/*
 * 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.tomcat.util.digester;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

Default implementation of the Rules interface that supports
the standard rule matching behavior.  This class can also be used as a
base class for specialized Rules implementations.
The matching policies implemented by this class support two different
types of pattern matching rules:

Exact Match - A pattern "a/b/c" exactly matches a
    <c> element, nested inside a <b>
    element, which is nested inside an <a> element.
Tail Match - A pattern "*/a/b" matches a
    <b> element, nested inside an <a>
     element, no matter how deeply the pair is nested.

/**
 * <p>Default implementation of the <code>Rules</code> interface that supports
 * the standard rule matching behavior.  This class can also be used as a
 * base class for specialized <code>Rules</code> implementations.</p>
 *
 * <p>The matching policies implemented by this class support two different
 * types of pattern matching rules:</p>
 * <ul>
 * <li><em>Exact Match</em> - A pattern "a/b/c" exactly matches a
 *     <code>&lt;c&gt;</code> element, nested inside a <code>&lt;b&gt;</code>
 *     element, which is nested inside an <code>&lt;a&gt;</code> element.</li>
 * <li><em>Tail Match</em> - A pattern "&#42;/a/b" matches a
 *     <code>&lt;b&gt;</code> element, nested inside an <code>&lt;a&gt;</code>
 *      element, no matter how deeply the pair is nested.</li>
 * </ul>
 */
public class RulesBase implements Rules {

    // ----------------------------------------------------- Instance Variables

    
The set of registered Rule instances, keyed by the matching pattern.
Each value is a List containing the Rules for that pattern, in the
order that they were originally registered.
/**
     * The set of registered Rule instances, keyed by the matching pattern.
     * Each value is a List containing the Rules for that pattern, in the
     * order that they were originally registered.
     */
    protected HashMap<String,List<Rule>> cache = new HashMap<>();


    
The Digester instance with which this Rules instance is associated.
/**
     * The Digester instance with which this Rules instance is associated.
     */
    protected Digester digester = null;


    
The set of registered Rule instances, in the order that they were
originally registered.
/**
     * The set of registered Rule instances, in the order that they were
     * originally registered.
     */
    protected ArrayList<Rule> rules = new ArrayList<>();


    // ------------------------------------------------------------- Properties

    
Return the Digester instance with which this Rules instance is
associated.
/**
     * Return the Digester instance with which this Rules instance is
     * associated.
     */
    @Override
    public Digester getDigester() {
        return this.digester;
    }


    
Set the Digester instance with which this Rules instance is associated.
Params:
digester – The newly associated Digester instance/**
     * Set the Digester instance with which this Rules instance is associated.
     *
     * @param digester The newly associated Digester instance
     */
    @Override
    public void setDigester(Digester digester) {
        this.digester = digester;
        for (Rule item : rules) {
            item.setDigester(digester);
        }
    }


    // --------------------------------------------------------- Public Methods

    
Register a new Rule instance matching the specified pattern.
Params:
pattern – Nesting pattern to be matched for this Rule
rule – Rule instance to be registered/**
     * Register a new Rule instance matching the specified pattern.
     *
     * @param pattern Nesting pattern to be matched for this Rule
     * @param rule Rule instance to be registered
     */
    @Override
    public void add(String pattern, Rule rule) {
        // to help users who accidentally add '/' to the end of their patterns
        int patternLength = pattern.length();
        if (patternLength>1 && pattern.endsWith("/")) {
            pattern = pattern.substring(0, patternLength-1);
        }

        List<Rule> list = cache.get(pattern);
        if (list == null) {
            list = new ArrayList<>();
            cache.put(pattern, list);
        }
        list.add(rule);
        rules.add(rule);
        if (this.digester != null) {
            rule.setDigester(this.digester);
        }
    }


    
Clear all existing Rule instance registrations.
/**
     * Clear all existing Rule instance registrations.
     */
    @Override
    public void clear() {
        cache.clear();
        rules.clear();
    }


    
Return a List of all registered Rule instances that match the specified
nesting pattern, or a zero-length List if there are no matches.  If more
than one Rule instance matches, they must be returned
in the order originally registered through the add()
method.
Params:
namespaceURI – Namespace URI for which to select matching rules,
 or null to match regardless of namespace URI
pattern – Nesting pattern to be matched/**
     * Return a List of all registered Rule instances that match the specified
     * nesting pattern, or a zero-length List if there are no matches.  If more
     * than one Rule instance matches, they <strong>must</strong> be returned
     * in the order originally registered through the <code>add()</code>
     * method.
     *
     * @param namespaceURI Namespace URI for which to select matching rules,
     *  or <code>null</code> to match regardless of namespace URI
     * @param pattern Nesting pattern to be matched
     */
    @Override
    public List<Rule> match(String namespaceURI, String pattern) {

        // List rulesList = (List) this.cache.get(pattern);
        List<Rule> rulesList = lookup(namespaceURI, pattern);
        if ((rulesList == null) || (rulesList.size() < 1)) {
            // Find the longest key, ie more discriminant
            String longKey = "";
            for (String key : this.cache.keySet()) {
                if (key.startsWith("*/")) {
                    if (pattern.equals(key.substring(2)) ||
                        pattern.endsWith(key.substring(1))) {
                        if (key.length() > longKey.length()) {
                            // rulesList = (List) this.cache.get(key);
                            rulesList = lookup(namespaceURI, key);
                            longKey = key;
                        }
                    }
                }
            }
        }
        if (rulesList == null) {
            rulesList = new ArrayList<>();
        }
        return rulesList;
    }


    
Return a List of all registered Rule instances, or a zero-length List
if there are no registered Rule instances.  If more than one Rule
instance has been registered, they must be returned
in the order originally registered through the add()
method.
/**
     * Return a List of all registered Rule instances, or a zero-length List
     * if there are no registered Rule instances.  If more than one Rule
     * instance has been registered, they <strong>must</strong> be returned
     * in the order originally registered through the <code>add()</code>
     * method.
     */
    @Override
    public List<Rule> rules() {
        return this.rules;
    }


    // ------------------------------------------------------ Protected Methods

    
Return a List of Rule instances for the specified pattern that also
match the specified namespace URI (if any).  If there are no such
rules, return null.
Params:
namespaceURI – Namespace URI to match, or null to
 select matching rules regardless of namespace URI
pattern – Pattern to be matched
Returns:
a rules list/**
     * Return a List of Rule instances for the specified pattern that also
     * match the specified namespace URI (if any).  If there are no such
     * rules, return <code>null</code>.
     *
     * @param namespaceURI Namespace URI to match, or <code>null</code> to
     *  select matching rules regardless of namespace URI
     * @param pattern Pattern to be matched
     * @return a rules list
     */
    protected List<Rule> lookup(String namespaceURI, String pattern) {
        // Optimize when no namespace URI is specified
        List<Rule> list = this.cache.get(pattern);
        if (list == null) {
            return null;
        }
        if ((namespaceURI == null) || (namespaceURI.length() == 0)) {
            return list;
        }

        // Select only Rules that match on the specified namespace URI
        List<Rule> results = new ArrayList<>();
        for (Rule item : list) {
            if ((namespaceURI.equals(item.getNamespaceURI())) ||
                    (item.getNamespaceURI() == null)) {
                results.add(item);
            }
        }
        return results;
    }
}