ExampleProvider.java

package de.zalando.toga.provider;

import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ObjectNode;
import com.google.common.annotations.VisibleForTesting;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import static java.util.Arrays.asList;
import static java.util.regex.Pattern.compile;
import static java.util.stream.Collectors.toList;

public final class ExampleProvider {

    private final File sourceDir;

    @VisibleForTesting
    ObjectMapper mapper = new ObjectMapper();;


    /**
     * Create a new ExampleProvider.
     * @param sourceDir the directory to read examples from. Must point to a folder and not a file.
     * @throws IllegalArgumentException if the directory is either null, does not exist or is a file.
     */
    public ExampleProvider(File sourceDir) {

        if (sourceDir == null) {
            throw new IllegalArgumentException("sourceDir must not be null!");
        }

        if (!sourceDir.exists()) {
            throw new IllegalArgumentException("sourceDir [" + sourceDir.getAbsolutePath() + "] does not exist.");
        }

        if (sourceDir.isFile()) {
            throw new IllegalArgumentException("sourceDir [" + sourceDir.getAbsolutePath() + "] is a file.");
        }

        this.sourceDir = sourceDir;
        mapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
    }

    public List<String> getExamples(Pattern pattern) {

        List<File> sources = collectSources(pattern);
        List<String> results = new ArrayList<>();

        for (File source : sources) {
            try {
                List<ObjectNode> nodes = mapper.readValue(source, new TypeReference<List<ObjectNode>>() {});
                List<String> strings = nodes.stream().map(ObjectNode::toString).collect(toList());
                results.addAll(strings);
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }

        return results;

    }

    public List<String> getExamples(String pattern) {
        return getExamples(compile(pattern));
    }

    private List<File> collectSources(Pattern pattern) {

        File[] files = sourceDir.listFiles((dir, name) -> {
            Matcher matcher = pattern.matcher(name);
            return matcher.find();
        });

        return new ArrayList<File>(asList(files));
    }
}