/* This file is part of Clementine.
   Copyright 2010, David Sansome <me@davidsansome.com>

   Clementine 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.

   Clementine 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 Clementine.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "stretchheaderview.h"
//#include "core/logging.h"

#include <QDataStream>
#include <QIODevice>

#include <algorithm>
#include <cmath>
#include <numeric>

const int StretchHeaderView::kMinimumColumnWidth = 10;
const int StretchHeaderView::kMagicNumber = 0x502c951f;
static const int constPrevMagicNumber = 0x502c950f;
StretchHeaderView::StretchHeaderView(Qt::Orientation orientation, QWidget* parent)
	: QHeaderView(orientation, parent),
	  stretch_enabled_(false),
	  in_mouse_move_event_(false)
{
	connect(this, SIGNAL(sectionResized(int, int, int)), SLOT(SectionResized(int, int, int)));
}

void StretchHeaderView::setModel(QAbstractItemModel* model)
{
	QHeaderView::setModel(model);

	if (stretch_enabled_) {
		column_widths_.resize(count());
		std::fill(column_widths_.begin(), column_widths_.end(), 1.0 / count());
	}
}

void StretchHeaderView::NormaliseWidths(const QList<int>& sections)
{
	if (!stretch_enabled_)
		return;

	const ColumnWidthType total_sum =
			std::accumulate(column_widths_.begin(), column_widths_.end(), 0.0);
	ColumnWidthType selected_sum = total_sum;

	if (!sections.isEmpty()) {
		selected_sum = 0.0;
		for (int i = 0; i < count(); ++i)
			if (sections.contains(i))
				selected_sum += column_widths_[i];
	}

	if (total_sum != 0.0 && !qFuzzyCompare(total_sum, 1.0)) {
		const ColumnWidthType mult = (selected_sum + (1.0 - total_sum)) / selected_sum;
		for (int i = 0; i < column_widths_.count(); ++i) {
			if (sections.isEmpty() || sections.contains(i))
				column_widths_[i] *= mult;
		}
	}
}

void StretchHeaderView::UpdateWidths(const QList<int>& sections)
{
	if (!stretch_enabled_)
		return;

	ColumnWidthType total_w = 0.0;
	int totalUsed = 0;
	for (int i = 0; i < column_widths_.count(); ++i) {
		const ColumnWidthType w = column_widths_[i];
		int pixels = static_cast<int>(w * width());

		if (pixels != 0 && total_w - int(total_w) > 0.5)
			pixels++;

		total_w += w;

		if (!sections.isEmpty() && !sections.contains(i))
			continue;

		if (pixels == 0 && !isSectionHidden(i))
			hideSection(i);
		else if (pixels != 0 && isSectionHidden(i)) {
			showSection(i);
			AssertMinimalColumnWidth(i);
		}
		if (pixels != 0) {
			if (totalUsed + pixels > width()) {
				pixels--;
			}
			totalUsed += pixels;
			resizeSection(i, pixels);
		}
	}
}

void StretchHeaderView::HideSection(int logical)
{
	// Would this hide the last section?
	bool all_hidden = true;
	for (int i = 0; i < count(); ++i) {
		if (i != logical && !isSectionHidden(i) && sectionSize(i) > 0) {
			all_hidden = false;
			break;
		}
	}
	if (all_hidden) {
		return;
	}

	if (!stretch_enabled_) {
		hideSection(logical);
		return;
	}

	column_widths_[logical] = 0.0;
	NormaliseWidths();
	UpdateWidths();
}

void StretchHeaderView::ShowSection(int logical)
{
	if (!stretch_enabled_) {
		showSection(logical);
		return;
	}

	// How many sections are visible already?
	int visible_count = 0;
	for (int i = 0; i < count(); ++i) {
		if (!isSectionHidden(i))
			visible_count++;
	}

	column_widths_[logical] =
			visible_count == 0 ? 1.0 : 1.0 / visible_count;
	NormaliseWidths();
	UpdateWidths();
}

void StretchHeaderView::SetSectionHidden(int logical, bool hidden)
{
	if (hidden) {
		HideSection(logical);
	}
	else {
		ShowSection(logical);
		AssertMinimalColumnWidth(logical);
	}
}

void StretchHeaderView::resizeEvent(QResizeEvent* event)
{
	QHeaderView::resizeEvent(event);

	if (!stretch_enabled_)
		return;

	UpdateWidths();
}

void StretchHeaderView::mouseMoveEvent(QMouseEvent* e)
{
	in_mouse_move_event_ = true;
	QHeaderView::mouseMoveEvent(e);
	in_mouse_move_event_ = false;
}

void StretchHeaderView::SectionResized(int logical, int, int new_size)
{
	if (!stretch_enabled_)
		return;

	if (in_mouse_move_event_) {
		// Update this section's proportional width
		column_widths_[logical] = ColumnWidthType(new_size) / width();

		// Find the visible sections to the right of the section that's being resized
		int visual = visualIndex(logical);
		QList<int> logical_sections_to_resize;
		for (int i = 0; i < count(); ++i) {
			if (!isSectionHidden(i) && visualIndex(i) > visual)
				logical_sections_to_resize << i;
		}

		// Resize just those columns
		if (!logical_sections_to_resize.isEmpty()) {
			in_mouse_move_event_ = false;
			UpdateWidths(logical_sections_to_resize);
			NormaliseWidths(logical_sections_to_resize);
			in_mouse_move_event_ = true;
		}
	}
}

void StretchHeaderView::ToggleStretchEnabled()
{
	SetStretchEnabled(!is_stretch_enabled());
}

void StretchHeaderView::SetStretchEnabled(bool enabled)
{
	stretch_enabled_ = enabled;

	if (enabled) {
		// Initialise the list of widths from the current state of the widget
		column_widths_.resize(count());
		for (int i = 0; i < count(); ++i) {
			column_widths_[i] = ColumnWidthType(sectionSize(i)) / width();
		}

		// Stretch the columns to fill the widget
		NormaliseWidths();
		UpdateWidths();
	}

	emit StretchEnabledChanged(enabled);
}

void StretchHeaderView::SetColumnWidth(int logical, ColumnWidthType width)
{
	if (!stretch_enabled_)
		return;

	column_widths_[logical] = width;

	QList<int> other_columns;
	for (int i = 0; i < count(); ++i)
		if (!isSectionHidden(i) && i != logical)
			other_columns << i;
	NormaliseWidths(other_columns);
}

// makes sure the column will apear no matter what
void StretchHeaderView::AssertMinimalColumnWidth(int logical)
{
	if (sectionSize(logical) < kMinimumColumnWidth) {
		resizeSection(logical, kMinimumColumnWidth);
	}
}

bool StretchHeaderView::RestoreState(const QByteArray& data)
{
	QDataStream s(data);
	s.setVersion(QDataStream::Qt_4_6);

	int magic_number = 0;
	s >> magic_number;

	if ((magic_number != kMagicNumber && magic_number != constPrevMagicNumber) || s.atEnd()) {
		return false;
	}

	QList<int> pixel_widths;
	QList<int> visual_indices;
	QList<int> alignments;
	int sort_indicator_order = Qt::AscendingOrder;
	int sort_indicator_section = 0;
	int version = 0;

	s >> stretch_enabled_;
	s >> pixel_widths;
	s >> visual_indices;
	if (magic_number == kMagicNumber) {
		s >> alignments;
		s >> version;
	}
	s >> column_widths_;
	s >> sort_indicator_order;
	s >> sort_indicator_section;

	setSortIndicator(sort_indicator_section, Qt::SortOrder(sort_indicator_order));

	const int persisted_column_count =
			qMin(qMin(visual_indices.count(), pixel_widths.count()), column_widths_.count());

	QAbstractItemModel* m = model();
	// Set column visible state, visual indices and, if we're not in stretch mode,
	// pixel widths.
	for (int i = 0; i < count() && i < persisted_column_count; ++i) {
		setSectionHidden(i, pixel_widths[i] <= kMinimumColumnWidth);
		moveSection(visualIndex(visual_indices[i]), i);

		if (!stretch_enabled_) {
			resizeSection(i, pixel_widths[i]);
		}
		if (m && magic_number == kMagicNumber) {
			m->setHeaderData(i, Qt::Horizontal, alignments[i], Qt::TextAlignmentRole);
		}
	}

	// Have we added more columns since the last time?
	while (column_widths_.count() < count()) {
		column_widths_ << 0;
	}

	if (stretch_enabled_) {
		// In stretch mode, we've already set the proportional column widths so apply
		// them now.
		UpdateWidths();
	}

	emit StretchEnabledChanged(stretch_enabled_);

	return true;
}

QByteArray StretchHeaderView::SaveState() const
{
	QByteArray ret;
	QDataStream s(&ret, QIODevice::WriteOnly);

	QList<int> pixel_widths;
	QList<int> visual_indices;
	QList<int> alignments;
	QAbstractItemModel* m = model();

	for (int i = 0; i < count(); ++i) {
		pixel_widths << sectionSize(i);
		visual_indices << logicalIndex(i);
		alignments << (m ? m->headerData(i, Qt::Horizontal, Qt::TextAlignmentRole).toInt() : -1);
	}

	s.setVersion(QDataStream::Qt_4_6);
	s << kMagicNumber;

	s << stretch_enabled_;
	s << pixel_widths;
	s << visual_indices;
	s << alignments;
	s << 0;// For future use...
	s << column_widths_;
	s << int(sortIndicatorOrder());
	s << sortIndicatorSection();

	return ret;
}

#include "moc_stretchheaderview.cpp"