package org.jabref.gui.mergeentries;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.function.Supplier;

import javafx.collections.FXCollections;
import javafx.collections.ListChangeListener;
import javafx.collections.MapChangeListener;
import javafx.fxml.FXML;
import javafx.scene.control.Button;
import javafx.scene.control.ButtonBar;
import javafx.scene.control.ButtonType;
import javafx.scene.control.ComboBox;
import javafx.scene.control.ContentDisplay;
import javafx.scene.control.Control;
import javafx.scene.control.Label;
import javafx.scene.control.ProgressIndicator;
import javafx.scene.control.ScrollPane;
import javafx.scene.control.TextArea;
import javafx.scene.control.TextField;
import javafx.scene.control.TextInputControl;
import javafx.scene.control.ToggleButton;
import javafx.scene.control.ToggleGroup;
import javafx.scene.control.Tooltip;
import javafx.scene.input.KeyEvent;
import javafx.scene.layout.ColumnConstraints;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Priority;
import javafx.scene.layout.Region;
import javafx.scene.layout.RowConstraints;
import javafx.scene.layout.VBox;
import javafx.scene.text.TextAlignment;

import org.jabref.gui.icon.IconTheme;
import org.jabref.gui.util.BaseDialog;
import org.jabref.gui.util.BindingsHelper;
import org.jabref.gui.util.DefaultTaskExecutor;
import org.jabref.gui.util.TaskExecutor;
import org.jabref.gui.util.ViewModelListCellFactory;
import org.jabref.logic.importer.FetcherException;
import org.jabref.logic.importer.fetcher.DoiFetcher;
import org.jabref.logic.l10n.Localization;
import org.jabref.model.entry.BibEntry;
import org.jabref.model.entry.field.Field;
import org.jabref.model.entry.field.FieldFactory;
import org.jabref.model.entry.field.StandardField;
import org.jabref.preferences.PreferencesService;

import com.airhacks.afterburner.views.ViewLoader;
import com.tobiasdiez.easybind.EasyBind;
import com.tobiasdiez.easybind.EasyObservableValue;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class MultiMergeEntriesView extends BaseDialog<BibEntry> {

    private static final Logger LOGGER = LoggerFactory.getLogger(MultiMergeEntriesView.class);

    // LEFT
    @FXML private ScrollPane leftScrollPane;
    @FXML private VBox fieldHeader;

    // CENTER
    @FXML private ScrollPane topScrollPane;
    @FXML private HBox supplierHeader;
    @FXML private ScrollPane centerScrollPane;
    @FXML private GridPane optionsGrid;

    // RIGHT
    @FXML private ScrollPane rightScrollPane;
    @FXML private VBox fieldEditor;

    @FXML private Label failedSuppliers;
    @FXML private ComboBox<DiffMode> diffMode;

    private final ToggleGroup headerToggleGroup = new ToggleGroup();
    private final HashMap<Field, FieldRow> fieldRows = new HashMap<>();

    private final MultiMergeEntriesViewModel viewModel;
    private final TaskExecutor taskExecutor;

    private final PreferencesService preferences;

    public MultiMergeEntriesView(PreferencesService preferences,
                                 TaskExecutor taskExecutor) {
        this.preferences = preferences;
        this.taskExecutor = taskExecutor;

        viewModel = new MultiMergeEntriesViewModel();

        ViewLoader.view(this)
                  .load()
                  .setAsDialogPane(this);

        ButtonType mergeEntries = new ButtonType(Localization.lang("Merge entries"), ButtonBar.ButtonData.OK_DONE);
        this.getDialogPane().getButtonTypes().setAll(ButtonType.CANCEL, mergeEntries);
        this.setResultConverter(viewModel::resultConverter);

        viewModel.entriesProperty().addListener((ListChangeListener<MultiMergeEntriesViewModel.EntrySource>) c -> {
            while (c.next()) {
                if (c.wasAdded()) {
                    for (MultiMergeEntriesViewModel.EntrySource entrySourceColumn : c.getAddedSubList()) {
                        addColumn(entrySourceColumn);
                    }
                }
            }
        });

        viewModel.mergedEntryProperty().get().getFieldsObservable().addListener((MapChangeListener<Field, String>) change -> {
            if (change.wasAdded() && !fieldRows.containsKey(change.getKey())) {
                FieldRow fieldRow = new FieldRow(
                        change.getKey(),
                        viewModel.mergedEntryProperty().get().getFields().size() - 1);
                fieldRows.put(change.getKey(), fieldRow);
            }
        });
    }

    @FXML
    public void initialize() {
        topScrollPane.hvalueProperty().bindBidirectional(centerScrollPane.hvalueProperty());
        leftScrollPane.vvalueProperty().bindBidirectional(centerScrollPane.vvalueProperty());
        rightScrollPane.vvalueProperty().bindBidirectional(centerScrollPane.vvalueProperty());

        viewModel.failedSuppliersProperty().addListener((obs, oldValue, newValue) ->
                failedSuppliers.setText(viewModel.failedSuppliersProperty().get().isEmpty() ? "" : Localization.lang(
                        "Could not extract Metadata from: %0",
                        String.join(", ", viewModel.failedSuppliersProperty())
                ))
        );

        fillDiffModes();
    }

    private void fillDiffModes() {
        diffMode.setItems(FXCollections.observableList(List.of(
                DiffMode.PLAIN,
                DiffMode.WORD,
                DiffMode.CHARACTER)));
        new ViewModelListCellFactory<DiffMode>()
                .withText(DiffMode::getDisplayText)
                .install(diffMode);
        diffMode.setValue(preferences.getGuiPreferences().getMergeDiffMode());
        EasyBind.subscribe(this.diffMode.valueProperty(), mode -> preferences.getGuiPreferences().setMergeDiffMode(mode));
    }

    private void addColumn(MultiMergeEntriesViewModel.EntrySource entrySourceColumn) {
        // add header
        int columnIndex = supplierHeader.getChildren().size();
        ToggleButton header = generateEntryHeader(entrySourceColumn, columnIndex);
        header.getStyleClass().add("toggle-button");
        HBox.setHgrow(header, Priority.ALWAYS);
        supplierHeader.getChildren().add(header);
        header.setMinWidth(250);

        // setup column constraints
        ColumnConstraints constraint = new ColumnConstraints();
        constraint.setMinWidth(Control.USE_PREF_SIZE);
        constraint.setMaxWidth(Control.USE_PREF_SIZE);
        constraint.prefWidthProperty().bind(header.widthProperty());
        optionsGrid.getColumnConstraints().add(constraint);

        if (!entrySourceColumn.isLoadingProperty().getValue()) {
            writeBibEntryToColumn(entrySourceColumn, columnIndex);
        } else {
            header.setDisable(true);
            entrySourceColumn.isLoadingProperty().addListener((observable, oldValue, newValue) -> {
                if (!newValue && entrySourceColumn.entryProperty().get() != null) {
                    writeBibEntryToColumn(entrySourceColumn, columnIndex);
                    header.setDisable(false);
                }
            });
        }
    }

    private ToggleButton generateEntryHeader(MultiMergeEntriesViewModel.EntrySource column, int columnIndex) {
        ToggleButton header = new ToggleButton();
        header.setToggleGroup(headerToggleGroup);
        header.textProperty().bind(column.titleProperty());
        setupSourceButtonAction(header, columnIndex);

        if (column.isLoadingProperty().getValue()) {
            ProgressIndicator progressIndicator = new ProgressIndicator(-1);
            progressIndicator.setPrefHeight(20);
            progressIndicator.setMinHeight(Control.USE_PREF_SIZE);
            progressIndicator.setMaxHeight(Control.USE_PREF_SIZE);
            header.setGraphic(progressIndicator);
            progressIndicator.visibleProperty().bind(column.isLoadingProperty());
        }

        column.isLoadingProperty().addListener((obs, oldValue, newValue) -> {
            if (!newValue) {
                header.setGraphic(null);
                if (column.entryProperty().get() == null) {
                    header.setMinWidth(0);
                    header.setMaxWidth(0);
                    header.setVisible(false);
                }
            }
        });

        return header;
    }

    /**
     * Adds ToggleButtons for all fields that are set for this BibEntry
     *
     * @param entrySourceColumn the entry to write
     * @param columnIndex       the index of the column to write this entry to
     */
    private void writeBibEntryToColumn(MultiMergeEntriesViewModel.EntrySource entrySourceColumn, int columnIndex) {
        for (Map.Entry<Field, String> entry : entrySourceColumn.entryProperty().get().getFieldsObservable().entrySet()) {
            Field key = entry.getKey();
            String value = entry.getValue();
            Cell cell = new Cell(value, key, columnIndex);
            optionsGrid.add(cell, columnIndex, fieldRows.get(key).rowIndex);
        }
    }

    /**
     * Set up the button that displays the name of the source so that if it is clicked, all toggles in that column are
     * selected.
     *
     * @param sourceButton the header button to setup
     * @param column       the column this button is heading
     */
    private void setupSourceButtonAction(ToggleButton sourceButton, int column) {
        sourceButton.selectedProperty().addListener((observable, oldValue, newValue) -> {
            if (newValue) {
                optionsGrid.getChildrenUnmodifiable().stream()
                           .filter(node -> GridPane.getColumnIndex(node) == column)
                           .filter(HBox.class::isInstance)
                           .forEach(hbox -> ((HBox) hbox).getChildrenUnmodifiable().stream()
                                                         .filter(ToggleButton.class::isInstance)
                                                         .forEach(toggleButton -> ((ToggleButton) toggleButton).setSelected(true)));
                sourceButton.setSelected(true);
            }
        });
    }

    /**
     * Checks if the Field can be multiline
     *
     * @param field the field to be checked
     * @return true if the field may be multiline, false otherwise
     */
    private boolean isMultilineField(Field field) {
        if (field.equals(StandardField.DOI)) {
            return false;
        }
        return FieldFactory.isMultiLineField(field, preferences.getFieldPreferences().getNonWrappableFields());
    }

    private class Cell extends HBox {

        private final String content;

        public Cell(String content, Field field, int columnIndex) {
            this.content = content;

            /*
            If this is not explicitly done on the JavaFX thread, the bindings to the text fields don't work properly.
            The text only shows up after one text in that same row is selected by the user.
             */
            DefaultTaskExecutor.runInJavaFXThread(() -> {

                FieldRow row = fieldRows.get(field);

                prefWidthProperty().bind(((Region) supplierHeader.getChildren().get(columnIndex)).widthProperty());
                setMinWidth(Control.USE_PREF_SIZE);
                setMaxWidth(Control.USE_PREF_SIZE);
                prefHeightProperty().bind(((Region) fieldEditor.getChildren().get(row.rowIndex)).heightProperty());
                setMinHeight(Control.USE_PREF_SIZE);
                setMaxHeight(Control.USE_PREF_SIZE);

                // Button
                ToggleButton cellButton = new ToggleButton();
                cellButton.prefHeightProperty().bind(heightProperty());
                cellButton.setMinHeight(Control.USE_PREF_SIZE);
                cellButton.setMaxHeight(Control.USE_PREF_SIZE);
                cellButton.setGraphicTextGap(0);
                getChildren().add(cellButton);
                cellButton.maxWidthProperty().bind(widthProperty());
                HBox.setHgrow(cellButton, Priority.ALWAYS);

                // Text
                DiffHighlightingEllipsingTextFlow buttonText = new DiffHighlightingEllipsingTextFlow(content, viewModel.mergedEntryProperty().get().getFieldBinding(field).asOrdinary(), diffMode.valueProperty());

                buttonText.maxWidthProperty().bind(widthProperty().add(-10));
                buttonText.maxHeightProperty().bind(heightProperty());
                cellButton.setGraphic(buttonText);
                cellButton.setContentDisplay(ContentDisplay.GRAPHIC_ONLY);
                cellButton.setContentDisplay(ContentDisplay.CENTER);

                // Tooltip
                Tooltip buttonTooltip = new Tooltip(content);
                buttonTooltip.setWrapText(true);
                buttonTooltip.prefWidthProperty().bind(widthProperty());
                buttonTooltip.setTextAlignment(TextAlignment.LEFT);
                cellButton.setTooltip(buttonTooltip);

                cellButton.setToggleGroup(row.toggleGroup);
                if (row.toggleGroup.getSelectedToggle() == null) {
                    cellButton.setSelected(true);
                }

                if (field.equals(StandardField.DOI)) {
                    Button doiButton = IconTheme.JabRefIcons.LOOKUP_IDENTIFIER.asButton();
                    HBox.setHgrow(doiButton, Priority.NEVER);
                    doiButton.prefHeightProperty().bind(cellButton.heightProperty());
                    doiButton.setMinHeight(Control.USE_PREF_SIZE);
                    doiButton.setMaxHeight(Control.USE_PREF_SIZE);

                    getChildren().add(doiButton);

                    doiButton.setOnAction(event -> {
                        DoiFetcher doiFetcher = new DoiFetcher(preferences.getImportFormatPreferences());
                        doiButton.setDisable(true);
                        addSource(Localization.lang("From DOI"), () -> {
                            try {
                                return doiFetcher.performSearchById(content).get();
                            } catch (FetcherException | NoSuchElementException e) {
                                LOGGER.warn("Failed to fetch BibEntry for DOI {}", content, e);
                                return null;
                            }
                        });
                    });
                }
            });
        }

        public String getContent() {
            return content;
        }
    }

    public void addSource(String title, BibEntry entry) {
        viewModel.addSource(new MultiMergeEntriesViewModel.EntrySource(title, entry));
    }

    public void addSource(String title, Supplier<BibEntry> supplier) {
        viewModel.addSource(new MultiMergeEntriesViewModel.EntrySource(title, supplier, taskExecutor));
    }

    private class FieldRow {

        public final ToggleGroup toggleGroup = new ToggleGroup();
        private final TextInputControl fieldEditorCell;

        private final int rowIndex;

        // Reference needs to be kept, since java garbage collection would otherwise destroy the subscription
        @SuppressWarnings("FieldCanBeLocal") private EasyObservableValue<String> fieldBinding;

        public FieldRow(Field field, int rowIndex) {
            this.rowIndex = rowIndex;

            // setup field editor column entry
            boolean isMultiLine = isMultilineField(field);
            if (isMultiLine) {
                fieldEditorCell = new TextArea();
                ((TextArea) fieldEditorCell).setWrapText(true);
            } else {
                fieldEditorCell = new TextField();
            }

            addRow(field);

            fieldEditorCell.addEventFilter(KeyEvent.KEY_PRESSED, event -> toggleGroup.selectToggle(null));

            toggleGroup.selectedToggleProperty().addListener((obs, oldValue, newValue) -> {
                if (newValue == null) {
                    viewModel.mergedEntryProperty().get().setField(field, "");
                } else {
                    viewModel.mergedEntryProperty().get().setField(field, ((DiffHighlightingEllipsingTextFlow) ((ToggleButton) newValue).getGraphic()).getFullText());
                    headerToggleGroup.selectToggle(null);
                }
            });
        }

        /**
         * Adds a row that represents this field
         *
         * @param field the field to add to the view as a new row in the table
         */
        private void addRow(Field field) {
            VBox.setVgrow(fieldEditorCell, Priority.ALWAYS);

            fieldBinding = viewModel.mergedEntryProperty().get().getFieldBinding(field).asOrdinary();
            BindingsHelper.bindBidirectional(
                    fieldEditorCell.textProperty(),
                    fieldBinding,
                    text -> {
                        if (text != null) {
                            fieldEditorCell.setText(text);
                        }
                    },
                    binding -> {
                        if (binding != null) {
                            viewModel.mergedEntryProperty().get().setField(field, binding);
                        }
                    });

            fieldEditorCell.setMaxHeight(Double.MAX_VALUE);
            VBox.setVgrow(fieldEditorCell, Priority.ALWAYS);
            fieldEditor.getChildren().add(fieldEditorCell);

            // setup header label
            Label fieldHeaderLabel = new Label(field.getDisplayName());
            fieldHeaderLabel.prefHeightProperty().bind(fieldEditorCell.heightProperty());
            fieldHeaderLabel.setMaxWidth(Control.USE_PREF_SIZE);
            fieldHeaderLabel.setMinWidth(Control.USE_PREF_SIZE);
            fieldHeader.getChildren().add(fieldHeaderLabel);

            // setup RowConstraints
            RowConstraints constraint = new RowConstraints();
            constraint.setMinHeight(Control.USE_PREF_SIZE);
            constraint.setMaxHeight(Control.USE_PREF_SIZE);
            constraint.prefHeightProperty().bind(fieldEditorCell.heightProperty());
            optionsGrid.getRowConstraints().add(constraint);
        }
    }
}
