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package io.nflow.engine.internal.dao;

import static io.nflow.engine.internal.dao.DaoUtil.firstColumnLengthExtractor;
import static io.nflow.engine.internal.dao.DaoUtil.getInt;
import static io.nflow.engine.internal.dao.DaoUtil.getLong;
import static io.nflow.engine.internal.dao.DaoUtil.toTimestamp;
import static io.nflow.engine.workflow.instance.WorkflowInstance.WorkflowInstanceStatus.created;
import static io.nflow.engine.workflow.instance.WorkflowInstance.WorkflowInstanceStatus.executing;
import static io.nflow.engine.workflow.instance.WorkflowInstance.WorkflowInstanceStatus.inProgress;
import static io.nflow.engine.workflow.instance.WorkflowInstanceAction.WorkflowActionType.recovery;
import static java.lang.Math.min;
import static java.util.Collections.emptyList;
import static java.util.Collections.emptyMap;
import static java.util.Collections.sort;
import static java.util.Optional.ofNullable;
import static java.util.stream.Collectors.toList;
import static java.util.stream.Stream.empty;
import static org.apache.commons.lang3.StringUtils.abbreviate;
import static org.apache.commons.lang3.StringUtils.join;
import static org.apache.commons.lang3.StringUtils.length;
import static org.joda.time.DateTime.now;
import static org.slf4j.LoggerFactory.getLogger;
import static org.springframework.transaction.annotation.Propagation.MANDATORY;
import static org.springframework.util.CollectionUtils.isEmpty;
import static org.springframework.util.StringUtils.collectionToDelimitedString;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.Timestamp;
import java.sql.Types;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Optional;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.stream.Stream;

import javax.inject.Inject;

import org.joda.time.DateTime;
import org.slf4j.Logger;
import org.springframework.core.env.Environment;
import org.springframework.dao.DuplicateKeyException;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.PreparedStatementCreator;
import org.springframework.jdbc.core.ResultSetExtractor;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.jdbc.core.namedparam.MapSqlParameterSource;
import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate;
import org.springframework.jdbc.core.support.AbstractInterruptibleBatchPreparedStatementSetter;
import org.springframework.jdbc.support.GeneratedKeyHolder;
import org.springframework.jdbc.support.KeyHolder;
import org.springframework.stereotype.Component;
import org.springframework.transaction.TransactionStatus;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.transaction.support.TransactionCallbackWithoutResult;
import org.springframework.transaction.support.TransactionTemplate;
import org.springframework.util.Assert;

import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
import io.nflow.engine.config.NFlow;
import io.nflow.engine.internal.executor.InstanceInfo;
import io.nflow.engine.internal.executor.WorkflowInstanceExecutor;
import io.nflow.engine.internal.storage.db.SQLVariants;
import io.nflow.engine.model.ModelObject;
import io.nflow.engine.service.WorkflowInstanceInclude;
import io.nflow.engine.workflow.executor.StateVariableValueTooLongException;
import io.nflow.engine.workflow.instance.QueryWorkflowInstances;
import io.nflow.engine.workflow.instance.WorkflowInstance;
import io.nflow.engine.workflow.instance.WorkflowInstance.WorkflowInstanceStatus;
import io.nflow.engine.workflow.instance.WorkflowInstanceAction;
import io.nflow.engine.workflow.instance.WorkflowInstanceAction.WorkflowActionType;
import io.nflow.engine.workflow.instance.WorkflowInstanceFactory;

/**
 * Use setter injection because constructor injection may not work when nFlow is used in some legacy systems.
 */
@Component
@SuppressFBWarnings(value = "SIC_INNER_SHOULD_BE_STATIC_ANON", justification = "common jdbctemplate practice")
public class WorkflowInstanceDao {

  private static final Logger logger = getLogger(WorkflowInstanceDao.class);
  static final Map> EMPTY_ACTION_STATE_MAP = emptyMap();

  private final ConcurrentMap workflowTypeByWorkflowIdCache = new ConcurrentHashMap<>();

  final JdbcTemplate jdbc;
  private final NamedParameterJdbcTemplate namedJdbc;
  private final TransactionTemplate transaction;
  final ExecutorDao executorInfo;
  final SQLVariants sqlVariants;
  private final WorkflowInstanceExecutor workflowInstanceExecutor;
  final WorkflowInstanceFactory workflowInstanceFactory;
  private final long workflowInstanceQueryMaxResults;
  private final long workflowInstanceQueryMaxResultsDefault;
  private final long workflowInstanceQueryMaxActions;
  private final long workflowInstanceQueryMaxActionsDefault;
  private final int workflowInstanceTypeCacheSize;
  private boolean disableBatchUpdates;
  int instanceStateTextLength;
  int actionStateTextLength;
  int stateVariableValueMaxLength;

  @Inject
  public WorkflowInstanceDao(SQLVariants sqlVariants, @NFlow JdbcTemplate nflowJdbcTemplate,
      @NFlow TransactionTemplate transactionTemplate, @NFlow NamedParameterJdbcTemplate nflowNamedParameterJdbcTemplate,
      ExecutorDao executorDao, WorkflowInstanceExecutor workflowInstanceExecutor, WorkflowInstanceFactory workflowInstanceFactory,
      Environment env) {

    this.sqlVariants = sqlVariants;
    this.jdbc = nflowJdbcTemplate;
    this.transaction = transactionTemplate;
    this.namedJdbc = nflowNamedParameterJdbcTemplate;
    this.executorInfo = executorDao;
    this.workflowInstanceExecutor = workflowInstanceExecutor;
    this.workflowInstanceFactory = workflowInstanceFactory;

    workflowInstanceQueryMaxResults = env.getRequiredProperty("nflow.workflow.instance.query.max.results", Long.class);
    workflowInstanceQueryMaxResultsDefault = env.getRequiredProperty("nflow.workflow.instance.query.max.results.default",
        Long.class);
    workflowInstanceQueryMaxActions = env.getRequiredProperty("nflow.workflow.instance.query.max.actions", Long.class);
    workflowInstanceQueryMaxActionsDefault = env.getRequiredProperty("nflow.workflow.instance.query.max.actions.default",
        Long.class);
    disableBatchUpdates = env.getRequiredProperty("nflow.db.disable_batch_updates", Boolean.class);
    if (disableBatchUpdates) {
      logger.info("nFlow DB batch updates are disabled (system property nflow.db.disable_batch_updates=true)");
    }
    workflowInstanceTypeCacheSize = env.getRequiredProperty("nflow.db.workflowInstanceType.cacheSize", Integer.class);
    // In one deployment, FirstColumnLengthExtractor returned 0 column length (H2), so allow explicit length setting.
    instanceStateTextLength = env.getProperty("nflow.workflow.instance.state.text.length", Integer.class, -1);
    actionStateTextLength = env.getProperty("nflow.workflow.action.state.text.length", Integer.class, -1);
    stateVariableValueMaxLength = env.getProperty("nflow.workflow.state.variable.value.length", Integer.class, -1);
  }

  private int getInstanceStateTextLength() {
    if (instanceStateTextLength == -1) {
      instanceStateTextLength = jdbc.query("select state_text from nflow_workflow where 1 = 0", firstColumnLengthExtractor);
    }
    return instanceStateTextLength;
  }

  int getActionStateTextLength() {
    if (actionStateTextLength == -1) {
      actionStateTextLength = jdbc.query("select state_text from nflow_workflow_action where 1 = 0", firstColumnLengthExtractor);
    }
    return actionStateTextLength;
  }

  int getStateVariableValueMaxLength() {
    if (stateVariableValueMaxLength == -1) {
      stateVariableValueMaxLength = jdbc.query("select state_value from nflow_workflow_state where 1 = 0",
          firstColumnLengthExtractor);
    }
    return stateVariableValueMaxLength;
  }

  public long insertWorkflowInstance(WorkflowInstance instance) {
    long id;
    if (sqlVariants.hasUpdateableCTE()) {
      id = insertWorkflowInstanceWithCte(instance);
    } else {
      id = insertWorkflowInstanceWithTransaction(instance);
    }
    if (instance.nextActivation != null && instance.nextActivation.isBeforeNow()) {
      workflowInstanceExecutor.wakeUpDispatcherIfNeeded();
    }
    return id;
  }

  private long insertWorkflowInstanceWithCte(WorkflowInstance instance) {
    try {
      StringBuilder sqlb = new StringBuilder(256);
      sqlb.append("with wf as (").append(insertWorkflowInstanceSql()).append(" returning id)");
      Object[] instanceValues = new Object[] { instance.type, instance.priority,
          instance.parentWorkflowId, instance.parentActionId, instance.businessKey, instance.externalId,
          executorInfo.getExecutorGroup(), instance.status.name(), instance.state,
          abbreviate(instance.stateText, getInstanceStateTextLength()), toTimestamp(instance.nextActivation),
          instance.signal.orElse(null) };
      int pos = instanceValues.length;
      Object[] args = Arrays.copyOf(instanceValues, pos + instance.stateVariables.size() * 2);
      for (Entry variable : instance.stateVariables.entrySet()) {
        sqlb.append(", ins").append(pos).append(" as (").append(insertWorkflowInstanceStateSql())
            .append(" select wf.id,0,?,? from wf)");
        args[pos++] = variable.getKey();
        args[pos++] = variable.getValue();
      }
      sqlb.append(" select wf.id from wf");
      return jdbc.queryForObject(sqlb.toString(), Long.class, args);
    } catch (DuplicateKeyException e) {
      logger.warn("Failed to insert workflow instance", e);
      return -1;
    }
  }

  boolean useBatchUpdate() {
    return !disableBatchUpdates && sqlVariants.useBatchUpdate();
  }

  String insertWorkflowInstanceSql() {
    return "insert into nflow_workflow(type, priority, parent_workflow_id, parent_action_id, business_key, external_id, "
        + "executor_group, status, state, state_text, next_activation, workflow_signal) values (?, ?, ?, ?, ?, ?, ?, "
        + sqlVariants.workflowStatus() + ", ?, ?, ?, ?)";
  }

  String insertWorkflowInstanceStateSql() {
    return "insert into nflow_workflow_state(workflow_id, action_id, state_key, state_value)";
  }

  @SuppressFBWarnings(value = { "OBL_UNSATISFIED_OBLIGATION_EXCEPTION_EDGE",
      "SQL_PREPARED_STATEMENT_GENERATED_FROM_NONCONSTANT_STRING" }, justification = "findbugs does not trust jdbctemplate, sql string is practically constant")
  private long insertWorkflowInstanceWithTransaction(final WorkflowInstance instance) {
    return transaction.execute(status -> {
      KeyHolder keyHolder = new GeneratedKeyHolder();
      try {
        jdbc.update((PreparedStatementCreator) connection -> {
          int p = 1;
          PreparedStatement ps = connection.prepareStatement(insertWorkflowInstanceSql(), new String[] { "id" });
          ps.setString(p++, instance.type);
          ps.setShort(p++, instance.priority);
          ps.setObject(p++, instance.parentWorkflowId);
          ps.setObject(p++, instance.parentActionId);
          ps.setString(p++, instance.businessKey);
          ps.setString(p++, instance.externalId);
          ps.setString(p++, executorInfo.getExecutorGroup());
          ps.setString(p++, instance.status.name());
          ps.setString(p++, instance.state);
          ps.setString(p++, abbreviate(instance.stateText, getInstanceStateTextLength()));
          sqlVariants.setDateTime(ps, p++, instance.nextActivation);
          if (instance.signal.isPresent()) {
            ps.setInt(p++, instance.signal.get());
          } else {
            ps.setNull(p++, Types.INTEGER);
          }
          return ps;
        }, keyHolder);
      } catch (DuplicateKeyException e) {
        logger.warn("Failed to insert workflow instance", e);
        return -1L;
      }
      long id = keyHolder.getKey().longValue();
      insertVariables(id, 0, instance.stateVariables);
      return id;
    });
  }

  void insertVariables(final long id, final long actionId, Map changedStateVariables) {
    if (changedStateVariables.isEmpty()) {
      return;
    }
    if (useBatchUpdate()) {
      insertVariablesWithBatchUpdate(id, actionId, changedStateVariables);
    } else {
      insertVariablesWithMultipleUpdates(id, actionId, changedStateVariables);
    }
  }

  private void insertVariablesWithMultipleUpdates(final long id, final long actionId, Map changedStateVariables) {
    for (Entry entry : changedStateVariables.entrySet()) {
      int updated = jdbc.update(insertWorkflowInstanceStateSql() + " values (?,?,?,?)", id, actionId, entry.getKey(),
          entry.getValue());
      if (updated != 1) {
        throw new IllegalStateException("Failed to insert state variable " + entry.getKey());
      }
    }
  }

  private void insertVariablesWithBatchUpdate(final long id, final long actionId, Map changedStateVariables) {
    final Iterator> variables = changedStateVariables.entrySet().iterator();
    int[] updateStatus = jdbc.batchUpdate(insertWorkflowInstanceStateSql() + " values (?,?,?,?)",
        new AbstractInterruptibleBatchPreparedStatementSetter() {
          @Override
          protected boolean setValuesIfAvailable(PreparedStatement ps, int i) throws SQLException {
            if (!variables.hasNext()) {
              return false;
            }
            Entry variable = variables.next();
            ps.setLong(1, id);
            ps.setLong(2, actionId);
            ps.setString(3, variable.getKey());
            ps.setString(4, variable.getValue());
            return true;
          }
        });
    int updatedRows = 0;
    boolean unknownResults = false;
    for (int i = 0; i < updateStatus.length; ++i) {
      if (updateStatus[i] == Statement.SUCCESS_NO_INFO) {
        unknownResults = true;
        continue;
      }
      if (updateStatus[i] == Statement.EXECUTE_FAILED) {
        throw new IllegalStateException("Failed to insert/update state variable at index " + i + " (" + updateStatus[i] + ")");
      }
      updatedRows += updateStatus[i];
    }
    int changedVariables = changedStateVariables.size();
    if (!unknownResults && updatedRows != changedVariables) {
      throw new IllegalStateException(
          "Failed to insert/update state variables, expected update count " + changedVariables + ", actual " + updatedRows);
    }
  }

  @SuppressWarnings("null")
  public void updateWorkflowInstanceAfterExecution(WorkflowInstance instance, WorkflowInstanceAction action,
      List childWorkflows, List workflows, boolean createAction) {
    Assert.isTrue(action != null, "action can not be null");
    Assert.isTrue(childWorkflows != null, "childWorkflows can not be null");
    Assert.isTrue(workflows != null, "workflows can not be null");
    Map changedStateVariables = instance.getChangedStateVariables();
    if (!createAction && (!childWorkflows.isEmpty() || !workflows.isEmpty() || !changedStateVariables.isEmpty())) {
      logger.info("Forcing action creation because new workflow instances are created or state variables are changed.");
      createAction = true;
    }
    if (createAction) {
      if (sqlVariants.hasUpdateableCTE() && childWorkflows.isEmpty() && workflows.isEmpty()) {
        updateWorkflowInstanceWithCTE(instance, action, changedStateVariables);
      } else {
        updateWorkflowInstanceWithTransaction(instance, action, childWorkflows, workflows, changedStateVariables);
      }
    } else {
      updateWorkflowInstance(instance);
    }
  }

  public int updateWorkflowInstance(WorkflowInstance instance) {
    // using sqlVariants.nextActivationUpdate() requires that nextActivation is used 3 times
    Object nextActivation = sqlVariants.toTimestampObject(instance.nextActivation);
    return jdbc.update(updateWorkflowInstanceSql(), instance.status.name(), instance.state,
        abbreviate(instance.stateText, getInstanceStateTextLength()), nextActivation, nextActivation, nextActivation,
        instance.status == executing ? executorInfo.getExecutorId() : null, instance.retries, toTimestamp(instance.started),
        instance.id);
  }

  private void updateWorkflowInstanceWithTransaction(final WorkflowInstance instance, final WorkflowInstanceAction action,
      final List childWorkflows, final List workflows,
      final Map changedStateVariables) {
    transaction.execute(new TransactionCallbackWithoutResult() {
      @Override
      protected void doInTransactionWithoutResult(TransactionStatus status) {
        updateWorkflowInstance(instance);
        long parentActionId = insertWorkflowInstanceAction(action);
        insertVariables(action.workflowInstanceId, parentActionId, changedStateVariables);
        for (WorkflowInstance childTemplate : childWorkflows) {
          WorkflowInstance childWorkflow = new WorkflowInstance.Builder(childTemplate).setParentWorkflowId(instance.id)
              .setParentActionId(parentActionId).build();
          insertWorkflowInstance(childWorkflow);
        }
        for (WorkflowInstance workflow : workflows) {
          insertWorkflowInstance(workflow);
        }
      }
    });
  }

  public void recoverWorkflowInstancesFromDeadNodes() {
    WorkflowInstanceAction.Builder builder = new WorkflowInstanceAction.Builder().setExecutionStart(now()).setExecutionEnd(now())
        .setType(recovery).setStateText("Recovered");
    for (InstanceInfo instance : getRecoverableInstances()) {
      WorkflowInstanceAction action = builder.setState(instance.state).setWorkflowInstanceId(instance.id).build();
      recoverWorkflowInstance(instance.id, action);
    }
  }

  private List getRecoverableInstances() {
    String sql = "select id, state from nflow_workflow where executor_id in (select id from nflow_executor where "
        + executorInfo.getExecutorGroupCondition() + " and id <> " + executorInfo.getExecutorId() + " and "
        + sqlVariants.dateLtEqDiff("expires", "current_timestamp") + ")";
    return jdbc.query(sql, new RowMapper() {
      @Override
      public InstanceInfo mapRow(ResultSet rs, int rowNum) throws SQLException {
        InstanceInfo instance = new InstanceInfo();
        instance.id = rs.getLong("id");
        instance.state = rs.getString("state");
        return instance;
      }
    });
  }

  private void recoverWorkflowInstance(final long instanceId, final WorkflowInstanceAction action) {
    transaction.execute(new TransactionCallbackWithoutResult() {
      @Override
      protected void doInTransactionWithoutResult(TransactionStatus status) {
        int executorId = executorInfo.getExecutorId();
        int updated = jdbc.update("update nflow_workflow set executor_id = null, status = "
            + sqlVariants.workflowStatus(inProgress) + " where id = ? and executor_id in (select id from nflow_executor where "
            + executorInfo.getExecutorGroupCondition() + " and id <> " + executorId + " and "
            + sqlVariants.dateLtEqDiff("expires", "current_timestamp") + ")", instanceId);
        if (updated > 0) {
          insertWorkflowInstanceAction(action);
        }
      }
    });
  }

  private void updateWorkflowInstanceWithCTE(WorkflowInstance instance, final WorkflowInstanceAction action,
      Map changedStateVariables) {
    int executorId = executorInfo.getExecutorId();
    StringBuilder sqlb = new StringBuilder(256);
    sqlb.append("with wf as (").append(updateWorkflowInstanceSql()).append(" returning id), ");
    sqlb.append("act as (").append(insertWorkflowActionSql()).append(" select wf.id, ?, ").append(sqlVariants.actionType())
        .append(", ?, ?, ?, ?, ? from wf returning id)");

    // using sqlVariants.nextActivationUpdate() requires that nextActivation is added 3 times
    Timestamp nextActivation = toTimestamp(instance.nextActivation);
    Object[] fixedValues = new Object[] { instance.status.name(), instance.state,
        abbreviate(instance.stateText, getInstanceStateTextLength()), nextActivation, nextActivation, nextActivation,
        instance.status == executing ? executorId : null, instance.retries, toTimestamp(action.executionStart), instance.id,
        executorId, action.type.name(), action.state, abbreviate(action.stateText, getActionStateTextLength()), action.retryNo,
        toTimestamp(action.executionStart), toTimestamp(action.executionEnd) };
    int pos = fixedValues.length;
    Object[] args = Arrays.copyOf(fixedValues, pos + changedStateVariables.size() * 2);
    for (Entry variable : changedStateVariables.entrySet()) {
      sqlb.append(", ins").append(pos).append(" as (").append(insertWorkflowInstanceStateSql())
          .append(" select wf.id,act.id,?,? from wf,act)");
      args[pos++] = variable.getKey();
      args[pos++] = variable.getValue();
    }
    sqlb.append(" select act.id from act");
    jdbc.queryForObject(sqlb.toString(), Long.class, args);
  }

  public void checkStateVariableValueLength(String name, String value) {
    if (length(value) > getStateVariableValueMaxLength()) {
      throw new StateVariableValueTooLongException("Too long value (length = " + length(value) + ") for state variable " + name
          + ": maximum allowed length is " + getStateVariableValueMaxLength());
    }
  }

  String insertWorkflowActionSql() {
    return "insert into nflow_workflow_action(workflow_id, executor_id, type, state, state_text, retry_no, execution_start, execution_end)";
  }

  private String updateWorkflowInstanceSql() {
    return "update nflow_workflow set status = " + sqlVariants.workflowStatus() + ", state = ?, state_text = ?, "
        + "next_activation = " + sqlVariants.nextActivationUpdate()
        + ", external_next_activation = null, executor_id = ?, retries = ?, "
        + "started = (case when started is null then ? else started end) where id = ? and executor_id = "
        + executorInfo.getExecutorId();
  }

  public boolean updateNotRunningWorkflowInstance(WorkflowInstance instance) {
    List vars = new ArrayList<>();
    List args = new ArrayList<>();
    if (instance.state != null) {
      vars.add("state = ?, retries = 0");
      args.add(instance.state);
    }
    if (instance.stateText != null) {
      vars.add("state_text = ?");
      args.add(instance.stateText);
    }
    if (instance.nextActivation != null) {
      vars.add("next_activation = ?");
      args.add(sqlVariants.toTimestampObject(instance.nextActivation));
    }
    if (instance.status != null) {
      vars.add("status = " + sqlVariants.workflowStatus());
      args.add(instance.status.name());
    }
    String sql = "update nflow_workflow set " + join(vars, ", ") + " where id = ? and executor_id is null";
    args.add(instance.id);
    return jdbc.update(sql, args.toArray()) == 1;
  }

  public boolean wakeUpWorkflowExternally(long workflowInstanceId, List expectedStates) {
    StringBuilder sql = new StringBuilder("update nflow_workflow set next_activation = (case when executor_id is null then ")
        .append("case when ").append(sqlVariants.dateLtEqDiff("next_activation", "current_timestamp"))
        .append(" then next_activation else current_timestamp end else next_activation end), ")
        .append("external_next_activation = current_timestamp where ").append(executorInfo.getExecutorGroupCondition())
        .append(" and id = ? and next_activation is not null");
    return addExpectedStatesToQueryAndUpdate(sql, workflowInstanceId, expectedStates);
  }

  public boolean wakeupWorkflowInstanceIfNotExecuting(long workflowInstanceId, List expectedStates) {
    StringBuilder sql = new StringBuilder("update nflow_workflow set next_activation = current_timestamp")
        .append(" where id = ? and executor_id is null and status in (").append(sqlVariants.workflowStatus(inProgress))
        .append(", ").append(sqlVariants.workflowStatus(created))
        .append(") and (next_activation is null or next_activation > current_timestamp)");
    return addExpectedStatesToQueryAndUpdate(sql, workflowInstanceId, expectedStates);
  }

  private boolean addExpectedStatesToQueryAndUpdate(StringBuilder sql, long workflowInstanceId, List expectedStates) {
    Object[] args = new Object[1 + expectedStates.size()];
    args[0] = workflowInstanceId;
    if (!expectedStates.isEmpty()) {
      sql.append(" and state in (");
      for (int i = 0; i < expectedStates.size(); i++) {
        sql.append("?,");
        args[i + 1] = expectedStates.get(i);
      }
      sql.setCharAt(sql.length() - 1, ')');
    }
    return jdbc.update(sql.toString(), args) == 1;
  }

  public WorkflowInstance getWorkflowInstance(long id, Set includes, Long maxActions) {
    String sql = "select * from nflow_workflow where id = ?";
    WorkflowInstance instance = jdbc.queryForObject(sql, new WorkflowInstanceRowMapper(), id).build();
    if (includes.contains(WorkflowInstanceInclude.CURRENT_STATE_VARIABLES)) {
      fillState(instance);
    }
    if (includes.contains(WorkflowInstanceInclude.CHILD_WORKFLOW_IDS)) {
      fillChildWorkflowIds(instance);
    }
    if (includes.contains(WorkflowInstanceInclude.ACTIONS)) {
      fillActions(instance, includes.contains(WorkflowInstanceInclude.ACTION_STATE_VARIABLES), maxActions);
    }
    return instance;
  }

  private void fillState(final WorkflowInstance instance) {
    jdbc.query("select outside.state_key, outside.state_value from nflow_workflow_state outside inner join "
        + "(select workflow_id, max(action_id) action_id, state_key from nflow_workflow_state where workflow_id = ? group by workflow_id, state_key) inside "
        + "on outside.workflow_id = inside.workflow_id and outside.action_id = inside.action_id and outside.state_key = inside.state_key",
            rs -> {
              instance.stateVariables.put(rs.getString(1), rs.getString(2));
            }, instance.id);
    instance.originalStateVariables.putAll(instance.stateVariables);
  }

  public List pollNextWorkflowInstanceIds(final int batchSize) {
    if (sqlVariants.hasUpdateReturning()) {
      return pollNextWorkflowInstanceIdsWithUpdateReturning(batchSize);
    }
    return pollNextWorkflowInstanceIdsWithTransaction(batchSize);
  }

  String updateInstanceForExecutionQuery() {
    return "update nflow_workflow set executor_id = " + executorInfo.getExecutorId() + ", status = "
        + sqlVariants.workflowStatus(executing) + ", " + "external_next_activation = null";
  }

  String whereConditionForInstanceUpdate() {
    return "where executor_id is null and status in (" + sqlVariants.workflowStatus(created) + ", "
        + sqlVariants.workflowStatus(inProgress) + ") and " + sqlVariants.dateLtEqDiff("next_activation", "current_timestamp")
        + " and " + executorInfo.getExecutorGroupCondition() + " order by priority desc, next_activation asc";
  }

  private List pollNextWorkflowInstanceIdsWithUpdateReturning(int batchSize) {
    String sql = updateInstanceForExecutionQuery() + " where id in ("
        + sqlVariants.limit("select id from nflow_workflow " + whereConditionForInstanceUpdate(), batchSize)
        + ") and executor_id is null returning id";
    return jdbc.queryForList(sql, Long.class);
  }

  private List pollNextWorkflowInstanceIdsWithTransaction(final int batchSize) {
    String sql = sqlVariants.limit("select id, modified from nflow_workflow " + whereConditionForInstanceUpdate(), batchSize);
    List instances = jdbc.query(sql,
            (rs, rowNum) -> new OptimisticLockKey(rs.getLong("id"), sqlVariants.getTimestamp(rs, "modified")));
    if (instances.isEmpty()) {
      return emptyList();
    }
    sort(instances);
    List ids = transaction.execute(transactionStatus -> {
      if (useBatchUpdate()) {
        return updateNextWorkflowInstancesWithBatchUpdate(instances);
      }
      return updateNextWorkflowInstancesWithMultipleUpdates(instances);
    });
    if (ids.isEmpty()) {
      throw new PollingRaceConditionException(
          "None of the workflow instances selected for processing were successfully reserved for this executor, trying again later.");
    }
    return ids;
  }

  private List updateNextWorkflowInstancesWithMultipleUpdates(List instances) {
    String sql = updateInstanceForExecutionQuery() + " where id = ? and modified = ? and executor_id is null";
    return instances.stream()
        .flatMap(instance -> jdbc.update(sql, instance.id, sqlVariants.tuneTimestampForDb(instance.modified)) == 1
            ? Stream.of(instance.id)
            : empty())
        .collect(toList());
  }

  private List updateNextWorkflowInstancesWithBatchUpdate(List instances) {
    String sql = updateInstanceForExecutionQuery() + " where id = ? and modified = ? and executor_id is null";
    List batchArgs = instances.stream()
        .map(instance -> new Object[] { instance.id, sqlVariants.tuneTimestampForDb(instance.modified) })
        .collect(toList());
    int[] updateStatuses = jdbc.batchUpdate(sql, batchArgs);
    List ids = new ArrayList<>(instances.size());
    for (int i = 0; i < updateStatuses.length; ++i) {
      int status = updateStatuses[i];
      if (status == 1) {
        ids.add(instances.get(i).id);
      } else if (status != 0) {
        disableBatchUpdates = true;
        throw new PollingBatchException(
            "Database was unable to provide information about affected rows in a batch update. Disabling batch updates.");
      }
    }
    return ids;
  }

  private static class OptimisticLockKey extends ModelObject implements Comparable {
    public final long id;
    public final Object modified;

    public OptimisticLockKey(long id, Object modified) {
      this.id = id;
      this.modified = modified;
    }

    @Override
    @SuppressFBWarnings(value = "EQ_COMPARETO_USE_OBJECT_EQUALS", justification = "This class has a natural ordering that is inconsistent with equals")
    public int compareTo(OptimisticLockKey other) {
      return Long.compare(this.id, other.id);
    }
  }

  public List queryWorkflowInstances(QueryWorkflowInstances query) {
    return queryWorkflowInstancesAsStream(query).collect(toList());
  }

  public Stream queryWorkflowInstancesAsStream(QueryWorkflowInstances query) {
    String sql = "select * from nflow_workflow ";
    List conditions = new ArrayList<>();
    MapSqlParameterSource params = new MapSqlParameterSource();
    conditions.add(executorInfo.getExecutorGroupCondition());
    if (!isEmpty(query.ids)) {
      conditions.add("id in (:ids)");
      params.addValue("ids", query.ids);
    }
    if (!isEmpty(query.types)) {
      conditions.add("type in (:types)");
      params.addValue("types", query.types);
    }
    if (query.parentWorkflowId != null) {
      conditions.add("parent_workflow_id = :parent_workflow_id");
      params.addValue("parent_workflow_id", query.parentWorkflowId);
    }
    if (query.parentActionId != null) {
      conditions.add("parent_action_id = :parent_action_id");
      params.addValue("parent_action_id", query.parentActionId);
    }
    if (!isEmpty(query.states)) {
      conditions.add("state in (:states)");
      params.addValue("states", query.states);
    }
    if (!isEmpty(query.statuses)) {
      List convertedStatuses = query.statuses.stream().map(WorkflowInstanceStatus::name).collect(toList());
      conditions.add("status" + sqlVariants.castToText() + " in (:statuses)");
      params.addValue("statuses", convertedStatuses);
    }
    if (query.businessKey != null) {
      conditions.add("business_key = :business_key");
      params.addValue("business_key", query.businessKey);
    }
    if (query.externalId != null) {
      conditions.add("external_id = :external_id");
      params.addValue("external_id", query.externalId);
    }
    conditions.add("executor_group = :executor_group");
    params.addValue("executor_group", executorInfo.getExecutorGroup());
    sql += " where " + collectionToDelimitedString(conditions, " and ") + " order by id desc";
    sql = sqlVariants.limit(sql, getMaxResults(query.maxResults));

    Stream ret = namedJdbc.query(sql, params, new WorkflowInstanceRowMapper()).stream()
            .map(WorkflowInstance.Builder::build);
    if (query.includeCurrentStateVariables) {
      ret = ret.peek(instance -> fillState(instance));
    }
    if (query.includeActions) {
      ret = ret.peek(instance -> fillActions(instance, query.includeActionStateVariables, query.maxActions));
    }
    if (query.includeChildWorkflows) {
      ret = ret.peek(instance -> fillChildWorkflowIds(instance));
    }
    return ret;
  }

  private void fillChildWorkflowIds(final WorkflowInstance instance) {
    jdbc.query("select parent_action_id, id from nflow_workflow where parent_workflow_id = ?", rs -> {
      long parentActionId = rs.getLong(1);
      long childWorkflowInstanceId = rs.getLong(2);
      List children = instance.childWorkflows.computeIfAbsent(parentActionId, k -> new ArrayList<>());
      children.add(childWorkflowInstanceId);
    }, instance.id);
  }

  private long getMaxResults(Long maxResults) {
    if (maxResults == null) {
      return workflowInstanceQueryMaxResultsDefault;
    }
    return min(maxResults, workflowInstanceQueryMaxResults);
  }

  private void fillActions(WorkflowInstance instance, boolean includeStateVariables, Long maxActions) {
    Map> actionStates = includeStateVariables ? fetchActionStateVariables(instance)
        : EMPTY_ACTION_STATE_MAP;
    String sql = sqlVariants.limit(
        "select nflow_workflow_action.* from nflow_workflow_action where workflow_id = ? order by id desc",
        getMaxActions(maxActions));
    instance.actions.addAll(jdbc.query(sql, new WorkflowInstanceActionRowMapper(sqlVariants, actionStates), instance.id));
  }

  private long getMaxActions(Long maxActions) {
    if (maxActions == null) {
      return workflowInstanceQueryMaxActionsDefault;
    }
    return min(maxActions, workflowInstanceQueryMaxActions);
  }

  private Map> fetchActionStateVariables(WorkflowInstance instance) {
    return jdbc.query("select * from nflow_workflow_state where workflow_id = ? order by action_id, state_key asc",
        new WorkflowActionStateRowMapper(), instance.id);
  }

  @Transactional(propagation = MANDATORY)
  public long insertWorkflowInstanceAction(final WorkflowInstance instance, final WorkflowInstanceAction action) {
    long actionId = insertWorkflowInstanceAction(action);
    insertVariables(action.workflowInstanceId, actionId, instance.getChangedStateVariables());
    return actionId;
  }

  public long insertWorkflowInstanceAction(final WorkflowInstanceAction action) {
    KeyHolder keyHolder = new GeneratedKeyHolder();
    jdbc.update(new PreparedStatementCreator() {
      @Override
      @SuppressFBWarnings(value = { "OBL_UNSATISFIED_OBLIGATION_EXCEPTION_EDGE",
          "SQL_PREPARED_STATEMENT_GENERATED_FROM_NONCONSTANT_STRING" }, justification = "findbugs does not trust jdbctemplate, sql string is practically constant")
      public PreparedStatement createPreparedStatement(Connection con) throws SQLException {
        PreparedStatement p = con.prepareStatement(
            insertWorkflowActionSql() + " values (?, ?, " + sqlVariants.actionType() + ", ?, ?, ?, ?, ?)", new String[] { "id" });
        int field = 1;
        p.setLong(field++, action.workflowInstanceId);
        p.setInt(field++, executorInfo.getExecutorId());
        p.setString(field++, action.type.name());
        p.setString(field++, action.state);
        p.setString(field++, abbreviate(action.stateText, getActionStateTextLength()));
        p.setInt(field++, action.retryNo);
        sqlVariants.setDateTime(p, field++, action.executionStart);
        sqlVariants.setDateTime(p, field++, action.executionEnd);
        return p;
      }
    }, keyHolder);
    return keyHolder.getKey().longValue();
  }

  public String getWorkflowInstanceState(long workflowInstanceId) {
    return jdbc.queryForObject("select state from nflow_workflow where id = ?", String.class, workflowInstanceId);
  }

  class WorkflowInstanceRowMapper implements RowMapper {
    @Override
    public WorkflowInstance.Builder mapRow(ResultSet rs, int rowNum) throws SQLException {
      return workflowInstanceFactory.newWorkflowInstanceBuilder() //
          .setId(rs.getLong("id")) //
          .setExecutorId(getInt(rs, "executor_id")) //
          .setParentWorkflowId(getLong(rs, "parent_workflow_id")) //
          .setParentActionId(getLong(rs, "parent_action_id")) //
          .setStatus(WorkflowInstanceStatus.valueOf(rs.getString("status"))) //
          .setType(rs.getString("type")) //
          .setPriority(rs.getShort("priority")) //
          .setBusinessKey(rs.getString("business_key")) //
          .setExternalId(rs.getString("external_id")) //
          .setState(rs.getString("state")) //
          .setStateText(rs.getString("state_text")) //
          .setActions(new ArrayList()) //
          .setNextActivation(sqlVariants.getDateTime(rs, "next_activation")) //
          .setRetries(rs.getInt("retries")) //
          .setCreated(sqlVariants.getDateTime(rs, "created")) //
          .setModified(sqlVariants.getDateTime(rs, "modified")) //
          .setStartedIfNotSet(sqlVariants.getDateTime(rs, "started")) //
          .setExecutorGroup(rs.getString("executor_group")) //
          .setSignal(ofNullable(getInt(rs, "workflow_signal")));
    }
  }

  static class WorkflowInstanceActionRowMapper implements RowMapper {
    private final SQLVariants sqlVariants;
    private final Map> actionStates;

    public WorkflowInstanceActionRowMapper(SQLVariants sqlVariants, Map> actionStates) {
      this.sqlVariants = sqlVariants;
      this.actionStates = actionStates;
    }

    @Override
    public WorkflowInstanceAction mapRow(ResultSet rs, int rowNum) throws SQLException {
      long actionId = rs.getLong("id");
      Map actionState = actionStates.getOrDefault(actionId, emptyMap());
      return new WorkflowInstanceAction.Builder() //
          .setId(actionId) //
          .setWorkflowInstanceId(rs.getLong("workflow_id")) //
          .setExecutorId(rs.getInt("executor_id")) //
          .setType(WorkflowActionType.valueOf(rs.getString("type"))) //
          .setState(rs.getString("state")) //
          .setStateText(rs.getString("state_text")) //
          .setUpdatedStateVariables(actionState) //
          .setRetryNo(rs.getInt("retry_no")) //
          .setExecutionStart(sqlVariants.getDateTime(rs, "execution_start")) //
          .setExecutionEnd(sqlVariants.getDateTime(rs, "execution_end")).build();
    }
  }

  static class WorkflowActionStateRowMapper implements ResultSetExtractor>> {
    private final Map> actionStates = new LinkedHashMap<>();

    @Override
    public Map> extractData(ResultSet rs) throws SQLException {
      while (rs.next()) {
        long actionId = rs.getLong("action_id");
        String stateKey = rs.getString("state_key");
        String stateValue = rs.getString("state_value");
        if (!actionStates.containsKey(actionId)) {
          actionStates.put(actionId, new LinkedHashMap());
        }
        Map stateMap = actionStates.get(actionId);
        stateMap.put(stateKey, stateValue);
      }
      return actionStates;
    }
  }

  public Optional getSignal(long workflowInstanceId) {
    return ofNullable(
        jdbc.queryForObject("select workflow_signal from nflow_workflow where id = ?", Integer.class, workflowInstanceId));
  }

  @Transactional
  public boolean setSignal(long workflowInstanceId, Optional signal, String reason, WorkflowActionType actionType) {
    boolean updated = jdbc.update("update nflow_workflow set workflow_signal = ? where id = ?", signal.orElse(null),
        workflowInstanceId) > 0;
    if (updated) {
      DateTime now = DateTime.now();
      WorkflowInstanceAction action = new WorkflowInstanceAction.Builder() //
          .setWorkflowInstanceId(workflowInstanceId) //
          .setExecutionStart(now) //
          .setExecutionEnd(now) //
          .setState(getWorkflowInstanceState(workflowInstanceId)) //
          .setStateText(reason) //
          .setType(actionType).build();
      insertWorkflowInstanceAction(action);
    }
    return updated;
  }

  public String getWorkflowInstanceType(long workflowInstanceId) {
    String type = workflowTypeByWorkflowIdCache.computeIfAbsent(workflowInstanceId,
        id -> jdbc.queryForObject("select type from nflow_workflow where id = ?", String.class, id).intern());
    if (workflowTypeByWorkflowIdCache.size() > workflowInstanceTypeCacheSize) {
      workflowTypeByWorkflowIdCache.clear();
    }
    return type;
  }

}