/*
 * 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.main;

import java.util.EnumMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import java.util.TreeSet;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.dom4j.DocumentFactory;
import org.dom4j.Element;
import org.wamblee.crawler.kiss.guide.Program;
import org.wamblee.crawler.kiss.guide.TimeInterval;
import org.wamblee.crawler.kiss.guide.Program.RecordingResult;

/**
 * Provides execution of actions for programs. Actions use this class to tell
 * the executor what to do. The executor then decides on exactly what to do and
 * in what order and makes decisions in case of conflicts.
 */
public class ProgramActionExecutor {

    private static final Log LOG = LogFactory
            .getLog(ProgramActionExecutor.class);

    /**
     * A map of category name to a set of program. Useful for displaying the
     * output of possibly interesting programs on a per category basis.
     */
    private Map<String, Set<Program>> _interestingShows;

    /**
     * Map of priority to set of programs.
     */
    private Map<Integer, Set<Program>> _showsToRecord;

    /**
     * Map or recording result to a set of programs.
     */
    private EnumMap<RecordingResult, Set<Program>> _recordings;

    /**
     * Constructs the program action executor.
     * 
     */
    public ProgramActionExecutor() {
        _interestingShows = new TreeMap<String, Set<Program>>();
        _showsToRecord = new TreeMap<Integer, Set<Program>>();
        _recordings = new EnumMap<RecordingResult, Set<Program>>(
                RecordingResult.class);
        for (RecordingResult result : RecordingResult.values()) {
            _recordings.put(result, new TreeSet<Program>(
                    new Program.TimeSorter()));
        }
    }

    /**
     * Called by an action to indicate the desire to record a program.
     * 
     * @param aPriority
     *            Priority of the program. Used to resolve conflicts.
     * @param aProgram
     *            Program to record.
     */
    public void recordProgram(int aPriority, Program aProgram) {
        LOG.info("priority = " + aPriority + ", program: " + aProgram);
        // Putting -priority into the set makes sure that iteration order 
        // over the priorities will go from higher priority to lower priority. 
        Set<Program> programs = _showsToRecord.get(-aPriority);
        if (programs == null) {
            programs = new TreeSet<Program>(new Program.TimeSorter());
            _showsToRecord.put(-aPriority, programs); 
        }
        programs.add(aProgram);
    }

    /**
     * Called by an action to indicate that a program is interesting.
     * 
     * @param aCategory
     *            Category of the program.
     * @param aProgram
     *            Program.
     */
    public void interestingProgram(String aCategory, Program aProgram) {
        LOG.info("category = '" + aCategory + "', program: " + aProgram);
        Set<Program> programs = _interestingShows.get(aCategory);
        if (programs == null) {
            programs = new TreeSet<Program>(new Program.TimeSorter());
            _interestingShows.put(aCategory, programs);
        }
        programs.add(aProgram);
    }

    /**
     * Makes sure that the actions are performed.
     * 
     */
    public void commit() {
        Set<TimeInterval> previouslyRecorded = new HashSet<TimeInterval>();
        for (Integer priority : _showsToRecord.keySet()) {
            for (Program program : _showsToRecord.get(priority)) {
                TimeInterval interval = program.getInterval(); 
                if ( recordingConflictExists(previouslyRecorded, interval)) { 
                    _recordings.get(RecordingResult.CONFLICT).add(program);
                } else {
                    RecordingResult result = program.record();
                    _recordings.get(result).add(program);
                    previouslyRecorded.add(interval);
                }
            }
        }
    }
    
    /**
     * Checks an interval for overlap with a previously recorded program. 
     * @param aPreviouslyRecorded Previously recorded programs. 
     * @param interval Interval. 
     * @return True iff there is a recording conflict.
     */
    private boolean recordingConflictExists(Set<TimeInterval> aPreviouslyRecorded, TimeInterval interval) { 
        for (TimeInterval recordedInterval: aPreviouslyRecorded ) { 
            if ( interval.overlap(recordedInterval)) {
                return true; 
            }
        }
        return false; 
    }

    /**
     * Get report as XML.
     * 
     * @return XML report
     */
    public Element getReport() {
        DocumentFactory factory = DocumentFactory.getInstance();
        Element report = factory.createElement("report");

        for (RecordingResult result : RecordingResult.values()) {
            if (_recordings.get(result).size() > 0) {
                Element recordingResult = report.addElement("recorded")
                        .addAttribute("result", result.toString());

                for (Program program : _recordings.get(result)) {
                    recordingResult.add(program.asXml());
                }
            }
        }

        if (_interestingShows.size() > 0) {
            Element interesting = report.addElement("interesting");
            for (String category : _interestingShows.keySet()) {
                Element categoryElem = interesting;
                if (category.length() > 0) {
                    categoryElem = interesting.addElement("category");
                    categoryElem.addAttribute("name", category);
                }
                for (Program program : _interestingShows.get(category)) {
                    categoryElem.add(program.asXml());
                }
            }

        }

        return report;
    }
}