/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.gallery3d.util;


public class LinkedNode {
    private LinkedNode mPrev;
    private LinkedNode mNext;

    public LinkedNode() {
        mPrev = mNext = this;
    }

    public void insert(LinkedNode node) {
        node.mNext = mNext;
        mNext.mPrev = node;
        node.mPrev = this;
        mNext = node;
    }

    public void remove() {
        if (mNext == this) throw new IllegalStateException();
        mPrev.mNext = mNext;
        mNext.mPrev = mPrev;
        mPrev = mNext = null;
    }

    @SuppressWarnings("unchecked")
    public static class List<T extends LinkedNode> {
        private LinkedNode mHead = new LinkedNode();

        public void insertFirst(T node) {
            mHead.insert(node);
        }

        public void insertLast(T node) {
            mHead.mPrev.insert(node);
        }

        public T getFirst() {
            return (T) (mHead.mNext == mHead ? null : mHead.mNext);
        }

        public T getLast() {
            return (T) (mHead.mPrev == mHead ? null : mHead.mPrev);
        }

        public T nextOf(T node) {
            return (T) (node.mNext == mHead ? null : node.mNext);
        }

        public T previousOf(T node) {
            return (T) (node.mPrev == mHead ? null : node.mPrev);
        }

    }

    public static <T extends LinkedNode> List<T> newList() {
        return new List<T>();
    }
}