Generator.java

package de.zalando.toga.generator;

import com.fasterxml.jackson.databind.JsonNode;
import com.github.fge.jackson.JsonLoader;
import de.zalando.toga.generator.dimensions.ObjectDimension;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.Writer;

/**
 *
 */
public class Generator {

    private ObjectDimension dimension;

    /**
     * Load a json-schema specification from a file. After this method returns one can use the Generator instance
     * to render all generated example objects into a file.
     * @param file the json-schema specification to use
     */
    public void load(File file) {
        try {
            JsonNode node = JsonLoader.fromFile(file);
            // TODO: this should also work without a title....
            String title = node.get("title").asText();
            JsonNode properties = node.get("properties");

            dimension = new ObjectDimension(title, properties);
        } catch (IOException e) {
            throw new IllegalStateException(e);
        }
    }

    /**
     * Generate the test data to an output file.
     * This method takes all examples generated by the spec loaded previously and renders the resulting json to a file.
     * @param file - the output file. If it exists it will be overwritten.
     */
    public void generate(File file) {

        if (file == null) {
            throw new NullPointerException("Target File may not be null");
        }

        if (file.isDirectory()) {
            throw new IllegalArgumentException("Target file is a directory.");
        }

        if (file.exists()) {
            if (!file.delete()) {
                throw new IllegalStateException("Could not delete already existing output file [" + file.getAbsolutePath() + "].");
            }
        } else {
            // TODO: tests
            File parent = file.getParentFile();
            if (!parent.exists() && !parent.mkdirs()) {
                throw new IllegalStateException("Could not create target directory.");
            }
        }

        if (dimension == null) {
            throw new IllegalStateException("No JSON schema has been loaded. Cannot generate output.");
        }

        try {
            Writer writer = new PrintWriter(file);
            writer.write(dimension.generateJson());
            writer.flush();
        } catch (FileNotFoundException e) {
            throw new IllegalArgumentException("File [" + file.getAbsolutePath() + "] could not be created.");
        } catch (IOException e) {
            throw new RuntimeException("There has been a problem with the output file.", e);
        }
    }
}