package org.apache.commons.digester3.plugins;

/*
 * 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.
 */

import java.util.List;
import java.util.LinkedList;

import org.apache.commons.digester3.plugins.strategies.FinderFromClass;
import org.apache.commons.digester3.plugins.strategies.FinderFromDfltClass;
import org.apache.commons.digester3.plugins.strategies.FinderFromDfltMethod;
import org.apache.commons.digester3.plugins.strategies.FinderFromDfltResource;
import org.apache.commons.digester3.plugins.strategies.FinderFromFile;
import org.apache.commons.digester3.plugins.strategies.FinderFromMethod;
import org.apache.commons.digester3.plugins.strategies.FinderFromResource;
import org.apache.commons.digester3.plugins.strategies.FinderSetProperties;

Provides data and services which should exist only once per digester.

This class holds a number of useful items which should be shared by all plugin objects. Such data cannot be stored on
the PluginRules or PluginManager classes, as there can be multiple instances of these at various times during a
parse.

The name "Context" refers to the similarity between this class and a ServletContext class in a servlet engine. A
ServletContext object provides access to the container's services such as obtaining global configuration parameters
for the container, or getting access to logging services. For plugins, a Digester instance can be regarded as
"the container".
Since:
1.6/**
 * Provides data and services which should exist only once per digester.
 * <p>
 * This class holds a number of useful items which should be shared by all plugin objects. Such data cannot be stored on
 * the PluginRules or PluginManager classes, as there can be multiple instances of these at various times during a
 * parse.
 * <p>
 * The name "Context" refers to the similarity between this class and a ServletContext class in a servlet engine. A
 * ServletContext object provides access to the container's services such as obtaining global configuration parameters
 * for the container, or getting access to logging services. For plugins, a Digester instance can be regarded as
 * "the container".
 * 
 * @since 1.6
 */
public class PluginContext
{

    private static final String DFLT_PLUGIN_CLASS_ATTR_NS = null;

    private static final String DFLT_PLUGIN_CLASS_ATTR = "plugin-class";

    // the xml attribute the user uses on an xml element to specify
    // the plugin's class
    private static final String DFLT_PLUGIN_ID_ATTR_NS = null;

    private static final String DFLT_PLUGIN_ID_ATTR = "plugin-id";

    
See setPluginClassAttribute. /** See {@link #setPluginClassAttribute}. */
    private String pluginClassAttrNs = DFLT_PLUGIN_CLASS_ATTR_NS;

    
See setPluginClassAttribute. /** See {@link #setPluginClassAttribute}. */
    private String pluginClassAttr = DFLT_PLUGIN_CLASS_ATTR;

    
See setPluginClassAttribute. /** See {@link #setPluginClassAttribute}. */
    private String pluginIdAttrNs = DFLT_PLUGIN_ID_ATTR_NS;

    
See setPluginClassAttribute. /** See {@link #setPluginClassAttribute}. */
    private String pluginIdAttr = DFLT_PLUGIN_ID_ATTR;

    
A list of RuleFinder objects used by all Declarations (and thus indirectly by all PluginCreateRules to locate the
custom rules for plugin classes.
/**
     * A list of RuleFinder objects used by all Declarations (and thus indirectly by all PluginCreateRules to locate the
     * custom rules for plugin classes.
     */
    private List<RuleFinder> ruleFinders;

    // ------------------- methods ---------------------------------------

    
Return the list of RuleFinder objects. Under normal circumstances this method creates a default list of these
objects when first called (ie "on-demand" or "lazy initialization"). However if setRuleFinders has been called
first, then the list specified there is returned.

It is explicitly permitted for the caller to modify this list by inserting or removing RuleFinder objects.
Returns:
the list of RuleFinder objects/**
     * Return the list of RuleFinder objects. Under normal circumstances this method creates a default list of these
     * objects when first called (ie "on-demand" or "lazy initialization"). However if setRuleFinders has been called
     * first, then the list specified there is returned.
     * <p>
     * It is explicitly permitted for the caller to modify this list by inserting or removing RuleFinder objects.
     *
     * @return the list of RuleFinder objects
     */
    public List<RuleFinder> getRuleFinders()
    {
        if ( ruleFinders == null )
        {
            // when processing a plugin declaration, attempts are made to
            // find custom rules in the order in which the Finder objects
            // are added below. However this list can be modified
            ruleFinders = new LinkedList<RuleFinder>();
            ruleFinders.add( new FinderFromFile() );
            ruleFinders.add( new FinderFromResource() );
            ruleFinders.add( new FinderFromClass() );
            ruleFinders.add( new FinderFromMethod() );
            ruleFinders.add( new FinderFromDfltMethod() );
            ruleFinders.add( new FinderFromDfltClass() );
            ruleFinders.add( new FinderFromDfltResource() );
            ruleFinders.add( new FinderFromDfltResource( ".xml" ) );
            ruleFinders.add( new FinderSetProperties() );
        }
        return ruleFinders;
    }

    
Set the list of RuleFinder objects. This may be useful if working in a non-english language, allowing the
application developer to replace the standard list with a list of objects which look for xml attributes in the
local language.

If the intent is just to add an additional rule-finding algorithm, then it may be better to call #getRuleFinders,
and insert a new object into the start of the list.
Params:
ruleFinders – the list of RuleFinder objects/**
     * Set the list of RuleFinder objects. This may be useful if working in a non-english language, allowing the
     * application developer to replace the standard list with a list of objects which look for xml attributes in the
     * local language.
     * <p>
     * If the intent is just to add an additional rule-finding algorithm, then it may be better to call #getRuleFinders,
     * and insert a new object into the start of the list.
     *
     * @param ruleFinders the list of RuleFinder objects
     */
    public void setRuleFinders( List<RuleFinder> ruleFinders )
    {
        this.ruleFinders = ruleFinders;
    }

    
Sets the xml attribute which the input xml uses to indicate to a PluginCreateRule which class should be
instantiated.

Example:
setPluginClassAttribute( null, "class" );

will allow this in the input xml:
 <root>
   <some-plugin class="com.acme.widget"> ......

instead of the default syntax:
 <root>
   <some-plugin plugin-class="com.acme.widget"> ......

This is particularly useful if the input xml document is not in English.

Note that the xml attributes used by PluginDeclarationRules are not affected by this method.
Params:
namespaceUri – is the namespace uri that the specified attribute is in. If the attribute is in no namespace,
           then this should be null. Note that if a namespace is used, the attrName value should not
           contain any kind of namespace-prefix. Note also that if you are using a non-namespace-aware parser,
           this parameter must be null.
attrName – is the attribute whose value contains the name of the class to be instantiated./**
     * Sets the xml attribute which the input xml uses to indicate to a PluginCreateRule which class should be
     * instantiated.
     * <p>
     * Example:
     * 
     * <pre>
     * setPluginClassAttribute( null, &quot;class&quot; );
     * </pre>
     * 
     * will allow this in the input xml:
     * 
     * <pre>
     *  &lt;root&gt;
     *    &lt;some-plugin class="com.acme.widget"&gt; ......
     * </pre>
     * 
     * instead of the default syntax:
     * 
     * <pre>
     *  &lt;root&gt;
     *    &lt;some-plugin plugin-class="com.acme.widget"&gt; ......
     * </pre>
     * 
     * This is particularly useful if the input xml document is not in English.
     * <p>
     * Note that the xml attributes used by PluginDeclarationRules are not affected by this method.
     * 
     * @param namespaceUri is the namespace uri that the specified attribute is in. If the attribute is in no namespace,
     *            then this should be null. Note that if a namespace is used, the attrName value should <i>not</i>
     *            contain any kind of namespace-prefix. Note also that if you are using a non-namespace-aware parser,
     *            this parameter <i>must</i> be null.
     * @param attrName is the attribute whose value contains the name of the class to be instantiated.
     */
    public void setPluginClassAttribute( String namespaceUri, String attrName )
    {
        pluginClassAttrNs = namespaceUri;
        pluginClassAttr = attrName;
    }

    
Sets the xml attribute which the input xml uses to indicate to a PluginCreateRule which plugin declaration is
being referenced.

Example:
setPluginIdAttribute( null, "id" );

will allow this in the input xml:
 <root>
   <some-plugin id="widget"> ......

rather than the default behaviour:
 <root>
   <some-plugin plugin-id="widget"> ......

This is particularly useful if the input xml document is not in English.

Note that the xml attributes used by PluginDeclarationRules are not affected by this method.
Params:
namespaceUri – is the namespace uri that the specified attribute is in. If the attribute is in no namespace,
           then this should be null. Note that if a namespace is used, the attrName value should not
           contain any kind of namespace-prefix. Note also that if you are using a non-namespace-aware parser,
           this parameter must be null.
attrName – is the attribute whose value contains the id of the plugin declaration to be used when
           instantiating an object./**
     * Sets the xml attribute which the input xml uses to indicate to a PluginCreateRule which plugin declaration is
     * being referenced.
     * <p>
     * Example:
     * 
     * <pre>
     * setPluginIdAttribute( null, &quot;id&quot; );
     * </pre>
     * 
     * will allow this in the input xml:
     * 
     * <pre>
     *  &lt;root&gt;
     *    &lt;some-plugin id="widget"&gt; ......
     * </pre>
     * 
     * rather than the default behaviour:
     * 
     * <pre>
     *  &lt;root&gt;
     *    &lt;some-plugin plugin-id="widget"&gt; ......
     * </pre>
     * 
     * This is particularly useful if the input xml document is not in English.
     * <p>
     * Note that the xml attributes used by PluginDeclarationRules are not affected by this method.
     * 
     * @param namespaceUri is the namespace uri that the specified attribute is in. If the attribute is in no namespace,
     *            then this should be null. Note that if a namespace is used, the attrName value should <i>not</i>
     *            contain any kind of namespace-prefix. Note also that if you are using a non-namespace-aware parser,
     *            this parameter <i>must</i> be null.
     * @param attrName is the attribute whose value contains the id of the plugin declaration to be used when
     *            instantiating an object.
     */
    public void setPluginIdAttribute( String namespaceUri, String attrName )
    {
        pluginIdAttrNs = namespaceUri;
        pluginIdAttr = attrName;
    }

    
Get the namespace for the xml attribute which indicates to a PluginCreateRule which class is to be plugged in.

May be null (in fact, normally will be).
Returns:
the namespace for the xml attribute which indicates which class is to be plugged in./**
     * Get the namespace for the xml attribute which indicates to a PluginCreateRule which class is to be plugged in.
     * <p>
     * May be null (in fact, normally will be).
     *
     * @return the namespace for the xml attribute which indicates which class is to be plugged in.
     */
    public String getPluginClassAttrNs()
    {
        return pluginClassAttrNs;
    }

    
Get the namespace for the xml attribute which indicates to a PluginCreateRule which class is to be plugged in.

The return value is never null.
Returns:
the namespace for the xml attribute which indicates which class is to be plugged in./**
     * Get the namespace for the xml attribute which indicates to a PluginCreateRule which class is to be plugged in.
     * <p>
     * The return value is never null.
     *
     * @return the namespace for the xml attribute which indicates which class is to be plugged in.
     */
    public String getPluginClassAttr()
    {
        return pluginClassAttr;
    }

    
Get the namespace for the xml attribute which indicates to a PluginCreateRule which previous plugin declaration
should be used.

May be null (in fact, normally will be).
Returns:
the namespace for the xml attribute which indicates which previous plugin declaration should be used./**
     * Get the namespace for the xml attribute which indicates to a PluginCreateRule which previous plugin declaration
     * should be used.
     * <p>
     * May be null (in fact, normally will be).
     *
     * @return the namespace for the xml attribute which indicates which previous plugin declaration should be used.
     */
    public String getPluginIdAttrNs()
    {
        return pluginIdAttrNs;
    }

    
Get the namespace for the xml attribute which indicates to a PluginCreateRule which previous plugin declaration
should be used.

The return value is never null.
Returns:
the namespace for the xml attribute which indicates which previous plugin declaration should be used./**
     * Get the namespace for the xml attribute which indicates to a PluginCreateRule which previous plugin declaration
     * should be used.
     * <p>
     * The return value is never null.
     *
     * @return the namespace for the xml attribute which indicates which previous plugin declaration should be used.
     */
    public String getPluginIdAttr()
    {
        return pluginIdAttr;
    }

}