#include "voicerecorder.h"

#include <QAudioDeviceInfo>
#include <QAudioInput>
#include <QDateTime>
#include <QDebug>
#include <QDir>
#include <QFile>
#include <QIODevice>
#include <QStandardPaths>
#include <QTimer>

#include "settings.h"

namespace {

void append16(QByteArray &b, quint16 v)
{
    b.append(char(v & 0xff));
    b.append(char((v >> 8) & 0xff));
}

void append32(QByteArray &b, quint32 v)
{
    b.append(char(v & 0xff));
    b.append(char((v >> 8) & 0xff));
    b.append(char((v >> 16) & 0xff));
    b.append(char((v >> 24) & 0xff));
}

// Picco (valore assoluto massimo) dei campioni 16 bit little-endian del blocco.
int peakOf(const QByteArray &chunk)
{
    int peak = 0;
    const char *d = chunk.constData();
    const int n = chunk.size() - (chunk.size() % 2);
    for (int i = 0; i < n; i += 2) {
        const qint16 s = qint16(quint8(d[i]) | (quint8(d[i + 1]) << 8));
        const int v = qAbs(int(s));
        if (v > peak)
            peak = v;
    }
    return peak;
}

} // namespace

VoiceRecorder::VoiceRecorder(Settings *settings, QObject *parent)
    : QObject(parent)
    , m_settings(settings)
    , m_input(nullptr)
    , m_device(nullptr)
    , m_silenceTimer(new QTimer(this))
    , m_lastVoiceMs(0)
    , m_lastLevelEmitMs(0)
    , m_hasVoice(false)
    , m_active(false)
    , m_level(0.0)
{
    m_silenceTimer->setInterval(150);
    connect(m_silenceTimer, &QTimer::timeout, this, &VoiceRecorder::onSilenceCheck);
}

void VoiceRecorder::start()
{
    if (m_active)
        return;

    const QAudioDeviceInfo info = QAudioDeviceInfo::defaultInputDevice();
    if (info.isNull()) {
        emit failed(tr("No audio input device"));
        return;
    }

    // PCM 16 bit mono: 16 kHz di solito basta per la voce; altrimenti si
    // ripiega su frequenze piu' comuni mantenendo il 16 bit mono.
    QAudioFormat format;
    format.setChannelCount(1);
    format.setSampleSize(16);
    format.setCodec(QStringLiteral("audio/pcm"));
    format.setByteOrder(QAudioFormat::LittleEndian);
    format.setSampleType(QAudioFormat::SignedInt);

    const int rates[] = { 16000, 48000, 44100, 32000, 8000 };
    bool found = false;
    for (unsigned i = 0; i < sizeof(rates) / sizeof(rates[0]); ++i) {
        format.setSampleRate(rates[i]);
        if (info.isFormatSupported(format)) {
            found = true;
            break;
        }
    }
    if (!found) {
        emit failed(tr("Audio input format not supported"));
        return;
    }

    m_format = format;
    m_pcm.clear();
    m_hasVoice = false;
    m_level = 0.0;
    m_lastVoiceMs = 0;
    m_lastLevelEmitMs = 0;

    m_input = new QAudioInput(info, m_format, this);
    m_device = m_input->start();
    if (!m_device) {
        delete m_input;
        m_input = nullptr;
        emit failed(tr("Could not start audio capture"));
        return;
    }
    connect(m_device, &QIODevice::readyRead, this, &VoiceRecorder::onReadyRead);

    m_elapsed.start();
    m_active = true;
    emit activeChanged();
    emit levelChanged();
    emit listening();
    qDebug() << "[voice] ascolto avviato:" << m_format.sampleRate() << "Hz mono 16 bit";
    m_silenceTimer->start();
}

void VoiceRecorder::stop()
{
    if (!m_active)
        return;
    finalize();
}

void VoiceRecorder::onReadyRead()
{
    if (!m_device)
        return;
    const QByteArray chunk = m_device->readAll();
    if (chunk.isEmpty())
        return;
    m_pcm.append(chunk);

    const int peak = peakOf(chunk);
    const qint64 elapsed = m_elapsed.elapsed();
    if (peak > m_settings->vadThreshold()) {
        m_lastVoiceMs = elapsed;
        m_hasVoice = true;
    }

    if (elapsed - m_lastLevelEmitMs >= 150) {
        m_lastLevelEmitMs = elapsed;
        m_level = qreal(peak) / 32768.0;
        emit levelChanged();
    }
}

void VoiceRecorder::onSilenceCheck()
{
    if (!m_active)
        return;
    const qint64 elapsed = m_elapsed.elapsed();

    // Nessuna voce dopo 12 s: la cattura viene scartata (failed "no-speech").
    if (!m_hasVoice && elapsed >= 12000) {
        qDebug() << "[voice] nessuna voce rilevata, stop";
        finalize();
        return;
    }

    // Stop automatico: almeno un frammento di voce udito e pausa oltre soglia.
    if (m_hasVoice
            && elapsed - m_lastVoiceMs >= qint64(m_settings->vadSilenceMs())
            && elapsed >= 800) {
        qDebug() << "[voice] stop automatico: pausa di" << (elapsed - m_lastVoiceMs)
                 << "ms dopo voce a" << m_lastVoiceMs << "ms";
        finalize();
        return;
    }

    // Tetto di sicurezza anti-registrazione infinita.
    if (elapsed >= 60000) {
        qDebug() << "[voice] stop automatico: durata massima raggiunta";
        finalize();
    }
}

void VoiceRecorder::finalize()
{
    m_silenceTimer->stop();

    if (m_device) {
        m_pcm.append(m_device->readAll());
        m_device = nullptr;
    }
    if (m_input) {
        m_input->stop();
        m_input->deleteLater();
        m_input = nullptr;
    }

    m_active = false;
    m_level = 0.0;
    emit activeChanged();
    emit levelChanged();

    if (!m_hasVoice) {
        m_pcm.clear();
        emit failed(QStringLiteral("no-speech"));
        return;
    }

    const QString path = makeWavPath();
    const int bytes = m_pcm.size();
    if (!writeWav(path)) {
        m_pcm.clear();
        emit failed(tr("Could not write the audio file"));
        return;
    }
    m_pcm.clear();
    qDebug() << "[voice] WAV pronto:" << path << bytes << "byte";
    emit finished(path);
}

QString VoiceRecorder::makeWavPath() const
{
    const QString dir = QStandardPaths::writableLocation(QStandardPaths::AppDataLocation)
            + QStringLiteral("/voice");
    QDir().mkpath(dir);
    return dir + QStringLiteral("/v_")
            + QString::number(QDateTime::currentMSecsSinceEpoch())
            + QStringLiteral(".wav");
}

bool VoiceRecorder::writeWav(const QString &path)
{
    QFile f(path);
    if (!f.open(QIODevice::WriteOnly))
        return false;

    const quint16 channels = quint16(m_format.channelCount());
    const quint32 sampleRate = quint32(m_format.sampleRate());
    const quint16 bits = quint16(m_format.sampleSize());
    const quint32 dataSize = quint32(m_pcm.size());
    const quint32 byteRate = sampleRate * channels * bits / 8;
    const quint16 blockAlign = quint16(channels * bits / 8);

    QByteArray header;
    header.reserve(44);
    header.append("RIFF");
    append32(header, 36 + dataSize);
    header.append("WAVE");
    header.append("fmt ");
    append32(header, 16);
    append16(header, 1); // PCM
    append16(header, channels);
    append32(header, sampleRate);
    append32(header, byteRate);
    append16(header, blockAlign);
    append16(header, bits);
    header.append("data");
    append32(header, dataSize);

    f.write(header);
    f.write(m_pcm);
    f.close();
    return true;
}