/***************************************************************************
 *   Copyright 2008-2010 Stefan Majewsky <majewsky@gmx.net>
 *
 *   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; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 ***************************************************************************/

#include "game.h"
#include "board.h"
#include "diamond.h"
#include "settings.h"

#include <cmath>
#include <QPainter>
#include <QTimerEvent>
#include <KGamePopupItem>
#include <KGameRenderer>
#include <KgTheme>
#include <KgThemeProvider>
#include <KGlobal>
#include <KNotification>

//BEGIN global KGameRenderer instance

namespace KDiamond
{
	class ThemeProvider : public KgThemeProvider
	{
		public:
			ThemeProvider(QObject* parent = 0)
				: KgThemeProvider("Theme", parent)
			{
				discoverThemes("appdata", QLatin1String("themes"));
			}
	};

	class Renderer : public KGameRenderer
	{
		public:
			Renderer() : KGameRenderer(new ThemeProvider, 10)
			{
				setFrameSuffix(QString::fromLatin1("-%1"));
			}
	};
}

K_GLOBAL_STATIC(KDiamond::Renderer, g_renderer)

KGameRenderer* KDiamond::renderer()
{
	return g_renderer;
}

//END global KGameRenderer instance

const int UpdateInterval = 40;

Game::Game(KDiamond::GameState* state)
	: m_timerId(-1)
	, m_board(new KDiamond::Board(g_renderer))
	, m_gameState(state)
	, m_messenger(new KGamePopupItem)
{
	connect(m_board, SIGNAL(animationsFinished()), SLOT(animationFinished()));
	connect(m_board, SIGNAL(clicked(QPoint)), SLOT(clickDiamond(QPoint)));
	connect(m_board, SIGNAL(dragged(QPoint,QPoint)), SLOT(dragDiamond(QPoint,QPoint)));
	//init scene (with some default scene size that makes board coordinates equal scene coordinates)
	const int minSize = m_board->gridSize();
	setSceneRect(0.0, 0.0, minSize, minSize);
	connect(this, SIGNAL(sceneRectChanged(QRectF)), SLOT(updateGraphics()));
	connect(g_renderer->themeProvider(), SIGNAL(currentThemeChanged(const KgTheme*)), SLOT(updateGraphics()));
	addItem(m_board);
	//init messenger
	m_messenger->setMessageOpacity(0.8);
	m_messenger->setHideOnMouseClick(false);
	addItem(m_messenger);
	//init time management
	m_timerId = startTimer(UpdateInterval);
	//schedule late initialisation
	m_jobQueue << KDiamond::UpdateAvailableMovesJob;
}

//Checks amount of possible moves remaining
void Game::getMoves()
{
#define C(X, Y) (m_board->hasDiamond(QPoint(X, Y)) ? m_board->diamond(QPoint(X, Y))->color() : KDiamond::Selection)
	m_availableMoves.clear();
	KDiamond::Color curColor;
	const int gridSize = m_board->gridSize();
	for (int x = 0; x < gridSize; ++x)
	{
		for (int y = 0; y < gridSize; ++y)
		{
			curColor = C(x, y);
			if (curColor == C(x + 1, y))
			{
				if (curColor == C(x - 2, y))
					m_availableMoves.append(QPoint(x - 2, y));
				if (curColor == C(x - 1, y - 1))
					m_availableMoves.append(QPoint(x - 1, y - 1));
				if (curColor == C(x - 1, y + 1))
					m_availableMoves.append(QPoint(x - 1, y + 1));
				if (curColor == C(x + 3, y))
					m_availableMoves.append(QPoint(x + 3, y));
				if (curColor == C(x + 2, y - 1))
					m_availableMoves.append(QPoint(x + 2, y - 1));
				if (curColor == C(x + 2, y + 1))
					m_availableMoves.append(QPoint(x + 2, y + 1));
			}
			if (curColor == C(x + 2, y))
			{
				if (curColor == C(x + 1, y - 1))
					m_availableMoves.append(QPoint(x + 1, y - 1));
				if (curColor == C(x + 1, y + 1))
					m_availableMoves.append(QPoint(x + 1, y + 1));
			}
			if (curColor == C(x, y + 1))
			{
				if (curColor == C(x, y - 2))
					m_availableMoves.append(QPoint(x, y - 2));
				if (curColor == C(x - 1, y - 1))
					m_availableMoves.append(QPoint(x - 1, y - 1));
				if (curColor == C(x + 1, y - 1))
					m_availableMoves.append(QPoint(x + 1, y - 1));
				if (curColor == C(x, y + 3))
					m_availableMoves.append(QPoint(x + 3, y));
				if (curColor == C(x - 1, y + 2))
					m_availableMoves.append(QPoint(x - 1, y + 2));
				if (curColor == C(x + 1, y + 2))
					m_availableMoves.append(QPoint(x + 1, y + 2));
			}
			if (curColor == C(x, y + 2))
			{
				if (curColor == C(x - 1, y + 1))
					m_availableMoves.append(QPoint(x - 1, y + 1));
				if (curColor == C(x + 1, y + 1))
					m_availableMoves.append(QPoint(x + 1, y + 1));
			}
		}
	}
#undef C
	emit numberMoves(m_availableMoves.size());
	if (m_availableMoves.isEmpty())
	{
		m_board->clearSelection();
		m_gameState->setState(KDiamond::Finished);
	}
}

void Game::updateGraphics()
{
	//calculate new metrics
	const QSize sceneSize = sceneRect().size().toSize();
	const int gridSize = m_board->gridSize();
	const int diamondSize = (int) floor(qMin(
		sceneSize.width() / (gridSize + 1.0), //the "+1" and "+0.5" make sure that some space is left on the window for the board border
		sceneSize.height() / (gridSize + 0.5)
	));
	const int boardSize = gridSize * diamondSize;
	const int leftOffset = (sceneSize.width() - boardSize) / 2.0;
	QTransform t;
	t.translate(leftOffset, 0).scale(diamondSize, diamondSize);
	m_board->setTransform(t);
	//render background
	QPixmap pix = g_renderer->spritePixmap("kdiamond-background", sceneSize);
	const KgTheme* theme = g_renderer->theme();
	const bool hasBorder = theme->customData("HasBorder").toInt() > 0;
	if (hasBorder)
	{
		const qreal borderPercentage = theme->customData("BorderPercentage").toFloat();
		const int padding = borderPercentage * boardSize;
		const int boardBorderSize = 2 * padding + boardSize;
		const QPixmap boardPix = g_renderer->spritePixmap("kdiamond-border", QSize(boardBorderSize, boardBorderSize));
		QPainter painter(&pix);
		painter.drawPixmap(QPoint(leftOffset - padding, -padding), boardPix);
	}
	setBackgroundBrush(pix);
}

void Game::clickDiamond(const QPoint& point)
{
	if (m_gameState->state() != KDiamond::Playing)
		return;
	//do not allow more than two selections
	const bool isSelected = m_board->hasSelection(point);
	if (!isSelected && m_board->selections().count() == 2)
		return;
	//select only adjacent diamonds (i.e. if a distant diamond is selected, deselect the first one)
	foreach (const QPoint& point2, m_board->selections())
	{
		const int diff = qAbs(point2.x() - point.x()) + qAbs(point2.y() - point.y());
		if (diff > 1)
			m_board->setSelection(point2, false);
	}
	//toggle selection state
	m_board->setSelection(point, !isSelected);
	if (m_board->selections().count() == 2)
		m_jobQueue << KDiamond::SwapDiamondsJob;
}

void Game::dragDiamond(const QPoint& point, const QPoint& direction)
{
	//direction must not be null, and must point along one axis
	if ((direction.x() == 0) ^ (direction.y() == 0))
	{
		//find target indices
		const QPoint point2 = point + direction;
		if (!m_board->hasDiamond(point2))
			return;
		//simulate the clicks involved in this operation
		m_board->clearSelection();
		m_board->setSelection(point, true);
		m_board->setSelection(point2, true);
		m_jobQueue << KDiamond::SwapDiamondsJob;
	}
}

void Game::timerEvent(QTimerEvent* event)
{
	//propagate event to superclass if necessary
	if (event->timerId() != m_timerId)
	{
		QGraphicsScene::timerEvent(event);
		return;
	}
	//do not handle any jobs while animations are running
	if (m_gameState->state() == KDiamond::Paused || m_board->hasRunningAnimations())
	{
		killTimer(m_timerId);
		m_timerId = -1;
		return;
	}
	//anything to do in this update?
	if (m_jobQueue.isEmpty())
	{
		return;
	}
	//execute next job in queue
	const KDiamond::Job job = m_jobQueue.takeFirst();
	switch (job)
	{
		case KDiamond::SwapDiamondsJob: {
			if (m_board->selections().count() != 2)
				break; //this can be the case if, during a cascade, two diamonds are selected (inserts SwapDiamondsJob) and then deselected
			//ensure that the selected diamonds are neighbors (this is not necessarily the case as diamonds can move to fill gaps)
			const QList<QPoint> points = m_board->selections();
			m_board->clearSelection();
			const int dx = qAbs(points[0].x() - points[1].x());
			const int dy = qAbs(points[0].y() - points[1].y());
			if (dx + dy != 1)
				break;
			//start a new cascade
			m_gameState->resetCascadeCounter();
			//copy selection info into another storage (to allow the user to select the next two diamonds while the cascade runs)
			m_swappingDiamonds = points;
			m_jobQueue << KDiamond::RemoveRowsJob; //We already insert this here to avoid another conditional statement.
		} //fall through
		case KDiamond::RevokeSwapDiamondsJob:
			//invoke movement
			KNotification::event("move");
			m_board->swapDiamonds(m_swappingDiamonds[0], m_swappingDiamonds[1]);
			break;
		case KDiamond::RemoveRowsJob: {
			//find diamond rows and delete these diamonds
			const QList<QPoint> diamondsToRemove = findCompletedRows();
			if (diamondsToRemove.isEmpty())
			{
				//no diamond rows were formed by the last move -> revoke movement (unless we are in a cascade)
				if (!m_swappingDiamonds.isEmpty())
					m_jobQueue.prepend(KDiamond::RevokeSwapDiamondsJob);
				else
					m_jobQueue << KDiamond::UpdateAvailableMovesJob;
			}
			else
			{
				//all moves may now be out-dated - flush the moves list
				if (!m_availableMoves.isEmpty())
				{
					m_availableMoves.clear();
					emit numberMoves(-1);
				}
				//it is now safe to delete the position of the swapping diamonds
				m_swappingDiamonds.clear();
				//report to Game
				m_gameState->addPoints(diamondsToRemove.count());
				//invoke remove animation, then fill gaps immediately after the animation
				KNotification::event("remove");
				foreach (const QPoint& diamondPos, diamondsToRemove)
					m_board->removeDiamond(diamondPos);
				m_jobQueue.prepend(KDiamond::FillGapsJob);
			}
			break;
		}
		case KDiamond::FillGapsJob:
			//fill gaps
			m_board->fillGaps();
			m_jobQueue.prepend(KDiamond::RemoveRowsJob); //allow cascades (i.e. clear rows that have been formed by falling diamonds)
			break;
		case KDiamond::UpdateAvailableMovesJob:
			if (m_gameState->state() != KDiamond::Finished)
				getMoves();
			break;
		case KDiamond::EndGameJob:
			emit pendingAnimationsFinished();
			killTimer(m_timerId);
			m_timerId = -1;
			break;
	}
}

QList<QPoint> Game::findCompletedRows()
{
	//The tactic of this function is brute-force. For now, I do not have a better idea: A friend of mine advised me to look in the environment of moved diamonds, but this is not easy since the re-filling after a deletion can lead to rows that are far away from the original movement. Therefore, we simply search through all diamonds looking for combinations in the horizonal and vertical direction.
	KDiamond::Color currentColor;
	QList<QPoint> diamonds;
	int x, y, xh, yh; //counters
	const int gridSize = m_board->gridSize();
#define C(X, Y) m_board->diamond(QPoint(X, Y))->color()
	//searching in horizontal direction
	for (y = 0; y < gridSize; ++y)
	{
		for (x = 0; x < gridSize - 2; ++x) //counter stops at gridSize - 2 to ensure availability of indices x + 1, x + 2
		{
			currentColor = C(x, y);
			if (currentColor != C(x + 1, y))
				continue;
			if (currentColor != C(x + 2, y))
				continue;
			//If the execution is here, we have found a row of three diamonds starting at (x,y).
			diamonds << QPoint(x, y);
			diamonds << QPoint(x + 1, y);
			diamonds << QPoint(x + 2, y);
			//Does the row have even more elements?
			if (x + 3 >= gridSize)
			{
				//impossible to locate more diamonds - do not go through the following loop
				x += 2;
				continue;
			}
			for (xh = x + 3; xh <= gridSize - 1; ++xh)
			{
				if (currentColor == C(xh, y))
					diamonds << QPoint(xh, y);
				else
					break; //row has stopped before this diamond - no need to continue searching
			}
			x = xh - 1; //do not search at this position in the row anymore (add -1 because x is incremented before the next loop)
		}
	}
	//searching in vertical direction (essentially the same algorithm, just with swapped indices -> no comments here, read the comments above)
	for (x = 0; x < gridSize; ++x)
	{
		for (y = 0; y < gridSize - 2; ++y)
		{
			currentColor = C(x, y);
			if (currentColor != C(x, y + 1))
				continue;
			if (currentColor != C(x, y + 2))
				continue;
			diamonds << QPoint(x, y);
			diamonds << QPoint(x, y + 1);
			diamonds << QPoint(x, y + 2);
			if (y + 3 >= gridSize)
			{
				y += 2;
				continue;
			}
			for (yh = y + 3; yh <= gridSize - 1; ++yh)
			{
				if (currentColor == C(x, yh))
					diamonds << QPoint(x, yh);
				else
					break;
			}
			y = yh - 1;
		}
	}
#undef C
	return diamonds;
}

void Game::showHint()
{
	if (m_availableMoves.isEmpty() || !m_board->selections().isEmpty())
		return;
	const QPoint location = m_availableMoves.value(qrand() % m_availableMoves.size());
	m_board->setSelection(location, true);
	m_gameState->removePoints(3);
}

void Game::animationFinished()
{
	if (m_timerId == -1)
		m_timerId = startTimer(UpdateInterval);
}

void Game::stateChange(KDiamond::State state)
{
	m_board->setPaused(state == KDiamond::Paused);
	switch ((int) state)
	{
		case KDiamond::Finished:
			m_board->clearSelection();
			m_jobQueue << KDiamond::EndGameJob;
			break;
		case KDiamond::Playing:
			if (m_timerId == -1)
				m_timerId = startTimer(UpdateInterval);
			break;
	}
}

void Game::message(const QString &message)
{
	if (message.isEmpty())
		m_messenger->forceHide();
	else
		m_messenger->showMessage(message, KGamePopupItem::TopLeft);
}

#include "game.moc"
