// This class stores information about settled blocks.
import java.awt.*;

public class TetrisMatrix
{
	// Two-dimensional matrix for holding the settled tetris pieces.
	TetrisBlock[][] matrix;
	
	public TetrisMatrix()
	{
		matrix = new TetrisBlock[20][10];
	}
	
	// Check to see if the position located at x, y is holding a block.
	public boolean positionEmpty(int x, int y)
	{
		if (x > 9 || x < 0 || y < 0 || y > 19)
			return false;
		
		return matrix[y][x] != null;
	}
	
	// Add a tetris piece to the matrix and return how many lines were cleared.
	public int addTetroid (TetrisPiece n)
	{
		TetrisBlock[] b = n.getBlocks();
		
		// Add the tetroid to the matrix.
		for (int i = 0; i < 4; i++)
			matrix[b[i].getY()][b[i].getX()] = b[i];
		
		int numLines = 0;
		int[] linesToClear = new int[4];
		
		// Find out which, if any, lines need clearing
		for (int i = 0; i < 20; i++)
		{
			for (int j = 0; j < 10; j++)
				if (matrix[i][j] == null)
					break;
			else if (j == 9)
				linesToClear[numLines++] = i;
				
		}
		
		// Clear any lines that need it
		if (numLines > 0)
		{
			for (int i = 0; i < numLines; i++)
			{
				for (int j = linesToClear[i]; j > 0; j--)
				{
					for (int k = 0; k < 10; k++)
					{
						matrix[j][k] = matrix[j-1][k];
						if (matrix[j][k] != null)
							matrix[j][k].modifyPosition(0,1); // move blocks drawing position down one
					}
				}
				
				for (int k = 0; k < 10; k++)
					matrix[0][k] = null;
			}
		}
		
		return numLines;
	}
	
	// For game over, fill in a line of the matrix with gray blocks.
	public void grayOutLine(int line)
	{
		for (int i = 0; i < 10; i++)
			matrix[line][i] = new TetrisBlock(0, i, line);
	}
	
	// Draw each block of the matrix.
	public void draw(Graphics g)
	{
		for (int i = 0; i < 20; i++)
			for(int j = 0; j < 10; j++)
				if (matrix[i][j] != null)
					matrix[i][j].draw(g);
	}
}