package org.hl7.fhir.r4.conformance;

/*
  Copyright (c) 2011+, HL7, Inc.
  All rights reserved.
  
  Redistribution and use in source and binary forms, with or without modification, 
  are permitted provided that the following conditions are met:
    
   * Redistributions of source code must retain the above copyright notice, this 
     list of conditions and the following disclaimer.
   * Redistributions in binary form must reproduce the above copyright notice, 
     this list of conditions and the following disclaimer in the documentation 
     and/or other materials provided with the distribution.
   * Neither the name of HL7 nor the names of its contributors may be used to 
     endorse or promote products derived from this software without specific 
     prior written permission.
  
  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND 
  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 
  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 
  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 
  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 
  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
  WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
  POSSIBILITY OF SUCH DAMAGE.
  
 */

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.hl7.fhir.exceptions.DefinitionException;
import org.hl7.fhir.exceptions.FHIRFormatError;
import org.hl7.fhir.r4.context.IWorkerContext;
import org.hl7.fhir.r4.formats.IParser;
import org.hl7.fhir.r4.model.Base;
import org.hl7.fhir.r4.model.Coding;
import org.hl7.fhir.r4.model.ElementDefinition;
import org.hl7.fhir.r4.model.ElementDefinition.ElementDefinitionBindingComponent;
import org.hl7.fhir.r4.model.ElementDefinition.ElementDefinitionConstraintComponent;
import org.hl7.fhir.r4.model.ElementDefinition.ElementDefinitionMappingComponent;
import org.hl7.fhir.r4.model.ElementDefinition.ElementDefinitionSlicingComponent;
import org.hl7.fhir.r4.model.ElementDefinition.TypeRefComponent;
import org.hl7.fhir.r4.model.Enumerations.BindingStrength;
import org.hl7.fhir.r4.model.Enumerations.PublicationStatus;
import org.hl7.fhir.r4.model.IntegerType;
import org.hl7.fhir.r4.model.PrimitiveType;
import org.hl7.fhir.r4.model.StringType;
import org.hl7.fhir.r4.model.StructureDefinition;
import org.hl7.fhir.r4.model.StructureDefinition.TypeDerivationRule;
import org.hl7.fhir.r4.model.Type;
import org.hl7.fhir.r4.model.ValueSet;
import org.hl7.fhir.r4.model.ValueSet.ConceptReferenceComponent;
import org.hl7.fhir.r4.model.ValueSet.ConceptSetComponent;
import org.hl7.fhir.r4.model.ValueSet.ValueSetExpansionContainsComponent;
import org.hl7.fhir.r4.terminologies.ValueSetExpander.ValueSetExpansionOutcome;
import org.hl7.fhir.r4.utils.DefinitionNavigator;
import org.hl7.fhir.r4.utils.ToolingExtensions;
import org.hl7.fhir.utilities.CommaSeparatedStringBuilder;
import org.hl7.fhir.utilities.TextFile;
import org.hl7.fhir.utilities.Utilities;
import org.hl7.fhir.utilities.filesystem.ManagedFileAccess;
import org.hl7.fhir.utilities.http.HTTPResult;
import org.hl7.fhir.utilities.http.ManagedWebAccess;
import org.hl7.fhir.utilities.validation.ValidationMessage;
import org.hl7.fhir.utilities.validation.ValidationMessage.Source;

/**
 * A engine that generates difference analysis between two sets of structure
 * definitions, typically from 2 different implementation guides.
 * 
 * How this class works is that you create it with access to a bunch of
 * underying resources that includes all the structure definitions from both
 * implementation guides
 * 
 * Once the class is created, you repeatedly pass pairs of structure
 * definitions, one from each IG, building up a web of difference analyses. This
 * class will automatically process any internal comparisons that it encounters
 * 
 * When all the comparisons have been performed, you can then generate a variety
 * of output formats
 * 
 * @author Grahame Grieve
 *
 */
public class ProfileComparer {

  private IWorkerContext context;

  public ProfileComparer(IWorkerContext context) {
    super();
    this.context = context;
  }

  private static final int BOTH_NULL = 0;
  private static final int EITHER_NULL = 1;

  public class ProfileComparison {
    private String id;
    /**
     * the first of two structures that were compared to generate this comparison
     * 
     * In a few cases - selection of example content and value sets - left gets
     * preference over right
     */
    private StructureDefinition left;

    /**
     * the second of two structures that were compared to generate this comparison
     * 
     * In a few cases - selection of example content and value sets - left gets
     * preference over right
     */
    private StructureDefinition right;

    public String getId() {
      return id;
    }

    private String leftName() {
      return left.getName();
    }

    private String rightName() {
      return right.getName();
    }

    /**
     * messages generated during the comparison. There are 4 grades of messages:
     * information - a list of differences between structures warnings - notifies
     * that the comparer is unable to fully compare the structures (constraints
     * differ, open value sets) errors - where the structures are incompatible fatal
     * errors - some error that prevented full analysis
     * 
     * @return
     */
    private List<ValidationMessage> messages = new ArrayList<ValidationMessage>();

    /**
     * The structure that describes all instances that will conform to both
     * structures
     */
    private StructureDefinition subset;

    /**
     * The structure that describes all instances that will conform to either
     * structures
     */
    private StructureDefinition superset;

    public StructureDefinition getLeft() {
      return left;
    }

    public StructureDefinition getRight() {
      return right;
    }

    public List<ValidationMessage> getMessages() {
      return messages;
    }

    public StructureDefinition getSubset() {
      return subset;
    }

    public StructureDefinition getSuperset() {
      return superset;
    }

    private boolean ruleEqual(String path, ElementDefinition ed, String vLeft, String vRight, String description,
        boolean nullOK) {
      if (vLeft == null && vRight == null && nullOK)
        return true;
      if (vLeft == null && vRight == null) {
        messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.STRUCTURE, path,
            description + " and not null (null/null)", ValidationMessage.IssueSeverity.ERROR));
        if (ed != null)
          status(ed, ProfileUtilities.STATUS_ERROR);
      }
      if (vLeft == null || !vLeft.equals(vRight)) {
        messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.STRUCTURE, path,
            description + " (" + vLeft + "/" + vRight + ")", ValidationMessage.IssueSeverity.ERROR));
        if (ed != null)
          status(ed, ProfileUtilities.STATUS_ERROR);
      }
      return true;
    }

    private boolean ruleCompares(ElementDefinition ed, Type vLeft, Type vRight, String path, int nullStatus)
        throws IOException {
      if (vLeft == null && vRight == null && nullStatus == BOTH_NULL)
        return true;
      if (vLeft == null && vRight == null) {
        messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.STRUCTURE, path,
            "Must be the same and not null (null/null)", ValidationMessage.IssueSeverity.ERROR));
        status(ed, ProfileUtilities.STATUS_ERROR);
      }
      if (vLeft == null && nullStatus == EITHER_NULL)
        return true;
      if (vRight == null && nullStatus == EITHER_NULL)
        return true;
      if (vLeft == null || vRight == null || !Base.compareDeep(vLeft, vRight, false)) {
        messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.STRUCTURE, path,
            "Must be the same (" + toString(vLeft) + "/" + toString(vRight) + ")",
            ValidationMessage.IssueSeverity.ERROR));
        status(ed, ProfileUtilities.STATUS_ERROR);
      }
      return true;
    }

    private boolean rule(ElementDefinition ed, boolean test, String path, String message) {
      if (!test) {
        messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.STRUCTURE, path, message,
            ValidationMessage.IssueSeverity.ERROR));
        status(ed, ProfileUtilities.STATUS_ERROR);
      }
      return test;
    }

    private boolean ruleEqual(ElementDefinition ed, boolean vLeft, boolean vRight, String path, String elementName) {
      if (vLeft != vRight) {
        messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.STRUCTURE, path,
            elementName + " must be the same (" + vLeft + "/" + vRight + ")", ValidationMessage.IssueSeverity.ERROR));
        status(ed, ProfileUtilities.STATUS_ERROR);
      }
      return true;
    }

    private String toString(Type val) throws IOException {
      if (val instanceof PrimitiveType)
        return "\"" + ((PrimitiveType) val).getValueAsString() + "\"";

      IParser jp = context.newJsonParser();
      return jp.composeString(val, "value");
    }

    public String getErrorCount() {
      int c = 0;
      for (ValidationMessage vm : messages)
        if (vm.getLevel() == ValidationMessage.IssueSeverity.ERROR)
          c++;
      return Integer.toString(c);
    }

    public String getWarningCount() {
      int c = 0;
      for (ValidationMessage vm : messages)
        if (vm.getLevel() == ValidationMessage.IssueSeverity.WARNING)
          c++;
      return Integer.toString(c);
    }

    public String getHintCount() {
      int c = 0;
      for (ValidationMessage vm : messages)
        if (vm.getLevel() == ValidationMessage.IssueSeverity.INFORMATION)
          c++;
      return Integer.toString(c);
    }
  }

  /**
   * Value sets used in the subset and superset
   */
  private List<ValueSet> valuesets = new ArrayList<ValueSet>();
  private List<ProfileComparison> comparisons = new ArrayList<ProfileComparison>();
  private String id;
  private String title;
  private String leftLink;
  private String leftName;
  private String rightLink;
  private String rightName;

  public List<ValueSet> getValuesets() {
    return valuesets;
  }

  public void status(ElementDefinition ed, int value) {
    ed.setUserData(ProfileUtilities.UD_ERROR_STATUS, Math.max(value, ed.getUserInt("error-status")));
  }

  public List<ProfileComparison> getComparisons() {
    return comparisons;
  }

  /**
   * Compare left and right structure definitions to see whether they are
   * consistent or not
   * 
   * Note that left and right are arbitrary choices. In one respect, left is
   * 'preferred' - the left's example value and data sets will be selected over
   * the right ones in the common structure definition
   * 
   * @throws DefinitionException
   * @throws IOException
   * @throws FHIRFormatError
   * 
   * @
   */
  public ProfileComparison compareProfiles(StructureDefinition left, StructureDefinition right)
      throws DefinitionException, IOException, FHIRFormatError {
    ProfileComparison outcome = new ProfileComparison();
    outcome.left = left;
    outcome.right = right;

    if (left == null)
      throw new DefinitionException("No StructureDefinition provided (left)");
    if (right == null)
      throw new DefinitionException("No StructureDefinition provided (right)");
    if (!left.hasSnapshot())
      throw new DefinitionException("StructureDefinition has no snapshot (left: " + outcome.leftName() + ")");
    if (!right.hasSnapshot())
      throw new DefinitionException("StructureDefinition has no snapshot (right: " + outcome.rightName() + ")");
    if (left.getSnapshot().getElement().isEmpty())
      throw new DefinitionException("StructureDefinition snapshot is empty (left: " + outcome.leftName() + ")");
    if (right.getSnapshot().getElement().isEmpty())
      throw new DefinitionException("StructureDefinition snapshot is empty (right: " + outcome.rightName() + ")");

    for (ProfileComparison pc : comparisons)
      if (pc.left.getUrl().equals(left.getUrl()) && pc.right.getUrl().equals(right.getUrl()))
        return pc;

    outcome.id = Integer.toString(comparisons.size() + 1);
    comparisons.add(outcome);

    DefinitionNavigator ln = new DefinitionNavigator(context, left);
    DefinitionNavigator rn = new DefinitionNavigator(context, right);

    // from here on in, any issues go in messages
    outcome.superset = new StructureDefinition();
    outcome.subset = new StructureDefinition();
    if (outcome.ruleEqual(ln.path(), null, ln.path(), rn.path(), "Base Type is not compatible", false)) {
      if (compareElements(outcome, ln.path(), ln, rn)) {
        outcome.subset.setName("intersection of " + outcome.leftName() + " and " + outcome.rightName());
        outcome.subset.setStatus(PublicationStatus.DRAFT);
        outcome.subset.setKind(outcome.left.getKind());
        outcome.subset.setType(outcome.left.getType());
        outcome.subset.setBaseDefinition("http://hl7.org/fhir/StructureDefinition/" + outcome.subset.getType());
        outcome.subset.setDerivation(TypeDerivationRule.CONSTRAINT);
        outcome.subset.setAbstract(false);
        outcome.superset.setName("union of " + outcome.leftName() + " and " + outcome.rightName());
        outcome.superset.setStatus(PublicationStatus.DRAFT);
        outcome.superset.setKind(outcome.left.getKind());
        outcome.superset.setType(outcome.left.getType());
        outcome.superset.setBaseDefinition("http://hl7.org/fhir/StructureDefinition/" + outcome.subset.getType());
        outcome.superset.setAbstract(false);
        outcome.superset.setDerivation(TypeDerivationRule.CONSTRAINT);
      } else {
        outcome.subset = null;
        outcome.superset = null;
      }
    }
    return outcome;
  }

  /**
   * left and right refer to the same element. Are they compatible?
   * 
   * @param outcome
   * @param outcome
   * @param path
   * @param left
   * @param right   @- if there's a problem that needs fixing in this code
   * @throws DefinitionException
   * @throws IOException
   * @throws FHIRFormatError
   */
  private boolean compareElements(ProfileComparison outcome, String path, DefinitionNavigator left,
      DefinitionNavigator right) throws DefinitionException, IOException, FHIRFormatError {
//    preconditions:
    assert (path != null);
    assert (left != null);
    assert (right != null);
    assert (left.path().equals(right.path()));

    // we ignore slicing right now - we're going to clone the root one anyway, and
    // then think about clones
    // simple stuff
    ElementDefinition subset = new ElementDefinition();
    subset.setPath(left.path());

    // not allowed to be different:
    subset.getRepresentation().addAll(left.current().getRepresentation()); // can't be bothered even testing this one
    if (!outcome.ruleCompares(subset, left.current().getDefaultValue(), right.current().getDefaultValue(),
        path + ".defaultValue[x]", BOTH_NULL))
      return false;
    subset.setDefaultValue(left.current().getDefaultValue());
    if (!outcome.ruleEqual(path, subset, left.current().getMeaningWhenMissing(),
        right.current().getMeaningWhenMissing(), "meaningWhenMissing Must be the same", true))
      return false;
    subset.setMeaningWhenMissing(left.current().getMeaningWhenMissing());
    if (!outcome.ruleEqual(subset, left.current().getIsModifier(), right.current().getIsModifier(), path, "isModifier"))
      return false;
    subset.setIsModifier(left.current().getIsModifier());
    if (!outcome.ruleEqual(subset, left.current().getIsSummary(), right.current().getIsSummary(), path, "isSummary"))
      return false;
    subset.setIsSummary(left.current().getIsSummary());

    // descriptive properties from ElementDefinition - merge them:
    subset.setLabel(mergeText(subset, outcome, path, "label", left.current().getLabel(), right.current().getLabel()));
    subset.setShort(mergeText(subset, outcome, path, "short", left.current().getShort(), right.current().getShort()));
    subset.setDefinition(mergeText(subset, outcome, path, "definition", left.current().getDefinition(),
        right.current().getDefinition()));
    subset.setComment(
        mergeText(subset, outcome, path, "comments", left.current().getComment(), right.current().getComment()));
    subset.setRequirements(mergeText(subset, outcome, path, "requirements", left.current().getRequirements(),
        right.current().getRequirements()));
    subset.getCode().addAll(mergeCodings(left.current().getCode(), right.current().getCode()));
    subset.getAlias().addAll(mergeStrings(left.current().getAlias(), right.current().getAlias()));
    subset.getMapping().addAll(mergeMappings(left.current().getMapping(), right.current().getMapping()));
    // left will win for example
    subset.setExample(left.current().hasExample() ? left.current().getExample() : right.current().getExample());

    subset.setMustSupport(left.current().getMustSupport() || right.current().getMustSupport());
    ElementDefinition superset = subset.copy();

    // compare and intersect
    superset.setMin(unionMin(left.current().getMin(), right.current().getMin()));
    superset.setMax(unionMax(left.current().getMax(), right.current().getMax()));
    subset.setMin(intersectMin(left.current().getMin(), right.current().getMin()));
    subset.setMax(intersectMax(left.current().getMax(), right.current().getMax()));
    outcome.rule(subset, subset.getMax().equals("*") || Integer.parseInt(subset.getMax()) >= subset.getMin(), path,
        "Cardinality Mismatch: " + card(left) + "/" + card(right));

    superset.getType().addAll(unionTypes(path, left.current().getType(), right.current().getType()));
    subset.getType().addAll(intersectTypes(subset, outcome, path, left.current().getType(), right.current().getType()));
    outcome.rule(subset, !subset.getType().isEmpty() || (!left.current().hasType() && !right.current().hasType()), path,
        "Type Mismatch:\r\n  " + typeCode(left) + "\r\n  " + typeCode(right));
//    <fixed[x]><!-- ?? 0..1 * Value must be exactly this --></fixed[x]>
//    <pattern[x]><!-- ?? 0..1 * Value must have at least these property values --></pattern[x]>
    superset.setMaxLengthElement(unionMaxLength(left.current().getMaxLength(), right.current().getMaxLength()));
    subset.setMaxLengthElement(intersectMaxLength(left.current().getMaxLength(), right.current().getMaxLength()));
    if (left.current().hasBinding() || right.current().hasBinding()) {
      compareBindings(outcome, subset, superset, path, left.current(), right.current());
    }

    // note these are backwards
    superset.getConstraint()
        .addAll(intersectConstraints(path, left.current().getConstraint(), right.current().getConstraint()));
    subset.getConstraint().addAll(
        unionConstraints(subset, outcome, path, left.current().getConstraint(), right.current().getConstraint()));

    // now process the slices
    if (left.current().hasSlicing() || right.current().hasSlicing()) {
      if (isExtension(left.path()))
        return compareExtensions(outcome, path, superset, subset, left, right);
//      return true;
      else {
        ElementDefinitionSlicingComponent slicingL = left.current().getSlicing();
        ElementDefinitionSlicingComponent slicingR = right.current().getSlicing();
        throw new DefinitionException("Slicing is not handled yet");
      }
      // todo: name
    }

    // add the children
    outcome.subset.getSnapshot().getElement().add(subset);
    outcome.superset.getSnapshot().getElement().add(superset);
    return compareChildren(subset, outcome, path, left, right);
  }

  private class ExtensionUsage {
    private DefinitionNavigator defn;
    private int minSuperset;
    private int minSubset;
    private String maxSuperset;
    private String maxSubset;
    private boolean both = false;

    public ExtensionUsage(DefinitionNavigator defn, int min, String max) {
      super();
      this.defn = defn;
      this.minSubset = min;
      this.minSuperset = min;
      this.maxSubset = max;
      this.maxSuperset = max;
    }

  }

  private boolean compareExtensions(ProfileComparison outcome, String path, ElementDefinition superset,
      ElementDefinition subset, DefinitionNavigator left, DefinitionNavigator right) throws DefinitionException {
    // for now, we don't handle sealed (or ordered) extensions

    // for an extension the superset is all extensions, and the subset is.. all
    // extensions - well, unless thay are sealed.
    // but it's not useful to report that. instead, we collate the defined ones, and
    // just adjust the cardinalities
    Map<String, ExtensionUsage> map = new HashMap<String, ExtensionUsage>();

    if (left.slices() != null)
      for (DefinitionNavigator ex : left.slices()) {
        String url = ex.current().getType().get(0).getProfile().get(0).getValue();
        if (map.containsKey(url))
          throw new DefinitionException("Duplicate Extension " + url + " at " + path);
        else
          map.put(url, new ExtensionUsage(ex, ex.current().getMin(), ex.current().getMax()));
      }
    if (right.slices() != null)
      for (DefinitionNavigator ex : right.slices()) {
        String url = ex.current().getType().get(0).getProfile().get(0).getValue();
        if (map.containsKey(url)) {
          ExtensionUsage exd = map.get(url);
          exd.minSuperset = unionMin(exd.defn.current().getMin(), ex.current().getMin());
          exd.maxSuperset = unionMax(exd.defn.current().getMax(), ex.current().getMax());
          exd.minSubset = intersectMin(exd.defn.current().getMin(), ex.current().getMin());
          exd.maxSubset = intersectMax(exd.defn.current().getMax(), ex.current().getMax());
          exd.both = true;
          outcome.rule(subset, exd.maxSubset.equals("*") || Integer.parseInt(exd.maxSubset) >= exd.minSubset, path,
              "Cardinality Mismatch on extension: " + card(exd.defn) + "/" + card(ex));
        } else {
          map.put(url, new ExtensionUsage(ex, ex.current().getMin(), ex.current().getMax()));
        }
      }
    List<String> names = new ArrayList<String>();
    names.addAll(map.keySet());
    Collections.sort(names);
    for (String name : names) {
      ExtensionUsage exd = map.get(name);
      if (exd.both)
        outcome.subset.getSnapshot().getElement()
            .add(exd.defn.current().copy().setMin(exd.minSubset).setMax(exd.maxSubset));
      outcome.superset.getSnapshot().getElement()
          .add(exd.defn.current().copy().setMin(exd.minSuperset).setMax(exd.maxSuperset));
    }
    return true;
  }

  private boolean isExtension(String path) {
    return path.endsWith(".extension") || path.endsWith(".modifierExtension");
  }

  private boolean compareChildren(ElementDefinition ed, ProfileComparison outcome, String path,
      DefinitionNavigator left, DefinitionNavigator right) throws DefinitionException, IOException, FHIRFormatError {
    List<DefinitionNavigator> lc = left.children();
    List<DefinitionNavigator> rc = right.children();
    // it's possible that one of these profiles walks into a data type and the other
    // doesn't
    // if it does, we have to load the children for that data into the profile that
    // doesn't
    // walk into it
    if (lc.isEmpty() && !rc.isEmpty() && right.current().getType().size() == 1
        && left.hasTypeChildren(right.current().getType().get(0)))
      lc = left.childrenFromType(right.current().getType().get(0));
    if (rc.isEmpty() && !lc.isEmpty() && left.current().getType().size() == 1
        && right.hasTypeChildren(left.current().getType().get(0)))
      rc = right.childrenFromType(left.current().getType().get(0));
    if (lc.size() != rc.size()) {
      outcome.messages.add(new ValidationMessage(
          Source.ProfileComparer, ValidationMessage.IssueType.STRUCTURE, path, "Different number of children at " + path
              + " (" + Integer.toString(lc.size()) + "/" + Integer.toString(rc.size()) + ")",
          ValidationMessage.IssueSeverity.ERROR));
      status(ed, ProfileUtilities.STATUS_ERROR);
      return false;
    } else {
      for (int i = 0; i < lc.size(); i++) {
        DefinitionNavigator l = lc.get(i);
        DefinitionNavigator r = rc.get(i);
        String cpath = comparePaths(l.path(), r.path(), path, l.nameTail(), r.nameTail());
        if (cpath != null) {
          if (!compareElements(outcome, cpath, l, r))
            return false;
        } else {
          outcome.messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.STRUCTURE,
              path, "Different path at " + path + "[" + Integer.toString(i) + "] (" + l.path() + "/" + r.path() + ")",
              ValidationMessage.IssueSeverity.ERROR));
          status(ed, ProfileUtilities.STATUS_ERROR);
          return false;
        }
      }
    }
    return true;
  }

  private String comparePaths(String path1, String path2, String path, String tail1, String tail2) {
    if (tail1.equals(tail2)) {
      return path + "." + tail1;
    } else if (tail1.endsWith("[x]") && tail2.startsWith(tail1.substring(0, tail1.length() - 3))) {
      return path + "." + tail1;
    } else if (tail2.endsWith("[x]") && tail1.startsWith(tail2.substring(0, tail2.length() - 3))) {
      return path + "." + tail2;
    } else
      return null;
  }

  private boolean compareBindings(ProfileComparison outcome, ElementDefinition subset, ElementDefinition superset,
      String path, ElementDefinition lDef, ElementDefinition rDef) throws FHIRFormatError {
    assert (lDef.hasBinding() || rDef.hasBinding());
    if (!lDef.hasBinding()) {
      subset.setBinding(rDef.getBinding());
      // technically, the super set is unbound, but that's not very useful - so we use
      // the provided on as an example
      superset.setBinding(rDef.getBinding().copy());
      superset.getBinding().setStrength(BindingStrength.EXAMPLE);
      return true;
    }
    if (!rDef.hasBinding()) {
      subset.setBinding(lDef.getBinding());
      superset.setBinding(lDef.getBinding().copy());
      superset.getBinding().setStrength(BindingStrength.EXAMPLE);
      return true;
    }
    ElementDefinitionBindingComponent left = lDef.getBinding();
    ElementDefinitionBindingComponent right = rDef.getBinding();
    if (Base.compareDeep(left, right, false)) {
      subset.setBinding(left);
      superset.setBinding(right);
    }

    // if they're both examples/preferred then:
    // subset: left wins if they're both the same
    // superset:
    if (isPreferredOrExample(left) && isPreferredOrExample(right)) {
      if (right.getStrength() == BindingStrength.PREFERRED && left.getStrength() == BindingStrength.EXAMPLE
          && !Base.compareDeep(left.getValueSet(), right.getValueSet(), false)) {
        outcome.messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.STRUCTURE, path,
            "Example/preferred bindings differ at " + path + " using binding from " + outcome.rightName(),
            ValidationMessage.IssueSeverity.INFORMATION));
        status(subset, ProfileUtilities.STATUS_HINT);
        subset.setBinding(right);
        superset.setBinding(unionBindings(superset, outcome, path, left, right));
      } else {
        if ((right.getStrength() != BindingStrength.EXAMPLE || left.getStrength() != BindingStrength.EXAMPLE)
            && !Base.compareDeep(left.getValueSet(), right.getValueSet(), false)) {
          outcome.messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.STRUCTURE,
              path, "Example/preferred bindings differ at " + path + " using binding from " + outcome.leftName(),
              ValidationMessage.IssueSeverity.INFORMATION));
          status(subset, ProfileUtilities.STATUS_HINT);
        }
        subset.setBinding(left);
        superset.setBinding(unionBindings(superset, outcome, path, left, right));
      }
      return true;
    }
    // if either of them are extensible/required, then it wins
    if (isPreferredOrExample(left)) {
      subset.setBinding(right);
      superset.setBinding(unionBindings(superset, outcome, path, left, right));
      return true;
    }
    if (isPreferredOrExample(right)) {
      subset.setBinding(left);
      superset.setBinding(unionBindings(superset, outcome, path, left, right));
      return true;
    }

    // ok, both are extensible or required.
    ElementDefinitionBindingComponent subBinding = new ElementDefinitionBindingComponent();
    subset.setBinding(subBinding);
    ElementDefinitionBindingComponent superBinding = new ElementDefinitionBindingComponent();
    superset.setBinding(superBinding);
    subBinding
        .setDescription(mergeText(subset, outcome, path, "description", left.getDescription(), right.getDescription()));
    superBinding
        .setDescription(mergeText(subset, outcome, null, "description", left.getDescription(), right.getDescription()));
    if (left.getStrength() == BindingStrength.REQUIRED || right.getStrength() == BindingStrength.REQUIRED)
      subBinding.setStrength(BindingStrength.REQUIRED);
    else
      subBinding.setStrength(BindingStrength.EXTENSIBLE);
    if (left.getStrength() == BindingStrength.EXTENSIBLE || right.getStrength() == BindingStrength.EXTENSIBLE)
      superBinding.setStrength(BindingStrength.EXTENSIBLE);
    else
      superBinding.setStrength(BindingStrength.REQUIRED);

    if (Base.compareDeep(left.getValueSet(), right.getValueSet(), false)) {
      subBinding.setValueSet(left.getValueSet());
      superBinding.setValueSet(left.getValueSet());
      return true;
    } else if (!left.hasValueSet()) {
      outcome.messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.STRUCTURE, path,
          "No left Value set at " + path, ValidationMessage.IssueSeverity.ERROR));
      return true;
    } else if (!right.hasValueSet()) {
      outcome.messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.STRUCTURE, path,
          "No right Value set at " + path, ValidationMessage.IssueSeverity.ERROR));
      return true;
    } else {
      // ok, now we compare the value sets. This may be unresolvable.
      ValueSet lvs = resolveVS(outcome.left, left.getValueSet());
      ValueSet rvs = resolveVS(outcome.right, right.getValueSet());
      if (lvs == null) {
        outcome.messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.STRUCTURE, path,
            "Unable to resolve left value set " + left.getValueSet().toString() + " at " + path,
            ValidationMessage.IssueSeverity.ERROR));
        return true;
      } else if (rvs == null) {
        outcome.messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.STRUCTURE, path,
            "Unable to resolve right value set " + right.getValueSet().toString() + " at " + path,
            ValidationMessage.IssueSeverity.ERROR));
        return true;
      } else {
        // first, we'll try to do it by definition
        ValueSet cvs = intersectByDefinition(lvs, rvs);
        if (cvs == null) {
          // if that didn't work, we'll do it by expansion
          ValueSetExpansionOutcome le;
          ValueSetExpansionOutcome re;
          try {
            le = context.expandVS(lvs, true, false);
            re = context.expandVS(rvs, true, false);
            if (!closed(le.getValueset()) || !closed(re.getValueset()))
              throw new DefinitionException("unclosed value sets are not handled yet");
            cvs = intersectByExpansion(lvs, rvs);
            if (!cvs.getCompose().hasInclude()) {
              outcome.messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.STRUCTURE,
                  path, "The value sets " + lvs.getUrl() + " and " + rvs.getUrl() + " do not intersect",
                  ValidationMessage.IssueSeverity.ERROR));
              status(subset, ProfileUtilities.STATUS_ERROR);
              return false;
            }
          } catch (Exception e) {
            outcome.messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.STRUCTURE,
                path, "Unable to expand or process value sets " + lvs.getUrl() + " and " + rvs.getUrl() + ": "
                    + e.getMessage(),
                ValidationMessage.IssueSeverity.ERROR));
            status(subset, ProfileUtilities.STATUS_ERROR);
            return false;
          }
        }
        subBinding.setValueSet("#" + addValueSet(cvs));
        superBinding.setValueSet("#" + addValueSet(unite(superset, outcome, path, lvs, rvs)));
      }
    }
    return false;
  }

  private ElementDefinitionBindingComponent unionBindings(ElementDefinition ed, ProfileComparison outcome, String path,
      ElementDefinitionBindingComponent left, ElementDefinitionBindingComponent right) throws FHIRFormatError {
    ElementDefinitionBindingComponent union = new ElementDefinitionBindingComponent();
    if (left.getStrength().compareTo(right.getStrength()) < 0)
      union.setStrength(left.getStrength());
    else
      union.setStrength(right.getStrength());
    union.setDescription(
        mergeText(ed, outcome, path, "binding.description", left.getDescription(), right.getDescription()));
    if (Base.compareDeep(left.getValueSet(), right.getValueSet(), false))
      union.setValueSet(left.getValueSet());
    else {
      ValueSet lvs = resolveVS(outcome.left, left.getValueSet());
      ValueSet rvs = resolveVS(outcome.left, right.getValueSet());
      if (lvs != null && rvs != null)
        union.setValueSet("#" + addValueSet(unite(ed, outcome, path, lvs, rvs)));
      else if (lvs != null)
        union.setValueSet("#" + addValueSet(lvs));
      else if (rvs != null)
        union.setValueSet("#" + addValueSet(rvs));
    }
    return union;
  }

  private ValueSet unite(ElementDefinition ed, ProfileComparison outcome, String path, ValueSet lvs, ValueSet rvs) {
    ValueSet vs = new ValueSet();
    if (lvs.hasCompose()) {
      for (ConceptSetComponent inc : lvs.getCompose().getInclude())
        vs.getCompose().getInclude().add(inc);
      if (lvs.getCompose().hasExclude()) {
        outcome.messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.STRUCTURE, path,
            "The value sets " + lvs.getUrl()
                + " has exclude statements, and no union involving it can be correctly determined",
            ValidationMessage.IssueSeverity.ERROR));
        status(ed, ProfileUtilities.STATUS_ERROR);
      }
    }
    if (rvs.hasCompose()) {
      for (ConceptSetComponent inc : rvs.getCompose().getInclude())
        if (!mergeIntoExisting(vs.getCompose().getInclude(), inc))
          vs.getCompose().getInclude().add(inc);
      if (rvs.getCompose().hasExclude()) {
        outcome.messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.STRUCTURE, path,
            "The value sets " + lvs.getUrl()
                + " has exclude statements, and no union involving it can be correctly determined",
            ValidationMessage.IssueSeverity.ERROR));
        status(ed, ProfileUtilities.STATUS_ERROR);
      }
    }
    return vs;
  }

  private boolean mergeIntoExisting(List<ConceptSetComponent> include, ConceptSetComponent inc) {
    for (ConceptSetComponent dst : include) {
      if (Base.compareDeep(dst, inc, false))
        return true; // they're actually the same
      if (dst.getSystem().equals(inc.getSystem())) {
        if (inc.hasFilter() || dst.hasFilter()) {
          return false; // just add the new one as a a parallel
        } else if (inc.hasConcept() && dst.hasConcept()) {
          for (ConceptReferenceComponent cc : inc.getConcept()) {
            boolean found = false;
            for (ConceptReferenceComponent dd : dst.getConcept()) {
              if (dd.getCode().equals(cc.getCode()))
                found = true;
              if (found) {
                if (cc.hasDisplay() && !dd.hasDisplay())
                  dd.setDisplay(cc.getDisplay());
                break;
              }
            }
            if (!found)
              dst.getConcept().add(cc.copy());
          }
        } else
          dst.getConcept().clear(); // one of them includes the entire code system
      }
    }
    return false;
  }

  private ValueSet resolveVS(StructureDefinition ctxtLeft, String vsRef) {
    if (vsRef == null)
      return null;
    return context.fetchResource(ValueSet.class, vsRef);
  }

  private ValueSet intersectByDefinition(ValueSet lvs, ValueSet rvs) {
    // this is just a stub. The idea is that we try to avoid expanding big open
    // value sets from SCT, RxNorm, LOINC.
    // there's a bit of long hand logic coming here, but that's ok.
    return null;
  }

  private ValueSet intersectByExpansion(ValueSet lvs, ValueSet rvs) {
    // this is pretty straight forward - we intersect the lists, and build a compose
    // out of the intersection
    ValueSet vs = new ValueSet();
    vs.setStatus(PublicationStatus.DRAFT);

    Map<String, ValueSetExpansionContainsComponent> left = new HashMap<String, ValueSetExpansionContainsComponent>();
    scan(lvs.getExpansion().getContains(), left);
    Map<String, ValueSetExpansionContainsComponent> right = new HashMap<String, ValueSetExpansionContainsComponent>();
    scan(rvs.getExpansion().getContains(), right);
    Map<String, ConceptSetComponent> inc = new HashMap<String, ConceptSetComponent>();

    for (String s : left.keySet()) {
      if (right.containsKey(s)) {
        ValueSetExpansionContainsComponent cc = left.get(s);
        ConceptSetComponent c = inc.get(cc.getSystem());
        if (c == null) {
          c = vs.getCompose().addInclude().setSystem(cc.getSystem());
          inc.put(cc.getSystem(), c);
        }
        c.addConcept().setCode(cc.getCode()).setDisplay(cc.getDisplay());
      }
    }
    return vs;
  }

  private void scan(List<ValueSetExpansionContainsComponent> list,
      Map<String, ValueSetExpansionContainsComponent> map) {
    for (ValueSetExpansionContainsComponent cc : list) {
      if (cc.hasSystem() && cc.hasCode()) {
        String s = cc.getSystem() + "::" + cc.getCode();
        if (!map.containsKey(s))
          map.put(s, cc);
      }
      if (cc.hasContains())
        scan(cc.getContains(), map);
    }
  }

  private boolean closed(ValueSet vs) {
    return !ToolingExtensions.findBooleanExtension(vs.getExpansion(), ToolingExtensions.EXT_UNCLOSED);
  }

  private boolean isPreferredOrExample(ElementDefinitionBindingComponent binding) {
    return binding.getStrength() == BindingStrength.EXAMPLE || binding.getStrength() == BindingStrength.PREFERRED;
  }

  private Collection<? extends TypeRefComponent> intersectTypes(ElementDefinition ed, ProfileComparison outcome,
      String path, List<TypeRefComponent> left, List<TypeRefComponent> right)
      throws DefinitionException, IOException, FHIRFormatError {
    List<TypeRefComponent> result = new ArrayList<TypeRefComponent>();
    for (TypeRefComponent l : left) {
      if (l.hasAggregation())
        throw new DefinitionException("Aggregation not supported: " + path);
      boolean pfound = false;
      boolean tfound = false;
      TypeRefComponent c = l.copy();
      for (TypeRefComponent r : right) {
        if (r.hasAggregation())
          throw new DefinitionException("Aggregation not supported: " + path);
        if (!l.hasProfile() && !r.hasProfile()) {
          pfound = true;
        } else if (!r.hasProfile()) {
          pfound = true;
        } else if (!l.hasProfile()) {
          pfound = true;
          c.setProfile(r.getProfile());
        } else {
          StructureDefinition sdl = resolveProfile(ed, outcome, path, l.getProfile().get(0).getValue(),
              outcome.leftName());
          StructureDefinition sdr = resolveProfile(ed, outcome, path, r.getProfile().get(0).getValue(),
              outcome.rightName());
          if (sdl != null && sdr != null) {
            if (sdl == sdr) {
              pfound = true;
            } else if (derivesFrom(sdl, sdr)) {
              pfound = true;
            } else if (derivesFrom(sdr, sdl)) {
              c.setProfile(r.getProfile());
              pfound = true;
            } else if (sdl.getType().equals(sdr.getType())) {
              ProfileComparison comp = compareProfiles(sdl, sdr);
              if (comp.getSubset() != null) {
                pfound = true;
                c.addProfile("#" + comp.id);
              }
            }
          }
        }
        if (!l.hasTargetProfile() && !r.hasTargetProfile()) {
          tfound = true;
        } else if (!r.hasTargetProfile()) {
          tfound = true;
        } else if (!l.hasTargetProfile()) {
          tfound = true;
          c.setTargetProfile(r.getTargetProfile());
        } else {
          StructureDefinition sdl = resolveProfile(ed, outcome, path, l.getProfile().get(0).getValue(),
              outcome.leftName());
          StructureDefinition sdr = resolveProfile(ed, outcome, path, r.getProfile().get(0).getValue(),
              outcome.rightName());
          if (sdl != null && sdr != null) {
            if (sdl == sdr) {
              tfound = true;
            } else if (derivesFrom(sdl, sdr)) {
              tfound = true;
            } else if (derivesFrom(sdr, sdl)) {
              c.setTargetProfile(r.getTargetProfile());
              tfound = true;
            } else if (sdl.getType().equals(sdr.getType())) {
              ProfileComparison comp = compareProfiles(sdl, sdr);
              if (comp.getSubset() != null) {
                tfound = true;
                c.addTargetProfile("#" + comp.id);
              }
            }
          }
        }
      }
      if (pfound && tfound)
        result.add(c);
    }
    return result;
  }

  private StructureDefinition resolveProfile(ElementDefinition ed, ProfileComparison outcome, String path, String url,
      String name) {
    StructureDefinition res = context.fetchResource(StructureDefinition.class, url);
    if (res == null) {
      outcome.messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.INFORMATIONAL,
          path, "Unable to resolve profile " + url + " in profile " + name, ValidationMessage.IssueSeverity.WARNING));
      status(ed, ProfileUtilities.STATUS_HINT);
    }
    return res;
  }

  private Collection<? extends TypeRefComponent> unionTypes(String path, List<TypeRefComponent> left,
      List<TypeRefComponent> right) throws DefinitionException, IOException, FHIRFormatError {
    List<TypeRefComponent> result = new ArrayList<TypeRefComponent>();
    for (TypeRefComponent l : left)
      checkAddTypeUnion(path, result, l);
    for (TypeRefComponent r : right)
      checkAddTypeUnion(path, result, r);
    return result;
  }

  private void checkAddTypeUnion(String path, List<TypeRefComponent> results, TypeRefComponent nw)
      throws DefinitionException, IOException, FHIRFormatError {
    boolean pfound = false;
    boolean tfound = false;
    nw = nw.copy();
    if (nw.hasAggregation())
      throw new DefinitionException("Aggregation not supported: " + path);
    for (TypeRefComponent ex : results) {
      if (Utilities.equals(ex.getWorkingCode(), nw.getWorkingCode())) {
        if (!ex.hasProfile() && !nw.hasProfile())
          pfound = true;
        else if (!ex.hasProfile()) {
          pfound = true;
        } else if (!nw.hasProfile()) {
          pfound = true;
          ex.setProfile(null);
        } else {
          // both have profiles. Is one derived from the other?
          StructureDefinition sdex = context.fetchResource(StructureDefinition.class,
              ex.getProfile().get(0).getValue());
          StructureDefinition sdnw = context.fetchResource(StructureDefinition.class,
              nw.getProfile().get(0).getValue());
          if (sdex != null && sdnw != null) {
            if (sdex == sdnw) {
              pfound = true;
            } else if (derivesFrom(sdex, sdnw)) {
              ex.setProfile(nw.getProfile());
              pfound = true;
            } else if (derivesFrom(sdnw, sdex)) {
              pfound = true;
            } else if (sdnw.getSnapshot().getElement().get(0).getPath()
                .equals(sdex.getSnapshot().getElement().get(0).getPath())) {
              ProfileComparison comp = compareProfiles(sdex, sdnw);
              if (comp.getSuperset() != null) {
                pfound = true;
                ex.addProfile("#" + comp.id);
              }
            }
          }
        }
        if (!ex.hasTargetProfile() && !nw.hasTargetProfile())
          tfound = true;
        else if (!ex.hasTargetProfile()) {
          tfound = true;
        } else if (!nw.hasTargetProfile()) {
          tfound = true;
          ex.setTargetProfile(null);
        } else {
          // both have profiles. Is one derived from the other?
          StructureDefinition sdex = context.fetchResource(StructureDefinition.class,
              ex.getTargetProfile().get(0).getValue());
          StructureDefinition sdnw = context.fetchResource(StructureDefinition.class,
              nw.getTargetProfile().get(0).getValue());
          if (sdex != null && sdnw != null) {
            if (sdex == sdnw) {
              tfound = true;
            } else if (derivesFrom(sdex, sdnw)) {
              ex.setTargetProfile(nw.getTargetProfile());
              tfound = true;
            } else if (derivesFrom(sdnw, sdex)) {
              tfound = true;
            } else if (sdnw.getSnapshot().getElement().get(0).getPath()
                .equals(sdex.getSnapshot().getElement().get(0).getPath())) {
              ProfileComparison comp = compareProfiles(sdex, sdnw);
              if (comp.getSuperset() != null) {
                tfound = true;
                ex.addTargetProfile("#" + comp.id);
              }
            }
          }
        }
      }
    }
    if (!tfound || !pfound)
      results.add(nw);
  }

  private boolean derivesFrom(StructureDefinition left, StructureDefinition right) {
    // left derives from right if it's base is the same as right
    // todo: recursive...
    return left.hasBaseDefinition() && left.getBaseDefinition().equals(right.getUrl());
  }

  private String mergeText(ElementDefinition ed, ProfileComparison outcome, String path, String name, String left,
      String right) {
    if (left == null && right == null)
      return null;
    if (left == null)
      return right;
    if (right == null)
      return left;
    if (left.equalsIgnoreCase(right))
      return left;
    if (path != null) {
      outcome.messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.INFORMATIONAL,
          path, "Elements differ in definition for " + name + ":\r\n  \"" + left + "\"\r\n  \"" + right + "\"",
          "Elements differ in definition for " + name + ":<br/>\"" + Utilities.escapeXml(left) + "\"<br/>\""
              + Utilities.escapeXml(right) + "\"",
          ValidationMessage.IssueSeverity.INFORMATION));
      status(ed, ProfileUtilities.STATUS_HINT);
    }
    return "left: " + left + "; right: " + right;
  }

  private List<Coding> mergeCodings(List<Coding> left, List<Coding> right) {
    List<Coding> result = new ArrayList<Coding>();
    result.addAll(left);
    for (Coding c : right) {
      boolean found = false;
      for (Coding ct : left)
        if (Utilities.equals(c.getSystem(), ct.getSystem()) && Utilities.equals(c.getCode(), ct.getCode()))
          found = true;
      if (!found)
        result.add(c);
    }
    return result;
  }

  private List<StringType> mergeStrings(List<StringType> left, List<StringType> right) {
    List<StringType> result = new ArrayList<StringType>();
    result.addAll(left);
    for (StringType c : right) {
      boolean found = false;
      for (StringType ct : left)
        if (Utilities.equals(c.getValue(), ct.getValue()))
          found = true;
      if (!found)
        result.add(c);
    }
    return result;
  }

  private List<ElementDefinitionMappingComponent> mergeMappings(List<ElementDefinitionMappingComponent> left,
      List<ElementDefinitionMappingComponent> right) {
    List<ElementDefinitionMappingComponent> result = new ArrayList<ElementDefinitionMappingComponent>();
    result.addAll(left);
    for (ElementDefinitionMappingComponent c : right) {
      boolean found = false;
      for (ElementDefinitionMappingComponent ct : left)
        if (Utilities.equals(c.getIdentity(), ct.getIdentity()) && Utilities.equals(c.getLanguage(), ct.getLanguage())
            && Utilities.equals(c.getMap(), ct.getMap()))
          found = true;
      if (!found)
        result.add(c);
    }
    return result;
  }

  // we can't really know about constraints. We create warnings, and collate them
  private List<ElementDefinitionConstraintComponent> unionConstraints(ElementDefinition ed, ProfileComparison outcome,
      String path, List<ElementDefinitionConstraintComponent> left, List<ElementDefinitionConstraintComponent> right) {
    List<ElementDefinitionConstraintComponent> result = new ArrayList<ElementDefinitionConstraintComponent>();
    for (ElementDefinitionConstraintComponent l : left) {
      boolean found = false;
      for (ElementDefinitionConstraintComponent r : right)
        if (Utilities.equals(r.getId(), l.getId())
            || (Utilities.equals(r.getXpath(), l.getXpath()) && r.getSeverity() == l.getSeverity()))
          found = true;
      if (!found) {
        outcome.messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.STRUCTURE, path,
            "StructureDefinition " + outcome.leftName() + " has a constraint that is not found in "
                + outcome.rightName() + " and it is uncertain whether they are compatible (" + l.getXpath() + ")",
            ValidationMessage.IssueSeverity.INFORMATION));
        status(ed, ProfileUtilities.STATUS_WARNING);
      }
      result.add(l);
    }
    for (ElementDefinitionConstraintComponent r : right) {
      boolean found = false;
      for (ElementDefinitionConstraintComponent l : left)
        if (Utilities.equals(r.getId(), l.getId())
            || (Utilities.equals(r.getXpath(), l.getXpath()) && r.getSeverity() == l.getSeverity()))
          found = true;
      if (!found) {
        outcome.messages.add(new ValidationMessage(Source.ProfileComparer, ValidationMessage.IssueType.STRUCTURE, path,
            "StructureDefinition " + outcome.rightName() + " has a constraint that is not found in "
                + outcome.leftName() + " and it is uncertain whether they are compatible (" + r.getXpath() + ")",
            ValidationMessage.IssueSeverity.INFORMATION));
        status(ed, ProfileUtilities.STATUS_WARNING);
        result.add(r);
      }
    }
    return result;
  }

  private List<ElementDefinitionConstraintComponent> intersectConstraints(String path,
      List<ElementDefinitionConstraintComponent> left, List<ElementDefinitionConstraintComponent> right) {
    List<ElementDefinitionConstraintComponent> result = new ArrayList<ElementDefinitionConstraintComponent>();
    for (ElementDefinitionConstraintComponent l : left) {
      boolean found = false;
      for (ElementDefinitionConstraintComponent r : right)
        if (Utilities.equals(r.getId(), l.getId())
            || (Utilities.equals(r.getXpath(), l.getXpath()) && r.getSeverity() == l.getSeverity()))
          found = true;
      if (found)
        result.add(l);
    }
    return result;
  }

  private String card(DefinitionNavigator defn) {
    return Integer.toString(defn.current().getMin()) + ".." + defn.current().getMax();
  }

  private String typeCode(DefinitionNavigator defn) {
    CommaSeparatedStringBuilder b = new CommaSeparatedStringBuilder();
    for (TypeRefComponent t : defn.current().getType())
      b.append(t.getWorkingCode() + (t.hasProfile() ? "(" + t.getProfile() + ")" : "")
          + (t.hasTargetProfile() ? "(" + t.getTargetProfile() + ")" : "")); // todo: other properties
    return b.toString();
  }

  private int intersectMin(int left, int right) {
    if (left > right)
      return left;
    else
      return right;
  }

  private int unionMin(int left, int right) {
    if (left > right)
      return right;
    else
      return left;
  }

  private String intersectMax(String left, String right) {
    int l = "*".equals(left) ? Integer.MAX_VALUE : Integer.parseInt(left);
    int r = "*".equals(right) ? Integer.MAX_VALUE : Integer.parseInt(right);
    if (l < r)
      return left;
    else
      return right;
  }

  private String unionMax(String left, String right) {
    int l = "*".equals(left) ? Integer.MAX_VALUE : Integer.parseInt(left);
    int r = "*".equals(right) ? Integer.MAX_VALUE : Integer.parseInt(right);
    if (l < r)
      return right;
    else
      return left;
  }

  private IntegerType intersectMaxLength(int left, int right) {
    if (left == 0)
      left = Integer.MAX_VALUE;
    if (right == 0)
      right = Integer.MAX_VALUE;
    if (left < right)
      return left == Integer.MAX_VALUE ? null : new IntegerType(left);
    else
      return right == Integer.MAX_VALUE ? null : new IntegerType(right);
  }

  private IntegerType unionMaxLength(int left, int right) {
    if (left == 0)
      left = Integer.MAX_VALUE;
    if (right == 0)
      right = Integer.MAX_VALUE;
    if (left < right)
      return right == Integer.MAX_VALUE ? null : new IntegerType(right);
    else
      return left == Integer.MAX_VALUE ? null : new IntegerType(left);
  }

  public String addValueSet(ValueSet cvs) {
    String id = Integer.toString(valuesets.size() + 1);
    cvs.setId(id);
    valuesets.add(cvs);
    return id;
  }

  public String getId() {
    return id;
  }

  public void setId(String id) {
    this.id = id;
  }

  public String getTitle() {
    return title;
  }

  public void setTitle(String title) {
    this.title = title;
  }

  public String getLeftLink() {
    return leftLink;
  }

  public void setLeftLink(String leftLink) {
    this.leftLink = leftLink;
  }

  public String getLeftName() {
    return leftName;
  }

  public void setLeftName(String leftName) {
    this.leftName = leftName;
  }

  public String getRightLink() {
    return rightLink;
  }

  public void setRightLink(String rightLink) {
    this.rightLink = rightLink;
  }

  public String getRightName() {
    return rightName;
  }

  public void setRightName(String rightName) {
    this.rightName = rightName;
  }

  private String genPCLink(String leftName, String leftLink) {
    return "<a href=\"" + leftLink + "\">" + Utilities.escapeXml(leftName) + "</a>";
  }

  private String genPCTable() {
    StringBuilder b = new StringBuilder();

    b.append("<table class=\"grid\">\r\n");
    b.append("<tr>");
    b.append(" <td><b>Left</b></td>");
    b.append(" <td><b>Right</b></td>");
    b.append(" <td><b>Comparison</b></td>");
    b.append(" <td><b>Error #</b></td>");
    b.append(" <td><b>Warning #</b></td>");
    b.append(" <td><b>Hint #</b></td>");
    b.append("</tr>");

    for (ProfileComparison cmp : getComparisons()) {
      b.append("<tr>");
      b.append(" <td><a href=\"" + cmp.getLeft().getUserString("path") + "\">"
          + Utilities.escapeXml(cmp.getLeft().getName()) + "</a></td>");
      b.append(" <td><a href=\"" + cmp.getRight().getUserString("path") + "\">"
          + Utilities.escapeXml(cmp.getRight().getName()) + "</a></td>");
      b.append(" <td><a href=\"" + getId() + "." + cmp.getId() + ".html\">Click Here</a></td>");
      b.append(" <td>" + cmp.getErrorCount() + "</td>");
      b.append(" <td>" + cmp.getWarningCount() + "</td>");
      b.append(" <td>" + cmp.getHintCount() + "</td>");
      b.append("</tr>");
    }
    b.append("</table>\r\n");

    return b.toString();
  }

  public String generate(String dest) throws IOException {
    // ok, all compared; now produce the output
    // first page we produce is simply the index
    Map<String, String> vars = new HashMap<String, String>();
    vars.put("title", getTitle());
    vars.put("left", genPCLink(getLeftName(), getLeftLink()));
    vars.put("right", genPCLink(getRightName(), getRightLink()));
    vars.put("table", genPCTable());
    producePage(summaryTemplate(), Utilities.path(dest, getId() + ".html"), vars);

//    page.log("   ... generate", LogMessageType.Process);
//    String src = TextFile.fileToString(page.getFolders().srcDir + "template-comparison-set.html");
//    src = page.processPageIncludes(n+".html", src, "?type", null, "??path", null, null, "Comparison", pc, null, null, page.getDefinitions().getWorkgroups().get("fhir"));
//    TextFile.stringToFile(src, Utilities.path(page.getFolders().dstDir, n+".html"));
//    cachePage(n + ".html", src, "Comparison "+pc.getTitle(), false);
//
//    // then we produce a comparison page for each pair
//    for (ProfileComparison cmp : pc.getComparisons()) {
//      src = TextFile.fileToString(page.getFolders().srcDir + "template-comparison.html");
//      src = page.processPageIncludes(n+"."+cmp.getId()+".html", src, "?type", null, "??path", null, null, "Comparison", cmp, null, null, page.getDefinitions().getWorkgroups().get("fhir"));
//      TextFile.stringToFile(src, Utilities.path(page.getFolders().dstDir, n+"."+cmp.getId()+".html"));
//      cachePage(n +"."+cmp.getId()+".html", src, "Comparison "+pc.getTitle(), false);
//    }
//      //   and also individual pages for each pair outcome
//    // then we produce value set pages for each value set
//
//    // TODO Auto-generated method stub
    return Utilities.path(dest, getId() + ".html");
  }

  private void producePage(String src, String path, Map<String, String> vars) throws IOException {
    while (src.contains("[%")) {
      int i1 = src.indexOf("[%");
      int i2 = src.substring(i1).indexOf("%]") + i1;
      String s1 = src.substring(0, i1);
      String s2 = src.substring(i1 + 2, i2).trim();
      String s3 = src.substring(i2 + 2);
      String v = vars.containsKey(s2) ? vars.get(s2) : "???";
      src = s1 + v + s3;
    }
    TextFile.stringToFile(src, path);
  }

  private String summaryTemplate() throws IOException {
    return cachedFetch("04a9d69a-47f2-4250-8645-bf5d880a8eaa-1.fhir-template",
        "http://build.fhir.org/template-comparison-set.html.template");
  }

  private String cachedFetch(String id, String source) throws IOException {
    String tmpDir = System.getProperty("java.io.tmpdir");
    String local = Utilities.path(tmpDir, id);
    File f = ManagedFileAccess.file(local);
    if (f.exists())
      return TextFile.fileToString(f);

    HTTPResult res = ManagedWebAccess.get(source);
    res.checkThrowException();
    String result = TextFile.bytesToString(res.getContent());
    TextFile.stringToFile(result, f);
    return result;
  }

}