/*
    * Copyright (C) 2010, Google Inc.
    * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
    * and other copyright owners as documented in the project's IP log.
    *
    * This program and the accompanying materials are made available
    * under the terms of the Eclipse Distribution License v1.0 which
    * accompanies this distribution, is reproduced below, and is
    * available at http://www.eclipse.org/org/documents/edl-v10.php
   *
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or
   * without modification, are permitted provided that the following
   * conditions are met:
   *
   * - Redistributions of source code must retain the above copyright
   *   notice, this list of conditions and the following disclaimer.
   *
   * - Redistributions in binary form must reproduce the above
   *   copyright notice, this list of conditions and the following
   *   disclaimer in the documentation and/or other materials provided
   *   with the distribution.
   *
   * - Neither the name of the Eclipse Foundation, Inc. nor the
   *   names of its contributors may be used to endorse or promote
   *   products derived from this software without specific prior
   *   written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
   * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
   * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
   * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  package org.eclipse.jgit.lib;
  
  import org.eclipse.jgit.annotations.NonNull;
  import org.eclipse.jgit.annotations.Nullable;
  
  /** A {@link Ref} that points directly at an {@link ObjectId}. */
  public abstract class ObjectIdRef implements Ref {
  	/** Any reference whose peeled value is not yet known. */
  	public static class Unpeeled extends ObjectIdRef {
  		/**
  		 * Create a new ref pairing.
  		 *
  		 * @param st
  		 *            method used to store this ref.
  		 * @param name
  		 *            name of this ref.
  		 * @param id
  		 *            current value of the ref. May be {@code null} to indicate
  		 *            a ref that does not exist yet.
  		 */
  		public Unpeeled(@NonNull Storage st, @NonNull String name,
  				@Nullable ObjectId id) {
  			super(st, name, id);
  		}
  
  		@Nullable
  		public ObjectId getPeeledObjectId() {
  			return null;
  		}
  
  		public boolean isPeeled() {
  			return false;
  		}
  	}
  
  	/** An annotated tag whose peeled object has been cached. */
  	public static class PeeledTag extends ObjectIdRef {
  		private final ObjectId peeledObjectId;
  
  		/**
  		 * Create a new ref pairing.
  		 *
  		 * @param st
  		 *            method used to store this ref.
  		 * @param name
  		 *            name of this ref.
  		 * @param id
  		 *            current value of the ref.
  		 * @param p
  		 *            the first non-tag object that tag {@code id} points to.
  		 */
  		public PeeledTag(@NonNull Storage st, @NonNull String name,
  				@Nullable ObjectId id, @NonNull ObjectId p) {
  			super(st, name, id);
  			peeledObjectId = p;
 		}
 
 		@NonNull
 		public ObjectId getPeeledObjectId() {
 			return peeledObjectId;
 		}
 
 		public boolean isPeeled() {
 			return true;
 		}
 	}
 
 	/** A reference to a non-tag object coming from a cached source. */
 	public static class PeeledNonTag extends ObjectIdRef {
 		/**
 		 * Create a new ref pairing.
 		 *
 		 * @param st
 		 *            method used to store this ref.
 		 * @param name
 		 *            name of this ref.
 		 * @param id
 		 *            current value of the ref. May be {@code null} to indicate
 		 *            a ref that does not exist yet.
 		 */
 		public PeeledNonTag(@NonNull Storage st, @NonNull String name,
 				@Nullable ObjectId id) {
 			super(st, name, id);
 		}
 
 		@Nullable
 		public ObjectId getPeeledObjectId() {
 			return null;
 		}
 
 		public boolean isPeeled() {
 			return true;
 		}
 	}
 
 	private final String name;
 
 	private final Storage storage;
 
 	private final ObjectId objectId;
 
 	/**
 	 * Create a new ref pairing.
 	 *
 	 * @param st
 	 *            method used to store this ref.
 	 * @param name
 	 *            name of this ref.
 	 * @param id
 	 *            current value of the ref. May be {@code null} to indicate a
 	 *            ref that does not exist yet.
 	 */
 	protected ObjectIdRef(@NonNull Storage st, @NonNull String name,
 			@Nullable ObjectId id) {
 		this.name = name;
 		this.storage = st;
 		this.objectId = id;
 	}
 
 	@NonNull
 	public String getName() {
 		return name;
 	}
 
 	public boolean isSymbolic() {
 		return false;
 	}
 
 	@NonNull
 	public Ref getLeaf() {
 		return this;
 	}
 
 	@NonNull
 	public Ref getTarget() {
 		return this;
 	}
 
 	@Nullable
 	public ObjectId getObjectId() {
 		return objectId;
 	}
 
 	@NonNull
 	public Storage getStorage() {
 		return storage;
 	}
 
 	@NonNull
 	@Override
 	public String toString() {
 		StringBuilder r = new StringBuilder();
 		r.append("Ref["); //$NON-NLS-1$
 		r.append(getName());
 		r.append('=');
 		r.append(ObjectId.toString(getObjectId()));
 		r.append(']');
 		return r.toString();
 	}
 }