/**
 *
 * 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.
 */
package org.apache.karaf.tooling.features;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.maven.artifact.Artifact;
import org.apache.maven.artifact.metadata.ArtifactMetadataRetrievalException;
import org.apache.maven.artifact.metadata.ArtifactMetadataSource;
import org.apache.maven.artifact.metadata.ResolutionGroup;
import org.apache.maven.artifact.repository.ArtifactRepository;
import org.apache.maven.artifact.resolver.ArtifactCollector;
import org.apache.maven.artifact.resolver.ArtifactResolutionException;
import org.apache.maven.artifact.resolver.ArtifactResolutionResult;
import org.apache.maven.artifact.resolver.CyclicDependencyException;
import org.apache.maven.artifact.resolver.ResolutionListener;
import org.apache.maven.artifact.resolver.ResolutionNode;
import org.apache.maven.artifact.resolver.filter.ArtifactFilter;
import org.apache.maven.artifact.versioning.ArtifactVersion;
import org.apache.maven.artifact.versioning.OverConstrainedVersionException;
import org.apache.maven.artifact.versioning.VersionRange;

/**
 * @version $Revision: 1.1 $
 */
public class GraphArtifactCollector implements ArtifactCollector {
    public ArtifactResolutionResult collect(
            Set artifacts,
            Artifact originatingArtifact,
            ArtifactRepository localRepository,
            List remoteRepositories,
            ArtifactMetadataSource source,
            ArtifactFilter filter,
            List listeners) throws ArtifactResolutionException {
        return collect(artifacts, originatingArtifact, Collections.EMPTY_MAP,
                localRepository, remoteRepositories, source, filter, listeners);
    }

    public ArtifactResolutionResult collect(
            Set artifacts,
            Artifact originatingArtifact,
            Map managedVersions,
            ArtifactRepository localRepository,
            List remoteRepositories,
            ArtifactMetadataSource source,
            ArtifactFilter filter,
            List listeners) throws ArtifactResolutionException {
        Map resolvedArtifacts = new HashMap();

        ResolutionNode root = new ResolutionNode(originatingArtifact, remoteRepositories);
        root.addDependencies(artifacts, remoteRepositories, filter);
        recurse(root, resolvedArtifacts, managedVersions, localRepository,
                remoteRepositories, source, filter, listeners);

        Set set = new HashSet();
        for (Iterator i = resolvedArtifacts.values().iterator(); i.hasNext();) {
            List nodes = (List) i.next();
            for (Iterator j = nodes.iterator(); j.hasNext();) {
                ResolutionNode node = (ResolutionNode) j.next();
                Artifact artifact = node.getArtifact();
                if (!node.equals(root) && node.isActive() && node.filterTrail(filter)
                        // If it was optional and not a direct dependency,
                        // we don't add it or its children, just allow the
                        // update of the version and scope
                        && (node.isChildOfRootNode() || !artifact.isOptional())) {
                    artifact.setDependencyTrail(node.getDependencyTrail());
                    set.add(node);
                }
            }
        }

        ArtifactResolutionResult result = new ArtifactResolutionResult();
        result.setArtifactResolutionNodes(set);
        return result;
    }

    private void recurse(
            ResolutionNode node,
            Map resolvedArtifacts,
            Map managedVersions,
            ArtifactRepository localRepository,
            List remoteRepositories,
            ArtifactMetadataSource source,
            ArtifactFilter filter,
            List listeners) throws CyclicDependencyException, ArtifactResolutionException,
            OverConstrainedVersionException {
        fireEvent(ResolutionListener.TEST_ARTIFACT, listeners, node);

        // TODO: use as a conflict resolver
        Object key = node.getKey();
        if (managedVersions.containsKey(key)) {
            Artifact artifact = (Artifact) managedVersions.get(key);
            fireEvent(ResolutionListener.MANAGE_ARTIFACT, listeners, node, artifact);
            if (artifact.getVersion() != null) {
                node.getArtifact().setVersion(artifact.getVersion());
            }
            if (artifact.getScope() != null) {
                node.getArtifact().setScope(artifact.getScope());
            }
        }

        List previousNodes = (List) resolvedArtifacts.get(key);
        if (previousNodes != null) {
            node = checkPreviousNodes(node, listeners, previousNodes);
        }
        else {
            previousNodes = new ArrayList();
            resolvedArtifacts.put(key, previousNodes);
        }
        previousNodes.add(node);

        if (node.isActive()) {
            fireEvent(ResolutionListener.INCLUDE_ARTIFACT, listeners, node);
        }

        // don't pull in the transitive deps of a system-scoped dependency.
        if (node.isActive() && !Artifact.SCOPE_SYSTEM.equals(node.getArtifact().getScope())) {
            fireEvent(ResolutionListener.PROCESS_CHILDREN, listeners, node);
            for (Iterator i = node.getChildrenIterator(); i.hasNext();) {
                ResolutionNode child = (ResolutionNode) i.next();
                // We leave in optional ones, but don't pick up its dependencies
                if (!child.isResolved()
                        && (!child.getArtifact().isOptional() || child.isChildOfRootNode())) {
                    Artifact artifact = child.getArtifact();
                    try {
                        if (artifact.getVersion() == null) {
                            // set the recommended version
                            // TODO: maybe its better to just pass the range
                            // through to retrieval and use a transformation?
                            ArtifactVersion version;
                            version = getArtifactVersion(localRepository, remoteRepositories, source, artifact);

                            artifact.selectVersion(version.toString());
                            fireEvent(ResolutionListener.SELECT_VERSION_FROM_RANGE,
                                    listeners, child);
                        }

                        ResolutionGroup rGroup = source.retrieve(artifact,
                                localRepository, remoteRepositories);

                        // TODO might be better to have source.retreive() throw
                        // a specific exception for this situation
                        // and catch here rather than have it return null
                        if (rGroup == null) {
                            // relocated dependency artifact is declared
                            // excluded, no need to add and recurse further
                            continue;
                        }

                        child.addDependencies(rGroup.getArtifacts(),
                                rGroup.getResolutionRepositories(), filter);
                    }
                    catch (CyclicDependencyException e) {
                        // would like to throw this, but we have crappy stuff in
                        // the repo

                        fireEvent(ResolutionListener.OMIT_FOR_CYCLE, listeners,
                                new ResolutionNode(e.getArtifact(), remoteRepositories, child));
                    }
                    catch (ArtifactMetadataRetrievalException e) {
                        artifact.setDependencyTrail(node.getDependencyTrail());
                        throw new ArtifactResolutionException(
                                "Unable to get dependency information: "
                                        + e.getMessage(), artifact, e);
                    }

                    recurse(child, resolvedArtifacts, managedVersions,
                            localRepository, remoteRepositories, source,
                            filter, listeners);
                }
            }
            fireEvent(ResolutionListener.FINISH_PROCESSING_CHILDREN, listeners,
                    node);
        }
    }

    private ArtifactVersion getArtifactVersion(
            ArtifactRepository localRepository,
            List remoteRepositories,
            ArtifactMetadataSource source,
            Artifact artifact) throws OverConstrainedVersionException,
            ArtifactMetadataRetrievalException {
        ArtifactVersion version;
        if (!artifact.isSelectedVersionKnown()) {
            List versions = artifact.getAvailableVersions();
            if (versions == null) {
                versions = source.retrieveAvailableVersions(
                        artifact, localRepository,
                        remoteRepositories);
                artifact.setAvailableVersions(versions);
            }

            VersionRange versionRange = artifact.getVersionRange();

            version = versionRange.matchVersion(versions);

            if (version == null) {
                if (versions.isEmpty()) {
                    throw new OverConstrainedVersionException(
                            "No versions are present in the repository for the artifact with a range "
                                    + versionRange, artifact, remoteRepositories);
                }
                else {
                    throw new OverConstrainedVersionException(
                            "Couldn't find a version in "
                                    + versions
                                    + " to match range "
                                    + versionRange,
                            artifact, remoteRepositories);
                }
            }
        }
        else {
            version = artifact.getSelectedVersion();
        }
        return version;
    }

    private ResolutionNode checkPreviousNodes(
            ResolutionNode node,
            List listeners,
            List previousNodes) throws OverConstrainedVersionException {
        for (Iterator i = previousNodes.iterator(); i.hasNext();) {
            ResolutionNode previous = (ResolutionNode) i.next();
            if (previous.isActive()) {
                // Version mediation
                VersionRange previousRange = previous.getArtifact().getVersionRange();
                VersionRange currentRange = node.getArtifact().getVersionRange();
                // TODO: why do we force the version on it? what if they
                // don't match?
                if (previousRange == null) {
                    // version was already resolved
                    node.getArtifact().setVersion(previous.getArtifact().getVersion());
                }
                else if (currentRange == null) {
                    // version was already resolved
                    previous.getArtifact().setVersion(node.getArtifact().getVersion());
                }
                else {
                    // TODO: shouldn't need to double up on this work, only
                    // done for simplicity of handling recommended
                    // version but the restriction is identical
                    VersionRange newRange = previousRange.restrict(currentRange);
                    // TODO: ick. this forces the OCE that should have come
                    // from the previous call. It is still correct
                    if (newRange.isSelectedVersionKnown(previous.getArtifact())) {
                        fireEvent(ResolutionListener.RESTRICT_RANGE,
                                listeners, node, previous.getArtifact(),
                                newRange);
                    }
                    previous.getArtifact().setVersionRange(newRange);
                    node.getArtifact().setVersionRange(
                            currentRange.restrict(previousRange));

                    // Select an appropriate available version from the (now
                    // restricted) range
                    // Note this version was selected before to get the
                    // appropriate POM
                    // But it was reset by the call to setVersionRange on
                    // restricting the version
                    ResolutionNode[] resetNodes = {previous, node};
                    for (int j = 0; j < 2; j++) {
                        Artifact resetArtifact = resetNodes[j]
                                .getArtifact();
                        if (resetArtifact.getVersion() == null
                                && resetArtifact.getVersionRange() != null
                                && resetArtifact.getAvailableVersions() != null) {

                            resetArtifact
                                    .selectVersion(resetArtifact
                                            .getVersionRange()
                                            .matchVersion(
                                                    resetArtifact
                                                            .getAvailableVersions())
                                            .toString());
                            fireEvent(ResolutionListener.SELECT_VERSION_FROM_RANGE,
                                    listeners, resetNodes[j]);
                        }
                    }
                }

                // Conflict Resolution
                // TODO: use as conflict resolver(s), chain

                // TODO: should this be part of mediation?
                // previous one is more dominant
                if (previous.getDepth() <= node.getDepth()) {
                    checkScopeUpdate(node, previous, listeners);
                }
                else {
                    checkScopeUpdate(previous, node, listeners);
                }

                if (previous.getDepth() <= node.getDepth()) {
                    // previous was nearer
                    fireEvent(ResolutionListener.OMIT_FOR_NEARER,
                            listeners, node, previous.getArtifact());
                    node.disable();
                    node = previous;
                }
                else {
                    fireEvent(ResolutionListener.OMIT_FOR_NEARER,
                            listeners, previous, node.getArtifact());
                    previous.disable();
                }
            }
        }
        return node;
    }

    private void checkScopeUpdate(ResolutionNode farthest,
            ResolutionNode nearest, List listeners) {
        boolean updateScope = false;
        Artifact farthestArtifact = farthest.getArtifact();
        Artifact nearestArtifact = nearest.getArtifact();

        if (Artifact.SCOPE_RUNTIME.equals(farthestArtifact.getScope())
                && (Artifact.SCOPE_TEST.equals(nearestArtifact.getScope()) || Artifact.SCOPE_PROVIDED
                .equals(nearestArtifact.getScope()))) {
            updateScope = true;
        }

        if (Artifact.SCOPE_COMPILE.equals(farthestArtifact.getScope())
                && !Artifact.SCOPE_COMPILE.equals(nearestArtifact.getScope())) {
            updateScope = true;
        }

        // current POM rules all
        if (nearest.getDepth() < 2 && updateScope) {
            updateScope = false;

            fireEvent(ResolutionListener.UPDATE_SCOPE_CURRENT_POM, listeners,
                    nearest, farthestArtifact);
        }

        if (updateScope) {
            fireEvent(ResolutionListener.UPDATE_SCOPE, listeners, nearest,
                    farthestArtifact);

            // previously we cloned the artifact, but it is more effecient to
            // just update the scope
            // if problems are later discovered that the original object needs
            // its original scope value, cloning may
            // again be appropriate
            nearestArtifact.setScope(farthestArtifact.getScope());
        }
    }

    private void fireEvent(int event, List listeners, ResolutionNode node) {
        fireEvent(event, listeners, node, null);
    }

    private void fireEvent(int event, List listeners, ResolutionNode node,
            Artifact replacement) {
        fireEvent(event, listeners, node, replacement, null);
    }

    private void fireEvent(int event, List listeners, ResolutionNode node,
            Artifact replacement, VersionRange newRange) {
        for (Iterator i = listeners.iterator(); i.hasNext();) {
            ResolutionListener listener = (ResolutionListener) i.next();

            switch (event) {
                case ResolutionListener.TEST_ARTIFACT:
                    listener.testArtifact(node.getArtifact());
                    break;
                case ResolutionListener.PROCESS_CHILDREN:
                    listener.startProcessChildren(node.getArtifact());
                    break;
                case ResolutionListener.FINISH_PROCESSING_CHILDREN:
                    listener.endProcessChildren(node.getArtifact());
                    break;
                case ResolutionListener.INCLUDE_ARTIFACT:
                    listener.includeArtifact(node.getArtifact());
                    break;
                case ResolutionListener.OMIT_FOR_NEARER:
                    String version = node.getArtifact().getVersion();
                    String replacementVersion = replacement.getVersion();
                    if (version != null ? !version.equals(replacementVersion)
                            : replacementVersion != null) {
                        listener.omitForNearer(node.getArtifact(), replacement);
                    }
                    break;
                case ResolutionListener.OMIT_FOR_CYCLE:
                    listener.omitForCycle(node.getArtifact());
                    break;
                case ResolutionListener.UPDATE_SCOPE:
                    listener
                            .updateScope(node.getArtifact(), replacement.getScope());
                    break;
                case ResolutionListener.UPDATE_SCOPE_CURRENT_POM:
                    listener.updateScopeCurrentPom(node.getArtifact(), replacement
                            .getScope());
                    break;
                case ResolutionListener.MANAGE_ARTIFACT:
                    listener.manageArtifact(node.getArtifact(), replacement);
                    break;
                case ResolutionListener.SELECT_VERSION_FROM_RANGE:
                    listener.selectVersionFromRange(node.getArtifact());
                    break;
                case ResolutionListener.RESTRICT_RANGE:
                    if (node.getArtifact().getVersionRange().hasRestrictions()
                            || replacement.getVersionRange().hasRestrictions()) {
                        listener.restrictRange(node.getArtifact(), replacement,
                                newRange);
                    }
                    break;
                default:
                    throw new IllegalStateException("Unknown event: " + event);
            }
        }
    }
}
