src/main/java/org/eclipse/mdm/api/base/model/MimeType.java

/********************************************************************************
 * Copyright (c) 2015-2018 Contributors to the Eclipse Foundation
 *
 * See the NOTICE file(s) distributed with this work for additional
 * information regarding copyright ownership.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 ********************************************************************************/


package org.eclipse.mdm.api.base.model;

import java.util.Locale;

/**
 * Class provides easy to use MIME type comparison methods.
 *
 * @since 1.0.0
 * @author Viktor Stoehr, Gigatronik Ingolstadt GmbH
 * @author Sebastian Dirsch, Gigatronik Ingolstadt GmbH
 * @see Entity
 */
public final class MimeType {

	// ======================================================================
	// Instance variables
	// ======================================================================

	private final String internal;

	// ======================================================================
	// Constructors
	// ======================================================================

	/**
	 * Constructor.
	 *
	 * @param mimeType
	 *            The MIME type will be changed to lower case.
	 */
	public MimeType(String mimeType) {
		internal = mimeType.toLowerCase(Locale.ROOT);
	}

	// ======================================================================
	// Public methods
	// ======================================================================

	public MimeType addSubType(String name) {
		return new MimeType(internal + '.' + name);
	}

	/**
	 * Checks whether given {@code MimeType} is either the same as or a sub type
	 * of this MIME type. See the following examples:
	 *
	 * <pre>
	 * MimeType type = new MimeType("application/x-asam.aomeasurement");
	 * MimeType subType = new MimeType("application/x-asam.aomeasurement.subtype");
	 *
	 * type.isParentOf(subType); // true
	 * subType.isParentOf(type); // false
	 * type.isParentOf(type); // true
	 * </pre>
	 *
	 * @param mimeType
	 *            The checked type.
	 * @return Returns true if either this MIME type and given one are the same
	 *         or the given one is a sub type of this MIME type.
	 */
	public boolean isParentOf(MimeType mimeType) {
		return mimeType != null && mimeType.compareString().startsWith(compareString());
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public int hashCode() {
		return internal.hashCode();
	}

	/**
	 * Checks whether given {@code Object} represents the same type as this MIME
	 * type.
	 *
	 * <pre>
	 * MimeType type = new MimeType("application/x-asam.aomeasurement");
	 * MimeType equalType = new MimeType("application/x-asam.aomeasurement");
	 * MimeType subType = new MimeType("application/x-asam.aomeasurement.subtype");
	 * MimeType anotherType = new MimeType("application/x-asam.aounit");
	 *
	 * type.equals(equalType); // true
	 * subType.equals(type); // false
	 * type.equals(anotherType); // false
	 * </pre>
	 *
	 * @param object
	 *            The checked object.
	 * @return True if given object is of type {@code MimeType} and represents
	 *         exactly the same type as this MIME type.
	 */
	@Override
	public boolean equals(Object object) {
		if (object instanceof MimeType) {
			return internal.equals(((MimeType) object).internal);
		}

		return false;
	}

	/**
	 * Returns the MIME type.
	 *
	 * @return The MIME type is returned in lower case.
	 */
	@Override
	public String toString() {
		return internal;
	}

	// ======================================================================
	// Private methods
	// ======================================================================

	/**
	 * Adds a termination character to the internally stored string
	 * representation.
	 *
	 * @return A closed comparison string is returned.
	 */
	private String compareString() {
		return internal + '.';
	}

}