/**

  * Copyright 2011 The Kuali Foundation Licensed under the

  * Educational Community 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.osedu.org/licenses/ECL-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.kuali.student.process.poc.krms;

 import org.joda.time.DateTime;

 import org.kuali.rice.krms.api.engine.EngineResults;

 import org.kuali.rice.krms.api.engine.ExecutionFlag;

 import org.kuali.rice.krms.api.engine.ExecutionOptions;

 import org.kuali.rice.krms.api.engine.ResultEvent;

 import org.kuali.rice.krms.api.engine.SelectionCriteria;

 import org.kuali.rice.krms.api.engine.TermResolver;

 import org.kuali.rice.krms.api.repository.LogicalOperator;

 import org.kuali.rice.krms.framework.engine.Agenda;

 import org.kuali.rice.krms.framework.engine.AgendaTreeEntry;

 import org.kuali.rice.krms.framework.engine.BasicAgenda;

 import org.kuali.rice.krms.framework.engine.BasicAgendaTree;

 import org.kuali.rice.krms.framework.engine.BasicAgendaTreeEntry;

 import org.kuali.rice.krms.framework.engine.BasicContext;

 import org.kuali.rice.krms.framework.engine.BasicRule;

 import org.kuali.rice.krms.framework.engine.CompoundProposition;

 import org.kuali.rice.krms.framework.engine.Context;

 import org.kuali.rice.krms.framework.engine.ContextProvider;

 import org.kuali.rice.krms.framework.engine.Proposition;

 import org.kuali.rice.krms.framework.engine.ProviderBasedEngine;

 import org.kuali.student.common.util.krms.ManualContextProvider;

 import org.kuali.student.common.util.krms.RulesExecutionConstants;

 import org.kuali.student.enrollment.acal.dto.TermInfo;

 import org.kuali.student.enrollment.acal.service.AcademicCalendarService;

 import org.kuali.student.process.poc.context.CourseRegistrationProcessContextInfo;

 import org.kuali.student.process.poc.evaluator.ProcessEvaluator;

 import org.kuali.student.process.poc.krms.proposition.ExemptionAwareProposition;

 import org.kuali.student.process.poc.krms.proposition.MilestoneDateComparisonProposition;

 import org.kuali.student.process.poc.krms.proposition.MilestoneDateComparisonProposition.DateComparisonType;

 import org.kuali.student.process.poc.krms.proposition.PersonLivingProposition;

 import org.kuali.student.process.poc.krms.proposition.RegistrationHoldProposition;

 import org.kuali.student.process.poc.krms.proposition.SubProcessProposition;

 import org.kuali.student.process.poc.krms.proposition.SummerTermProposition;

 import org.kuali.student.process.poc.util.InstructionComparator;

 import org.kuali.student.r2.common.dto.ContextInfo;

 import org.kuali.student.r2.common.dto.ValidationResultInfo;

 import org.kuali.student.r2.common.exceptions.DoesNotExistException;

 import org.kuali.student.r2.common.exceptions.InvalidParameterException;

 import org.kuali.student.r2.common.exceptions.MissingParameterException;

 import org.kuali.student.r2.common.exceptions.OperationFailedException;

 import org.kuali.student.r2.common.exceptions.PermissionDeniedException;

 import org.kuali.student.r2.common.infc.ValidationResult;

 import org.kuali.student.r2.common.util.constants.ExemptionServiceConstants;

 import org.kuali.student.r2.common.util.constants.ProcessServiceConstants;

 import org.kuali.student.r2.core.exemption.dto.ExemptionInfo;

 import org.kuali.student.r2.core.exemption.infc.DateOverride;

 import org.kuali.student.r2.core.exemption.service.ExemptionService;

 import org.kuali.student.r2.core.hold.dto.HoldInfo;

 import org.kuali.student.r2.core.hold.service.HoldService;

 import org.kuali.student.r2.core.population.service.PopulationService;

 import org.kuali.student.r2.core.process.dto.CheckInfo;

 import org.kuali.student.r2.core.process.dto.InstructionInfo;

 import org.kuali.student.r2.core.process.service.ProcessService;

 import java.util.ArrayList;

 import java.util.Arrays;

 import java.util.Collections;

 import java.util.HashMap;

 import java.util.LinkedHashMap;

 import java.util.List;

 import java.util.Map;

 /**

  * Utility class to build up a Proposition tree for to evaluate checks from a Process

  *

  * @author alubbers

  */

 public class KRMSProcessEvaluator implements ProcessEvaluator<CourseRegistrationProcessContextInfo> {

     public static final String EXEMPTION_WAS_USED_MESSAGE_SUFFIX = " (exemption applied)";

     private AcademicCalendarService acalService;

     private ProcessService processService;

     private PopulationService populationService;

     private ExemptionService exemptionService;

     private HoldService holdService;

     private List<TermResolver<?>> termResolvers;

     private ExecutionOptions executionOptions;

     private SelectionCriteria selectionCriteria;

     public void setAcalService(AcademicCalendarService acalService) {

         this.acalService = acalService;

     }

     public void setProcessService(ProcessService processService) {

         this.processService = processService;

     }

     public void setPopulationService(PopulationService populationService) {

         this.populationService = populationService;

     }

     public void setExemptionService(ExemptionService exemptionService) {

         this.exemptionService = exemptionService;

     }

     public void setHoldService(HoldService holdService) {

         this.holdService = holdService;

     }

     @Override

     public List<ValidationResultInfo> evaluate(CourseRegistrationProcessContextInfo processContext, ContextInfo context)

             throws OperationFailedException {

         List<InstructionInfo> instructions;

         try {

             instructions = processService.getInstructionsByProcess(processContext.getProcessKey(), context);

         } catch (OperationFailedException ex) {

             throw ex;

         } catch (Exception ex) {

             throw new OperationFailedException("unexpected", ex);

         }

         TermInfo term = null;

         if (processContext.getTermKey() != null) {

             try {

                 term = acalService.getTerm(processContext.getTermKey(), context);

             } catch (OperationFailedException ex) {

                 throw ex;

             } catch (Exception ex) {

                 throw new OperationFailedException("unexpected", ex);

             }

         }

         List<InstructionInfo> sortedInstructions = new ArrayList<InstructionInfo>();

         // filter out Instructions that do apply to the context

         for (InstructionInfo instruction : instructions) {

             // filter out by term

             if (term != null && !instruction.getAppliedAtpTypeKeys().isEmpty() && !instruction.getAppliedAtpTypeKeys().contains(term.getTypeKey())) {

                 continue;

             }

             // filter out by applicable Population

             boolean skipInstruction = true;

             for (String popKey : instruction.getAppliedPopulationKeys()) {

                 try {

                     if (populationService.isMember(processContext.getStudentId(), popKey, context)) {

                         skipInstruction = false;

                         break;

                     }

                 } catch (OperationFailedException ex) {

                     throw ex;

                 } catch (Exception ex) {

                     throw new OperationFailedException("unexpected", ex);

                 }

             }

             // check for any direct exemptions the student may have for this check

             List<ExemptionInfo> exemptions;

             try {

                 exemptions = exemptionService.getActiveExemptionsByTypeProcessAndCheckForPerson(ExemptionServiceConstants.CHECK_EXEMPTION_TYPE_KEY, processContext.getProcessKey(), instruction.getCheckKey(), processContext.getStudentId(), context);

             } catch (OperationFailedException ex) {

                 throw ex;

             } catch (Exception ex) {

                 throw new OperationFailedException("unexpected", ex);

             }

             if (!exemptions.isEmpty()) {

                 skipInstruction = true;

             }

             if (skipInstruction) {

                 continue;

             }

             sortedInstructions.add(instruction);

         }

         Collections.sort(sortedInstructions, new InstructionComparator());

         // build a list of propositions based on the sorted instructions, using a LinkedHashMap to maintain the same sorting order

         Map<Proposition, InstructionInfo> propositions = new LinkedHashMap<Proposition, InstructionInfo>(sortedInstructions.size());

         for (InstructionInfo instruction : sortedInstructions) {

             CheckInfo check;

             try {

                 check = processService.getCheck(instruction.getCheckKey(), context);

             } catch (OperationFailedException ex) {

                 throw ex;

             } catch (Exception ex) {

                 throw new OperationFailedException("unexpected", ex);

             }

             // if a sub-process is found,

             if (check.getTypeKey().equals(ProcessServiceConstants.PROCESS_CHECK_TYPE_KEY)) {

                 CourseRegistrationProcessContextInfo checkContext = CourseRegistrationProcessContextInfo.createForRegistrationEligibility(processContext.getStudentId(), processContext.getTermKey());

                 checkContext.setProcessKey(check.getProcessKey());

                 propositions.put(new SubProcessProposition(checkContext, this), instruction);

             }

             if (check.getTypeKey().equals(ProcessServiceConstants.HOLD_CHECK_TYPE_KEY)) {

                 propositions.put(new RegistrationHoldProposition(check.getIssueKey()), instruction);

             } else if (check.getKey().equals(ProcessServiceConstants.CHECK_KEY_IS_ALIVE)) {

                 propositions.put(new PersonLivingProposition(), instruction);

             } else if (check.getKey().equals(ProcessServiceConstants.CHECK_KEY_IS_NOT_SUMMER_TERM)) {

                 propositions.put(new SummerTermProposition(term), instruction);

             } else if (check.getTypeKey().equals(ProcessServiceConstants.START_DATE_CHECK_TYPE_KEY)) {

                 propositions.put(buildMilestoneCheckProposition(check, DateComparisonType.AFTER, processContext, context), instruction);

             } else if (check.getTypeKey().equals(ProcessServiceConstants.DEADLINE_CHECK_TYPE_KEY)) {

                 propositions.put(buildMilestoneCheckProposition(check, DateComparisonType.BEFORE, processContext, context), instruction);

             } else if (check.getTypeKey().equals(ProcessServiceConstants.TIME_PERIOD_CHECK_TYPE_KEY)) {

                 propositions.put(buildMilestoneCheckProposition(check, DateComparisonType.BETWEEN, processContext, context), instruction);

             }

         }

         // if all instructions are skipped, and no propositions were generated, return one "success" message

         if(propositions.isEmpty()) {

             ValidationResultInfo success = new ValidationResultInfo();

             success.setLevel(ValidationResult.ErrorLevel.OK);

             return Collections.singletonList(success);

         }

         // Build the list of known facts prior to execution

         Map<String, Object> executionFacts = buildExecutionFacts(processContext, context);

         // Combine all propositions into a CompoundProposition and evaluate the results

         EngineResults krmsResults = evaluateProposition(new CompoundProposition(LogicalOperator.AND, new ArrayList<Proposition>(propositions.keySet())), executionFacts);

         List<ValidationResultInfo> results;

         try {

             results = buildValidationResultsFromEngineResults(krmsResults, propositions, context);   

         } catch (OperationFailedException ex) {

             throw ex;

         } catch (Exception ex) {

             throw new OperationFailedException("unexpected", ex);

         }

         return results;

     }

     private MilestoneDateComparisonProposition buildMilestoneCheckProposition(CheckInfo check, DateComparisonType comparisonType, CourseRegistrationProcessContextInfo processContext, ContextInfo context)

             throws OperationFailedException {

         List<ExemptionInfo> exemptions;

         try {

             exemptions = exemptionService.getActiveExemptionsByTypeProcessAndCheckForPerson(ExemptionServiceConstants.MILESTONE_DATE_EXEMPTION_TYPE_KEY, processContext.getProcessKey(), check.getKey(), processContext.getStudentId(), context);

         } catch (OperationFailedException ex) {

             throw ex;

         } catch (Exception ex) {

             throw new OperationFailedException("unexpected", ex);

         }

         if (exemptions.isEmpty()) {

             return new MilestoneDateComparisonProposition(RulesExecutionConstants.CURRENT_DATE_TERM_NAME, comparisonType, check.getMilestoneTypeKey(), processContext.getTermKey(), true, null);

         }

         // For now, assume there is only one active Exemption

         DateOverride dateOverrideInfo = exemptions.get(0).getDateOverride();

         return new MilestoneDateComparisonProposition(RulesExecutionConstants.CURRENT_DATE_TERM_NAME, comparisonType, check.getMilestoneTypeKey(), processContext.getTermKey(), true, dateOverrideInfo);

     }

     private EngineResults evaluateProposition(Proposition proposition, Map<String, Object> executionFacts) {

         // Build the KRMS agenda and other startup objects to execute

         List<AgendaTreeEntry> treeEntries = new ArrayList<AgendaTreeEntry>(1);

         treeEntries.add(new BasicAgendaTreeEntry(new BasicRule(proposition, null)));

         Map<String, String> qualifiers = Collections.emptyMap();

         Agenda agenda = new BasicAgenda(qualifiers, new BasicAgendaTree(treeEntries));

         Context context = new BasicContext(Arrays.asList(agenda), termResolvers);

         ContextProvider contextProvider = new ManualContextProvider(context);

         ProviderBasedEngine engine = new ProviderBasedEngine();

         engine.setContextProvider(contextProvider);

         if (executionOptions == null) {

             executionOptions = new ExecutionOptions();

             executionOptions.setFlag(ExecutionFlag.LOG_EXECUTION, true);

             executionOptions.setFlag(ExecutionFlag.EVALUATE_ALL_PROPOSITIONS, true);

         }

         if (selectionCriteria == null) {

             Map<String, String> contextQualifiers = Collections.singletonMap(RulesExecutionConstants.DOCTYPE_CONTEXT_QUALIFIER, RulesExecutionConstants.STUDENT_ELIGIBILITY_DOCTYPE);

             Map<String, String> empty = Collections.emptyMap();

             selectionCriteria = SelectionCriteria.createCriteria(new DateTime(), contextQualifiers, empty);

         }

         return engine.execute(selectionCriteria, executionFacts, executionOptions);

     }

     private List<ValidationResultInfo> buildValidationResultsFromEngineResults(EngineResults engineResults, Map<Proposition, InstructionInfo> propositionInstructionMap, ContextInfo context) throws InvalidParameterException, MissingParameterException, DoesNotExistException, PermissionDeniedException, OperationFailedException {

         List<ValidationResultInfo> results = new ArrayList<ValidationResultInfo>();

         // go through all the results from the Propositions, and build validation results based on any propositions that failed

         List<ResultEvent> events = engineResults.getResultsOfType(ResultEvent.PropositionEvaluated);

         for (ResultEvent e : events) {

             Proposition prop = (Proposition) e.getSource();

             InstructionInfo instruction = propositionInstructionMap.get(prop);

             ValidationResultInfo result = new ValidationResultInfo();

             String message = instruction.getMessage().getPlain();

             ExemptionAwareProposition exemptionProp = null;

             if(prop instanceof SubProcessProposition) {

                 List<ValidationResultInfo> subResults = (List<ValidationResultInfo>) e.getResultDetails().get(RulesExecutionConstants.SUBPROCESS_EVALUATION_RESULTS);

                 results.addAll(subResults);

             }

             else {

                 // if the proposition is could have an exemption, check for the exemption and add a suffix to the message

                 if(prop instanceof ExemptionAwareProposition) {

                     exemptionProp = (ExemptionAwareProposition)prop;

                     if(exemptionProp.isExemptionUsed()) {

                         message += EXEMPTION_WAS_USED_MESSAGE_SUFFIX;

                     }

                 }

                 if (e.getResult()) {

                     result.setLevel(ValidationResult.ErrorLevel.OK);

                     // add a message to an OK result only if an exemption was used

                     if(exemptionProp != null && exemptionProp.isExemptionUsed()) {

                         result.setMessage(message);

                     }

                 }

                 else {

                     if (instruction.getIsWarning()) {

                         result.setWarn(message);

                     } else {

                         result.setError(message);

                     }

                 }

                 results.add(result);

             }

             if (!e.getResult() && !instruction.getContinueOnFail()) {

                 break;

             }

         }

         // Now check if there are any warnings from Holds that are marked as warning only

         List<String> warningHoldIds = (List<String>) engineResults.getAttribute(RulesExecutionConstants.REGISTRATION_HOLD_WARNINGS_ATTRIBUTE);

         if (warningHoldIds != null && !warningHoldIds.isEmpty()) {

             for (String holdId : warningHoldIds) {

                 HoldInfo hold = holdService.getHold(holdId, context);

                 ValidationResultInfo result = new ValidationResultInfo();

                 result.setWarn("The following hold was found on the student's account, but set as a warning: " + hold.getDescr().getPlain());

                 results.add(result);

             }

         }

         return results;

     }

     public List<ValidationResultInfo> evaluateStudentAliveRule(InstructionInfo instruction, CourseRegistrationProcessContextInfo processContext, ContextInfo context) throws InvalidParameterException, MissingParameterException, DoesNotExistException, OperationFailedException, PermissionDeniedException {

         List<ValidationResultInfo> results = new ArrayList<ValidationResultInfo>();

         // Build the list of known facts prior to execution

         Map<String, Object> executionFacts = buildExecutionFacts(processContext, context);

         // evaluate the results for just the one proposition

         Proposition prop = new PersonLivingProposition();

         EngineResults engineResults = evaluateProposition(prop, executionFacts);

         Map<Proposition, InstructionInfo> propInstructionMap = Collections.singletonMap(prop, instruction);

         return buildValidationResultsFromEngineResults(engineResults, propInstructionMap, context);

     }

     public List<ValidationResultInfo> evaluateSummerTermRule(InstructionInfo instruction, CourseRegistrationProcessContextInfo processContext, ContextInfo context) throws InvalidParameterException, MissingParameterException, DoesNotExistException, OperationFailedException, PermissionDeniedException {

         List<ValidationResultInfo> results = new ArrayList<ValidationResultInfo>();

         TermInfo term = acalService.getTerm(processContext.getTermKey(), context);

         // Build the list of known facts prior to execution

         Map<String, Object> executionFacts = buildExecutionFacts(processContext, context);

         // evaluate the results for just the one proposition

         Proposition prop = new SummerTermProposition(term);

         EngineResults engineResults = evaluateProposition(prop, executionFacts);

         Map<Proposition, InstructionInfo> propInstructionMap = Collections.singletonMap(prop, instruction);

         return buildValidationResultsFromEngineResults(engineResults, propInstructionMap, context);

     }

     private Map<String, Object> buildExecutionFacts(CourseRegistrationProcessContextInfo processContext, ContextInfo context) {

         Map<String, Object> executionFacts = new HashMap<String, Object>();

         executionFacts.put(RulesExecutionConstants.STUDENT_ID_TERM_NAME, processContext.getStudentId());

         executionFacts.put(RulesExecutionConstants.CONTEXT_INFO_TERM_NAME, context);

         if (processContext.getTermKey() != null) {

             executionFacts.put(RulesExecutionConstants.REGISTRATION_TERM_TERM_NAME, processContext.getTermKey());

         }

         return executionFacts;

     }

     public void setTermResolvers(List<TermResolver<?>> termResolvers) {

         this.termResolvers = termResolvers;

     }

     public void setExecutionOptions(ExecutionOptions executionOptions) {

         this.executionOptions = executionOptions;

     }

 }