/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.bookkeeper.net;

/**
 * A base class that implements interface Node.
 */
public class NodeBase implements Node {
    /**
     * Path separator {@value}.
     */
    public static final char PATH_SEPARATOR = '/';
    /**
     * Path separator as a string {@value}.
     */
    public static final String PATH_SEPARATOR_STR = "/";
    /**
     * String representation of root {@value}.
     */
    public static final String ROOT = "";

    protected String name; //host:port#
    protected String location; //string representation of this node's location
    protected int level; //which level of the tree the node resides
    protected Node parent; //its parent

    /**
     * Default constructor.
     */
    public NodeBase() {
    }

    /**
     * Construct a node from its path.
     * @param path
     *   a concatenation of this node's location, the path seperator, and its name
     */
    public NodeBase(String path) {
        path = normalize(path);
        int index = path.lastIndexOf(PATH_SEPARATOR);
        if (index == -1) {
            set(ROOT, path);
        } else {
            set(path.substring(index + 1), path.substring(0, index));
        }
    }

    /**
     * Construct a node from its name and its location.
     * @param name this node's name (can be null, must not contain {@link #PATH_SEPARATOR})
     * @param location this node's location
     */
    public NodeBase(String name, String location) {
        set(name, normalize(location));
    }

    /**
     * Construct a node from its name and its location.
     * @param name this node's name (can be null, must not contain {@link #PATH_SEPARATOR})
     * @param location this node's location
     * @param parent this node's parent node
     * @param level this node's level in the tree
     */
    public NodeBase(String name, String location, Node parent, int level) {
        set(name, normalize(location));
        this.parent = parent;
        this.level = level;
    }

    /**
     * Set this node's name and location.
     * @param name the (nullable) name -which cannot contain the {@link #PATH_SEPARATOR}
     * @param location the location
     */
    private void set(String name, String location) {
        if (name != null && name.contains(PATH_SEPARATOR_STR)) {
            throw new IllegalArgumentException("Network location name contains /: " + name);
        }
        this.name = (name == null) ? "" : name;
        this.location = location;
    }

    /** @return this node's name */
    @Override
    public String getName() {
        return name;
    }

    /** @return this node's network location */
    @Override
    public String getNetworkLocation() {
        return location;
    }

    /**
     * Set this node's network location.
     * @param location the location
     */
    @Override
    public void setNetworkLocation(String location) {
        this.location = location;
    }

    /**
     * Get the path of a node.
     * @param node a non-null node
     * @return the path of a node
     */
    public static String getPath(Node node) {
        return node.getNetworkLocation() + PATH_SEPARATOR_STR + node.getName();
    }

    /** @return this node's path as its string representation */
    @Override
    public String toString() {
        return getPath(this);
    }

    /**
     * Normalize a path by stripping off any trailing {@link #PATH_SEPARATOR}.
     * @param path path to normalize.
     * @return the normalised path
     * If <i>path</i>is null or empty {@link #ROOT} is returned
     * @throws IllegalArgumentException if the first character of a non empty path
     * is not {@link #PATH_SEPARATOR}
     */
    public static String normalize(String path) {
        if (path == null || path.length() == 0) {
            return ROOT;
        }

        if (path.charAt(0) != PATH_SEPARATOR) {
            throw new IllegalArgumentException("Network Location path does not start with " + PATH_SEPARATOR_STR + ": "
                    + path);
        }

        int len = path.length();
        if (path.charAt(len - 1) == PATH_SEPARATOR) {
            return path.substring(0, len - 1);
        }
        return path;
    }

    /** @return this node's parent */
    @Override
    public Node getParent() {
        return parent;
    }

    /**
     * Set this node's parent.
     * @param parent the parent
     */
    @Override
    public void setParent(Node parent) {
        this.parent = parent;
    }

    /** @return this node's level in the tree.
     * E.g. the root of a tree returns 0 and its children return 1
     */
    @Override
    public int getLevel() {
        return level;
    }

    /**
     * Set this node's level in the tree.
     * @param level the level
     */
    @Override
    public void setLevel(int level) {
        this.level = level;
    }

    public static int locationToDepth(String location) {
        String normalizedLocation = normalize(location);
        int length = normalizedLocation.length();
        int depth = 0;
        for (int i = 0; i < length; i++) {
            if (normalizedLocation.charAt(i) == PATH_SEPARATOR) {
                depth++;
            }
        }
        return depth;
    }

    @Override
    public String getNetworkLocation(int distanceFromLeaves) {
        Node node = this;
        while (distanceFromLeaves > 1) {
            Node parent = node.getParent();
            if (null == parent) {
                break;
            }
            node = parent;
            distanceFromLeaves--;
        }
        return node.getNetworkLocation();
    }
}
