maze-generator/src/main/java/ch/fritteli/maze/generator/renderer/text/Generator.java

package ch.fritteli.maze.generator.renderer.text;

import ch.fritteli.maze.generator.model.Direction;
import ch.fritteli.maze.generator.model.Maze;
import ch.fritteli.maze.generator.model.Tile;
import io.vavr.control.Option;
import lombok.AccessLevel;
import lombok.NonNull;
import lombok.RequiredArgsConstructor;

@RequiredArgsConstructor(access = AccessLevel.PACKAGE)
class Generator {
    @NonNull
    private final Maze maze;
    private final boolean renderSolution;
    private int x = 0;
    private int y = 0;
    // Each row has three lines:
    // - The top border
    // - The central pathway
    // - The bottom border
    // The bottom border of one row is identical to the top border of the following row. We use this variable here in
    // order to be able to render the bottom border of the last row, which obviously does not have a following row with
    // a top border.
    private int line = 0;

    boolean hasNext() {
        return this.y < this.maze.getHeight();
    }

    String next() {
        final Tile currentTile = this.maze.getTileAt(this.x, this.y).get();
        final Option<Tile> topTile = this.maze.getTileAt(this.x, this.y - 1);
        final Option<Tile> rightTile = this.maze.getTileAt(this.x + 1, this.y);
        final Option<Tile> bottomTile = this.maze.getTileAt(this.x, this.y + 1);
        final Option<Tile> leftTile = this.maze.getTileAt(this.x - 1, this.y);
        final String s;
        switch (this.line) {
            case 0:
                s = this.renderTopLine(currentTile, leftTile, topTile);
                break;
            case 1:
                s = this.renderCenterLine(currentTile, topTile, rightTile, bottomTile, leftTile);
                break;
            case 2:
                s = this.renderBottomLine(currentTile, leftTile);
                break;
            default:
                s = "";
                break;
        }
        this.prepareNextStep();
        return s;
    }

    private void prepareNextStep() {
        // do some magic ...
        this.x++;
        if (this.x == this.maze.getWidth()) {
            // Reached the end of the row?
            // On to the next line then!
            this.x = 0;
            this.line++;
        }
        if (this.line == 2 && this.y < this.maze.getHeight() - 1) {
            // Finished rendering the center line, and more rows available?
            // On to the next row then!
            this.line = 0;
            this.y++;
        }
        if (this.line == 3) {
            // Finished rendering the bottom line (of the last row)?
            // Increment row counter one more time => this is the exit condition.
            this.line = 0;
            this.y++;
        }
    }

    private String renderTopLine(@NonNull final Tile currentTile, @NonNull final Option<Tile> leftTile, @NonNull final Option<Tile> topTile) {
        final CharDefinition charDef1 = new CharDefinition();
        final CharDefinition charDef2 = new CharDefinition();
        final CharDefinition charDef3 = new CharDefinition();
        String result;
        if (currentTile.hasWallAt(Direction.LEFT)) {
            charDef1.down();
        }
        if (currentTile.hasWallAt(Direction.TOP)) {
            charDef1.right();
            charDef2.horizontal();
            charDef3.left();
        } else {
            if (this.isSolution(currentTile) && (this.isSolution(topTile) || topTile.isEmpty())) {
                charDef2.solution().vertical();
            }
        }
        if (currentTile.hasWallAt(Direction.RIGHT)) {
            charDef3.down();
        }
        if (this.hasWallAt(leftTile, Direction.TOP)) {
            charDef1.left();
        }
        if (this.hasWallAt(topTile, Direction.LEFT)) {
            charDef1.up();
        }
        if (this.hasWallAt(topTile, Direction.RIGHT)) {
            charDef3.up();
        }
        result = charDef1.toString() + charDef2;
        if (this.x == this.maze.getWidth() - 1) {
            result += charDef3 + "\n";
        }
        return result;
    }

    private String renderCenterLine(@NonNull final Tile currentTile,
                                    @NonNull final Option<Tile> topTile,
                                    @NonNull final Option<Tile> rightTile,
                                    @NonNull final Option<Tile> bottomTile,
                                    @NonNull final Option<Tile> leftTile) {
        final CharDefinition charDef1 = new CharDefinition();
        final CharDefinition charDef2 = new CharDefinition();
        final CharDefinition charDef3 = new CharDefinition();
        String result;
        if (currentTile.hasWallAt(Direction.LEFT)) {
            charDef1.vertical();
        } else {
            if (this.isSolution(currentTile) && this.isSolution(leftTile)) {
                charDef1.solution().horizontal();
            }
        }
        if (this.isSolution(currentTile)) {
            charDef2.solution();
            if (!currentTile.hasWallAt(Direction.LEFT) && (this.isSolution(leftTile) || leftTile.isEmpty())) {
                charDef2.left();
            }
            if (!currentTile.hasWallAt(Direction.TOP) && (this.isSolution(topTile) || topTile.isEmpty())) {
                charDef2.up();
            }
            if (!currentTile.hasWallAt(Direction.RIGHT) && (this.isSolution(rightTile) || rightTile.isEmpty())) {
                charDef2.right();
            }
            if (!currentTile.hasWallAt(Direction.BOTTOM) && (this.isSolution(bottomTile) || bottomTile.isEmpty())) {
                charDef2.down();
            }
        }
        if (currentTile.hasWallAt(Direction.RIGHT)) {
            charDef3.vertical();
        } else {
            if (this.isSolution(currentTile) && this.isSolution(rightTile)) {
                charDef3.solution().horizontal();
            }
        }

        result = charDef1.toString() + charDef2;

        if (this.x == this.maze.getWidth() - 1) {
            result += charDef3 + "\n";
        }

        return result;
    }

    private String renderBottomLine(@NonNull final Tile currentTile, @NonNull final Option<Tile> leftTile) {
        String result;
        final CharDefinition charDef1 = new CharDefinition();
        final CharDefinition charDef2 = new CharDefinition();
        final CharDefinition charDef3 = new CharDefinition();

        if (currentTile.hasWallAt(Direction.LEFT)) {
            charDef1.up();
        }
        if (currentTile.hasWallAt(Direction.BOTTOM)) {
            charDef1.right();
            charDef2.horizontal();
            charDef3.left();
        } else {
            if (this.isSolution(currentTile)) {
                charDef2.solution().vertical();
            }
        }
        if (currentTile.hasWallAt(Direction.RIGHT)) {
            charDef3.up();
        }
        if (this.hasWallAt(leftTile, Direction.BOTTOM)) {
            charDef1.left();
        }

        result = charDef1.toString() + charDef2;

        if (this.x == this.maze.getWidth() - 1) {
            result += charDef3;
        }
        return result;
    }

    private boolean hasWallAt(@NonNull final Option<Tile> tile, @NonNull final Direction direction) {
        return tile.map(t -> t.hasWallAt(direction)).getOrElse(false);
    }

    private boolean isSolution(@NonNull final Tile tile) {
        return this.renderSolution && tile != null && tile.isSolution();
    }

    private boolean isSolution(@NonNull final Option<Tile> tile) {
        return this.renderSolution && tile.map(Tile::isSolution).getOrElse(false);
    }
}