package io.ebeaninternal.server.transaction;

import io.ebean.ProfileLocation;
import io.ebean.TransactionCallback;
import io.ebean.annotation.DocStoreMode;
import io.ebean.bean.PersistenceContext;
import io.ebean.event.changelog.BeanChange;
import io.ebean.event.changelog.ChangeSet;
import io.ebeaninternal.api.SpiProfileTransactionEvent;
import io.ebeaninternal.api.SpiTransaction;
import io.ebeaninternal.api.TransactionEvent;
import io.ebeaninternal.api.TxnProfileEventCodes;
import io.ebeaninternal.server.core.PersistDeferredRelationship;
import io.ebeaninternal.server.core.PersistRequestBean;
import io.ebeaninternal.server.persist.BatchControl;
import io.ebeanservice.docstore.api.DocStoreTransaction;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.persistence.PersistenceException;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.Map;

/**
 * Read only transaction expected to use autoCommit connection and for implicit use only.
 * <p>
 * This transaction is created implicitly and not expected to be exposed to application code and has
 * none of the features for supporting inserts, updates and deletes etc (and throws errors if those
 * persisting features are attempted to be used - which is not expected).
 * </p>
 */
class ImplicitReadOnlyTransaction implements SpiTransaction, TxnProfileEventCodes {

  private static final Logger logger = LoggerFactory.getLogger(ImplicitReadOnlyTransaction.class);

  private static final String illegalStateMessage = "Transaction is Inactive";

  private static final String notExpectedMessage = "Not expected on read only transaction";

  private final TransactionManager manager;

  private final boolean logSql;
  private final boolean logSummary;

  /**
   * The status of the transaction.
   */
  private boolean active;

  /**
   * The underlying Connection which is expected to use autoCommit such that we avoid the
   * explicit commit call at the end of the 'transaction' (for performance).
   */
  private Connection connection;

  /**
   * Holder of the objects fetched to ensure unique objects are used.
   */
  private PersistenceContext persistenceContext;

  private Object tenantId;

  private Map<String, Object> userObjects;

  private final long startNanos;

  private ProfileLocation profileLocation;

  /**
   * Create without a tenantId.
   */
  ImplicitReadOnlyTransaction(TransactionManager manager, Connection connection) {
    this.manager = manager;
    this.logSql = manager.isLogSql();
    this.logSummary = manager.isLogSummary();
    this.active = true;
    this.connection = connection;
    this.persistenceContext = new DefaultPersistenceContext();
    this.startNanos = System.nanoTime();
  }

  /**
   * Create with a tenantId.
   */
  ImplicitReadOnlyTransaction(TransactionManager manager, Connection connection, Object tenantId) {
    this(manager, connection);
    this.tenantId = tenantId;
  }

  @Override
  public long getStartNanoTime() {
    // not used on read only transaction
    return startNanos;
  }

  @Override
  public void setLabel(String label) {
    // do nothing
  }

  @Override
  public String getLabel() {
    return null;
  }

  @Override
  public long profileOffset() {
    return 0;
  }

  @Override
  public void profileEvent(SpiProfileTransactionEvent event) {
    // do nothing
  }

  @Override
  public void setProfileStream(ProfileStream profileStream) {
    // do nothing
  }

  @Override
  public ProfileStream profileStream() {
    return null;
  }

  @Override
  public void setProfileLocation(ProfileLocation profileLocation) {
    this.profileLocation = profileLocation;
  }

  @Override
  public ProfileLocation getProfileLocation() {
    return profileLocation;
  }

  @Override
  public boolean isSkipCache() {
    return false;
  }

  @Override
  public boolean isSkipCacheExplicit() {
    return false;
  }

  @Override
  public void setSkipCache(boolean skipCache) {
  }

  @Override
  public String getLogPrefix() {
    return null;
  }

  @Override
  public void addBeanChange(BeanChange beanChange) {
    throw new IllegalStateException(notExpectedMessage);
  }

  @Override
  public void sendChangeLog(ChangeSet changesRequest) {
    throw new IllegalStateException(notExpectedMessage);
  }

  @Override
  public void register(TransactionCallback callback) {
    throw new IllegalStateException(notExpectedMessage);
  }

  @Override
  public int getDocStoreBatchSize() {
    return 0;
  }

  @Override
  public void setDocStoreBatchSize(int docStoreBatchSize) {
    throw new IllegalStateException(notExpectedMessage);
  }

  @Override
  public DocStoreMode getDocStoreMode() {
    return null;
  }

  @Override
  public void setDocStoreMode(DocStoreMode docStoreMode) {
    throw new IllegalStateException(notExpectedMessage);
  }

  @Override
  public void registerDeferred(PersistDeferredRelationship derived) {
    throw new IllegalStateException(notExpectedMessage);
  }

  @Override
  public void registerDeleteBean(Integer persistingBean) {
    throw new IllegalStateException(notExpectedMessage);
  }

  /**
   * Return true if this is a bean that has already been saved/deleted.
   */
  @Override
  public boolean isRegisteredDeleteBean(Integer persistingBean) {
    return false;
  }

  @Override
  public void unregisterBeans() {
    throw new IllegalStateException(notExpectedMessage);
  }

  /**
   * Return true if this is a bean that has already been saved. This will
   * register the bean if it is not already.
   */
  @Override
  public boolean isRegisteredBean(Object bean) {
    return false;
  }

  @Override
  public boolean isSaveAssocManyIntersection(String intersectionTable, String beanName) {
    throw new IllegalStateException(notExpectedMessage);
  }

  @Override
  public void depth(int diff) {
  }

  /**
   * Return the current depth.
   */
  @Override
  public int depth() {
    return 0;
  }

  @Override
  public void markNotQueryOnly() {
  }

  @Override
  public boolean isNestedUseSavepoint() {
    return false;
  }

  @Override
  public void setNestedUseSavepoint() {

  }

  @Override
  public boolean isReadOnly() {
    if (!isActive()) {
      throw new IllegalStateException(illegalStateMessage);
    }
    try {
      return connection.isReadOnly();
    } catch (SQLException e) {
      throw new PersistenceException(e);
    }
  }

  @Override
  public void setReadOnly(boolean readOnly) {
    if (!isActive()) {
      throw new IllegalStateException(illegalStateMessage);
    }
    try {
      connection.setReadOnly(readOnly);
    } catch (SQLException e) {
      throw new PersistenceException(e);
    }
  }

  @Override
  public void setUpdateAllLoadedProperties(boolean updateAllLoadedProperties) {
  }

  @Override
  public Boolean isUpdateAllLoadedProperties() {
    return null;
  }

  @Override
  public void setBatchMode(boolean batchMode) {
  }

  @Override
  public boolean isBatchMode() {
    return false;
  }

  @Override
  public boolean isBatchOnCascade() {
    return false;
  }

  @Override
  public void setBatchOnCascade(boolean batchMode) {
  }

  @Override
  public Boolean getBatchGetGeneratedKeys() {
    return null;
  }

  @Override
  public void setGetGeneratedKeys(boolean getGeneratedKeys) {
  }

  @Override
  public void setFlushOnMixed(boolean batchFlushOnMixed) {
  }

  /**
   * Return the batchSize specifically set for this transaction or 0.
   * <p>
   * Returning 0 implies to use the system wide default batch size.
   * </p>
   */
  @Override
  public int getBatchSize() {
    return 0;
  }

  @Override
  public void setBatchSize(int batchSize) {
  }

  @Override
  public boolean isFlushOnQuery() {
    return false;
  }

  @Override
  public void setFlushOnQuery(boolean batchFlushOnQuery) {
  }

  /**
   * Return true if this request should be batched. Returning false means that
   * this request should be executed immediately.
   */
  @Override
  public boolean isBatchThisRequest() {
    return false;
  }

  @Override
  public void checkBatchEscalationOnCollection() {
  }

  @Override
  public void flushBatchOnCollection() {
  }

  @Override
  public PersistenceException translate(String message, SQLException cause) {
    return new PersistenceException(message, cause);
  }

  /**
   * Flush after completing persist cascade.
   */
  @Override
  public void flushBatchOnCascade() {
  }

  @Override
  public void flushBatchOnRollback() {
  }

  @Override
  public boolean checkBatchEscalationOnCascade(PersistRequestBean<?> request) {
    return false;
  }

  @Override
  public BatchControl getBatchControl() {
    return null;
  }

  /**
   * Set the BatchControl to the transaction. This is done once per transaction
   * on the first persist request.
   */
  @Override
  public void setBatchControl(BatchControl batchControl) {
  }

  /**
   * Flush any queued persist requests.
   * <p>
   * This is general will result in a number of batched PreparedStatements
   * executing.
   * </p>
   */
  @Override
  public void flush() {
  }

  @Override
  public void flushBatch() {
    flush();
  }

  /**
   * Return the persistence context associated with this transaction.
   */
  @Override
  public PersistenceContext getPersistenceContext() {
    return persistenceContext;
  }

  /**
   * Set the persistence context to this transaction.
   * <p>
   * This could be considered similar to EJB3 Extended PersistanceContext. In
   * that you get the PersistanceContext from a transaction, hold onto it, and
   * then set it back later to a second transaction.
   * </p>
   */
  @Override
  public void setPersistenceContext(PersistenceContext context) {
    if (!isActive()) {
      throw new IllegalStateException(illegalStateMessage);
    }
    this.persistenceContext = context;
  }

  @Override
  public TransactionEvent getEvent() {
    throw new IllegalStateException(notExpectedMessage);
  }

  /**
   * Return true if this was an explicitly created transaction.
   */
  @Override
  public boolean isExplicit() {
    return false;
  }

  @Override
  public boolean isLogSql() {
    return logSql;
  }

  @Override
  public boolean isLogSummary() {
    return logSummary;
  }

  @Override
  public void logSql(String msg) {
    manager.log().sql().debug(msg);
  }

  @Override
  public void logSummary(String msg) {
    manager.log().sum().debug(msg);
  }

  /**
   * Return the transaction id.
   */
  @Override
  public String getId() {
    return null;
  }

  @Override
  public void setTenantId(Object tenantId) {
    this.tenantId = tenantId;
  }

  @Override
  public Object getTenantId() {
    return tenantId;
  }

  /**
   * Return the underlying connection for internal use.
   */
  @Override
  public Connection getInternalConnection() {
    if (!isActive()) {
      throw new IllegalStateException(illegalStateMessage);
    }
    return connection;
  }

  /**
   * Return the underlying connection for public use.
   */
  @Override
  public Connection getConnection() {
    return getInternalConnection();
  }

  private void deactivate() {
    try {
      connection.close();
    } catch (Exception ex) {
      // the connection pool will automatically remove the
      // connection if it does not pass the test
      logger.error("Error closing connection", ex);
    }
    connection = null;
    active = false;
    manager.collectMetricReadOnly((System.nanoTime() - startNanos) / 1000L);
  }

  /**
   * Perform a commit, fire callbacks and notify l2 cache etc.
   * <p>
   * This leaves the transaction active and expects another commit
   * to occur later (which closes the underlying connection etc).
   * </p>
   */
  @Override
  public void commitAndContinue() {
    // do nothing, expect AutoCommit
  }

  /**
   * Commit the transaction.
   */
  @Override
  public void commit() {
    if (!isActive()) {
      throw new IllegalStateException(illegalStateMessage);
    }
    // expect AutoCommit so just deactivate / put back into pool
    deactivate();
  }

  /**
   * Return true if the transaction is marked as rollback only.
   */
  @Override
  public boolean isRollbackOnly() {
    return false;
  }

  /**
   * Mark the transaction as rollback only.
   */
  @Override
  public void setRollbackOnly() {
    // expect AutoCommit so we can't really support rollbackOnly
    throw new IllegalStateException(notExpectedMessage);
  }

  /**
   * Rollback the transaction.
   */
  @Override
  public void rollback() throws PersistenceException {
    rollback(null);
  }

  /**
   * Rollback the transaction. If there is a throwable it is logged as the cause
   * in the transaction log.
   */
  @Override
  public void rollback(Throwable cause) throws PersistenceException {
    if (!isActive()) {
      throw new IllegalStateException(illegalStateMessage);
    }
    // expect AutoCommit so it really has already committed
    deactivate();
  }

  /**
   * If the transaction is active then perform rollback.
   */
  @Override
  public void end() throws PersistenceException {
    if (isActive()) {
      rollback();
    }
  }

  /**
   * Return true if the transaction is active.
   */
  @Override
  public boolean isActive() {
    return active;
  }

  @Override
  public boolean isPersistCascade() {
    return false;
  }

  @Override
  public void setPersistCascade(boolean persistCascade) {
  }

  @Override
  public void addModification(String tableName, boolean inserts, boolean updates, boolean deletes) {
    throw new IllegalStateException(notExpectedMessage);
  }

  @Override
  public DocStoreTransaction getDocStoreTransaction() {
    throw new IllegalStateException(notExpectedMessage);
  }

  @Override
  public void putUserObject(String name, Object value) {
    if (userObjects == null) {
      userObjects = new HashMap<>();
    }
    userObjects.put(name, value);
  }

  @Override
  public Object getUserObject(String name) {
    if (userObjects == null) {
      return null;
    }
    return userObjects.get(name);
  }

  /**
   * Alias for end(), which enables this class to be used in try-with-resources.
   */
  @Override
  public void close() {
    end();
  }
}