/*************************************************************************
         LevelMeter.cpp  -  multi-track audio level meter
                             -------------------
    original copyright   : Copyright 2002 Rik Hemsley (rikkus) <rik@kde.org>

    begin                : Mon Nov 17 2003
    copyright            : (C) 2003 by Thomas Eschenbacher
    email                : Thomas.Eschenbacher@gmx.de
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   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 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#include "config.h"
#include <math.h>

#include <QApplication>
#include <QBrush>
#include <QColor>
#include <QFont>
#include <QImage>
#include <QPainter>
#include <QPixmap>
#include <QTimer>

#include <KLocalizedString>

#include "libkwave/Utils.h"

#include "LevelMeter.h"

/** number of display updates per second */
static const float UPDATES_PER_SECOND = 8.0f;

/** lowpass frequency used for rising the current (fast) value [Hz] */
static const float F_FAST_RISE = (20.0f);

/** lowpass frequency used for decay of the current (fast) value [Hz] */
static const float F_FAST_DECAY = (0.5f);

/** lowpass frequency used for rising the peak values */
static const float F_PEAK_RISE = (F_FAST_RISE);

/** lowpass frequency used for decay of peak values [Hz] */
static const float F_PEAK_DECAY = (0.005f);

//***************************************************************************
Kwave::LevelMeter::LevelMeter(QWidget *parent)
    :QWidget(parent),
    m_tracks(0), m_sample_rate(0), m_yf(), m_yp(),
    m_fast_queue(), m_peak_queue(),
    m_current_fast(), m_current_peak(), m_timer(),
    m_color_low(Qt::green),
    m_color_normal(Qt::yellow),
    m_color_high(Qt::red)
{
    setAttribute(Qt::WA_NoBackground);
    m_timer = new QTimer(this);
    Q_ASSERT(m_timer);
    connect(m_timer, SIGNAL(timeout()),
            this, SLOT(timedUpdate()));
}

//***************************************************************************
Kwave::LevelMeter::~LevelMeter()
{
    setTracks(0);
}

//***************************************************************************
void Kwave::LevelMeter::paintEvent(QPaintEvent *)
{
    drawContents();
}

//***************************************************************************
void Kwave::LevelMeter::resizeEvent(QResizeEvent *)
{
    repaint();
}

//***************************************************************************
void Kwave::LevelMeter::setTracks(unsigned int tracks)
{
    if (Kwave::toInt(tracks) == m_tracks) return;
    m_tracks = tracks;
    reset(); // re-create all arrays etc.
}

//***************************************************************************
void Kwave::LevelMeter::setSampleRate(double rate)
{
    if (qFuzzyCompare(static_cast<float>(rate), m_sample_rate)) return;
    m_sample_rate = static_cast<float>(rate);
}

//***************************************************************************
void Kwave::LevelMeter::updateTrack(unsigned int track,
                                    const Kwave::SampleArray &buffer)
{
    Q_ASSERT(Kwave::toInt(track) < m_tracks);
    if (Kwave::toInt(track) >= m_tracks) return;

    // calculate the number of samples per update (approx)
    const unsigned int samples = buffer.size();
    const unsigned int samples_per_update = Kwave::toUint(
        rint(ceil(m_sample_rate / UPDATES_PER_SECOND)));
    unsigned int next_fraction = samples_per_update;
    const unsigned int queue_depth = ((samples / samples_per_update) + 2);

    /* fast update: rise */
    float Fg = F_FAST_RISE / m_sample_rate;
    float n = 1.0f / tanf(float(M_PI) * Fg);
    const float a0_fr = 1.0f / (1.0f + n);
    const float b1_fr = (1.0f - n) / (1.0f + n);

    /* fast update: decay */
    Fg = F_FAST_DECAY / m_sample_rate;
    n = 1.0f / tanf(float(M_PI) * Fg);
    const float a0_fd = 1.0f / (1.0f + n);
    const float b1_fd = (1.0f - n) / (1.0f + n);

    /* peak value: rise */
    Fg = F_PEAK_RISE / m_sample_rate;
    n = 1.0f / tanf(float(M_PI) * Fg);
    const float a0_pr = 1.0f / (1.0f + n);
    const float b1_pr = (1.0f - n) / (1.0f + n);

    /* peak value: decay */
    Fg = F_PEAK_DECAY / m_sample_rate;
    n = 1.0f / tanf(float(M_PI) * Fg);
    const float a0_pd = 1.0f / (1.0f + n);
    const float b1_pd = (1.0f - n) / (1.0f + n);

    float yf = m_yf[track];
    float yp = m_yp[track];
    float last_x = yf;
    for (unsigned int t = 0; t < samples; ++t) {
	float x = fabsf(sample2float(buffer[t])); /* rectifier */

	/* fast value */
	if (x > yf) yf = (a0_fr * x) + (a0_fr * last_x) - (b1_fr * yf); // rise
	yf = (a0_fd * x) + (a0_fd * last_x) - (b1_fd * yf); // decay

	/* peak value */
	if (x > yp) yp = (a0_pr * x) + (a0_pr * last_x) - (b1_pr * yp); // rise
	yp = (a0_pd * x) + (a0_pd * last_x) - (b1_pd * yp); // decay

	// remember x[t-1]
	last_x = x;

	// enqueue new values if limit reached
	if ((t > next_fraction) || (t == samples-1)) {
	    next_fraction += samples_per_update;

	    // merge the last fractional part to the last normal part
	    if ((next_fraction + samples_per_update) > samples)
	       next_fraction = samples-1;

	    enqueue(track, yf, yp, queue_depth);
	}
    }
    m_yf[track] = yf;
    m_yp[track] = yp;
}

//***************************************************************************
void Kwave::LevelMeter::reset()
{
    if (m_timer && m_timer->isActive()) m_timer->stop();

    m_yf.resize(m_tracks);
    m_yf.fill(0.0);
    m_fast_queue.resize(m_tracks);
    m_current_fast.resize(m_tracks);
    m_current_fast.fill(0.0);

    m_yp.resize(m_tracks);
    m_yp.fill(0.0);
    m_peak_queue.resize(m_tracks);
    m_current_peak.resize(m_tracks);
    m_current_peak.fill(0.0);
}

//***************************************************************************
void Kwave::LevelMeter::enqueue(unsigned int track, float fast, float peak,
                                unsigned int queue_depth)
{
    Q_ASSERT(Kwave::toInt(track) < m_tracks);
    Q_ASSERT(m_peak_queue.size() == m_fast_queue.size());
    Q_ASSERT(m_fast_queue.size() >= m_tracks);
    Q_ASSERT(m_peak_queue.size() >= m_tracks);
    if ((Kwave::toInt(track) >= m_tracks) ||
	(m_fast_queue.size() < Kwave::toInt(m_tracks)) ||
	(m_peak_queue.size() < m_tracks)) return;
    Q_ASSERT(m_peak_queue[track].size() == m_fast_queue[track].size());
    if (m_peak_queue[track].size() != m_fast_queue[track].size()) return;

    // remove old entries
    while (m_fast_queue[track].size() > Kwave::toInt(queue_depth)) {
//	qDebug("LevelMeter::enqueue(): purging old entry (%u/%u)",
//	       m_fast_queue.size(), queue_depth);
	m_fast_queue[track].dequeue();
	m_peak_queue[track].dequeue();
    }

    // put into the queue
    m_fast_queue[track].enqueue(fast);
    m_peak_queue[track].enqueue(peak);

    // restart the timer if necessary
    if (m_timer && !m_timer->isActive()) {
	m_timer->setInterval(Kwave::toInt(1000 / UPDATES_PER_SECOND));
	m_timer->setSingleShot(false);
	m_timer->start();
    }
}

//***************************************************************************
bool Kwave::LevelMeter::dequeue(unsigned int track, float &fast, float &peak)
{
    Q_ASSERT(m_peak_queue.size() == m_fast_queue.size());
    Q_ASSERT(m_fast_queue.size() >= m_tracks);
    Q_ASSERT(m_peak_queue.size() >= m_tracks);
    if ((Kwave::toInt(track) >= m_tracks) ||
	(m_fast_queue.size() < m_tracks) ||
	(m_peak_queue.size() < m_tracks)) return false;
    Q_ASSERT(m_peak_queue[track].size() == m_fast_queue[track].size());
    if (m_peak_queue[track].size() != m_fast_queue[track].size())
        return false;

    // check if the queues are empty
    if (m_fast_queue[track].isEmpty()) return false;
    if (m_peak_queue[track].isEmpty()) return false;

    // get the values from the front of the queue
    fast = m_fast_queue[track].dequeue();
    peak = m_peak_queue[track].dequeue();

    return true;
}

//***************************************************************************
void Kwave::LevelMeter::timedUpdate()
{
    float fast;
    float peak;
    bool need_update = false;

    for (int track=0; track < m_tracks; track++) {
	if (dequeue(track, fast, peak)) {
	    // set the new "current" values
	    m_current_fast[track] = fast;
	    m_current_peak[track] = peak;

	    // remember that we have to update the display
	    need_update = true;
	}
    }

    // refresh the display if needed
    if (need_update) repaint();
}

//***************************************************************************
void Kwave::LevelMeter::drawScale(QPainter &p)
{
    // draw the levels in 3dB steps, like -12dB -9dB  -6dB  -3dB and 0dB
    QFontMetrics fm = p.fontMetrics();
    QRect rect = fm.boundingRect(i18n("%1 dB", -999));

    const int border = 4;
    const int w  = width() - 2 * border;
    const int h  = height();
    const int tw = rect.width();
    const int th = rect.height();
    const int y  = ((height() - th) / 2);
    const int r  = 5;
    int db       = 0;
    int right    = width();
    const QColor textcolor = palette().buttonText().color();
    const QBrush brush(palette().background().color());

    Q_ASSERT(th);
    if (!th) return;

    p.setBrush(brush);
    while (right > tw + border) {
	// find the first position in dB which is not overlapping
	// the last output position
	QString txt;
	int x;
	do {
	    txt = i18n("%1 dB", db);
	    x = Kwave::toInt(static_cast<double>(w) *
		pow(10.0, static_cast<double>(db) / 20.0));
	    db -= 3; // one step left == -3dB
	} while ((x > right) && (x >= tw));
	if (x < tw) break;

	// calculate the text position
	int text_width = fm.boundingRect(txt).width();
	x += border;
	x -= text_width + 3;

	// dim the text background area
	p.setOpacity(0.66);
	p.setPen(Qt::NoPen);
	p.drawRoundRect(x - r, y - r, text_width + 2 * r, th + 2 * r,
	                (200 * r) / th, (200 * r) / th);

	// draw the text, right/center aligned
	p.setOpacity(1.0);
	p.setPen(textcolor);
	p.drawText(x, 1, text_width, h, Qt::AlignCenter, txt);

	// new right border == one character left from last one
	right = x - th;
    }

}

//***************************************************************************
/*
  Original idea:
  Copyright 2002 Rik Hemsley (rikkus) <rik@kde.org>

  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to
  deal in the Software without restriction, including without limitation the
  rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
  sell copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:

  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.
*/
void Kwave::LevelMeter::drawContents()
{
    QPainter p;
    int track;

    Q_ASSERT(width() > 0);
    Q_ASSERT(height() > 0);

    p.begin(this);

    // fill the background
    p.fillRect(rect(), palette().background().color());

    const unsigned int border = 4;
    const unsigned int cell = 3;
    const unsigned int w = width() - (border * 2) - (cell * 2);
    const unsigned int h = (height() - border) / (m_tracks ? m_tracks : 1);

    const unsigned int w_low  = Kwave::toUint(w * 0.7);  // -3 dB
    const unsigned int w_high = Kwave::toUint(w * 0.85); // -1.5dB

    for (track = 0; track < m_tracks; ++track) {
	// show a bar up to the "fast" value
	const unsigned int fast = Kwave::toUint(m_current_fast[track] * w);
	for (unsigned int i = 0; i < w; i += cell * 2) {
	    QColor color;
	    if (i >= w_high)
		color = m_color_high;
	    else if (i >= w_low)
		color = m_color_normal;
	    else
		color = m_color_low;

	    p.fillRect(
		border + cell + i,
		border + (track * h),
		cell, h-border,
		(i > fast) ? color.dark() : color
	    );
	}

	// draw the peak value
	unsigned int peak = Kwave::toUint(m_current_peak[track] * w);
	QColor peak_color;
	if (peak >= w_high)
	    peak_color = m_color_high;
	else if (peak >= w_low)
	    peak_color = m_color_normal;
	else
	    peak_color = m_color_low;

	p.fillRect(
	    border + cell + peak,
	    border + (track * h),
	    cell, h - border,
	    peak_color.light()
	);
    }

    // draw the scale / dB numbers
    drawScale(p);

    p.end();
}

//***************************************************************************
//***************************************************************************
