/*
 * FlexibleListView.cpp - list view with flexible icon positions
 *
 * Copyright (c) 2018-2021 Tobias Junghans <tobydox@veyon.io>
 *
 * This file is part of Veyon - https://veyon.io
 *
 * 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.
 *
 * 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 (see COPYING); if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 */

#include <QHelpEvent>
#include <QJsonArray>
#include <QJsonObject>
#include <QUuid>

#include "FlexibleListView.h"
#include "QtCompat.h"


FlexibleListView::FlexibleListView( QWidget* parent ) :
	QListView( parent ),
	m_uidRole( Qt::UserRole )
{
	connect( this, &QListView::indexesMoved, this, &FlexibleListView::updatePositions );
}



void FlexibleListView::setUidRole( int role )
{
	m_uidRole = role;
}



void FlexibleListView::setFlexible( bool enabled )
{
	if( enabled )
	{
		setMovement( QListView::Free );
	}
	else
	{
		setMovement( QListView::Static );
	}

	doItemsLayout();
}



bool FlexibleListView::flexible() const
{
	return movement() == QListView::Free;
}



void FlexibleListView::alignToGrid()
{
	auto m = model();

	for( int i = 0, count = m->rowCount(); i < count; ++i )
	{
		const auto index = m->index( i, 0 );
		const auto uid = m->data( index, m_uidRole ).toUuid();

		if( uid.isNull() == false && m_positions.contains( uid ) )
		{
			m_positions[uid] = QPointF( qMax<int>( 0, qRound( m_positions[uid].x() ) ),
										qMax<int>( 0, qRound( m_positions[uid].y() ) ) );
			setPositionForIndex( toItemPosition( qAsConst(m_positions)[uid] ), index );
		}
	}
}



QJsonArray FlexibleListView::savePositions()
{
	QJsonArray data;

	for( auto it = m_positions.constBegin(), end = m_positions.constEnd(); it != end; ++it )
	{
		QJsonObject object;
		object[QStringLiteral("uid")] = it.key().toString();
		object[QStringLiteral("x")] = it.value().x();
		object[QStringLiteral("y")] = it.value().y();
		data += object;
	}

	return data;
}



void FlexibleListView::loadPositions( const QJsonArray& data )
{
	m_positions.clear();

	for( const auto& item : data )
	{
		const auto object = item.toObject();
		const QUuid uid( object[QStringLiteral("uid")].toString() );
		if( uid.isNull() == false )
		{
			m_positions[uid] = QPointF( object[QStringLiteral("x")].toDouble(), object[QStringLiteral("y")].toDouble() );
		}
	}
}



void FlexibleListView::doItemsLayout()
{
	QListView::doItemsLayout();

	if( movement() == QListView::Free )
	{
		restorePositions();
	}
}



bool FlexibleListView::viewportEvent( QEvent* event )
{
	const auto ret = QListView::viewportEvent( event );
	if( event->type() == QEvent::ToolTip )
	{
		m_toolTipPos = ret ? static_cast<QHelpEvent*>(event)->pos() : QPoint{};
	}

	return ret;
}



void FlexibleListView::dataChanged( const QModelIndex& topLeft, const QModelIndex& bottomRight, const QVector<int>& roles )
{
	QListView::dataChanged( topLeft, bottomRight, roles );

	if( m_toolTipPos.isNull() == false && ( roles.isEmpty() || roles.contains(Qt::ToolTipRole) ) )
	{
		if( viewport()->mapToGlobal(m_toolTipPos) != QCursor::pos() )
		{
			m_toolTipPos = QPoint();
			return;
		}

		const auto index = indexAt( m_toolTipPos );
		if( index.row() >= topLeft.row() && index.row() <= bottomRight.row() )
		{
			QHelpEvent he( QEvent::ToolTip, m_toolTipPos, viewport()->mapToGlobal(m_toolTipPos) );
			QListView::viewportEvent( &he );
		}
	}
}



void FlexibleListView::restorePositions()
{
	auto m = model();

	if( m == nullptr )
	{
		return;
	}

	for( int i = 0, count = m->rowCount(); i < count; ++i )
	{
		const auto index = m->index( i, 0 );
		const auto uid = m->data( index, m_uidRole ).toUuid();

		if( uid.isNull() == false && m_positions.contains( uid ) )
		{
			setPositionForIndex( toItemPosition( qAsConst(m_positions)[uid] ), index );
		}
	}
}



void FlexibleListView::updatePositions()
{
	if( movement() == QListView::Free && model() )
	{
		auto m = model();

		for( int i = 0, count = m->rowCount(); i < count; ++i )
		{
			const auto index = m->index( i, 0 );
			const auto uid = m->data( index, m_uidRole ).toUuid();

			if( uid.isNull() == false )
			{
				m_positions[uid] = toGridPoint( rectForIndex( index ).topLeft() );
			}
		}
	}
}



QSizeF FlexibleListView::effectiveGridSize() const
{
	auto m = model();

	if( m && m->rowCount() > 0 )
	{
		return rectForIndex( m->index( 0, 0 ) ).size() + QSize( spacing(), spacing() );
	}
	else if( iconSize().isEmpty() == false )
	{
		return iconSize() + QSize( spacing(), spacing() );
	}

	return { spacing() + 1.0, spacing() + 1.0 };
}



QPointF FlexibleListView::toGridPoint( QPoint pos ) const
{
	const auto gridSize = effectiveGridSize();

	return { ( pos.x() - spacing() ) / gridSize.width(),
				( pos.y() - spacing() ) / gridSize.height() };
}



QPoint FlexibleListView::toItemPosition( QPointF gridPoint ) const
{
	const auto gridSize = effectiveGridSize();

	return { spacing() + qMax<int>( 0, static_cast<int>( gridPoint.x() * gridSize.width() ) ),
				spacing() + qMax<int>( 0, static_cast<int>( gridPoint.y() * gridSize.height() ) ) };
}
