { return m_videoWidth; }
    int videoHeight() const { return m_videoHeight; }
    QString filePath() const { return m_path; }
    QImage currentFrame() const { return m_renderFrame; }

signals:
    void opened(int width, int height, qint64 durationMs, bool hasAudio);
    void positionChanged(qint64 ms);
    void stateChanged(int state);
    void finished();
    void error(const QString& msg);
    void framePresented();

private slots:
    void onWorkerOpened(int width, int height, qint64 durationMs, bool hasAudio);
    void onAudioDecoded(std::shared_ptr<std::vector<int16_t>> pcm, int sampleRate, int channels, qint64 durationMs);
    void onFrameDecoded(const QImage& image, qint64 ptsMs, int epoch);
    void onWorkerError(const QString& msg);
    void onWorkerFinished();
    void presentTick();

private:
    void setState(State s);
    qint64 clockMs() const;
    void clearPending();

    QString m_path;
    QThread* m_thread = nullptr;
    class Worker* m_worker = nullptr;

    State m_state = Stopped;
    qint64 m_durationMs = 0;
    qint64 m_positionMs = 0;
    bool m_hasAudio = false;
    int m_videoWidth = 0;
    int m_videoHeight = 0;

    /* управление worker'ом (атомики, доступны из обоих потоков) */
    QAtomicInt m_abort{0};
    QAtomicInt m_paused{0};
    QAtomicInt m_seekReq{0};
    QAtomicInteger<qint64> m_seekTargetMs{0};
    QAtomicInt m_buffered{0};
    QAtomicInt m_epoch{0};

    /* презентация (только GUI-поток) */
    std::deque<std::pair<QImage, qint64>> m_pending;
    QImage m_renderFrame;
    QTimer m_presentTimer;
    int m_audioSampleRate = 0;
    QElapsedTimer m_elapsed;
    qint64 m_elapsedBaseMs = 0;
};