package dotsandboxes;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.function.Consumer;
/**
* The state of a dots and boxes grid.
*
* A (4, 3) dots and boxes grid looks like this:
*
* *-*-*-*
* | | | |
* *-*-*-*
* | | | |
* *-*-*-*
*
* Notice that:
*
* - for each row, there is one less horizontal than the number of corner dots
* - for each row, there are as many verticals as there are corner dots
* - for each row, there is one less box than the number of corner dots
* - for each column, there is one less vertical than the number of corner dots.
* - for each column, there are as many horizontals as there are corner dots.
* - for each column, there is one less box than the number of corner dots
*
* For example, in this (4, 3) grid, there are (3, 3) horizontal lines, and (4, 2) vertical lines, and (3, 2) boxes.
*
* We number all lines and boxes by their top-left coordinate.
*
* In Java 14+, we might use a Record class for this, but we're using 11+ as an LTS version, so we don't have that yet.
*/
public class DotsAndBoxesGrid {
final int width;
final int height;
/** The horizontal lines in the grid. True if drawn. */
private boolean[][] horizontals;
/** The vertical lines in the grid. True if drawn. */
private boolean[][] verticals;
/** Which owner (if any) claimed any given box. */
private int[][] boxOwners;
/** A list of functions to notify when there is an update */
private ArrayList<Consumer<DotsAndBoxesGrid>> watchers = new ArrayList<>();
final int players;
private int player = 1;
public int getPlayer() {
return player;
}
/** Moves to the next player */
private void nextPlayer() {
player++;
if (player > players) {
player = 1;
}
}
public DotsAndBoxesGrid(int width, int height, int players) {
this.width = width;
this.height = height;
this.players = players;
this.horizontals = new boolean[width - 1][height];
this.verticals = new boolean[width][height - 1];
this.boxOwners = new int[width - 1][height - 1];
}
private void notifyObservers() {
for (Consumer<DotsAndBoxesGrid> consumer : watchers) {
consumer.accept(this);
}
}
/** Listens to this grid for changes */
public void addConsumer(Consumer<DotsAndBoxesGrid> consumer) {
watchers.add(consumer);
}
/** Returns whether a horizontal line has been drawn */
public boolean getHorizontal(int x, int y) {
return horizontals[x][y];
}
/** Returns whether a vertical line has been drawn */
public boolean getVertical(int x, int y) {
return verticals[x][y];
}
/** Returns which player owns a box. By convention, 0 is unowned. */
public int getBoxOwner(int x, int y) {
return boxOwners[x][y];
}
/**
* Checks whether a box has been fully drawn (all four sides)
* @param x coordinate of the left side of the box
* @param y coordinate of the top of the box
* @return true if all four sides have been drawn.
*/
public boolean boxComplete(int x, int y) {
if (x >= width - 1 || x < 0 || y >= height - 1 || y < 0) {
return false;
}
// A box is complete if the north and south horizontals and the east and west verticals have all been drawn.
if (this.verticals[x][y] && this.verticals[x+1][y] && this.horizontals[x][y] && this.horizontals[x][y+1]){
return true;
}
return false;
}
/** Tries to claim a box for a player. If the box is complete, sets the ownership and returns true. */
private boolean claimBox(int x, int y, int p) {
if (boxComplete(x, y)) {
boxOwners[x][y] = player;
return true;
} else {
return false;
}
}
/**
* "Draws" a horizontal line, from grid point (x, y) to (x + 1, y). (i.e. sets that line to true)
* @param x
* @param y
* @return true if it completes a box
*/
public boolean drawHorizontal(int x, int y, int player) {
if (x >= width - 1 || x < 0) {
throw new IndexOutOfBoundsException(String.format("x was %d, which is out of range. Range is 0 to %d", x, width - 1));
}
if (y >= height || y < 0) {
throw new IndexOutOfBoundsException(String.format("y was %d, which is out of range. Range is 0 to %d", y, height));
}
if (this.horizontals[x][y]){
throw new IllegalStateException(String.format("Attempted redraw of preexisting line"));
}
this.horizontals[x][y] = true;
// Try to claim the north or south boxes
boolean claimN = claimBox(x, y-1, player);
boolean claimS = claimBox(x, y, player);
if (claimN || claimS) {
notifyObservers();
return true;
} else {
nextPlayer();
notifyObservers();
return false;
}
}
/**
* "Draws" a vertical line, from grid point (x, y) to (x, y + 1). (i.e. sets that line to true)
* @param x
* @param y
* @return true if it completes a box
*/
public boolean drawVertical(int x, int y, int player) {
if (x >= width || x < 0) {
throw new IndexOutOfBoundsException(String.format("x was %d, which is out of range. Range is 0 to %d", x, width));
}
if (y >= height - 1 || y < 0) {
throw new IndexOutOfBoundsException(String.format("y was %d, which is out of range. Range is 0 to %d", y, height - 1));
}
if (this.verticals[x][y]){
throw new IllegalStateException(String.format("Attempted redraw of preexisting line"));
}
this.verticals[x][y] = true;
// Try to claim the north or south boxes
boolean claimE = claimBox(x, y, player);
boolean claimW = claimBox(x-1, y, player);
if (claimE || claimW) {
notifyObservers();
return true;
} else {
nextPlayer();
notifyObservers();
return false;
}
}
public boolean gameComplete() {
// Students who took COSC250 might recognise this style of code. This is Java's version of higher order functions.
// The grid is complete if "for all rows, all the boxes in that row have a non-zero owner"
return Arrays.stream(boxOwners).allMatch((row) -> Arrays.stream(row).allMatch((owner) -> owner > 0));
}
}