oglimmer/utils

package de.oglimmer.utils;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.text.DateFormat;
import java.util.Date;
import java.util.jar.Attributes;
import java.util.jar.Manifest;

import lombok.Getter;

/**
 * Helps to read attributes from a Manifest file and provides a uniform "version" string which has version, git-commit,
 * creation date and a html-link to git
 * 
 * @author Oli Zimpasser
 *
 */
public class VersionFromManifest {

    // CHECK: com.jcabi.manifests.Manifests

    private static final int DATEFORMAT = DateFormat.FULL;

    @Getter
    private String commit;
    @Getter
    private String version;
    @Getter
    private String creationDate;
    @Getter
    private String gitUrl;

    @Getter
    private boolean initFailed;

    /**
     * Init with a given inputStream.
     * 
     * @param inputStream
     *            to read the Manifest file from
     */
    public void init(final InputStream inputStream) {
        try (final InputStream is = inputStream) {
            final Manifest mf = new Manifest(is);
            final Attributes attr = mf.getMainAttributes();
            commit = attr.getValue("git-commit");
            gitUrl = attr.getValue("git-url");
            version = attr.getValue("project-version");
            final long time = Long.parseLong(attr.getValue("creation-date"));
            creationDate = DateFormat.getDateTimeInstance(DATEFORMAT, DATEFORMAT).format(new Date(time));
        } catch (Exception e) {
            initBackToDefaults();
        }
    }

    /**
     * Init with a given filename. This is usually called from ServletContextListener with
     * sce.getServletContext().getRealPath("/META-INF/MANIFEST.MF")
     * 
     * @param filename
     *            to read the Manifest file from
     */
    public void initFromFile(final String filename) {
        try (final InputStream is = new FileInputStream(filename)) {
            init(is);
        } catch (IOException e) {
            initBackToDefaults();
        }
    }

    private void initBackToDefaults() {
        creationDate = DateFormat.getDateTimeInstance(DATEFORMAT, DATEFORMAT).format(new Date());
        commit = "?";
        version = "?";
        gitUrl = "?";
        initFailed = true;
    }

    /**
     * Returns the version with all details
     * 
     * @return string with version, html-link to git, git commit hash and creation date
     */
    public String getLongVersion() {
        return "V" + version + " [<a href='" + gitUrl + "/commits/" + commit + "'>Commit#" + commit + "</a>] build "
                + creationDate;
    }

}