Implement a JSON and a JSON-file renderer.

pom.xml

@@ -15,6 +15,7 @@
     <url>https://manuel.friedli.info/labyrinth.html</url>
 
     <properties>
+        <jackson.version>2.14.2</jackson.version>
         <java.source.version>17</java.source.version>
         <java.target.version>17</java.target.version>
         <jetbrains-annotations.version>24.0.1</jetbrains-annotations.version>
@@ -59,6 +60,16 @@
             <artifactId>pdfbox</artifactId>
             <version>${pdfbox.version}</version>
         </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-annotations</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
         <dependency>
             <groupId>org.slf4j</groupId>
             <artifactId>slf4j-api</artifactId>
@@ -82,6 +93,24 @@
     </dependencies>
     <build>
         <plugins>
+            <plugin>
+                <groupId>org.jsonschema2pojo</groupId>
+                <artifactId>jsonschema2pojo-maven-plugin</artifactId>
+                <version>1.2.1</version>
+                <executions>
+                    <execution>
+                        <phase>generate-sources</phase>
+                        <goals>
+                            <goal>generate</goal>
+                        </goals>
+                        <configuration>
+                            <sourcePaths>
+                                <sourcePath>src/main/resources/labyrinth.schema.json</sourcePath>
+                            </sourcePaths>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
             <plugin>
                 <artifactId>maven-assembly-plugin</artifactId>
                 <configuration>

src/main/java/ch/fritteli/labyrinth/generator/Main.java

@@ -3,23 +3,28 @@ package ch.fritteli.labyrinth.generator;
 import ch.fritteli.labyrinth.generator.model.Labyrinth;
 import ch.fritteli.labyrinth.generator.renderer.html.HTMLRenderer;
 import ch.fritteli.labyrinth.generator.renderer.htmlfile.HTMLFileRenderer;
+import ch.fritteli.labyrinth.generator.renderer.json.JsonRenderer;
+import ch.fritteli.labyrinth.generator.renderer.jsonfile.JsonFileRenderer;
 import ch.fritteli.labyrinth.generator.renderer.pdffile.PDFFileRenderer;
 import ch.fritteli.labyrinth.generator.renderer.text.TextRenderer;
 import ch.fritteli.labyrinth.generator.renderer.textfile.TextFileRenderer;
-import lombok.NonNull;
-import lombok.extern.slf4j.Slf4j;
-
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import lombok.NonNull;
+import lombok.experimental.UtilityClass;
+import lombok.extern.slf4j.Slf4j;
 
 @Slf4j
+@UtilityClass
 public class Main {
+
     public static void main(@NonNull final String[] args) {
         final int width = 20;
         final int height = 30;
         final Labyrinth labyrinth = new Labyrinth(width, height/*, 0*/);
         final TextRenderer textRenderer = TextRenderer.newInstance();
         final HTMLRenderer htmlRenderer = HTMLRenderer.newInstance();
+        final JsonRenderer jsonRenderer = JsonRenderer.newInstance();
         final Path userHome = Paths.get(System.getProperty("user.home"));
         final String baseFilename = getBaseFilename(labyrinth);
         final TextFileRenderer textFileRenderer = TextFileRenderer.newInstance()
@@ -27,6 +32,8 @@ public class Main {
                 .setTargetSolutionFile(userHome.resolve(baseFilename + "-solution.txt"));
         final HTMLFileRenderer htmlFileRenderer = HTMLFileRenderer.newInstance()
                 .setTargetFile(userHome.resolve(baseFilename + ".html"));
+        final JsonFileRenderer jsonFileRenderer = JsonFileRenderer.newInstance()
+                .setTargetFile(userHome.resolve(baseFilename + ".json"));
         final PDFFileRenderer pdfFileRenderer = PDFFileRenderer.newInstance()
                 .setTargetFile(userHome.resolve(baseFilename + ".pdf"));
 
@@ -37,10 +44,14 @@ public class Main {
         log.info("Text rendering with solution:\n{}", textRenderer.setRenderSolution(true).render(labyrinth));
         // Render HTML to stdout
         log.info("HTML rendering:\n{}", htmlRenderer.render(labyrinth));
+        // Render JSON to stdout
+        log.info("JSON rendering:\n{}", jsonRenderer.render(labyrinth));
         // Render Labyrinth and solution to (separate) files
         log.info("Text rendering to file:\n{}", textFileRenderer.render(labyrinth));
         // Render HTML to file
         log.info("HTML rendering to file:\n{}", htmlFileRenderer.render(labyrinth));
+        // Render JSON to file
+        log.info("JSON rendering to file:\n{}", jsonFileRenderer.render(labyrinth));
         // Render PDF to file
         log.info("PDF rendering to file:\n{}", pdfFileRenderer.render(labyrinth));
     }

src/main/java/ch/fritteli/labyrinth/generator/renderer/json/Generator.java

@@ -0,0 +1,48 @@
+package ch.fritteli.labyrinth.generator.renderer.json;
+
+import ch.fritteli.labyrinth.generator.json.JsonCell;
+import ch.fritteli.labyrinth.generator.json.JsonLabyrinth;
+import ch.fritteli.labyrinth.generator.model.Direction;
+import ch.fritteli.labyrinth.generator.model.Labyrinth;
+import ch.fritteli.labyrinth.generator.model.Tile;
+import java.util.ArrayList;
+import java.util.List;
+import lombok.AccessLevel;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
+
+@RequiredArgsConstructor(access = AccessLevel.PACKAGE)
+class Generator {
+
+    @NonNull
+    private final Labyrinth labyrinth;
+
+    @NonNull
+    JsonLabyrinth generate() {
+        final JsonLabyrinth result = new JsonLabyrinth();
+        result.setId(this.labyrinth.getRandomSeed());
+        result.setWidth(this.labyrinth.getWidth());
+        result.setHeight(this.labyrinth.getHeight());
+        final List<List<JsonCell>> rows = new ArrayList<>();
+        for (int y = 0; y < this.labyrinth.getHeight(); y++) {
+            final ArrayList<JsonCell> row = new ArrayList<>();
+            for (int x = 0; x < this.labyrinth.getWidth(); x++) {
+                // x and y are not effectively final and can therefore not be accessed from within the lambda. Hence, create the string beforehand.
+                final String exceptionString = "Failed to obtain tile at %dx%d, although labyrinth has dimensoins %dx%d"
+                        .formatted(x, y, this.labyrinth.getWidth(), this.labyrinth.getHeight());
+                final Tile tile = this.labyrinth.getTileAt(x, y)
+                        .getOrElseThrow(() -> new IllegalStateException(exceptionString));
+                final JsonCell cell = new JsonCell();
+                cell.setTop(tile.hasWallAt(Direction.TOP));
+                cell.setRight(tile.hasWallAt(Direction.RIGHT));
+                cell.setBottom(tile.hasWallAt(Direction.BOTTOM));
+                cell.setLeft(tile.hasWallAt(Direction.LEFT));
+                cell.setSolution(tile.isSolution());
+                row.add(cell);
+            }
+            rows.add(row);
+        }
+        result.setGrid(rows);
+        return result;
+    }
+}

src/main/java/ch/fritteli/labyrinth/generator/renderer/json/JsonRenderer.java

@@ -0,0 +1,68 @@
+package ch.fritteli.labyrinth.generator.renderer.json;
+
+import ch.fritteli.labyrinth.generator.json.JsonCell;
+import ch.fritteli.labyrinth.generator.json.JsonLabyrinth;
+import ch.fritteli.labyrinth.generator.model.Labyrinth;
+import ch.fritteli.labyrinth.generator.renderer.Renderer;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.SerializationFeature;
+import java.util.ArrayList;
+import java.util.List;
+import lombok.NonNull;
+
+public class JsonRenderer implements Renderer<String> {
+
+    @NonNull
+    private final ObjectMapper objectMapper;
+
+    private JsonRenderer() {
+        this.objectMapper = new ObjectMapper()
+                .enable(SerializationFeature.INDENT_OUTPUT);
+    }
+
+    @NonNull
+    public static JsonRenderer newInstance() {
+        return new JsonRenderer();
+    }
+
+    @NonNull
+    private static JsonLabyrinth createSingleCellLabyrinth() {
+        // This is the only cell.
+        final JsonCell cell = new JsonCell();
+        cell.setRight(true);
+        cell.setLeft(true);
+        cell.setSolution(true);
+        // Wrap that in a nested list.
+        final List<List<JsonCell>> rows = new ArrayList<>();
+        rows.add(new ArrayList<>());
+        rows.get(0).add(cell);
+        // Wrap it all in an instance of JsonLabyrinth.
+        final JsonLabyrinth jsonLabyrinth = new JsonLabyrinth();
+        jsonLabyrinth.setId(0L);
+        jsonLabyrinth.setGrid(rows);
+        return jsonLabyrinth;
+    }
+
+    @NonNull
+    private String toString(@NonNull final JsonLabyrinth jsonLabyrinth) {
+        try {
+            return this.objectMapper.writeValueAsString(jsonLabyrinth);
+        } catch (final JsonProcessingException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    @NonNull
+    @Override
+    public String render(@NonNull final Labyrinth labyrinth) {
+        final JsonLabyrinth jsonLabyrinth;
+        if (labyrinth.getWidth() == 0 || labyrinth.getHeight() == 0) {
+            jsonLabyrinth = createSingleCellLabyrinth();
+        } else {
+            final Generator generator = new Generator(labyrinth);
+            jsonLabyrinth = generator.generate();
+        }
+        return toString(jsonLabyrinth);
+    }
+}

src/main/java/ch/fritteli/labyrinth/generator/renderer/jsonfile/JsonFileRenderer.java

@@ -0,0 +1,68 @@
+package ch.fritteli.labyrinth.generator.renderer.jsonfile;
+
+import ch.fritteli.labyrinth.generator.model.Labyrinth;
+import ch.fritteli.labyrinth.generator.renderer.Renderer;
+import ch.fritteli.labyrinth.generator.renderer.json.JsonRenderer;
+import io.vavr.control.Option;
+import io.vavr.control.Try;
+import java.io.File;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.NoSuchElementException;
+import lombok.NonNull;
+import lombok.extern.slf4j.Slf4j;
+
+@Slf4j
+public class JsonFileRenderer implements Renderer<Path> {
+
+    @NonNull
+    private static final JsonRenderer JSON_RENDERER = JsonRenderer.newInstance();
+    @NonNull
+    private Option<Path> targetFile;
+
+    private JsonFileRenderer() {
+        this.targetFile = Try
+                .of(() -> Files.createTempFile("labyrinth_", ".json"))
+                .onFailure(ex -> log.error("Unable to set default target file.", ex))
+                .toOption();
+    }
+
+    @NonNull
+    public static JsonFileRenderer newInstance() {
+        return new JsonFileRenderer();
+    }
+
+    public boolean isTargetFileDefinedAndWritable() {
+        return this.targetFile
+                .map(Path::toFile)
+                .exists(File::canWrite);
+    }
+
+    @NonNull
+    public JsonFileRenderer setTargetFile(@NonNull final Path targetFile) {
+        this.targetFile = Option.of(targetFile);
+        return this;
+    }
+
+    @NonNull
+    @Override
+    public Path render(@NonNull final Labyrinth labyrinth) {
+        if (!this.isTargetFileDefinedAndWritable()) {
+            try {
+                Files.createFile(this.targetFile.get());
+            } catch (final IOException | NoSuchElementException e) {
+                throw new IllegalArgumentException("Cannot write to target file.", e);
+            }
+        }
+        final String json = JSON_RENDERER.render(labyrinth);
+        final Path outputFile = this.targetFile.get();
+        try {
+            Files.writeString(outputFile, json, StandardCharsets.UTF_8);
+        } catch (final IOException e) {
+            log.error("Failed writing to file %s".formatted(outputFile.normalize()), e);
+        }
+        return outputFile;
+    }
+}

src/main/resources/labyrinth.schema.json

@@ -0,0 +1,69 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://manuel.friedli.info/labyrinth-1/labyrinth.schema.json",
+  "javaType": "ch.fritteli.labyrinth.generator.json.JsonLabyrinth",
+  "type": "object",
+  "additionalProperties": false,
+  "required": [
+    "id",
+    "width",
+    "height",
+    "grid"
+  ],
+  "properties": {
+    "id": {
+      "type": "integer",
+      "existingJavaType": "java.lang.Long"
+    },
+    "width": {
+      "type": "integer",
+      "minimum": 1
+    },
+    "height": {
+      "type": "integer",
+      "minimum": 1
+    },
+    "grid": {
+      "$ref": "#/$defs/grid"
+    }
+  },
+  "$defs": {
+    "grid": {
+      "type": "array",
+      "items": {
+        "$ref": "#/$defs/row"
+      },
+      "minItems": 1
+    },
+    "row": {
+      "type": "array",
+      "items": {
+        "$ref": "#/$defs/cell"
+      },
+      "minItems": 1
+    },
+    "cell": {
+      "type": "object",
+      "javaType": "ch.fritteli.labyrinth.generator.json.JsonCell",
+      "additionalProperties": false,
+      "required": [],
+      "properties": {
+        "top": {
+          "type": "boolean"
+        },
+        "right": {
+          "type": "boolean"
+        },
+        "bottom": {
+          "type": "boolean"
+        },
+        "left": {
+          "type": "boolean"
+        },
+        "solution": {
+          "type": "boolean"
+        }
+      }
+    }
+  }
+}