package org.hl7.fhir.dstu3.terminologies;

import static org.apache.commons.lang3.StringUtils.isNotBlank;

import java.io.FileNotFoundException;
import java.io.IOException;

/*
 * 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.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.UUID;

import org.apache.commons.lang3.NotImplementedException;
import org.hl7.fhir.dstu3.context.IWorkerContext;
import org.hl7.fhir.dstu3.model.CodeSystem;
import org.hl7.fhir.dstu3.model.CodeSystem.CodeSystemContentMode;
import org.hl7.fhir.dstu3.model.CodeSystem.ConceptDefinitionComponent;
import org.hl7.fhir.dstu3.model.CodeSystem.ConceptDefinitionDesignationComponent;
import org.hl7.fhir.dstu3.model.DateTimeType;
import org.hl7.fhir.dstu3.model.ExpansionProfile;
import org.hl7.fhir.dstu3.model.Factory;
import org.hl7.fhir.dstu3.model.PrimitiveType;
import org.hl7.fhir.dstu3.model.Type;
import org.hl7.fhir.dstu3.model.UriType;
import org.hl7.fhir.dstu3.model.ValueSet;
import org.hl7.fhir.dstu3.model.ValueSet.ConceptReferenceComponent;
import org.hl7.fhir.dstu3.model.ValueSet.ConceptReferenceDesignationComponent;
import org.hl7.fhir.dstu3.model.ValueSet.ConceptSetComponent;
import org.hl7.fhir.dstu3.model.ValueSet.ConceptSetFilterComponent;
import org.hl7.fhir.dstu3.model.ValueSet.FilterOperator;
import org.hl7.fhir.dstu3.model.ValueSet.ValueSetComposeComponent;
import org.hl7.fhir.dstu3.model.ValueSet.ValueSetExpansionComponent;
import org.hl7.fhir.dstu3.model.ValueSet.ValueSetExpansionContainsComponent;
import org.hl7.fhir.dstu3.model.ValueSet.ValueSetExpansionParameterComponent;
import org.hl7.fhir.dstu3.utils.ToolingExtensions;
import org.hl7.fhir.exceptions.FHIRException;
import org.hl7.fhir.exceptions.NoTerminologyServiceException;
import org.hl7.fhir.exceptions.TerminologyServiceException;
import org.hl7.fhir.utilities.Utilities;

public class ValueSetExpanderSimple implements ValueSetExpander {

  private List<ValueSetExpansionContainsComponent> codes = new ArrayList<ValueSet.ValueSetExpansionContainsComponent>();
  private List<ValueSetExpansionContainsComponent> roots = new ArrayList<ValueSet.ValueSetExpansionContainsComponent>();
  private Map<String, ValueSetExpansionContainsComponent> map = new HashMap<String, ValueSet.ValueSetExpansionContainsComponent>();
  private IWorkerContext context;
  private boolean canBeHeirarchy = true;
  private Set<String> excludeKeys = new HashSet<String>();
  private Set<String> excludeSystems = new HashSet<String>();
  private ValueSetExpanderFactory factory;
  private ValueSet focus;
  private int maxExpansionSize = 500;

  private int total;

  public ValueSetExpanderSimple(IWorkerContext context, ValueSetExpanderFactory factory) {
    super();
    this.context = context;
    this.factory = factory;
  }

  public void setMaxExpansionSize(int theMaxExpansionSize) {
    maxExpansionSize = theMaxExpansionSize;
  }

  private ValueSetExpansionContainsComponent addCode(String system, String code, String display, ValueSetExpansionContainsComponent parent, List<ConceptDefinitionDesignationComponent> designations,
      ExpansionProfile profile, boolean isAbstract, boolean inactive, List<ValueSet> filters) {
    if (filters != null && !filters.isEmpty() && !filterContainsCode(filters, system, code))
      return null;
    ValueSetExpansionContainsComponent n = new ValueSet.ValueSetExpansionContainsComponent();
    n.setSystem(system);
    n.setCode(code);
    if (isAbstract)
      n.setAbstract(true);
    if (inactive)
      n.setInactive(true);

    if (profile.getIncludeDesignations() && designations != null) {
      for (ConceptDefinitionDesignationComponent t : designations) {
        ToolingExtensions.addLanguageTranslation(n, t.getLanguage(), t.getValue());
      }
    }
    ConceptDefinitionDesignationComponent t = profile.hasLanguage() ? getMatchingLang(designations, profile.getLanguage()) : null;
    if (t == null)
      n.setDisplay(display);
    else
      n.setDisplay(t.getValue());

    String s = key(n);
    if (map.containsKey(s) || excludeKeys.contains(s)) {
      canBeHeirarchy = false;
    } else {
      codes.add(n);
      map.put(s, n);
      total++;
    }
    if (canBeHeirarchy && parent != null) {
      parent.getContains().add(n);
    } else {
      roots.add(n);
    }
    return n;
  }

  private boolean filterContainsCode(List<ValueSet> filters, String system, String code) {
    for (ValueSet vse : filters)
      if (expansionContainsCode(vse.getExpansion().getContains(), system, code))
        return true;
    return false;
  }

  private boolean expansionContainsCode(List<ValueSetExpansionContainsComponent> contains, String system, String code) {
    for (ValueSetExpansionContainsComponent cc : contains) {
      if (system.equals(cc.getSystem()) && code.equals(cc.getCode()))
        return true;
      if (expansionContainsCode(cc.getContains(), system, code))
        return true;
    }
    return false;
  }

  private ConceptDefinitionDesignationComponent getMatchingLang(List<ConceptDefinitionDesignationComponent> list, String lang) {
    for (ConceptDefinitionDesignationComponent t : list)
      if (t.getLanguage().equals(lang))
        return t;
    for (ConceptDefinitionDesignationComponent t : list)
      if (t.getLanguage().startsWith(lang))
        return t;
    return null;
  }

  private void addCodeAndDescendents(CodeSystem cs, String system, ConceptDefinitionComponent def, ValueSetExpansionContainsComponent parent, ExpansionProfile profile, List<ValueSet> filters)
      throws FHIRException {
    if (!CodeSystemUtilities.isDeprecated(cs, def)) {
      ValueSetExpansionContainsComponent np = null;
      boolean abs = CodeSystemUtilities.isNotSelectable(cs, def);
      boolean inc = CodeSystemUtilities.isInactive(cs, def);
      if (canBeHeirarchy || !abs)
        np = addCode(system, def.getCode(), def.getDisplay(), parent, def.getDesignation(), profile, abs, inc, filters);
      for (ConceptDefinitionComponent c : def.getConcept())
        addCodeAndDescendents(cs, system, c, np, profile, filters);
    } else
      for (ConceptDefinitionComponent c : def.getConcept())
        addCodeAndDescendents(cs, system, c, null, profile, filters);

  }

  private void addCodes(ValueSetExpansionComponent expand, List<ValueSetExpansionParameterComponent> params, ExpansionProfile profile, List<ValueSet> filters) throws ETooCostly {
    if (expand.getContains().size() > maxExpansionSize)
      throw new ETooCostly("Too many codes to display (>" + Integer.toString(expand.getContains().size()) + ")");
    for (ValueSetExpansionParameterComponent p : expand.getParameter()) {
      if (!existsInParams(params, p.getName(), p.getValue()))
        params.add(p);
    }

    copyImportContains(expand.getContains(), null, profile, filters);
  }

  private void excludeCode(String theSystem, String theCode) {
    ValueSetExpansionContainsComponent n = new ValueSet.ValueSetExpansionContainsComponent();
    n.setSystem(theSystem);
    n.setCode(theCode);
    String s = key(n);
    excludeKeys.add(s);
  }

  private void excludeCodes(ConceptSetComponent exc, List<ValueSetExpansionParameterComponent> params) throws TerminologyServiceException {
    if (exc.hasSystem() && exc.getConcept().size() == 0 && exc.getFilter().size() == 0) {
      excludeSystems.add(exc.getSystem());
    }

    if (exc.hasValueSet())
      throw new Error("Processing Value set references in exclude is not yet done");
    // importValueSet(imp.getValue(), params, profile);

    CodeSystem cs = context.fetchCodeSystem(exc.getSystem());
    if ((cs == null || cs.getContent() != CodeSystemContentMode.COMPLETE) && context.supportsSystem(exc.getSystem())) {
      excludeCodes(context.expandVS(exc, false), params);
      return;
    }

    for (ConceptReferenceComponent c : exc.getConcept()) {
      excludeCode(exc.getSystem(), c.getCode());
    }

    if (exc.getFilter().size() > 0)
      throw new NotImplementedException("not done yet");
  }

  private void excludeCodes(ValueSetExpansionComponent expand, List<ValueSetExpansionParameterComponent> params) {
    for (ValueSetExpansionContainsComponent c : expand.getContains()) {
      excludeCode(c.getSystem(), c.getCode());
    }
  }

  private boolean existsInParams(List<ValueSetExpansionParameterComponent> params, String name, Type value) {
    for (ValueSetExpansionParameterComponent p : params) {
      if (p.getName().equals(name) && PrimitiveType.compareDeep(p.getValue(), value, false))
        return true;
    }
    return false;
  }

  @Override
  public ValueSetExpansionOutcome expand(ValueSet source, ExpansionProfile profile) {

    if (profile == null)
      profile = makeDefaultExpansion();
    try {
      focus = source.copy();
      focus.setExpansion(new ValueSet.ValueSetExpansionComponent());
      focus.getExpansion().setTimestampElement(DateTimeType.now());
      focus.getExpansion().setIdentifier(Factory.createUUID());
      if (!profile.getUrl().startsWith("urn:uuid:"))
        focus.getExpansion().addParameter().setName("profile").setValue(new UriType(profile.getUrl()));

      if (source.hasCompose())
        handleCompose(source.getCompose(), focus.getExpansion().getParameter(), profile);

      if (canBeHeirarchy) {
        for (ValueSetExpansionContainsComponent c : roots) {
          focus.getExpansion().getContains().add(c);
        }
      } else {
        for (ValueSetExpansionContainsComponent c : codes) {
          if (map.containsKey(key(c)) && !c.getAbstract()) { // we may have added abstract codes earlier while we still thought it might be heirarchical, but later we gave up, so now ignore them
            focus.getExpansion().getContains().add(c);
            c.getContains().clear(); // make sure any heirarchy is wiped
          }
        }
      }

      if (total > 0) {
        focus.getExpansion().setTotal(total);
      }

      return new ValueSetExpansionOutcome(focus);
    } catch (RuntimeException e) {
      // TODO: we should put something more specific instead of just Exception below, since
      // it swallows bugs.. what would be expected to be caught there?
      throw e;
    } catch (NoTerminologyServiceException e) {
      // well, we couldn't expand, so we'll return an interface to a checker that can check membership of the set
      // that might fail too, but it might not, later.
      return new ValueSetExpansionOutcome(new ValueSetCheckerSimple(source, factory, context), e.getMessage(), TerminologyServiceErrorClass.NOSERVICE);
    } catch (Exception e) {
      // well, we couldn't expand, so we'll return an interface to a checker that can check membership of the set
      // that might fail too, but it might not, later.
      return new ValueSetExpansionOutcome(new ValueSetCheckerSimple(source, factory, context), e.getMessage(), TerminologyServiceErrorClass.UNKNOWN);
    }
  }

  private ExpansionProfile makeDefaultExpansion() {
    ExpansionProfile res = new ExpansionProfile();
    res.setUrl("urn:uuid:" + UUID.randomUUID().toString().toLowerCase());
    res.setExcludeNested(true);
    res.setIncludeDesignations(false);
    return res;
  }

  private void addToHeirarchy(List<ValueSetExpansionContainsComponent> target, List<ValueSetExpansionContainsComponent> source) {
    for (ValueSetExpansionContainsComponent s : source) {
      target.add(s);
    }
  }

  private String getCodeDisplay(CodeSystem cs, String code) throws TerminologyServiceException {
    ConceptDefinitionComponent def = getConceptForCode(cs.getConcept(), code);
    if (def == null)
      throw new TerminologyServiceException("Unable to find code '" + code + "' in code system " + cs.getUrl());
    return def.getDisplay();
  }

  private ConceptDefinitionComponent getConceptForCode(List<ConceptDefinitionComponent> clist, String code) {
    for (ConceptDefinitionComponent c : clist) {
      if (code.equals(c.getCode()))
        return c;
      ConceptDefinitionComponent v = getConceptForCode(c.getConcept(), code);
      if (v != null)
        return v;
    }
    return null;
  }

  private void handleCompose(ValueSetComposeComponent compose, List<ValueSetExpansionParameterComponent> params, ExpansionProfile profile)
      throws ETooCostly, FileNotFoundException, IOException, FHIRException {
    // Exclude comes first because we build up a map of things to exclude
    for (ConceptSetComponent inc : compose.getExclude())
      excludeCodes(inc, params);
    canBeHeirarchy = !profile.getExcludeNested() && excludeKeys.isEmpty() && excludeSystems.isEmpty();
    boolean first = true;
    for (ConceptSetComponent inc : compose.getInclude()) {
      if (first == true)
        first = false;
      else
        canBeHeirarchy = false;
      includeCodes(inc, params, profile);
    }

  }

  private ValueSet importValueSet(String value, List<ValueSetExpansionParameterComponent> params, ExpansionProfile profile)
      throws ETooCostly, TerminologyServiceException, FileNotFoundException, IOException {
    if (value == null)
      throw new TerminologyServiceException("unable to find value set with no identity");
    ValueSet vs = context.fetchResource(ValueSet.class, value);
    if (vs == null)
      throw new TerminologyServiceException("Unable to find imported value set " + value);
    ValueSetExpansionOutcome vso = factory.getExpander().expand(vs, profile);
    if (vso.getError() != null)
      throw new TerminologyServiceException("Unable to expand imported value set: " + vso.getError());
    if (vso.getService() != null)
      throw new TerminologyServiceException("Unable to expand imported value set " + value);
    if (vs.hasVersion())
      if (!existsInParams(params, "version", new UriType(vs.getUrl() + "|" + vs.getVersion())))
        params.add(new ValueSetExpansionParameterComponent().setName("version").setValue(new UriType(vs.getUrl() + "|" + vs.getVersion())));
    for (ValueSetExpansionParameterComponent p : vso.getValueset().getExpansion().getParameter()) {
      if (!existsInParams(params, p.getName(), p.getValue()))
        params.add(p);
    }
    canBeHeirarchy = false; // if we're importing a value set, we have to be combining, so we won't try for a heirarchy
    return vso.getValueset();
  }

  private void copyImportContains(List<ValueSetExpansionContainsComponent> list, ValueSetExpansionContainsComponent parent, ExpansionProfile profile, List<ValueSet> filter) {
    for (ValueSetExpansionContainsComponent c : list) {
      ValueSetExpansionContainsComponent np = addCode(c.getSystem(), c.getCode(), c.getDisplay(), parent, null, profile, c.getAbstract(), c.getInactive(), filter);
      copyImportContains(c.getContains(), np, profile, filter);
    }
  }

  private void includeCodes(ConceptSetComponent inc, List<ValueSetExpansionParameterComponent> params, ExpansionProfile profile) throws ETooCostly, FileNotFoundException, IOException, FHIRException {
    List<ValueSet> imports = new ArrayList<ValueSet>();
    for (UriType imp : inc.getValueSet())
      imports.add(importValueSet(imp.getValue(), params, profile));

    if (!inc.hasSystem()) {
      if (imports.isEmpty()) // though this is not supposed to be the case
        return;
      ValueSet base = imports.get(0);
      imports.remove(0);
      copyImportContains(base.getExpansion().getContains(), null, profile, imports);
    } else {
      CodeSystem cs = context.fetchCodeSystem(inc.getSystem());
      if ((cs == null || cs.getContent() != CodeSystemContentMode.COMPLETE) && context.supportsSystem(inc.getSystem())) {
        addCodes(context.expandVS(inc, canBeHeirarchy), params, profile, imports);
        return;
      }

      if (cs == null) {
        if (context.isNoTerminologyServer())
          throw new NoTerminologyServiceException("unable to find code system " + inc.getSystem().toString());
        else
          throw new TerminologyServiceException("unable to find code system " + inc.getSystem().toString());
      }
      if (cs.getContent() != CodeSystemContentMode.COMPLETE)
        throw new TerminologyServiceException("Code system " + inc.getSystem().toString() + " is incomplete");
      if (cs.hasVersion())
        if (!existsInParams(params, "version", new UriType(cs.getUrl() + "|" + cs.getVersion())))
          params.add(new ValueSetExpansionParameterComponent().setName("version").setValue(new UriType(cs.getUrl() + "|" + cs.getVersion())));

      if (inc.getConcept().size() == 0 && inc.getFilter().size() == 0) {
        // special case - add all the code system
        for (ConceptDefinitionComponent def : cs.getConcept()) {
          addCodeAndDescendents(cs, inc.getSystem(), def, null, profile, imports);
        }
      }

      if (!inc.getConcept().isEmpty()) {
        canBeHeirarchy = false;
        for (ConceptReferenceComponent c : inc.getConcept()) {
          addCode(inc.getSystem(), c.getCode(), Utilities.noString(c.getDisplay()) ? getCodeDisplay(cs, c.getCode()) : c.getDisplay(), null, convertDesignations(c.getDesignation()), profile, false,
              CodeSystemUtilities.isInactive(cs, c.getCode()), imports);
        }
      }
      if (inc.getFilter().size() > 1) {
        canBeHeirarchy = false; // which will bt the case if we get around to supporting this
        throw new TerminologyServiceException("Multiple filters not handled yet"); // need to and them, and this isn't done yet. But this shouldn't arise in non loinc and snomed value sets
      }
      if (inc.getFilter().size() == 1) {
        ConceptSetFilterComponent fc = inc.getFilter().get(0);
        if ("concept".equals(fc.getProperty()) && fc.getOp() == FilterOperator.ISA) {
          // special: all codes in the target code system under the value
          ConceptDefinitionComponent def = getConceptForCode(cs.getConcept(), fc.getValue());
          if (def == null)
            throw new TerminologyServiceException("Code '" + fc.getValue() + "' not found in system '" + inc.getSystem() + "'");
          addCodeAndDescendents(cs, inc.getSystem(), def, null, profile, imports);
        } else if ("concept".equals(fc.getProperty()) && fc.getOp() == FilterOperator.DESCENDENTOF) {
          // special: all codes in the target code system under the value
          ConceptDefinitionComponent def = getConceptForCode(cs.getConcept(), fc.getValue());
          if (def == null)
            throw new TerminologyServiceException("Code '" + fc.getValue() + "' not found in system '" + inc.getSystem() + "'");
          for (ConceptDefinitionComponent c : def.getConcept())
            addCodeAndDescendents(cs, inc.getSystem(), c, null, profile, imports);
        } else if ("display".equals(fc.getProperty()) && fc.getOp() == FilterOperator.EQUAL) {
          // gg; note: wtf is this: if the filter is display=v, look up the code 'v', and see if it's diplsay is 'v'?
          canBeHeirarchy = false;
          ConceptDefinitionComponent def = getConceptForCode(cs.getConcept(), fc.getValue());
          if (def != null) {
            if (isNotBlank(def.getDisplay()) && isNotBlank(fc.getValue())) {
              if (def.getDisplay().contains(fc.getValue())) {
                addCode(inc.getSystem(), def.getCode(), def.getDisplay(), null, def.getDesignation(), profile, CodeSystemUtilities.isNotSelectable(cs, def), CodeSystemUtilities.isInactive(cs, def),
                    imports);
              }
            }
          }
        } else
          throw new NotImplementedException("Search by property[" + fc.getProperty() + "] and op[" + fc.getOp() + "] is not supported yet");
      }
    }
  }

  private List<ConceptDefinitionDesignationComponent> convertDesignations(List<ConceptReferenceDesignationComponent> list) {
    List<ConceptDefinitionDesignationComponent> res = new ArrayList<CodeSystem.ConceptDefinitionDesignationComponent>();
    for (ConceptReferenceDesignationComponent t : list) {
      ConceptDefinitionDesignationComponent c = new ConceptDefinitionDesignationComponent();
      c.setLanguage(t.getLanguage());
      c.setUse(t.getUse());
      c.setValue(t.getValue());
    }
    return res;
  }

  private String key(String uri, String code) {
    return "{" + uri + "}" + code;
  }

  private String key(ValueSetExpansionContainsComponent c) {
    return key(c.getSystem(), c.getCode());
  }

}
