//   Copyright 2012 Georg-August-Universität Göttingen, Germany
//
//   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 de.ugoe.cs.autoquest.tasktrees.temporalrelation;

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

import de.ugoe.cs.autoquest.tasktrees.nodeequality.NodeEquality;
import de.ugoe.cs.autoquest.tasktrees.nodeequality.NodeEqualityRuleManager;
import de.ugoe.cs.autoquest.tasktrees.treeifc.ISequence;
import de.ugoe.cs.autoquest.tasktrees.treeifc.ITaskTreeBuilder;
import de.ugoe.cs.autoquest.tasktrees.treeifc.ITaskTreeNode;
import de.ugoe.cs.autoquest.tasktrees.treeifc.ITaskTreeNodeFactory;
import de.ugoe.cs.autoquest.usageprofiles.SymbolComparator;
import de.ugoe.cs.autoquest.usageprofiles.Trie;
import de.ugoe.cs.autoquest.usageprofiles.TrieProcessor;

/**
 * <p>
 * TODO comment
 * </p>
 * 
 * @author Patrick Harms
 */
class DefaultTaskSequenceDetectionRule implements TemporalRelationshipRule {
    
    /**
     * <p>
     * the task tree node factory to be used for creating substructures for the temporal
     * relationships identified during rule
     * </p>
     */
    private ITaskTreeNodeFactory taskTreeNodeFactory;
    /**
     * <p>
     * the task tree builder to be used for creating substructures for the temporal relationships
     * identified during rule application
     * </p>
     */
    private ITaskTreeBuilder taskTreeBuilder;

    /**
     * <p>
     * the node comparator to be used for comparing task tree nodes
     * </p>
     */
    private SymbolComparator<ITaskTreeNode> nodeComparator;

    /**
     * <p>
     * instantiates the rule and initializes it with a node equality rule manager and the minimal
     * node equality identified sublist must have to consider them as iterated.
     * </p>
     */
    DefaultTaskSequenceDetectionRule(NodeEqualityRuleManager nodeEqualityRuleManager,
                                     NodeEquality            minimalNodeEquality,
                                     ITaskTreeNodeFactory    taskTreeNodeFactory,
                                     ITaskTreeBuilder        taskTreeBuilder)
    {
        this.taskTreeNodeFactory = taskTreeNodeFactory;
        this.taskTreeBuilder = taskTreeBuilder;
        
        this.nodeComparator =
            new TaskTreeNodeComparator(nodeEqualityRuleManager, minimalNodeEquality);
    }

    /* (non-Javadoc)
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {
        return "DefaultTaskSequenceDetectionRule";
    }

    /*
     * (non-Javadoc)
     * 
     * @see de.ugoe.cs.tasktree.temporalrelation.TemporalRelationshipRule#apply(TaskTreeNode,
     * boolean)
     */
    @Override
    public RuleApplicationResult apply(ITaskTreeNode parent, boolean finalize) {
        if (!(parent instanceof ISequence)) {
            return null;
        }

        if (!finalize) {
            // the rule is always feasible as tasks may occur at any time
            RuleApplicationResult result = new RuleApplicationResult();
            result.setRuleApplicationStatus(RuleApplicationStatus.RULE_APPLICATION_FEASIBLE);
            return result;
        }

        RuleApplicationData<ITaskTreeNode> appData = new RuleApplicationData<ITaskTreeNode>(parent);
        
        appData.getStopWatch().start("whole rule application");
        
        do {
            getSequencesOccuringMostOften(appData);
            
            if ((appData.getLastFoundSequences().size() > 0) &&
                (appData.getLastFoundSequences().getOccurrenceCount() > 1))
            {
                System.out.println("found " + appData.getLastFoundSequences().size() +
                                   " tasks occurring " +
                                   appData.getLastFoundSequences().getOccurrenceCount() + " times");

                for (List<ITaskTreeNode> task : appData.getLastFoundSequences()) {
                    // only tasks occurring more often than once are of interest
                    appData.stopWatch.start("creating task sequences");

                    String taskId = "task " + RuleUtils.getNewId();
                    System.out.println(taskId + ": " + task);
                    
                    appData.resetReplacementCounter();
                    createSequenceForTaskOccurrences(taskId, task, parent, appData);
                    
                    if (appData.getReplacementCounter() <
                        appData.getLastFoundSequences().getOccurrenceCount())
                    {
                        System.out.println(taskId + ": replaced task only " +
                                           appData.getReplacementCounter() +
                                           " times instead of expected " +
                                           appData.getLastFoundSequences().getOccurrenceCount());
                        
                    }

                    appData.stopWatch.stop("creating task sequences");
                }
            }
            
        }
        while (appData.getLastFoundSequences().getOccurrenceCount() > 2);
        
        appData.getStopWatch().stop("whole rule application");
        appData.getStopWatch().dumpStatistics(System.out);
        
        if (appData.getResult().getNewlyCreatedParentNodes().size() > 0) {
            appData.getResult().setRuleApplicationStatus
                (RuleApplicationStatus.RULE_APPLICATION_FINISHED);
        }
        
        System.out.println(appData.getResult().getNewlyCreatedParentNodes().size());
        
        for (ITaskTreeNode node : appData.getResult().getNewlyCreatedParentNodes()) {
            for (ITaskTreeNode child : node.getChildren()) {
                System.out.println(child);
            }
            System.out.println();
        }
        
        return appData.getResult();
    }

    /**
     * <p>
     * TODO: comment
     * </p>
     *
     * @param i
     * @return
     */
    private void getSequencesOccuringMostOften(RuleApplicationData<ITaskTreeNode> appData) {
        System.out.println("determining most prominent tasks with a maximum of " +
                           (appData.getLastFoundSequences().getOccurrenceCount() - 1) +
                           " occurrences");

        Sequences<ITaskTreeNode> sequences;
        boolean createNewTrie = (appData.getLastTrie() == null) ||
            appData.getReplacementCounter() > 0; // tree has changed
        
        do {
            if (createNewTrie) {
                createNewTrie(appData);
            }
            
            /*PathDumper dumper = new PathDumper();
            trie.process(dumper);
        
            dumper.dump();*/
        
            appData.getStopWatch().start("determining tasks");

            MaxCountAndLongestSequenceFinder finder = new MaxCountAndLongestSequenceFinder
                  (appData.getLastFoundSequences().getOccurrenceCount() - 1);
            appData.getLastTrie().process(finder);
        
            sequences = finder.getFoundSequences();
            
            createNewTrie = false;
            
            for (List<ITaskTreeNode> task : sequences) {
                if (task.size() >= appData.getTrainedSequenceLength()) {
                    // Trie must be recreated with a longer sequence length to be sure that
                    // the found sequences occurring most often are found in their whole length
                    appData.setTrainedSequenceLength(appData.getTrainedSequenceLength() + 1);
                    createNewTrie = true;
                    break;
                }
            }
            
            appData.getStopWatch().stop("determining tasks");
        }
        while (createNewTrie);
        
        appData.setLastFoundSequences(sequences);
    }

    /**
     * <p>
     * TODO: comment
     * </p>
     *
     * @param parent
     * @return
     */
    private void createNewTrie(RuleApplicationData<ITaskTreeNode> appData) {
        System.out.println("training trie with a maximum sequence length of " +
                           appData.getTrainedSequenceLength());

        appData.getStopWatch().start("training trie");
        appData.setLastTrie(new Trie<ITaskTreeNode>(nodeComparator));
    
        trainTrie(appData.getTree(), appData);
        appData.getStopWatch().stop("training trie");
    }

    /**
     * <p>
     * TODO: comment
     * </p>
     *
     * @param trie
     * @param parent
     */
    private void trainTrie(ITaskTreeNode parent, RuleApplicationData<ITaskTreeNode> appData) {
        // prevent training of already replaces sequences as those shall not be replaced anymore
        if (!appData.getResult().getNewlyCreatedParentNodes().contains(parent)) {
            List<ITaskTreeNode> children = parent.getChildren();
        
            if ((children != null) && (children.size() > 0)) {
                
                /*System.out.println();
                for (int i = 0; i < children.size(); i++) {
                    System.out.println(children.get(i));
                }*/
                
                appData.getLastTrie().train(children, appData.getTrainedSequenceLength());
            
                for (ITaskTreeNode child : children) {
                    trainTrie(child, appData);
                }
            }
        }
    }

    /**
     * <p>
     * TODO: comment
     * </p>
     *
     * @param task
     * @param parent
     * @param treeBuilder
     * @param nodeFactory
     * @param result
     */
    private void createSequenceForTaskOccurrences(String                             taskId,
                                                  List<ITaskTreeNode>                task,
                                                  ITaskTreeNode                      parent,
                                                  RuleApplicationData<ITaskTreeNode> appData)
    {
        List<ITaskTreeNode> children = parent.getChildren();
        
        if ((children == null) || (children.size() == 0)) {
            return;
        }
        
        // first traverse the children
        for (ITaskTreeNode child : children) {
            createSequenceForTaskOccurrences(taskId, task, child, appData);
        }
        
        // now check the children themselves for an occurrence of the task
        int index = -1;
        
        do {
            index = getSubListIndex(children, task, ++index);
            
            if (index > -1) {
                if (task.size() < children.size()) {
                    ISequence sequence = RuleUtils.createNewSubSequenceInRange
                        (parent, index, index + task.size() - 1, taskId,
                         taskTreeNodeFactory, taskTreeBuilder);
                    
                    appData.getResult().addNewlyCreatedParentNode(sequence);
                    appData.incrementReplacementCounter();
                 
                    children = parent.getChildren();
                }
                else {
                    // the whole list of children is an occurrence of this task. Just set the
                    // description of the parent and break up
                    String description = parent.getDescription();
                    
                    if ((description != null) && (description.length() > 0)) {
                        description += "; " + taskId;
                    }
                    else {
                        description = taskId;
                    }
                    
                    taskTreeBuilder.setDescription(parent, description);
                    break;
                }
            }
        }
        while (index > -1);
    }

    /**
     * <p>
     * TODO: comment
     * </p>
     *
     * @param trie
     * @param object
     * @return
     */
    private int getSubListIndex(List<ITaskTreeNode> list,
                                List<ITaskTreeNode> subList,
                                int                 startIndex)
    {
        boolean matchFound;
        int result = -1;
        
        for (int i = startIndex; i <= list.size() - subList.size(); i++) {
            matchFound = true;
            
            for (int j = 0; j < subList.size(); j++) {
                if (!nodeComparator.equals(list.get(i + j), subList.get(j))) {
                    matchFound = false;
                    break;
                }
                else if (!nodeComparator.equals(subList.get(j), list.get(i + j))){
                    throw new RuntimeException("comparator not commutative");
                }
            }
            
            if (matchFound) {
                result = i;
                break;
            }
        }
        
        return result;
    }
    
    /**
     * <p>
     * TODO comment
     * </p>
     * 
     * @author Patrick Harms
     */
    private class MaxCountAndLongestSequenceFinder implements TrieProcessor<ITaskTreeNode> {
        
        /**
         * 
         */
        private int maxCount;
        
        /**
         * 
         */
        private int currentCount;
        
        /**
         * 
         */
        private List<List<ITaskTreeNode>> foundSequences = new LinkedList<List<ITaskTreeNode>>();

        /**
         * <p>
         * TODO: comment
         * </p>
         *
         * @param maxCount
         */
        public MaxCountAndLongestSequenceFinder(int maxCount) {
            super();
            this.maxCount = maxCount;
            this.currentCount = 0;
        }

        /* (non-Javadoc)
         * @see de.ugoe.cs.autoquest.usageprofiles.TrieProcessor#process(java.util.List, int)
         */
        @Override
        public TrieProcessor.Result process(List<ITaskTreeNode> sequence, int count) {
            if (sequence.size() < 2) {
                // ignore single nodes
                return TrieProcessor.Result.CONTINUE;
            }
            
            if (count < 2) {
                // ignore singular occurrences
                return TrieProcessor.Result.SKIP_NODE;
            }

            if (count > this.maxCount) {
                // ignore sequences that occur too often
                return TrieProcessor.Result.CONTINUE;
            }
            
            if (this.currentCount > count) {
                // ignore this children of this node, as they may have only smaller counts than
                // the already found sequences
                return TrieProcessor.Result.SKIP_NODE;
            }
            
            if (this.currentCount < count) {
                // the provided sequence occurs more often that all sequences found so far.
                // clear all found sequences and use the new count as the one searched for
                foundSequences.clear();
                this.currentCount = count;
            }
            
            if (this.currentCount == count) {
                // the sequence is of interest. Sort it into the other found sequences so that
                // the longest come first
                boolean added = false;
                for (int i = 0; i < foundSequences.size(); i++) {
                    if (foundSequences.get(i).size() < sequence.size()) {
                        // defensive copy
                        foundSequences.add(i, new LinkedList<ITaskTreeNode>(sequence)); // defensive copy
                        added = true;
                        break;
                    }
                }
                
                if (!added) {
                    foundSequences.add(new LinkedList<ITaskTreeNode>(sequence)); // defensive copy
                }
            }
            
            return TrieProcessor.Result.CONTINUE;
        }

        /**
         * <p>
         * TODO: comment
         * </p>
         *
         * @return
         */
        public Sequences<ITaskTreeNode> getFoundSequences() {
            removePermutationsOfShorterTasks();
            return new Sequences<ITaskTreeNode>(currentCount, foundSequences);
        }

        /**
         * <p>
         * TODO: comment
         * </p>
         *
         */
        private void removePermutationsOfShorterTasks() {
            // now iterate the sorted list and for each task remove all other tasks that are shorter
            // (i.e. come later in the sorted list) and that represent a subpart of the task
            for (int i = 0; i < foundSequences.size(); i++) {
                for (int j = i + 1; j < foundSequences.size();) {
                    if (foundSequences.get(j).size() < foundSequences.get(i).size()) {
                        // found a task that is a potential subtask. Check for this and remove the
                        // subtask if needed
                        List<ITaskTreeNode> longTask = foundSequences.get(i);
                        List<ITaskTreeNode> shortTask = foundSequences.get(j);
                        
                        if (getSubListIndex(longTask, shortTask, 0) > -1) {
                            foundSequences.remove(j);
                        }
                        else {
                            j++;
                        }
                    }
                    else {
                        j++;
                    }
                }
            }
        }

    }
    
    /**
     * 
     */
    private class RuleApplicationData<T> {
        
        /**
         * 
         */
        private T tree;
        
        /**
         * 
         */
        private RuleApplicationResult result = new RuleApplicationResult();
        
        /**
         * 
         */
        private Sequences<T> lastFoundSequences = new Sequences<T>(Integer.MAX_VALUE, null);
        
        /**
         * 
         */
        private Trie<T> lastTrie;
        
        /**
         * default and minimum trained sequence length is 3
         */
        private int trainedSequenceLength = 3;
        
        /**
         * 
         */
        private int replacementCounter;
        
        /**
         * 
         */
        private StopWatch stopWatch = new StopWatch();
        
        /**
         * 
         */
        private RuleApplicationData(T tree) {
            this.tree = tree;
        }

        /**
         * @return the lastFoundSequences
         */
        private Sequences<T> getLastFoundSequences() {
            return lastFoundSequences;
        }

        /**
         * @param lastFoundSequences the lastFoundSequences to set
         */
        private void setLastFoundSequences(Sequences<T> lastFoundSequences) {
            this.lastFoundSequences = lastFoundSequences;
        }

        /**
         * @return the lastTrie
         */
        private Trie<T> getLastTrie() {
            return lastTrie;
        }

        /**
         * @return the trainedSequenceLength
         */
        private int getTrainedSequenceLength() {
            return trainedSequenceLength;
        }

        /**
         * @param trainedSequenceLength the trainedSequenceLength to set
         */
        private void setTrainedSequenceLength(int trainedSequenceLength) {
            this.trainedSequenceLength = trainedSequenceLength;
        }

        /**
         * @param lastTrie the lastTrie to set
         */
        private void setLastTrie(Trie<T> lastTrie) {
            this.lastTrie = lastTrie;
        }

        /**
         * @return the tree
         */
        private T getTree() {
            return tree;
        }

        /**
         * @return the result
         */
        private RuleApplicationResult getResult() {
            return result;
        }

        /**
         * @return the stopWatch
         */
        private StopWatch getStopWatch() {
            return stopWatch;
        }

        /**
         *
         */
        private void resetReplacementCounter() {
            replacementCounter = 0;
        }

        /**
         *
         */
        private void incrementReplacementCounter() {
            replacementCounter++;
        }

        /**
         *
         */
        private int getReplacementCounter() {
            return replacementCounter;
        }
    }
    

    /**
     * <p>
     * TODO comment
     * </p>
     * 
     * @author Patrick Harms
     */
    private class Sequences<T> implements Iterable<List<T>> {
        
        /**
         * 
         */
        private int occurrenceCount;
        
        /**
         * 
         */
        private List<List<T>> sequences;

        /**
         * <p>
         * TODO: comment
         * </p>
         *
         * @param occurrenceCount
         * @param sequences
         */
        private Sequences(int occurrenceCount, List<List<T>> sequences) {
            super();
            this.occurrenceCount = occurrenceCount;
            this.sequences = sequences;
        }

        /**
         * <p>
         * TODO: comment
         * </p>
         *
         * @return
         */
        private int getOccurrenceCount() {
            return occurrenceCount;
        }

        /**
         * <p>
         * TODO: comment
         * </p>
         *
         * @return
         */
        private int size() {
            return this.sequences.size();
        }

        /**
         * 
         */

        /* (non-Javadoc)
         * @see java.lang.Iterable#iterator()
         */
        @Override
        public Iterator<List<T>> iterator() {
            return this.sequences.iterator();
        }

    }

}