/**
 * Relational pipes
 * Copyright © 2020 František Kučera (Frantovo.cz, GlobalCode.info)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, version 3 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
import java.io.File;
import java.io.IOException;
import java.util.LinkedList;
import java.util.List;
import java.util.jar.JarFile;

/**
 * <p>
 * This streamlet provides metadata from JAR (or ZIP) files.</p>
 *
 * <p>
 * With no options it returns the main class (if any) and number of entries (files and directories) in the archive.</p>
 *
 * <p>
 * Specific attributes can be selected using options – e.g. --option 'attribute' '…' Supported attributes are:</p>
 *
 * <ul>
 * <li>comment</li>
 * <li>entries</li>
 * <li>main_class</li>
 * </ul>
 */
public class JarInfo extends Streamlet {

	// TODO: total size 
	// TODO: OSGi metadata etc.
	// TODO: more OOP, move to separate repository, proper Maven project, clean-up, stabilize API
	public static final String ATTRIBUTE_COMMENT = "comment";
	public static final String ATTRIBUTE_ENTRIES = "entries";
	public static final String ATTRIBUTE_MAIN_CLASS = "main_class";

	private final List<String> jarAttributes = new LinkedList<>();

	public static void main(String[] args) throws IOException {
		JarInfo s = new JarInfo();
		int status = s.run();
		System.exit(status);
	}

	protected List<Streamlet.AttributeMetadata> getOutputAttributesMetadata() {

		List<Option> attributeOptions = getOptions("attribute");
		if (attributeOptions.isEmpty()) {
			attributeOptions.add(new Option("attribute", ATTRIBUTE_MAIN_CLASS));
			attributeOptions.add(new Option("attribute", ATTRIBUTE_ENTRIES));
		}

		List<Streamlet.AttributeMetadata> result = new LinkedList<>();

		for (int i = 0; i < attributeOptions.size(); i++) {
			Streamlet.Option o = attributeOptions.get(i);
			Streamlet.Type type;
			switch (o.value) {
				case ATTRIBUTE_COMMENT:
				case ATTRIBUTE_MAIN_CLASS:
					type = Streamlet.Type.STRING;
					break;
				case ATTRIBUTE_ENTRIES:
					type = Streamlet.Type.INTEGER;
					break;
				default:
					throw new IllegalArgumentException("Unsupported attribute: " + o.value);
			}
			result.add(new Streamlet.AttributeMetadata(getAlias(i, o.value), type));
			jarAttributes.add(o.value);
		}

		return result;
	}

	@Override
	protected List<Object> getOutputAttributes() {
		List<Object> result = new LinkedList<>();

		try {
			JarFile jar = new JarFile(new File(getCurrentFile()));

			for (String attributeName : jarAttributes) {
				switch (attributeName) {
					case ATTRIBUTE_COMMENT:
						result.add(jar.getComment());
						break;
					case ATTRIBUTE_MAIN_CLASS:
						String mainClass = jar.getManifest() == null ? null : jar.getManifest().getMainAttributes().getValue("Main-Class");
						result.add(mainClass);
						break;
					case ATTRIBUTE_ENTRIES:
						result.add(jar.size());
						break;
				}
			}

		} catch (Exception e) {
			for (String attributeName : jarAttributes) {
				result.add(null);
			}
		}
		return result;
	}
}