/*
 * Copyright 2005 the original author or authors.
 * 
 * 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 org.wamblee.crawler.kiss;

import java.io.InputStream;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.dom4j.Attribute;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import org.wamblee.conditions.AndCondition;
import org.wamblee.conditions.Condition;
import org.wamblee.conditions.PropertyRegexCondition;
import org.wamblee.crawler.kiss.ProgramFilter.ProgramAction;

/**
 * Parse the configuration of desired programs.
 */
class ProgramConfigurationParser {

    private static final String ELEM_PROGRAM = "program";

    private static final String ELEM_PATTERN = "match";

    private static final String ELEM_ACTION = "action";

    private static final String ACTION_NOTIFY = "notify";

    /**
     * Parses the condition used to match the desired programs.
     * 
     * @param aStream
     *            Input stream to parse from.
     * @return Condition.
     */
    List<ProgramFilter> parse(InputStream aStream) {
        List<ProgramFilter> filters = new ArrayList<ProgramFilter>();
        try {
            SAXReader reader = new SAXReader();
            Document document = reader.read(aStream);

            Element root = document.getRootElement();

            for (Iterator i = root.elementIterator(ELEM_PROGRAM); i.hasNext();) {
                Element program = (Element) i.next();

                Element actionElem = program.element(ELEM_ACTION);
                ProgramAction action = ProgramAction.RECORD;
                if (actionElem != null) {
                    if (actionElem.getText().equals(ACTION_NOTIFY)) {
                        action = ProgramAction.NOTIFY;
                    }
                }
                List<Condition<Program>> regexConditions = 
                    new ArrayList<Condition<Program>>();
                for (Iterator j = program.elementIterator(ELEM_PATTERN); j.hasNext(); ) {
                    Element patternElem = (Element)j.next();
                    String fieldName = "name"; 
                    Attribute fieldAttribute = patternElem.attribute("field"); 
                    if ( fieldAttribute != null ) { 
                        fieldName = fieldAttribute.getText(); 
                    }
                    String pattern = ".*(" + patternElem.getText()
                    + ").*";
                    regexConditions.add(new PropertyRegexCondition<Program>(fieldName, pattern, true));
                }
                Condition<Program> condition = new AndCondition<Program>(regexConditions);
                filters.add(new ProgramFilter(condition, action));
            }
            return filters;
        } catch (DocumentException e) {
            throw new RuntimeException("Error parsing program configuraiton", e);
        }
    }
}