//   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.plugin.uml;

import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import org.eclipse.emf.common.util.EList;
import org.eclipse.uml2.uml.Association;
import org.eclipse.uml2.uml.Class;
import org.eclipse.uml2.uml.Comment;
import org.eclipse.uml2.uml.Element;
import org.eclipse.uml2.uml.Interaction;
import org.eclipse.uml2.uml.Lifeline;
import org.eclipse.uml2.uml.Message;
import org.eclipse.uml2.uml.MessageOccurrenceSpecification;
import org.eclipse.uml2.uml.Model;
import org.eclipse.uml2.uml.Operation;
import org.eclipse.uml2.uml.Region;
import org.eclipse.uml2.uml.StateMachine;
import org.eclipse.uml2.uml.Transition;
import org.eclipse.uml2.uml.UMLPackage;
import org.eclipse.uml2.uml.Vertex;

import de.ugoe.cs.autoquest.eventcore.Event;
import de.ugoe.cs.autoquest.plugin.http.eventcore.SOAPEventType;
import de.ugoe.cs.autoquest.plugin.uml.eventcore.UMLTransitionType;

/**
 * <p>
 * Utilities for working with UML.
 * </p>
 * 
 * @author Steffen Herbold
 */
public class UMLUtils {

    /**
     * <p>
     * Creates a sequence of events with {@link UMLTransitionType} as event type from a given
     * sequence of events with the {@link SOAPEventType}, by matching the sequences to a state
     * machine.
     * </p>
     * 
     * @param sequence
     *            SOAP sequences
     * @param stateMachine
     *            the state machine
     * @return create UML sequences
     */
    public static List<Event> createUMLTransitionSequence(List<Event> sequence,
                                                          StateMachine stateMachine)
    {
        List<List<Transition>> matchingSequences =
            determineMatchingTransitionSequences(sequence, stateMachine);

        if (matchingSequences.size() != 1) {
            throw new RuntimeException("no unique match found; " + matchingSequences.size() +
                " matches");
        }
        List<Event> umlEventSequence = new LinkedList<>();
        for (Transition transition : matchingSequences.get(0)) {
            umlEventSequence.add(new Event(new UMLTransitionType(transition)));
        }
        return umlEventSequence;
    }

    /**
     * <p>
     * Uses a sequences of events with the {@link UMLTransitionType} to determine the transition
     * probabilities for the state machine.
     * </p>
     * 
     * @param sequences
     *            UML sequences
     * @param stateMachine
     *            state machine to be converted to a usage profile
     */
    public static void convertStateMachineToUsageProfile(Collection<List<Event>> sequences,
                                                         StateMachine stateMachine)
    {
        // create state->outgoings hashmap
        Map<Vertex, Map<Transition, Integer>> stateMap = new HashMap<>();
        for (Region region : stateMachine.getRegions()) {
            for (Vertex state : region.getSubvertices()) {
                stateMap.put(state, new HashMap<Transition, Integer>());
            }
        }

        // create counters for each transition
        for (List<Event> sequence : sequences) {
            for (Event event : sequence) {
                if (event.getType() instanceof UMLTransitionType) {
                    Transition transition = ((UMLTransitionType) event.getType()).getTransition();
                    Map<Transition, Integer> transitionMap = stateMap.get(transition.getSource());
                    Integer value = transitionMap.get(transition);
                    if (value == null) {
                        value = 0;
                    }
                    transitionMap.put(transition, value + 1);
                }
                else {
                    throw new RuntimeException(
                                               "Wrong event type. Only UMLTransitionType supported but was: " +
                                                   event.getType().getClass().getName());
                }
            }
        }

        // calculate probabilities
        for (Region region : stateMachine.getRegions()) {
            for (Vertex state : region.getSubvertices()) {
                Map<Transition, Integer> transitionMap = stateMap.get(state);
                int totalCount = 0;
                for (Entry<Transition, Integer> entry : transitionMap.entrySet()) {
                    totalCount += entry.getValue();
                }
                if (totalCount != 0) {
                    for (Transition transition : state.getOutgoings()) {
                        double prob = 0.0d;
                        if (transitionMap.containsKey(transition)) {
                            prob = ((double) transitionMap.get(transition)) / totalCount;
                        }
                        Comment comment = transition.createOwnedComment();
                        comment.setBody("" + prob);
                    }
                }
                else {
                    // system has never been in this state, all transitions equally likely
                    int numOutgoings = state.getOutgoings().size();
                    for (Transition transition : state.getOutgoings()) {
                        Comment comment = transition.createOwnedComment();
                        comment.setBody("" + (1.0d / numOutgoings));
                    }
                }
            }
        }
    }

    /**
     * <p>
     * Determines all matching {@link Transition} sequences in a state machine for a given sequence
     * of SOAP events.
     * </p>
     * 
     * @param sequence
     *            SOAP sequence
     * @param stateMachine
     *            the state machine
     * @return all matching {@link Transition} sequences
     */
    public static List<List<Transition>> determineMatchingTransitionSequences(List<Event> sequence,
                                                                              StateMachine stateMachine)
    {
        EList<Region> regions = stateMachine.getRegions();
        EList<Vertex> states = null;
        for (Region region : regions) {
            if (states == null) {
                states = region.getSubvertices();
            }
            else {
                states.addAll(region.getSubvertices());
            }
        }
        List<Transition> allTransitions = new LinkedList<>();
        for (Vertex state : states) {
            allTransitions.addAll(state.getOutgoings());
        }

        List<List<Transition>> matchingSequences = null;
        List<Transition> currentTransitions = null;

        // first, we try to find a single unique transition that we can match using the method name
        for (Iterator<Event> eventIterator = sequence.iterator(); eventIterator.hasNext();) {
            Event event = eventIterator.next();
            if (event.getType() instanceof SOAPEventType) {
                SOAPEventType eventType = (SOAPEventType) event.getType();
                if (matchingSequences == null) {
                    matchingSequences = new LinkedList<>();
                    List<Transition> initialMatches = matchTransitions(allTransitions, eventType);
                    for (Transition transition : initialMatches) {
                        List<Transition> candidate = new LinkedList<>();
                        candidate.add(transition);
                        matchingSequences.add(candidate);
                    }
                    currentTransitions = initialMatches;
                }
                else {
                    List<List<Transition>> nextMatchingSequences = new LinkedList<>();
                    List<Transition> nextCurrentTransitions = new LinkedList<>();
                    Iterator<Transition> currentTransitionIterator = currentTransitions.iterator();
                    Iterator<List<Transition>> currentMatchingSequencesIterator =
                        matchingSequences.iterator();
                    while (currentTransitionIterator.hasNext()) {
                        Transition currentTransition = currentTransitionIterator.next();
                        List<Transition> currentMatch = currentMatchingSequencesIterator.next();

                        List<Transition> matches =
                            matchTransitions(currentTransition.getTarget().getOutgoings(),
                                             eventType);
                        if (matches.isEmpty()) {
                            throw new RuntimeException("no matches found");
                        }
                        for (Transition matchingTransition : matches) {
                            List<Transition> candidate = new LinkedList<>(currentMatch);
                            candidate.add(matchingTransition);
                            nextMatchingSequences.add(candidate);
                            nextCurrentTransitions.add(matchingTransition);
                        }
                    }
                    matchingSequences = nextMatchingSequences;
                    currentTransitions = nextCurrentTransitions;
                }
            }
            else {
                throw new RuntimeException(
                                           "Wrong event type. Only UMLTransitionType supported but was: " +
                                               event.getType().getClass().getName());
            }
        }
        return matchingSequences;
    }

    /**
     * <p>
     * Extends a given model with an interaction that represents an observed sequence. 
     * </p>
     *
     * @param sequence sequence that is added as sequence diagram
     * @param model UML model to which the interaction is added
     * @param interactionName name of the interaction
     */
    public static void createInteractionFromEventSequence(List<Event> sequence, Model model, String interactionName)
    {
        Map<String, Class> classMap = new HashMap<>();

        EList<Element> elements = model.getOwnedElements();
        for (Element element : elements) {
            if (element instanceof Class) {
                classMap.put(((Class) element).getName(), (Class) element);
            }
        }

        Interaction interaction =
            (Interaction) model
                .createPackagedElement(interactionName, UMLPackage.Literals.INTERACTION);

        Lifeline userLifeline = interaction.createLifeline("user");

        int i = 0;
        for (Event event : sequence) {
            if (event.getType() instanceof SOAPEventType) {
                SOAPEventType eventType = (SOAPEventType) event.getType();
                String serviceName = eventType.getServiceName();
                String methodName = eventType.getCalledMethod();
                Class targetClass = classMap.get(serviceName);
                if (targetClass == null) {
                    throw new RuntimeException(
                                               "Could not find class in the UML model that belong to the service: " +
                                                   serviceName);
                }

                Lifeline targetLifeline = interaction.getLifeline(serviceName);
                if (targetLifeline == null) {
                    targetLifeline = interaction.createLifeline(serviceName);
                    Association association =
                        (Association) model.getPackagedElement("user_" + serviceName, true,
                                                               UMLPackage.Literals.ASSOCIATION,
                                                               true);
                    targetLifeline
                        .setRepresents(association.getMemberEnd(serviceName,
                                                                classMap.get(serviceName)));
                }
                MessageOccurrenceSpecification sendFragment =
                    (MessageOccurrenceSpecification) interaction
                        .createFragment(i + ":" + methodName + "_sendFragment",
                                        UMLPackage.Literals.MESSAGE_OCCURRENCE_SPECIFICATION);
                MessageOccurrenceSpecification recvFragment =
                    (MessageOccurrenceSpecification) interaction
                        .createFragment(i + ":" + methodName + "_recvFragment",
                                        UMLPackage.Literals.MESSAGE_OCCURRENCE_SPECIFICATION);

                sendFragment.setCovered(userLifeline);
                recvFragment.setCovered(targetLifeline);

                Message message = interaction.createMessage(methodName);
                message.setSignature(getOperationFromName(targetClass.getOperations(), methodName));
                message.setSendEvent(sendFragment);
                message.setReceiveEvent(recvFragment);

                sendFragment.setMessage(message);
                recvFragment.setMessage(message);
            }
            else {
                throw new RuntimeException(
                                           "Wrong event type. Only SOAPEventType supported but was: " +
                                               event.getType().getClass().getName());
            }
            i++;
        }
    }

    /**
     * <p>
     * Fetches an operation using only its name from a list of operations. Returns the first match
     * found or null if no match is found.
     * </p>
     * 
     * @param operations
     *            list of operations
     * @param name
     *            name of the operation
     * @return first matching operation; null if no match is found
     */
    private static Operation getOperationFromName(EList<Operation> operations, String name) {
        if (name == null) {
            throw new IllegalArgumentException("name of the operation must not be null");
        }
        if (operations != null) {
            for (Operation operation : operations) {
                if (operation.getName() != null && operation.getName().equals(name)) {
                    return operation;
                }
            }
        }
        return null;
    }

    /**
     * <p>
     * Determines which transitions match a given {@link SOAPEventType}.
     * </p>
     * 
     * @param transitions
     *            the transitions
     * @param eventType
     *            the SOAP event
     * @return matching transitions
     */
    private static List<Transition> matchTransitions(List<Transition> transitions,
                                                     SOAPEventType eventType)
    {
        List<Transition> matching = new LinkedList<>();
        for (Transition transition : transitions) {
            // String serviceName = transition.getName().split("\\.")[0]; // TODO service name check
            String methodName = transition.getName().split("\\.")[1];
            if (methodName.equals(eventType.getCalledMethod())) {
                matching.add(transition);
            }
        }
        return matching;
    }

}