com.goeuro.sync4j.utils.Applications Maven / Gradle / Ivy

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package com.goeuro.sync4j.utils;

import javax.annotation.Nonnull;
import java.io.IOException;
import java.io.InputStream;
import java.io.UncheckedIOException;
import java.time.OffsetDateTime;
import java.util.Optional;
import java.util.Properties;

import static java.time.format.DateTimeFormatter.ISO_OFFSET_DATE_TIME;

public final class Applications {

    @Nonnull
    private static final String PROPERTIES_FILENAME = "com/goeuro/sync4j/version.properties";
    @Nonnull
    private static final Properties PROPERTIES = loadProperties();
    @Nonnull
    private static final String VERSION = getProperty(PROPERTIES, "project.version");
    @Nonnull
    private static final String NAME = getProperty(PROPERTIES, "project.name");
    @Nonnull
    private static final OffsetDateTime BUILD_TIMESTAMP = getOffsetDateTimeProperty(PROPERTIES, "project.build.timestamp");

    @Nonnull
    public static String version() {
        return VERSION;
    }

    @Nonnull
    public static String name() {
        return NAME;
    }

    @Nonnull
    public static OffsetDateTime buildTimestamp() {
        return BUILD_TIMESTAMP;
    }

    @Nonnull
    private static OffsetDateTime getOffsetDateTimeProperty(@Nonnull Properties properties, @Nonnull String propertyName) {
        final String plain = getProperty(properties, propertyName);
        return OffsetDateTime.parse(plain, ISO_OFFSET_DATE_TIME);
    }

    @Nonnull
    private static String getProperty(@Nonnull Properties properties, @Nonnull String propertyName) {
        return findProperty(properties, propertyName)
            .orElseThrow(() -> new IllegalStateException("'" + PROPERTIES_FILENAME + "' in classpath does not contain required property '" + propertyName + "'."))
            ;
    }

    @Nonnull
    private static Optional findProperty(@Nonnull Properties properties, @Nonnull String propertyName) {
        return Optional.ofNullable(properties.getProperty(propertyName));
    }

    @Nonnull
    private static Properties loadProperties() {
        final Properties properties = new Properties();
        try (final InputStream is = Applications.class.getClassLoader().getResourceAsStream(PROPERTIES_FILENAME)) {
            if (is == null) {
                throw new IllegalStateException("The classpath does not contain '" + PROPERTIES_FILENAME + "'.");
            }
            properties.load(is);
        } catch (final IOException e) {
            throw new UncheckedIOException("Could not load '" + PROPERTIES_FILENAME + "'.", e);
        }
        return properties;
    }

}