function TetrixBoard(ui)

{

    this.ui = ui;

    this.isStarted = false;

    this.isPaused = false;

    this.inKeyPress = false;

    this._board = new Array(TetrixBoard.BoardWidth * TetrixBoard.BoardHeight);

    this.clearBoard();

    this.curPiece = new TetrixPiece();

    this.nextPiece = new TetrixPiece();

    this.nextPiece.setRandomShape();

    ui.timer.singleShot = true;

    ui.timer.timeout.connect(this, this.onTimer);

    ui.keyPressed.connect(this, this.onKeyPress);

    ui.paintRequested.connect(this, this.onPaint);

    ui.paintNextPieceRequested.connect(this, this.onPaintNextPiece);

}

TetrixBoard.BoardWidth = 10;

TetrixBoard.BoardHeight = 22;

TetrixBoard.prototype.start = function() {

    if (this.isPaused)

        return;

    this.isStarted = true;

    this.isWaitingAfterLine = false;

    this.numLinesRemoved = 0;

    this.numPiecesDropped = 0;

    this.score = 0;

    this.level = 1;

    this.clearBoard();

    this.ui.linesRemovedChanged(this.numLinesRemoved);

    this.ui.scoreChanged(this.score);

    this.ui.levelChanged(this.level);

    this.newPiece();

    this.ui.timer.start(this.timeoutTime());

}

TetrixBoard.prototype.pause = function() {

    if (!this.isStarted)

        return;

    this.isPaused = !this.isPaused;

    if (this.isPaused) {

        this.ui.timer.stop();

    } else {

        this.ui.timer.start(this.timeoutTime());

    }

    this.ui.update();

}

TetrixBoard.prototype.getShapeAt = function(x, y) {

    return this._board[(y * TetrixBoard.BoardWidth) + x];

}

TetrixBoard.prototype.setShapeAt = function(x, y, newShape) {

    this._board[(y * TetrixBoard.BoardWidth) + x] = newShape;

}

TetrixBoard.prototype.clearBoard = function() {

    for (var i = 0; i < TetrixBoard.BoardHeight * TetrixBoard.BoardWidth; ++i)

        this._board[i] = TetrixShape.NoShape;

}

TetrixBoard.prototype.dropDown = function() {

    var dropHeight = 0;

    var newY = this.curY;

    while (newY > 0) {

        if (!this.tryMove(this.curPiece, this.curX, newY - 1))

            break;

        --newY;

        ++dropHeight;

    }

    this.pieceDropped(dropHeight);

}

TetrixBoard.prototype.oneLineDown = function() {

    if (!this.tryMove(this.curPiece, this.curX, this.curY - 1))

        this.pieceDropped(0);

}

TetrixBoard.prototype.pieceDropped = function(dropHeight) {

    for (var i = 0; i < 4; ++i) {

        var x = this.curX + this.curPiece.getX(i);

        var y = this.curY - this.curPiece.getY(i);

        this.setShapeAt(x, y, this.curPiece.shape);

    }

    ++this.numPiecesDropped;

    if ((this.numPiecesDropped % 25) == 0) {

        ++this.level;

        this.ui.timer.start(this.timeoutTime());

        this.ui.levelChanged(this.level);

    }

    this.score += dropHeight + 7;

    this.ui.scoreChanged(this.score);

    this.removeFullLines();

    if (!this.isWaitingAfterLine)

        this.newPiece();

    if (this.isStarted && !this.ui.timer.active)

        this.ui.timer.start(this.timeoutTime());

}

TetrixBoard.prototype.removeFullLines = function() {

    var numFullLines = 0;

    for (var i = TetrixBoard.BoardHeight - 1; i >= 0; --i) {

        var lineIsFull = true;

        for (var j = 0; j < TetrixBoard.BoardWidth; ++j) {

            if (this.getShapeAt(j, i) == TetrixShape.NoShape) {

                lineIsFull = false;

                break;

            }

        }

        if (lineIsFull) {

            ++numFullLines;

            for (var k = i; k < TetrixBoard.BoardHeight - 1; ++k) {

                for (var j = 0; j < TetrixBoard.BoardWidth; ++j)

                    this.setShapeAt(j, k, this.getShapeAt(j, k + 1));

            }

            for (var j = 0; j < TetrixBoard.BoardWidth; ++j)

                this.setShapeAt(j, TetrixBoard.BoardHeight - 1, TetrixShape.NoShape);

        }

    }

    if (numFullLines > 0) {

        this.numLinesRemoved += numFullLines;

        this.score += 10 * numFullLines;

        this.ui.linesRemovedChanged(this.numLinesRemoved);

        this.ui.scoreChanged(this.score);

        this.ui.timer.start(500);

        this.isWaitingAfterLine = true;

        this.curPiece.shape = TetrixShape.NoShape;

        this.ui.update();

    }

}

TetrixBoard.prototype.newPiece = function() {

    this.curPiece = this.nextPiece;

    this.nextPiece = new TetrixPiece();

    this.nextPiece.setRandomShape();

    this.ui.showNextPiece(this.nextPiece.maxX - this.nextPiece.minX + 1,

                          this.nextPiece.maxY - this.nextPiece.minY + 1);

    this.curX = TetrixBoard.BoardWidth / 2 + 1;

    this.curY = TetrixBoard.BoardHeight - 1 + this.curPiece.minY;

    if (!this.tryMove(this.curPiece, this.curX, this.curY)) {

        this.curPiece.shape = TetrixShape.NoShape;

        this.ui.timer.stop();

        this.isStarted = false;

    }

}

TetrixBoard.prototype.tryMove = function(newPiece, newX, newY) {

    for (var i = 0; i < 4; ++i) {

        var x = newX + newPiece.getX(i);

        var y = newY - newPiece.getY(i);

        if ((x < 0) || (x >= TetrixBoard.BoardWidth) || (y < 0) || (y >= TetrixBoard.BoardHeight))

            return false;

        if (this.getShapeAt(x, y) != TetrixShape.NoShape)

            return false;

    }

    this.curPiece = newPiece;

    this.curX = newX;

    this.curY = newY;

    this.ui.update();

    return true;

}

TetrixBoard.prototype.onPaint = function(painter) {

    if (this.isPaused) {

        this.ui.drawPauseScreen(painter);

        return;

    }

    for (var i = 0; i < TetrixBoard.BoardHeight; ++i) {

        for (var j = 0; j < TetrixBoard.BoardWidth; ++j) {

            var shape = this.getShapeAt(j, TetrixBoard.BoardHeight - i - 1);

            if (shape != TetrixShape.NoShape)

                this.ui.drawSquare(painter, j, i, shape);

        }

    }

    if (this.curPiece.shape != TetrixShape.NoShape) {

        for (var i = 0; i < 4; ++i) {

            var x = this.curX + this.curPiece.getX(i);

            var y = this.curY - this.curPiece.getY(i);

            this.ui.drawSquare(painter, x, TetrixBoard.BoardHeight - y - 1,

                               this.curPiece.shape);

        }

    }

}

TetrixBoard.prototype.onPaintNextPiece = function(painter) {

    for (var i = 0; i < 4; ++i) {

        var x = this.nextPiece.getX(i) - this.nextPiece.minX;

        var y = this.nextPiece.getY(i) - this.nextPiece.minY;

        this.ui.drawSquare(painter, x, y, this.nextPiece.shape);

    }

}

TetrixBoard.prototype.onKeyPress = function(key) {

    if (!this.isStarted || this.isPaused || (this.curPiece.shape == TetrixShape.NoShape))

        return;

    this.inKeyPress = true;

    switch (key) {

        case Qt.Key_Left:

            this.tryMove(this.curPiece, this.curX - 1, this.curY);

            break;

        case Qt.Key_Right:

            this.tryMove(this.curPiece, this.curX + 1, this.curY);

            break;

        case Qt.Key_Down:

            this.tryMove(this.curPiece.rotatedRight(), this.curX, this.curY);

            break;

        case Qt.Key_Up:

            this.tryMove(this.curPiece.rotatedLeft(), this.curX, this.curY);

            break;

        case Qt.Key_Space:

            this.dropDown();

            break;

        case Qt.Key_D:

            this.oneLineDown();

            break;

    }

    this.inKeyPress = false;

    if (this.isStarted && !this.ui.timer.active)

        this.ui.timer.start(this.timeoutTime());

}

TetrixBoard.prototype.onTimer = function() {

    if (this.isWaitingAfterLine) {

        this.isWaitingAfterLine = false;

        this.newPiece();

        this.ui.timer.start(this.timeoutTime());

    } else {

        if (!this.inKeyPress) {

            this.oneLineDown();

            if (this.isStarted && !this.ui.timer.active)

                this.ui.timer.start(this.timeoutTime());

        }

    }

}

TetrixBoard.prototype.timeoutTime = function() {

    return 1000 / (1 + this.level);

}