maze-generator/src/main/java/ch/fritteli/maze/generator/model/Maze.java

package ch.fritteli.maze.generator.model;

import io.vavr.control.Option;
import lombok.EqualsAndHashCode;
import lombok.Getter;
import lombok.NonNull;
import lombok.ToString;

@EqualsAndHashCode
@ToString
public class Maze {

    private final Tile[][] field;
    @Getter
    private final int width;
    @Getter
    private final int height;
    @Getter
    private final long randomSeed;
    @Getter
    private final Position start;
    @Getter
    private final Position end;

    public Maze(final int width, final int height) {
        this(width, height, System.nanoTime());
    }

    public Maze(final int width, final int height, @NonNull final Position start, @NonNull final Position end) {
        this(width, height, System.nanoTime(), start, end);
    }

    public Maze(final int width, final int height, final long randomSeed) {
        this(width, height, randomSeed, new Position(0, 0), new Position(width - 1, height - 1));
    }

    public Maze(final int width, final int height, final long randomSeed, @NonNull final Position start, @NonNull final Position end) {
        if (width <= 1 || height <= 1) {
            throw new IllegalArgumentException("width and height must be >1");
        }
        if (start.equals(end)) {
            throw new IllegalArgumentException("'start' must not be equal to 'end'");
        }
        if (start.getX() != 0 && start.getX() != width - 1 && start.getY() != 0 && start.getY() != height - 1) {
            throw new IllegalArgumentException("'start' must be at the edge of the maze");
        }
        if (end.getX() != 0 && end.getX() != width - 1 && end.getY() != 0 && end.getY() != height - 1) {
            throw new IllegalArgumentException("'end' must be at the edge of the maze");
        }
        this.width = width;
        this.height = height;
        this.randomSeed = randomSeed;
        this.field = new Tile[width][height];
        this.start = start;
        this.end = end;
        this.initField();
    }

    /**
     * INTERNAL API. Exists only for deserialization. Not to be called from user code.
     */
    private Maze(@NonNull final Tile[][] field, final int width, final int height, final long randomSeed) {
        this.field = field;
        this.width = width;
        this.height = height;
        this.randomSeed = randomSeed;
        this.start = new Position(0, 0);
        this.end = new Position(this.width - 1, this.height - 1);
    }

    /**
     * INTERNAL API. Exists only for deserialization. Not to be called from user code.
     */
    private Maze(@NonNull final Tile[][] field, final int width, final int height, @NonNull final Position start, @NonNull final Position end, final long randomSeed) {
        this.field = field;
        this.width = width;
        this.height = height;
        this.randomSeed = randomSeed;
        this.start = start;
        this.end = end;
    }

    @NonNull
    public Option<Tile> getTileAt(@NonNull final Position position) {
        return this.getTileAt(position.getX(), position.getY());
    }

    @NonNull
    public Option<Tile> getTileAt(final int x, final int y) {
        if (x < 0 || y < 0 || x >= this.width || y >= this.height) {
            return Option.none();
        }
        return Option.of(this.field[x][y]);
    }

    @NonNull
    public Tile getStartTile() {
        return this.getTileAt(this.start).get();
    }

    @NonNull
    public Tile getEndTile() {
        return this.getTileAt(this.end).get();
    }

    private void initField() {
        for (int x = 0; x < this.width; x++) {
            this.field[x] = new Tile[this.height];
            for (int y = 0; y < this.height; y++) {
                final Tile tile = new Tile();
                this.hardenWalls(tile, x, y);
                this.field[x][y] = tile;
            }
        }
    }

    private void hardenWalls(@NonNull final Tile tile, final int x, final int y) {
        if (x == 0) {
            tile.preventDiggingToOrFrom(Direction.LEFT);
        }
        if (x == this.width - 1) {
            tile.preventDiggingToOrFrom(Direction.RIGHT);
        }
        if (y == 0) {
            tile.preventDiggingToOrFrom(Direction.TOP);
        }
        if (y == this.height - 1) {
            tile.preventDiggingToOrFrom(Direction.BOTTOM);
        }
    }
}