// Ruler class implementation
//
//  A QWidget displaying a ruler and allowing user zooming and shifting
//
// QATSH Copyright 2009 Jean-Philippe MEURET <jpmeuret@free.fr>

#include <iostream>

#include <QtGui/QPainter>
#include <QtGui/QPalette>
#include <QtGui/QFontMetrics>
#include <QtGui/QResizeEvent>
#include <QtGui/QWheelEvent>

#include "ATSMath.h"
#include "Ruler.h"
#include "RulerSpec.h"


Ruler::Ruler(QWidget *parent)
: QWidget(parent), _bShifting(false), _dZoomFactor(1.0), _dValueOffset(0.0)
{
    //std::cout << "Ruler::Ruler : viewRect = "
    //      << width() << "x" << height() << std::endl;
}

void Ruler::onSpecChanged(const RulerSpec* pSpec)
{
    _pSpec = pSpec;

    // Check and fix value offset / zoom factor in case they are no longer
    // compatible with new ruler spec.
    const double dScaleMinValue = _pSpec->minValue();
    const double dScaleMaxValue = _pSpec->maxValue();
    const double dScaleLength = dScaleMaxValue - dScaleMinValue;
    const double dViewMaxValue = 
	dScaleMinValue + _dValueOffset + dScaleLength / _dZoomFactor;
    if (dViewMaxValue > dScaleMaxValue)
	_dValueOffset = dScaleMaxValue - dScaleLength / _dZoomFactor;
    if (_dValueOffset < 0.0)
    {
	_dZoomFactor = 1.0;
	_dValueOffset = 0.0;
    }

    // Force a resize, in order for each ruler-driven view 
    // to be notified of new offset and zoom factor.
    resize(size());
}

void Ruler::zoom(double dRelativeAnchor, double dRelativeFactor)
{
    const QPoint qpAnchorPoint((int)(width() * dRelativeAnchor),
                               (int)(height() * dRelativeAnchor));
    zoom(qpAnchorPoint, dRelativeFactor);
}

void Ruler::zoomAll()
{
    // Back to unzoomed aspect.
    _dZoomFactor = 1.0;
    _dValueOffset = 0.0;

    // Redraw the ruler.
    repaint();

    // Post zoom event properties for other views to apply it.
    const int nViewLength = _pSpec->orientation() == RulerSpec::eHorizontal ? width() : height();
    propagateZoomShift(nViewLength);
}

// Event handlers =============================================================
void Ruler::mousePressEvent(QMouseEvent *pqEvent)
{
    if (pqEvent->button() == Qt::LeftButton) 
    {
	_bShifting = true;
	_qpLastShiftingPos = pqEvent->pos();
    }
}

void Ruler::mouseMoveEvent(QMouseEvent *pqEvent)
{
    if ((pqEvent->buttons() & Qt::LeftButton) && _bShifting)
    {
	shift(pqEvent->pos());
	_qpLastShiftingPos = pqEvent->pos();
    }
}

void Ruler::mouseReleaseEvent(QMouseEvent *pqEvent)
{
    if (pqEvent->button() == Qt::LeftButton && _bShifting) 
    {
	_bShifting = false;
	shift(pqEvent->pos());
    }
}

void Ruler::wheelEvent(QWheelEvent *pqEvent)
{
    //std::cout << "Ruler::zoom : delta=" << pqEvent->delta() << std::endl;
    zoom(pqEvent->pos(), pow(2.0, -pqEvent->delta() / 240.0));
}

void Ruler::resizeEvent(QResizeEvent *pqEvent)
{
//     std::cout << "Ruler::resizeEvent(" << pqEvent->size().width() 
// 	      << "x" << pqEvent->size().height() << ")" << std::endl;

    resize(pqEvent->size());
}

// Actually draw the ruler (triggered after a call repaint()).
void Ruler::paintEvent(QPaintEvent *pqEvent)
{
  Q_UNUSED(pqEvent);

  QPainter qPainter(this);

  draw(qPainter);
}


// ===========================================================================
void Ruler::propagateZoomShift(int nViewLength)
{
    // Get ruler spec.
    const double dScaleMinValue = _pSpec->minValue();
    const double dScaleMaxValue = _pSpec->maxValue();
    const double dScaleLength = dScaleMaxValue - dScaleMinValue;

    const bool bPositiveDir = _pSpec->direction() == RulerSpec::ePositive;
    const bool bHorizontal = _pSpec->orientation() == RulerSpec::eHorizontal;
    const bool bInverted = (bPositiveDir && !bHorizontal) || (!bPositiveDir && bHorizontal);

    //
    double dAbsoluteFactor = _dZoomFactor * nViewLength / dScaleLength;
    if (bInverted)
        dAbsoluteFactor = -dAbsoluteFactor;

    //
    double dAbsoluteShiftValue = - dAbsoluteFactor;
    if (bInverted)
        dAbsoluteShiftValue *= _dValueOffset + dScaleLength / _dZoomFactor;
    else
        dAbsoluteShiftValue *= _dValueOffset;

    // Post zoom event properties for other views to apply it.
    emit zoomShift(dAbsoluteFactor, dAbsoluteShiftValue);
}

void Ruler::resize(const QSize& qSize)
{
    // Get ruler spec.
    const bool bHorizontal = _pSpec->orientation() == RulerSpec::eHorizontal;

    // Get new view length.
    const int nViewLength = bHorizontal ? qSize.width() : qSize.height();

    // Post zoom event properties for other views to apply it.
    propagateZoomShift(nViewLength);
}

void Ruler::zoom(const QPoint& qpAnchorPos, double dRelativeFactor)
{
    // Get ruler spec.
    const double dScaleMinValue = _pSpec->minValue();
    const double dScaleMaxValue = _pSpec->maxValue();
    const double dScaleLength = dScaleMaxValue - dScaleMinValue;

    const bool bPositiveDir = _pSpec->direction() == RulerSpec::ePositive;
    const bool bHorizontal = _pSpec->orientation() == RulerSpec::eHorizontal;
    const bool bInverted = (bPositiveDir && !bHorizontal) || (!bPositiveDir && bHorizontal);

    // Keep from zooming under 1.0 factor.
    if (_dZoomFactor == 1.0 && dRelativeFactor < 1.0)
	return;

    // Determine new absolute zoom factor (>= 1.0).
    const double dOldZoomFactor = _dZoomFactor;
    _dZoomFactor *= dRelativeFactor;

    if (_dZoomFactor < 1.01)
    {
	// Prevent zoom factor from being < 1, force it to 1 when positive but close enough,
	// and force offset to 0 in such cases (to fix errors due to repeated * and /)
	_dZoomFactor = 1.0;
	_dValueOffset = 0.0;
	dRelativeFactor = _dZoomFactor / dOldZoomFactor;
    }
    
    // Determine the new view offset (but keep it inside [0, scaleMax-viewMaxVal+viewMinVal]).
    const int nViewLength = bHorizontal ? width() : height();

    const double dOldPixelValue = dScaleLength / dOldZoomFactor / nViewLength;
    const double dNewPixelValue = dScaleLength / _dZoomFactor / nViewLength;

    int nValue = bHorizontal ? qpAnchorPos.x() : qpAnchorPos.y();
    if (bInverted)
	nValue = nViewLength - 1 - nValue;

    _dValueOffset += nValue * (dOldPixelValue - dNewPixelValue);
    if (_dValueOffset < 0 || _dValueOffset + dScaleLength / _dZoomFactor > dScaleMaxValue)
    	_dValueOffset = 0;
    // Note: No need to update _dZoomFactor, as already forced to >= 1.0

    // Redraw the ruler.
    repaint();

//     std::cout << "Ruler::wheelEvent(relFact=" << dRelativeFactor
// 	      << ", anchor=" << nValue
// 	      << ") : zoomFactor=" << _dZoomFactor
// 	      << ", offsetValue=" << _dValueOffset << std::endl;

    // Post zoom event properties for other views to apply it.
    propagateZoomShift(nViewLength);
}

void Ruler::shift(const QPoint& qpNewPos)
{
    // Get ruler spec.
    const double dScaleMinValue = _pSpec->minValue();
    const double dScaleMaxValue = _pSpec->maxValue();
    const double dScaleLength = dScaleMaxValue - dScaleMinValue;

    const bool bPositiveDir = _pSpec->direction() == RulerSpec::ePositive;
    const bool bHorizontal = _pSpec->orientation() == RulerSpec::eHorizontal;
    const bool bInverted = (bPositiveDir && !bHorizontal) || (!bPositiveDir && bHorizontal);

    // Compute view properties.
    const int nViewLength = bHorizontal ? width() : height();
    const double dPixelValue = dScaleLength / _dZoomFactor / nViewLength;

    // Compute the shifting amount
    int nShift;
    if (bHorizontal)
	nShift = _qpLastShiftingPos.x() - qpNewPos.x();
    else
	nShift = _qpLastShiftingPos.y() - qpNewPos.y();
    if (bInverted)
	nShift = - nShift;

    // Update current offset from scale origin.
    _dValueOffset += nShift * dPixelValue;
    if (_dValueOffset < 0)
	_dValueOffset = 0;
    const double dNewViewMaxValue = 
	dScaleMinValue + _dValueOffset + dScaleLength / _dZoomFactor;
    if (dNewViewMaxValue > dScaleMaxValue)
	_dValueOffset = dScaleMaxValue - nViewLength * dPixelValue;
        //_dValueOffset = dScaleMaxValue - dScaleLength / _dZoomFactor;

    // Redraw the scale.
    repaint();

//     std::cout << "Ruler::shift : shift=" << nShift
// 	      << ", offsetValue=" << _dValueOffset 
// 	      << ", absFactor=" << _dZoomFactor  
// 	      << ", pixValue=" << dPixelValue << std::endl;

    // Post zoom event properties for other views to apply it.
    propagateZoomShift(nViewLength);
}

//===================================================================================
// Draw the scale according to the ruler spec and current zoom factor and translation
static const int nUnitPrefixMinIndex = -3;
static const int nUnitPrefixMaxIndex = +3;
static const int nUnitPrefixes = nUnitPrefixMaxIndex - nUnitPrefixMinIndex + 1;
static const char* pszUnitPrefix[nUnitPrefixes] = { "n", "u", "m", "", "k", "M", "g" };

void Ruler::draw(QPainter& qPainter)
{
    qPainter.setPen(Qt::black);

    // Get ruler specs.
    const bool bPositiveDir = _pSpec->direction() == RulerSpec::ePositive;
    const bool bPositiveSide = _pSpec->marksSide() == RulerSpec::ePositiveSide;
    const bool bHorizontal = _pSpec->orientation() == RulerSpec::eHorizontal;

    typedef enum { eNorth = 0, eWest, eSouth, eEast } EOrientation;
    const EOrientation eOrient = 
	(bHorizontal ? (bPositiveSide ? eNorth : eSouth) : (bPositiveSide ? eEast : eWest));
 
    const double dScaleMinValue = _pSpec->minValue();
    const double dScaleMaxValue = _pSpec->maxValue();
    const double dScaleLength = dScaleMaxValue - dScaleMinValue;

    // Get widget dimensions.
    const int nViewLength = bHorizontal ? width() : height();
    const int nViewThickness = bHorizontal ? height() : width();
    

    // Draw the main line of the ruler.
    switch (eOrient) 
    {
        case eNorth:
	    qPainter.drawLine(0, 0, nViewLength - 1, 0);
	    break;

        case eSouth:
	    qPainter.drawLine(0, nViewThickness - 1, nViewLength - 1, nViewThickness - 1);
	    break;

        case eWest:
	    qPainter.drawLine(0, 0, 0, nViewLength - 1);
	    break;

        case eEast:
	    qPainter.drawLine(nViewThickness - 1, 0, nViewThickness - 1, nViewLength - 1);
	    break;
    }

    // Determine the value interval of the view
    double dViewMinValue = dScaleMinValue + _dValueOffset;
    double dViewMaxValue = dViewMinValue + dScaleLength / _dZoomFactor;

    // Determine the resolution of a pixel in the view
    const double dPixelValue = dScaleLength / _dZoomFactor / nViewLength;

    //std::cout << "Ruler::draw(orient=" << eOrient << ", dir=" << _pSpec->direction() 
    //	      << ") : viewMinValue=" << dViewMinValue 
    //	      << ", viewMaxValue=" << dViewMaxValue  
    //	      << ", pixelValue=" << dPixelValue << std::endl;

    // Determine the distance between main scale marks
    // (criteria = at least 5 pixels between 1st secondary scale marks).
    const int nMinValueStep = 5;
    const double dLevelDivisor = _pSpec->levelDivisor();
    double dValueStep = _pSpec->baseStep();
    //while (dValueStep >= nMinValueStep * dLevelDivisor * dPixelValue)
    while (2 * dValueStep > dScaleLength / _dZoomFactor)
    {
	dValueStep /= dLevelDivisor;
    }

    // Determine the lowest value of any main scale mark visible in the view
    double dFirstMarkValue = 
	dScaleMinValue + _pSpec->baseOffset()
	+ dValueStep
	  * ceil((dViewMinValue - dScaleMinValue - _pSpec->baseOffset()) / dValueStep);

    //std::cout << "Ruler::draw(main) : markLength=" << nViewThickness
    //      << ", valueStep=" << dValueStep 
    //      << ", 1stMarkValue=" << dFirstMarkValue << std::endl;

    // Draw the main scale marks and associated labels
    //const QFont qFont("Tahoma", 7); // Windows very good.
    //qPainter.setFont(qFont);
    const QFontMetrics qFontMtrx = qPainter.fontMetrics();
    const bool bInverted = (bPositiveDir && !bHorizontal) || (!bPositiveDir && bHorizontal);
    double dValue = dFirstMarkValue;
    int nValue;
    while (dValue <= dViewMaxValue)
    {
	// Mark coordinate (pixel) in the "long" direction of the view.
        nValue = (int)round((dValue - dViewMinValue) / dPixelValue);
	if (nValue == nViewLength)
	    nValue--;
	if (bInverted)
	    nValue = nViewLength - 1 - nValue;
	
	switch (eOrient) 
	{
	    case eNorth:
            case eSouth:
		qPainter.drawLine(nValue, 0, nValue, nViewThickness - 1);
		break;

            case eWest:
            case eEast:
		qPainter.drawLine(0, nValue, nViewThickness - 1, nValue);
		break;
	}

	// Convert value to a user-friendly label string.
	const char* pszLabelSign = dValue > 0.0 ? "" : "-";
	double dLabelValue = fabs(dValue);
	QString qsLabel("0");
	if (dValue != 0.0)
	{
	    const int nUnitPrefixIndex = (int)(floor(log10(dLabelValue))) / 3;
	    if (nUnitPrefixIndex < nUnitPrefixMinIndex || nUnitPrefixIndex > nUnitPrefixMaxIndex)
		qsLabel = QString("%1").arg(dValue, 0, 'g', 3);
	    else
	    {
		dLabelValue /= pow(10.0, 3*nUnitPrefixIndex);
		qsLabel = QString("%1%2%3").arg(pszLabelSign).arg(dLabelValue, 0, 'g', 3)
		          .arg(pszUnitPrefix[nUnitPrefixIndex - nUnitPrefixMinIndex]);
	    }
	}

	// Draw the mark label.
        const QSize qsLabelSize = qFontMtrx.size(Qt::TextSingleLine, qsLabel);
        const int nLabeWidth = qsLabelSize.width();
        const int nLabeHeight = qsLabelSize.height();

	nValue += (bHorizontal ? (bInverted ? -3 - nLabeWidth : 3) : -3);
	    
	switch (eOrient) 
	{
	    case eNorth:
		qPainter.drawText(nValue, nViewThickness - 1, qsLabel);
		break;

            case eSouth:
		qPainter.drawText(nValue, nLabeHeight, qsLabel);
		break;

            case eWest:
		qPainter.drawText(nViewThickness - nLabeWidth, nValue, qsLabel);
		break;

            case eEast:
		qPainter.drawText(0, nValue, qsLabel);
		break;
	}

	// Next mark.
	dValue += dValueStep;
    }

    // Draw the secondary scale marks
    const QList<double>& qlSecondDivisors = _pSpec->secondaryDivisors();
    const QList<double>& qlSecondSizes = _pSpec->secondaryMarksSizes();
    for (int nSecondInd = 0; nSecondInd < qlSecondDivisors.size(); nSecondInd++)
    {
        const int nMarkLength = (int)round(qlSecondSizes[nSecondInd] * nViewThickness);
	dValueStep /= qlSecondDivisors[nSecondInd];

	// Don't draw secondary scales under a certain inter-mark distance threshold.
	if (dValueStep < nMinValueStep * dPixelValue)
	    break;

	dFirstMarkValue = 
	    dScaleMinValue + _pSpec->baseOffset()
	    + dValueStep
	    * ceil((dViewMinValue - dScaleMinValue - _pSpec->baseOffset()) / dValueStep);

	//dFirstMarkValue = remainder(dFirstMarkValue - dViewMinValue, dValueStep);
	dValue = dFirstMarkValue;

        //std::cout << "Ruler::draw(secondary) : markLength=" << nMarkLength
	//	  << ", valueStep=" << dValueStep 
	//	  << ", 1stMarkValue=" << dFirstMarkValue << std::endl;

	while (dValue <= dViewMaxValue)
	{
	    // mark coordinate (pixel) in the "long" direction of the view.
            nValue = (int)round((dValue - dViewMinValue) / dPixelValue);
	    if (nValue == nViewLength)
		nValue--;
	    if (bInverted)
		nValue = nViewLength - 1 - nValue;
	    
	    switch (eOrient) 
	    {
		case eNorth:
                    qPainter.drawLine(nValue, 0, nValue, nMarkLength - 1);
		    break;

		case eSouth:
                    qPainter.drawLine(nValue, nViewThickness - nMarkLength,
				      nValue, nViewThickness - 1);
		    break;

		case eWest:
                    qPainter.drawLine(0, nValue, nMarkLength - 1, nValue);
		    break;

		case eEast:
                    qPainter.drawLine(nViewThickness - nMarkLength, nValue,
				      nViewThickness - 1, nValue);
		    break;
	    }
	    
	    dValue += dValueStep;
	}
    }
}