package de.marhali.easyi18n.service;

import com.intellij.openapi.application.ApplicationManager;
import com.intellij.openapi.application.ModalityState;
import com.intellij.openapi.project.Project;

import de.marhali.easyi18n.model.LocalizedNode;
import de.marhali.easyi18n.model.Translations;
import de.marhali.easyi18n.io.TranslatorIO;
import de.marhali.easyi18n.model.DataSynchronizer;
import de.marhali.easyi18n.model.KeyedTranslation;
import de.marhali.easyi18n.model.TranslationDelete;
import de.marhali.easyi18n.model.TranslationUpdate;
import de.marhali.easyi18n.util.IOUtil;
import de.marhali.easyi18n.util.TranslationsUtil;

import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.WeakHashMap;
import java.util.function.Consumer;

/**
 * Factory service to manage localized messages for multiple projects at once.
 * @author marhali
 */
public class DataStore {

    private static final Map<Project, DataStore> INSTANCES = new WeakHashMap<>();

    private final Project project;
    private final List<DataSynchronizer> synchronizer;

    private Translations translations;
    private String searchQuery;

    public static DataStore getInstance(@NotNull Project project) {
        DataStore store = INSTANCES.get(project);

        if(store == null) {
            store = new DataStore(project);
            INSTANCES.put(project, store);
        }

        return store;
    }

    private DataStore(@NotNull Project project) {
        this.project = project;
        this.synchronizer = new ArrayList<>();
        this.translations = Translations.empty();

        // Load data after first initialization
        ApplicationManager.getApplication().invokeLater(this::reloadFromDisk, ModalityState.NON_MODAL);
    }

    /**
     * Registers a new synchronizer which will receive {@link #translations} updates.
     * @param synchronizer Synchronizer. See {@link DataSynchronizer}
     */
    public void addSynchronizer(DataSynchronizer synchronizer) {
        this.synchronizer.add(synchronizer);
    }

    /**
     * Loads all translations from disk and overrides current {@link #translations} state.
     */
    public void reloadFromDisk() {
        String localesPath = SettingsService.getInstance(project).getState().getLocalesPath();

        if(localesPath == null || localesPath.isEmpty()) {
            // Propagate empty state
            this.translations = Translations.empty();
            synchronize(searchQuery, null);

        } else {
            TranslatorIO io = IOUtil.determineFormat(localesPath);

            io.read(project, localesPath, (loadedTranslations) -> {
                this.translations = loadedTranslations == null ? Translations.empty() : loadedTranslations;
                synchronize(searchQuery, null);
            });
        }
    }

    /**
     * Saves the current translation state to disk. See {@link TranslatorIO#save(Project, Translations, String, Consumer)}
     * @param callback Complete callback. Indicates if operation was successful(true) or not
     */
    public void saveToDisk(@NotNull Consumer<Boolean> callback) {
        String localesPath = SettingsService.getInstance(project).getState().getLocalesPath();

        if(localesPath == null || localesPath.isEmpty()) { // Cannot save without valid path
            return;
        }

        TranslatorIO io = IOUtil.determineFormat(localesPath);
        io.save(project, translations, localesPath, callback);
    }

    /**
     * Propagates provided search string to all synchronizer to display only relevant keys
     * @param fullPath Full i18n key (e.g. user.username.title). Can be null to display all keys
     */
    public void searchBeyKey(@Nullable String fullPath) {
        // Use synchronizer to propagate search instance to all views
        synchronize(this.searchQuery = fullPath, null);
    }

    /**
     * Processes the provided update. Updates translation instance and propagates changes. See {@link DataSynchronizer}
     * @param update The update to process. For more information see {@link TranslationUpdate}
     */
    public void processUpdate(TranslationUpdate update) {
        if(update.isDeletion() || update.isKeyChange()) { // Delete origin i18n key
            String originKey = update.getOrigin().getKey();
            List<String> sections = TranslationsUtil.getSections(originKey);
            String nodeKey = sections.remove(sections.size() - 1); // Remove last node, which needs to be removed by parent

            LocalizedNode node = translations.getNodes();
            for(String section : sections) {
                if(node == null) { // Might be possible on multi-delete
                    break;
                }

                node = node.getChildren(section);
            }

            if(node != null) { // Only remove if parent exists. Might be already deleted on multi-delete
                node.removeChildren(nodeKey);

                // Parent is empty now, we need to remove it as well (except root)
                if(node.getChildren().isEmpty() && !node.getKey().equals(LocalizedNode.ROOT_KEY)) {
                    processUpdate(new TranslationDelete(new KeyedTranslation(
                            TranslationsUtil.sectionsToFullPath(sections), null)));
                }
            }
        }

        String scrollTo = update.isDeletion() ? null : update.getChange().getKey();

        if(!update.isDeletion()) { // Recreate with changed val / create
            LocalizedNode node = translations.getOrCreateNode(update.getChange().getKey());
            node.setValue(update.getChange().getTranslations());
        }

        // Persist changes and propagate them on success
        saveToDisk(success -> {
            if(success) {
                synchronize(searchQuery, scrollTo);
            }
        });
    }

    /**
     * @return Current translation state
     */
    public @NotNull Translations getTranslations() {
        return translations;
    }

    /**
     * Synchronizes current translation's state to all connected subscribers.
     * @param searchQuery Optional search by full key filter (ui view)
     * @param scrollTo Optional scroll to full key (ui view)
     */
    public void synchronize(@Nullable String searchQuery, @Nullable String scrollTo) {
        synchronizer.forEach(subscriber -> subscriber.synchronize(this.translations, searchQuery, scrollTo));
    }
}