package de.thm.tlf.photoViewer;

import de.thm.tlf.photoViewer.data.PicturePreview;
import javafx.application.Application;
import javafx.application.Platform;
import javafx.beans.binding.Bindings;
import javafx.beans.property.DoubleProperty;
import javafx.beans.property.SimpleDoubleProperty;
import javafx.concurrent.Task;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.geometry.Orientation;
import javafx.geometry.Pos;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyCodeCombination;
import javafx.scene.input.KeyCombination;
import javafx.scene.layout.*;
import javafx.stage.FileChooser;
import javafx.stage.Stage;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.List;

/**
 * Controller Class for Image-viewer.
 * Holds GUI elements as well as the handling of any user input.
 *
 * @author Tim Lukas Förster
 * @version 1.0
 * repository: https://gitlab.com/n0x_io/PhotoViewer
 */
public class PVController extends Application {
    ////////////////////////////
    //------ Attributes ------//
    ////////////////////////////

    // Constants //
    private static final String ARROWPREV = "icons/left-arrow.png";
    private static final String ARROWNEXT = "icons/right-arrow.png";

    // CENTER //
    private final ScrollPane currentViewSP = new ScrollPane();
    private final ImageView centerImageView = new ImageView();

    // TOP //
    private final VBox menu = new VBox();
    private final MenuBar menuBar = new MenuBar();
    private final Menu fileMenu = new Menu("File");
    private final Menu aboutMenu = new Menu("About");
    private final MenuItem menuItemOpenFiles = new MenuItem("Open");
    private final MenuItem menuItemClearViewer = new Menu("Close all pictures");
    private final MenuItem menuItemStartSlideShow = new MenuItem("Start Slide Show");
    private final MenuItem menuItemExitViewer = new Menu("Exit");
    private final MenuItem menuItemShowInfo = new Menu("Information");

    // BOTTOM //
    private final VBox bottomPanel = new VBox();

    //private final HBox selectionPane = new HBox();
    private final ListView<ImageView> previewPane = new ListView<>();
    private final VBox pictureSelector = new VBox();

    private final BorderPane bottomLowerPanel = new BorderPane();
    private final HBox bottomLeft = new HBox();
    private final HBox bottomMid = new HBox();
    private final HBox bottomRight = new HBox();

    private final Button openFilesButton = new Button("Open Pictures");
    private Slider zoomSlider;
    private Slider slideShowSpeedSlider;

    private final Button prevPicBtn = new Button("<-");
    private final Button nextPicBtn = new Button("->");
    private final Button slideShowBtn = new Button("Slide Show");

    private final Button fullScreenBtn = new Button("Fullscreen");

    // Picture handling //
    private PictureHandler picHandler;

    // Etc. //
    private Thread slideShowThread;
    private boolean bIsFullScreen = false;
    private boolean bSlideShowActive = false;
    private final DoubleProperty slideShowSpeed = new SimpleDoubleProperty(4);
    private final DoubleProperty zoomProperty = new SimpleDoubleProperty(200);

    // Key Combinations & Shortcuts //
    private final KeyCombination keyCrtlQ = new KeyCodeCombination(KeyCode.Q, KeyCombination.CONTROL_ANY);
    ////////////////////////////////
    //------ End Attributes ------//
    ////////////////////////////////


    /////////////////////////
    //------ Methods ------//
    /////////////////////////
    /**
     * Entrypoint to program
     * @param args String-Array supplied when starting the application
     */
    public static void main(String[] args) {
        launch(args);
    }

    /**
     * Method initializing GUI
     * @param primaryStage Default stage supplied when GUI is created
     */
    @Override
    public void start(Stage primaryStage) {
        picHandler = PictureHandler.getInstance();

        BorderPane root = new BorderPane();
        root.setCenter(createCenter());
        root.setTop(createTop());
        root.setBottom(createBottom());
        Scene mainScene = new Scene(root, 1200, 800);

        // Create all Actions //
        createSliderActions();
        createMenuActions(primaryStage);
        createClickActions(primaryStage);

        // Keypress Actions //
        mainScene.setOnKeyPressed(event -> {

            if (keyCrtlQ.match(event)) {
                Platform.exit();
            }
            else{
                switch (event.getCode()) {
                    case RIGHT:
                    case A:
                        try {
                            centerImageView.setImage(picHandler.getPrevPicture().getImage());
                        } catch (NoPicturesLoadedException npl) {
                            showNoPicturesLoadedWarning();
                        }
                        break;
                    case LEFT:
                    case D:
                        try {
                            centerImageView.setImage(picHandler.getNextPicture().getImage());
                        } catch (NoPicturesLoadedException npl) {
                            showNoPicturesLoadedWarning();
                        }
                        break;
                }
            }
        });

        primaryStage.setTitle("Photo Viewer");
        primaryStage.setScene(mainScene);
        primaryStage.show();
    }

    /**
     * Task used to run the slideshow in separate Threat.
     */
    @SuppressWarnings("rawtypes")
    private final Task slideShowTask = new Task<Void>(){
        @Override
        @SuppressWarnings("BusyWait")
        protected Void call() throws Exception {
            while(bSlideShowActive) {
                Thread.sleep((long)(slideShowSpeed.get()*1000));
                centerImageView.setImage(picHandler.getNextPicture().getImage());
            }
            return null;
        }
    };

    /**
     * Even wrapper for openFileDialogEvent
     * @param stage the primary stage, used to display the file-open-dialog
     * @return EventHandler for dialog handling
     */
    private EventHandler<ActionEvent> openFileDialogEvent(Stage stage) {
        return e -> openFileDialog(stage);
    }

    /**
     * Event wrapper for clear function
     * @return EventHandle executing the clearPreviewView function
     */
    private EventHandler<ActionEvent> clearPreviewViewEvent(){
        return e -> clearViewer();
    }

    /**
     * Event wrapper for showAboutDialog function
     * @return EventHandle executing the showAboutDialog function
     */
    private EventHandler<ActionEvent> showAboutDialogEvent(){
        return e -> showAboutDialog();
    }

    /**
     * Event wrapper for showAboutDialog function
     * @return EventHandle executing the showAboutDialog function
     */
    private EventHandler<ActionEvent> toggleSlidesHowEvent(){
        return e -> toggleSlideShow();
    }

    ////////////////////////////////
    //------ Helper-Methods ------//
    ////////////////////////////////
    /**
     * Helper method for handling sliders
     */
    private void createSliderActions() {
        //TODO: Zoom kinda wonky... should be redone.
        // Zoom Action //
        zoomProperty.addListener(observable -> {
            centerImageView.setFitWidth(zoomProperty.get() * 4);
            centerImageView.setFitHeight(zoomProperty.get() * 3);
        });

        zoomSlider.valueProperty().addListener((observableValue, oldVal, newVal) -> {
            if (oldVal.doubleValue() < newVal.doubleValue()){
                zoomProperty.set(zoomProperty.get() + 10);
            }
            else if (oldVal.doubleValue() > newVal.doubleValue()){
                zoomProperty.set(zoomProperty.get() - 10);
            }
        });

        // SlideShowSpeed Action //
        slideShowSpeed.addListener(observable -> {});
        slideShowSpeedSlider.valueProperty().addListener((observableValue, oldVal, newVal) -> slideShowSpeed.set((double)newVal));
    }

    /**
     * Helper method for handling menus and -entries
     * @param stage the primary stage, used to display the file-open-dialog
     */
    private void createMenuActions(Stage stage) {
        menuItemOpenFiles.setOnAction(openFileDialogEvent(stage));
        menuItemExitViewer.setOnAction(e -> Platform.exit());
        menuItemClearViewer.setOnAction(clearPreviewViewEvent());
        menuItemStartSlideShow.setOnAction(toggleSlidesHowEvent());
        menuItemShowInfo.setOnAction(showAboutDialogEvent());
    }

    /**
     * Helper method for handling button interaction
     * @param stage the primary stage, used to display the file-open-dialog and control fullscreen functions
     */
    private void createClickActions(Stage stage) {
        // Opens the File dialog
        openFilesButton.setOnAction(openFileDialogEvent(stage));

        // Displays the previous Picture
        prevPicBtn.setOnAction(e -> {
            try{
                centerImageView.setImage(picHandler.getPrevPicture().getImage());
            }
            catch (NoPicturesLoadedException npl){ showNoPicturesLoadedWarning();}
        });

        // Displays the next picture
        nextPicBtn.setOnAction(e -> {
            try{
                centerImageView.setImage(picHandler.getNextPicture().getImage());
            }
            catch (NoPicturesLoadedException npl){ showNoPicturesLoadedWarning();}
        });

        // Sets the PictureViewer to fullscreen
        fullScreenBtn.setOnAction(e -> {
            stage.setFullScreen(!bIsFullScreen);
            bIsFullScreen ^= true;
        });

        // Starts the slideshow on first click, stops it on the next one
        slideShowBtn.setOnAction(toggleSlidesHowEvent());

        // Clicking on any picture in the Previews opens said picture in the main view
        previewPane.setOnMouseClicked(e -> {
            try {
                centerImageView.setImage(picHandler.getPictureByID(previewPane.getSelectionModel().getSelectedIndex()).getImage());
            } catch (NoPicturesLoadedException ignored) {

            }
        });
    }

    /**
     * Method that will start and stop (toggle) the Slide show and set the corresponding texts to all buttons etc.
     */
    private void toggleSlideShow(){
        try {
            if (!bSlideShowActive) {
                // This statement is to catch any errors regarding no images loaded
                centerImageView.setImage(picHandler.getNextPicture().getImage());
                bSlideShowActive = true;
                slideShowThread = new Thread(slideShowTask);
                slideShowThread.start();
                // Change text of slideshow switches
                slideShowBtn.setText("Stop Slide Show");
                menuItemStartSlideShow.setText("Stop Slide Show");
            } else {
                bSlideShowActive = false;
                // Change text of slideshow switches
                slideShowBtn.setText("Slide Show");
                menuItemStartSlideShow.setText("Start Slide Show");
                assert slideShowThread != null;
                    slideShowThread.interrupt();
            }
        } catch (NoPicturesLoadedException npl){
            showNoPicturesLoadedWarning();
        }
    }

    /**
     * Open file-dialog allowing to select multiple pictures (via filter),
     * adds them to the PictureHandler and updates the picture preview
     * @param stage the primary stage, used to display the file-open-dialog
     */
    private void openFileDialog(Stage stage) {
        FileChooser fileChooser = new FileChooser();
        fileChooser.setTitle("Open Pictures");
        fileChooser.getExtensionFilters().addAll(
                new FileChooser.ExtensionFilter("Image Files", "*.png", "*.jpg", "*.gif"));
        List<File> selectedPictures = fileChooser.showOpenMultipleDialog(stage);
        if (selectedPictures != null) {
            try {
                picHandler.loadPictures(selectedPictures);
                PVController.this.updatePreviewView();
                centerImageView.setImage(picHandler.getNextPicture().getImage());
            } catch (NoPicturesLoadedException npl) {
                showNoPicturesLoadedWarning();
            }
        }
    }

    /**
     * Method that updates the preview Pane with all PreviewPictures provided by the Picture Handler
     */
    private void updatePreviewView(){
        clearViewer();
        //previewPane.setPadding(new Insets(5,5,5,5));
        for(PicturePreview pp: picHandler.getPreviews()){
            ImageView iv = new ImageView(pp.getImage());
            iv.setFitWidth(150);
            iv.setFitHeight(150);
            iv.setSmooth(true);
            iv.setPreserveRatio(true);
            previewPane.getItems().add(iv);
        }
    }

    /**
     * Used to clear the preview and center panel
     */
    private void clearViewer(){
        previewPane.getItems().clear();
        //previewPane.setPadding(new Insets(5,5,5,5));
        centerImageView.setImage(null);
    }

    /**
     * Show a dialogue displaying copyright information about the program.
     */
    private void showAboutDialog(){
        Dialog<String> aboutDialog = new Dialog<>();
        aboutDialog.setTitle("About this program");
        ButtonType btnType = new ButtonType("Ok", ButtonBar.ButtonData.OK_DONE);
        aboutDialog.setContentText("""
                Created by Tim Lukas Förster
                
                Icons made by www.flaticon.com/authors/roundicons 
                for www.flaticon.com""");

        //Adding buttons to the aboutDialog pane
        aboutDialog.getDialogPane().getButtonTypes().add(btnType);
        aboutDialog.show();
    }

    /**
     * Displays a warning dialogue informing the user that no pictures has been loaded yet
     * and the executed action is not possible.
     */
    private void showNoPicturesLoadedWarning(){
        Alert alert = new Alert(Alert.AlertType.WARNING);
        alert.setTitle("No pictures loaded");
        alert.setContentText("No pictures have been loaded" +
                "\nPlease select pictures via the menu or via the open button to view them.");
        alert.showAndWait().ifPresent(rs -> {
        });
    }

    /**
     * Method that handles the settings and layout of the top Panel
     * @return Node, set up for displaying on the top of a GridPane
     */
    private Node createTop(){
        SeparatorMenuItem sep = new SeparatorMenuItem();
        // File Menu
        fileMenu.getItems().addAll(menuItemOpenFiles, menuItemClearViewer, sep, menuItemStartSlideShow, menuItemExitViewer);
        // About Menu
        aboutMenu.getItems().addAll(menuItemShowInfo);
        // Menu bar
        menuBar.getMenus().addAll(fileMenu, aboutMenu);
        // Adding Menus to Top Panel
        menu.getChildren().addAll(menuBar);
        return menu;
    }

    /**
     * Method that handles the settings and layout of the center Panel
     * @return Node, set up for displaying on the center of a GridPane
     */
    private Node createCenter(){
        // Use stack pane and magic to center the image on screen
        StackPane imageHolder = new StackPane(centerImageView);
        GridPane grid = new GridPane();
        currentViewSP.setContent(imageHolder);

        imageHolder.minWidthProperty().bind(Bindings.createDoubleBinding(() ->
                currentViewSP.getViewportBounds().getWidth(), currentViewSP.viewportBoundsProperty()));

        imageHolder.minHeightProperty().bind(Bindings.createDoubleBinding(() ->
                currentViewSP.getViewportBounds().getHeight(), currentViewSP.viewportBoundsProperty()));

        grid.getChildren().add(imageHolder);

        centerImageView.setX(10);
        centerImageView.setY(10);
        centerImageView.setPreserveRatio(true);
        return currentViewSP;
    }

    /**
     * Method that handles the settings and layout of the bottom Panel
     * @return Node, set up for displaying on the bottom of a GridPane
     */
    private Node createBottom() {
        bottomLowerPanel.setPadding(new Insets(5, 5, 5, 5));

        // Left Bottom Part
        zoomSlider = new Slider(0, 100, 25);
        zoomSlider.setShowTickMarks(true);
        Label zoomLabel = new Label("Zoom:");
        bottomLeft.getChildren().addAll(openFilesButton, zoomLabel, zoomSlider);
        bottomLeft.setSpacing(5);
        bottomLowerPanel.setLeft(bottomLeft);

        // Middle Bottom Part
        try {
            // Set pictures as prev/next buttons
            ImageView prevPic = new ImageView(new Image(new FileInputStream(ARROWPREV)));
            prevPic.setFitHeight(10);
            prevPic.setPreserveRatio(true);
            prevPicBtn.setText(null);
            prevPicBtn.setGraphic(prevPic);

            ImageView nextPic = new ImageView(new Image(new FileInputStream(ARROWNEXT)));
            nextPic.setFitHeight(10);
            nextPic.setPreserveRatio(true);
            nextPicBtn.setText(null);
            nextPicBtn.setGraphic(nextPic);
        } catch (FileNotFoundException ignored){
            // fallback to text
            prevPicBtn.setGraphic(null);
            nextPicBtn.setGraphic(null);

            prevPicBtn.setText("<-");
            nextPicBtn.setText("->");
        }
        bottomMid.setAlignment(Pos.CENTER);
        bottomMid.setSpacing(5);
        bottomMid.getChildren().addAll(prevPicBtn, slideShowBtn, nextPicBtn);
        bottomLowerPanel.setCenter(bottomMid);

        // Right Bottom Part
        slideShowSpeedSlider = new Slider(0.5, 15, 4);
        slideShowSpeedSlider.setShowTickMarks(true);
        slideShowSpeedSlider.setShowTickLabels(true);
        Label sssLabel = new Label("Speed:");
        bottomRight.getChildren().addAll(sssLabel,slideShowSpeedSlider, fullScreenBtn);
        bottomLowerPanel.setRight(bottomRight);

        // Bottom upper Part -> Picture preview
        pictureSelector.setPadding(new Insets(2,2,2,2));
        previewPane.setOrientation(Orientation.HORIZONTAL);
        previewPane.setMaxHeight(150);
        //selectionPane.setSpacing(5);
        pictureSelector.getChildren().add(previewPane);

        bottomPanel.getChildren().addAll(pictureSelector, bottomLowerPanel);

        return (bottomPanel);
    }
    ////////////////////////////////////
    //------ End Helper-Methods ------//
    ////////////////////////////////////

    /////////////////////////////
    //------ End Methods ------//
    /////////////////////////////
}