/*
 * This file is part of ELKI:
 * Environment for Developing KDD-Applications Supported by Index-Structures
 *
 * Copyright (C) 2022
 * ELKI Development Team
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package elki.gui.multistep.panels;

import java.lang.ref.WeakReference;

import elki.database.Database;
import elki.utilities.exceptions.AbortException;
import elki.utilities.optionhandling.parameterization.Parameterization;
import elki.workflow.OutputStep;

/**
 * Panel to handle result output / visualization
 *
 * @author Erich Schubert
 * @since 0.4.0
 */
public class OutputTabPanel extends ParameterTabPanel {
  /**
   * Serial version.
   */
  private static final long serialVersionUID = 1L;

  /**
   * The data input configured
   */
  private OutputStep outs = null;

  /**
   * Result we ran last on
   */
  private WeakReference<?> basedOnResult = null;

  /**
   * Input step to run on.
   */
  private final InputTabPanel input;

  /**
   * Algorithm step to run on.
   */
  private final EvaluationTabPanel evals;

  /**
   * Constructor. We depend on an input panel.
   *
   * @param input Input panel to depend on.
   */
  public OutputTabPanel(InputTabPanel input, EvaluationTabPanel evals) {
    super();
    this.input = input;
    this.evals = evals;
    input.addPanelListener(this);
    evals.addPanelListener(this);
  }

  @Override
  protected synchronized void configureStep(Parameterization config) {
    outs = config.tryInstantiate(OutputStep.class);
    if(config.getErrors().size() > 0) {
      outs = null;
    }
    basedOnResult = null;
  }

  @Override
  protected void executeStep() {
    if(input.canRun() && !input.isComplete()) {
      input.execute();
    }
    if(evals.canRun() && !evals.isComplete()) {
      evals.execute();
    }
    if(!input.isComplete()) {
      throw new AbortException("Input data not available.");
    }
    if(!evals.isComplete()) {
      throw new AbortException("Evaluation failed.");
    }
    // Get the database and run the algorithms
    Database database = input.getInputStep().getDatabase();
    outs.runResultHandlers(database);
    Object eres = evals.getEvaluationStep().getResult();
    basedOnResult = new WeakReference<Object>(eres);
  }

  @Override
  protected Status getStatus() {
    if(outs == null) {
      return Status.STATUS_UNCONFIGURED;
    }
    if(!input.canRun() || !evals.canRun()) {
      return Status.STATUS_CONFIGURED;
    }
    checkDependencies();
    if(input.isComplete() && evals.isComplete() && basedOnResult != null) {
      // TODO: is there a FAILED state here, too?
      return Status.STATUS_COMPLETE;
    }
    return Status.STATUS_READY;
  }

  @Override
  public void panelUpdated(ParameterTabPanel o) {
    if(o == input || o == evals) {
      checkDependencies();
      updateStatus();
    }
  }

  /**
   * Test if the dependencies are still valid.
   */
  private void checkDependencies() {
    if(basedOnResult != null) {
      if(!input.isComplete() || !evals.isComplete() || basedOnResult.get() != evals.getEvaluationStep().getResult()) {
        // We've become invalidated, notify.
        basedOnResult = null;
        firePanelUpdated();
      }
    }
  }
}
