/*
 * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the GNU Public License v3.0
 * which accompanies this distribution, and is available at
 * http://www.gnu.org/licenses/gpl.html
 */
package at.bitfire.davdroid.syncadapter;

import android.accounts.Account;
import android.content.AbstractThreadedSyncAdapter;
import android.content.ContentProviderClient;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.Context;
import android.content.SyncResult;
import android.database.Cursor;
import android.database.DatabaseUtils;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;

import org.dmfs.provider.tasks.TaskContract;

import java.util.LinkedHashMap;
import java.util.Map;
import java.util.logging.Level;

import at.bitfire.davdroid.AccountSettings;
import at.bitfire.davdroid.App;
import at.bitfire.davdroid.InvalidAccountException;
import at.bitfire.davdroid.model.CollectionInfo;
import at.bitfire.davdroid.model.ServiceDB;
import at.bitfire.davdroid.model.ServiceDB.Collections;
import at.bitfire.davdroid.model.ServiceDB.Services;
import at.bitfire.davdroid.resource.LocalTaskList;
import at.bitfire.ical4android.CalendarStorageException;
import at.bitfire.ical4android.TaskProvider;
import lombok.Cleanup;

/**
 * Synchronization manager for CalDAV collections; handles tasks ({@code VTODO}).
 */
public class TasksSyncAdapterService extends SyncAdapterService {

    @Override
    protected AbstractThreadedSyncAdapter syncAdapter() {
        return new SyncAdapter(this);
    }


	private static class SyncAdapter extends SyncAdapterService.SyncAdapter {

        public SyncAdapter(Context context) {
            super(context);
        }

        @Override
        public void onPerformSync(Account account, Bundle extras, String authority, ContentProviderClient providerClient, SyncResult syncResult) {
            super.onPerformSync(account, extras, authority, providerClient, syncResult);

            try {
                @Cleanup TaskProvider provider = TaskProvider.acquire(getContext().getContentResolver(), TaskProvider.ProviderName.OpenTasks);
                if (provider == null)
                    throw new CalendarStorageException("Couldn't access OpenTasks provider");

                AccountSettings settings = new AccountSettings(getContext(), account);
                if (!extras.containsKey(ContentResolver.SYNC_EXTRAS_MANUAL) && !checkSyncConditions(settings))
                    return;

                updateLocalTaskLists(provider, account, settings);

                for (LocalTaskList taskList : (LocalTaskList[])LocalTaskList.find(account, provider, LocalTaskList.Factory.INSTANCE, TaskContract.TaskLists.SYNC_ENABLED + "!=0", null)) {
                    App.log.info("Synchronizing task list #" + taskList.getId() + " [" + taskList.getSyncId() + "]");
                    TasksSyncManager syncManager = new TasksSyncManager(getContext(), account, settings, extras, authority, provider, syncResult, taskList);
                    syncManager.performSync();
                }
            } catch (CalendarStorageException e) {
                App.log.log(Level.SEVERE, "Couldn't enumerate local task lists", e);
            } catch (InvalidAccountException e) {
                App.log.log(Level.SEVERE, "Couldn't get account settings", e);
            }

            App.log.info("Task sync complete");
        }

        private void updateLocalTaskLists(TaskProvider provider, Account account, AccountSettings settings) throws CalendarStorageException {
            SQLiteOpenHelper dbHelper = new ServiceDB.OpenHelper(getContext());
            try {
                // enumerate remote and local task lists
                SQLiteDatabase db = dbHelper.getReadableDatabase();
                Long service = getService(db, account);
                Map<String, CollectionInfo> remote = remoteTaskLists(db, service);
                LocalTaskList[] local = (LocalTaskList[])LocalTaskList.find(account, provider, LocalTaskList.Factory.INSTANCE, null, null);

                boolean updateColors = settings.getManageCalendarColors();

                // delete obsolete local task lists
                for (LocalTaskList list : local) {
                    String url = list.getSyncId();
                    if (!remote.containsKey(url)) {
                        App.log.fine("Deleting obsolete local task list" + url);
                        list.delete();
                    } else {
                        // remote CollectionInfo found for this local collection, update data
                        CollectionInfo info = remote.get(url);
                        App.log.fine("Updating local task list " + url + " with " + info);
                        list.update(info, updateColors);
                        // we already have a local task list for this remote collection, don't take into consideration anymore
                        remote.remove(url);
                    }
                }

                // create new local task lists
                for (String url : remote.keySet()) {
                    CollectionInfo info = remote.get(url);
                    App.log.info("Adding local task list " + info);
                    LocalTaskList.create(account, provider, info);
                }
            } finally {
                dbHelper.close();
            }
        }

        @Nullable
        Long getService(@NonNull SQLiteDatabase db, @NonNull Account account) {
            @Cleanup Cursor c = db.query(Services._TABLE, new String[] { Services.ID },
                    Services.ACCOUNT_NAME + "=? AND " + Services.SERVICE + "=?", new String[] { account.name, Services.SERVICE_CALDAV }, null, null, null);
            if (c.moveToNext())
                return c.getLong(0);
            else
                return null;
        }

        @NonNull
        private Map<String, CollectionInfo> remoteTaskLists(@NonNull SQLiteDatabase db, Long service) {
            Map<String, CollectionInfo> collections = new LinkedHashMap<>();
            if (service != null) {
                @Cleanup Cursor cursor = db.query(Collections._TABLE, null,
                        Collections.SERVICE_ID + "=? AND " + Collections.SUPPORTS_VTODO + "!=0 AND " + Collections.SYNC,
                        new String[] { String.valueOf(service) }, null, null, null);
                while (cursor.moveToNext()) {
                    ContentValues values = new ContentValues();
                    DatabaseUtils.cursorRowToContentValues(cursor, values);
                    CollectionInfo info = CollectionInfo.fromDB(values);
                    collections.put(info.url, info);
                }
            }
            return collections;
        }
    }

}