/**
 ********************************************************************************
 * Copyright (c) 2020-2022 Robert Bosch GmbH.
 *
 * This program and the accompanying materials are made
 * available under the terms of the Eclipse Public License 2.0
 * which is available at https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     Robert Bosch GmbH - initial API and implementation
 *******************************************************************************/

package org.eclipse.app4mc.amalthea.visualization.hw;

import java.io.BufferedWriter;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;

import javax.inject.Named;

import org.eclipse.app4mc.amalthea.model.HWModel;
import org.eclipse.app4mc.amalthea.model.HwStructure;
import org.eclipse.app4mc.amalthea.visualization.hw.templates.HWBlockDiagramCreator;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.NullProgressMonitor;
import org.eclipse.core.runtime.Status;
import org.eclipse.core.runtime.jobs.IJobChangeListener;
import org.eclipse.core.runtime.jobs.Job;
import org.eclipse.e4.core.di.annotations.Execute;
import org.eclipse.e4.core.di.annotations.Optional;
import org.eclipse.e4.core.di.extensions.Preference;
import org.eclipse.e4.ui.di.UISynchronize;
import org.eclipse.e4.ui.services.IServiceConstants;
import org.eclipse.emf.ecore.EObject;
import org.eclipse.jface.dialogs.MessageDialog;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.swt.widgets.Shell;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import net.sourceforge.plantuml.FileFormat;
import net.sourceforge.plantuml.FileFormatOption;
import net.sourceforge.plantuml.SourceStringReader;
import net.sourceforge.plantuml.core.DiagramDescription;
import net.sourceforge.plantuml.eclipse.utils.PlantumlConstants;

public class VisualizationHandler {

	private static final String SYSTEM_PROPERTY = "SystemProperty";
	private static final String PLANT_UML_PREFERENCE = "PlantUMLPreference";
	private static final String PROPERTY_GRAPHVIZ_DOT = "GRAPHVIZ_DOT";
	private static final Logger LOGGER = LoggerFactory.getLogger(VisualizationHandler.class);

	@Execute
	public void execute(
			Shell shell,
			UISynchronize sync,
			@Optional
			@Preference(
					nodePath = "net.sourceforge.plantuml.eclipse",
					value = PlantumlConstants.GRAPHVIZ_PATH)
			String dotPath,
			@Named(IServiceConstants.ACTIVE_SELECTION) IStructuredSelection selection) {

		// **** Check selection and set HW model

		if (selection.isEmpty()) {
			LOGGER.info("No EObject selected!");
			return;
		}

		if (selection.getFirstElement() instanceof EObject) {
			EObject eObject = ((EObject) selection.getFirstElement());

			DiagramLocation diagramLocation = new DiagramLocation(eObject);
			if (!diagramLocation.isValid()) return;

			// Execute job
			List<HwStructure> structures = new ArrayList<>();

			if (eObject instanceof HWModel) {
				structures.addAll(((HWModel) eObject).getStructures());
			} else if (eObject instanceof HwStructure) {
				structures.add((HwStructure) eObject);
			}

			execute(shell, sync, dotPath, structures, diagramLocation, true, null);
		}

	}

	/**
	 *
	 * @param shell The active Shell needed for info/error dialog creation.
	 * @param dotPathFromPlantUMLPreferencePage The path to Graphviz dot.exe needed for visualization.
	 * @param hwModel The {@link HWModel} that should be visualized.
	 * @param listener optional listener that is notified on diagram generation job changes.
	 * @return The path to the SVG.
	 */
	public void execute(
			Shell shell,
			UISynchronize sync,
			String dotPathFromPlantUMLPreferencePage,
			List<HwStructure> structures,
			DiagramLocation diagramLocation,
			boolean showSuccessInfo,
			IJobChangeListener listener) {

		// **** Check dot path and set GRAPHVIZ_DOT property

		String dotPathFromSystemProperty = System.getenv(PROPERTY_GRAPHVIZ_DOT);

		File dotFile = null;

		if (dotPathFromPlantUMLPreferencePage != null) {
			dotFile = ensureValidDotFile(shell, sync, dotPathFromPlantUMLPreferencePage, PLANT_UML_PREFERENCE);
		} else if (dotPathFromSystemProperty != null) {
			dotFile = ensureValidDotFile(shell, sync, dotPathFromSystemProperty, SYSTEM_PROPERTY);
		} else {
			showErrorDialog(shell, sync, "Missing Graphviz dot.exe location."
					+ "\nPlease specify location via Window - Preferences - PlantUML - Path to the dot executable of Graphviz.");
		}

		if (dotFile == null)
			return;

		System.setProperty(PROPERTY_GRAPHVIZ_DOT, dotFile.getAbsolutePath());

		LOGGER.info("GRAPHVIZ_DOT: {}", System.getProperty(PROPERTY_GRAPHVIZ_DOT));

		// **** Generate Plant-UML file

		Job job = Job.create("Generate diagram", monitor -> {

			ModelToTextResult umlOutput = HWBlockDiagramCreator.generatePlantUML(structures);
			if (umlOutput.error()) {
				showErrorDialog(shell, sync, "Errors on generating HW Visualization for selected AMALTHEA model file: " + umlOutput.getErrorMessage());
				return Status.CANCEL_STATUS;
			}

			// **** Write to UML to file

			try (BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(diagramLocation.getPlantUmlFilePath()))) {
				bufferedWriter.write(umlOutput.getOutput().toString());
			} catch (IOException e) {
				return Status.CANCEL_STATUS;
			}

			LOGGER.info("{} created: {}", diagramLocation.getPlantUmlFileName(), umlOutput.getOutput());

			// **** Render SVG output

			try (ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
					FileOutputStream fileStream = new FileOutputStream(diagramLocation.getDiagramFilePath())) {

				SourceStringReader reader = new SourceStringReader(umlOutput.getOutput().toString());
				DiagramDescription description = reader.outputImage(outputStream, new FileFormatOption(FileFormat.SVG));

				byte[] svgBytes = outputStream.toByteArray();
				String svgString = new String(svgBytes, StandardCharsets.UTF_8);

				fileStream.write(svgBytes);
				fileStream.flush();

				if (description == null || svgString.contains("An error has occured")) {
					showErrorDialog(shell, sync, "SVG rendering failed."
							+ "\nCheck Graphviz dot.exe location via Window - Preferences - PlantUML - Path to the dot executable of Graphviz..");
					return Status.CANCEL_STATUS;
				}

				LOGGER.info("{} created.", diagramLocation.getDiagramFileName());

				if (showSuccessInfo) {
					showInfoDialog(shell, sync, "Successfully generated HW Visualization for amalthea model file.");
				}
			} catch (Exception e) {
				showErrorDialog(shell, sync, "Unable to generate HW Visualization for selected AMALTHEA model file.");
				LOGGER.error("Unable to generate HW Visualization for selected AMALTHEA model file.", e);
			} finally {
				try {
					diagramLocation.getDiagramFolder().refreshLocal(1, new NullProgressMonitor());
				} catch (CoreException ex) {
					// no action required
				}
			}

			return Status.OK_STATUS;
		});

		if (listener != null) {
			job.addJobChangeListener(listener);
		}

		job.schedule();
	}

	private File ensureValidDotFile(Shell shell, UISynchronize sync, String dotPath, String origin) {


		if (dotPath == null || dotPath.equals("")) {
			showErrorDialog(shell, sync, "Missing Graphviz dot.exe location."
						+ "\nPlease specify location via Window - Preferences - PlantUML - Path to the dot executable of Graphviz.");
			return null;
		}

		final File dotFile = new File(dotPath);
		if (!dotFile.canExecute()) {

			if (origin.equals(PLANT_UML_PREFERENCE)) {
				showErrorDialog(shell, sync, "Invalid Graphviz dot.exe location: \'" + dotFile.getAbsolutePath()+"\'"
				+ "\nPlease set location via Window - Preferences - PlantUML - Path to the 'dot executable of Graphviz'.");
			} else {
				showErrorDialog(shell, sync, "Invalid Graphviz dot.exe location found in System Property 'GRAPHVIZ_DOT' : \'" + dotFile.getAbsolutePath()+"\'"
				+ "\nPlease update the System Property 'GRAPHVIZ_DOT' with valid Path to the 'dot executable of Graphviz'.");
			}
			return null;
		}

		return dotFile;
	}

	private void showInfoDialog(Shell shell, UISynchronize sync, String message) {
		sync.asyncExec(() ->
			MessageDialog.openInformation(shell, "AMALTHEA HW Visualization", message)
		);
	}

	private void showErrorDialog(Shell shell, UISynchronize sync, String message) {
		sync.asyncExec(() ->
			MessageDialog.openError(shell, "AMALTHEA HW Visualization", message)
		);
	}

}