/*
    Copyright (C) 2019-2021 Doug McLain
    Modified Copyright (C) 2024 Rohith Namboothiri
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/
#ifndef AUDIOENGINE_H
#define AUDIOENGINE_H

#include <QObject>
#if QT_VERSION < QT_VERSION_CHECK(6, 3, 0)
#include <QAudio>
#include <QAudioFormat>
#include <QAudioInput>
#else
#include <QAudioDevice>
#include <QAudioSink>
#include <QAudioSource>
#include <QMediaDevices>
#endif
#include <QAudioOutput>
#include <QQueue>


#define AUDIO_OUT 1
#define AUDIO_IN  0

class AudioEngine : public QObject
{
    Q_OBJECT
public:
    //explicit AudioEngine(QObject *parent = nullptr);
    AudioEngine(QString in, QString out);
    ~AudioEngine();
    QStringList discover_audio_devices(uint8_t d);
    void init();
    void start_capture();
    void stop_capture();
    void start_playback();
    void stop_playback();
    void write(int16_t *, size_t);
    void set_output_buffer_size(uint32_t b) { m_out->setBufferSize(b); }
    void set_input_buffer_size(uint32_t b) { if(m_in != nullptr) m_in->setBufferSize(b); }
    void set_output_volume(qreal v){ m_out->setVolume(v); }
    void set_input_volume(qreal v){ if(m_in != nullptr) m_in->setVolume(v); }
    void set_agc(bool agc) { m_agc = agc; }
    bool frame_available() { return (m_audioinq.size() >= 320) ? true : false; }
    uint16_t read(int16_t *, int);
    uint16_t read(int16_t *);
    uint16_t level() { return m_maxlevel; }
    bool shouldResumePlayback();
    bool shouldRestartPlayback();
    bool m_dataWritten;
    void setOutputDevice(const QString &deviceName);
    void setInputDevice(const QString &deviceName);
    QString getFriendlyName(const QString& deviceIdentifier);
    QString mapFriendlyNameToDevice(const QString &friendlyName);
    //QStringList devices = audioEngine->discover_audio_devices(1);

signals:
    void audioDeviceListChanged();
    void audioEngineChanged();

private:
    QString m_outputdevice;
    QString m_inputdevice;
#if QT_VERSION < QT_VERSION_CHECK(6, 3, 0)
    QAudioOutput *m_out;
    QAudioInput *m_in;
#else
    QAudioSink *m_out;
    QAudioSource *m_in;
#endif
    QIODevice *m_outdev;
    QIODevice *m_indev;
    QQueue<int16_t> m_audioinq;
    uint16_t m_maxlevel;
    bool m_agc;
    float m_srm; // sample rate multiplier for macOS HACK

    // Audio IO rates
    int m_captureDeviceRate { 8000 };
    int m_playbackDeviceRate { 8000 };

    // Capture resampling state: deviceRate -> 8000 Hz (mono)
    qint64 m_capStreamIndex { -1 };
    double m_capNextOutPos { 0.0 }; // in input-sample index units
    float m_capPrevSample { 0.0f };

    // Playback resampling state: 8000 Hz -> deviceRate (mono)
    qint64 m_playStreamIndex { -1 };
    double m_playNextOutPos { 0.0 }; // in input-sample index units (8 kHz domain)
    float m_playPrevSample { 0.0f };

    // Simple capture low-pass (to reduce aliasing before downsampling)
    struct Biquad {
        float b0 { 1.0f }, b1 { 0.0f }, b2 { 0.0f };
        float a1 { 0.0f }, a2 { 0.0f };
        float z1 { 0.0f }, z2 { 0.0f };
    };
    Biquad m_capLowpass;

    static Biquad makeLowpassBiquad(float fs, float fc, float Q);
    static float biquadProcess(Biquad &bq, float x);

    float m_audio_out_temp_buf[320];   //!< output of decoder
    float *m_audio_out_temp_buf_p;

    //float m_audio_out_float_buf[1120]; //!< output of upsampler - 1 frame of 160 samples upampled up to 7 times
    //float *m_audio_out_float_buf_p;

    float m_aout_max_buf[200];
    float *m_aout_max_buf_p;
    int m_aout_max_buf_idx;

    //short m_audio_out_buf[2*48000];    //!< final result - 1s of L+R S16LE samples
    //short *m_audio_out_buf_p;
    //int   m_audio_out_nb_samples;
    //int   m_audio_out_buf_size;
    //int   m_audio_out_idx;
    //int   m_audio_out_idx2;

    float m_aout_gain;
    float m_volume;

private slots:
    void input_data_received();
    void process_audio(int16_t *pcm, size_t s);
    void handleStateChanged(QAudio::State newState);
};

#endif // AUDIOENGINE_H