package org_scala_tools_maven_dependency;
   
   import org.apache.maven.artifact.Artifact;
   import org.apache.maven.plugin.logging.Log;
   import org.apache.maven.shared.dependency.tree.DependencyNode;
   import org.apache.maven.shared.dependency.tree.traversal.DependencyNodeVisitor;
   import org_scala_tools_maven.VersionNumber;
   
   import java.util.ArrayList;
  import java.util.List;
  
  import static org_scala_tools_maven_dependency.ScalaConstants.*;
  /**
   * Ensures that all scala versions match the given version.
   * @author JSuereth
   *
   */
  public class CheckScalaVersionVisitor implements DependencyNodeVisitor {
      private VersionNumber _version;
      private boolean _failed = false;
      private Log _log;
  
      private List<String> scalaDependentArtifactStrings = new ArrayList<String>();
  
      public boolean endVisit(@SuppressWarnings("unused") DependencyNode node) {
          return !_failed;
      }
  
      public CheckScalaVersionVisitor(String projectVerison, Log log) {
          this._version = new VersionNumber(projectVerison);
          this._log = log;
      }
  
      public boolean isScalaDistroArtifact(Artifact artifact) {
          return SCALA_DISTRO_GROUP.equalsIgnoreCase(artifact.getGroupId()) &&
          SCALA_DISTRO_ARTIFACTS.contains(artifact.getArtifactId());
      }
      public boolean visit(DependencyNode node) {
          //TODO - Do we care about provided scope?
          Artifact artifact = node.getArtifact();
          _log.debug("checking ["+artifact+"] for scala version");
          //TODO - Handle version ranges???? does that make sense given scala's binary incompatability!
          if(isScalaDistroArtifact(artifact) && artifact.getVersion() != null) {
              VersionNumber originalVersion = new VersionNumber(artifact.getVersion());
              if(originalVersion.compareTo(_version) != 0) {
                  _failed = true;
              }
              //If this dependency is transitive, we want to track which artifact requires this...
              if(node.getParent() != null) { //TODO - Go all the way up the parent chain till we hit the bottom....
                  final Artifact parentArtifact = node.getParent().getArtifact();
                  scalaDependentArtifactStrings.add(" " + StringUtil.makeArtifactNameString(parentArtifact) + " requires scala version: " + originalVersion);
              }
          } else {
              //TODO - What now?
          }
          return !_failed;
      }
  
      public boolean isFailed() {
          return _failed;
      }
      public void logScalaDependents() {
          _log.warn(" Expected all dependencies to require Scala version: " + _version);
          for(String dependString : scalaDependentArtifactStrings) {
              _log.warn(dependString);
          }
      }
  }