using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;



using System.Data.SQLite;



using ActivityInfo.Api;

using System.Windows.Forms;



namespace ActivityInfo.Sync

{

    class LocalDb

    {

        private ActivityInfoService service;

        private SQLiteConnection connection;



        private List<SyncRegion>.Enumerator regionEnum;

        private bool currentRegionIsComplete = true;



        public LocalDb(ActivityInfoService service)

        {

            this.service = service;



            var builder = new SQLiteConnectionStringBuilder();

            builder.DataSource = Application.UserAppDataPath + "\\ActivityInfo.db";



            connection = new SQLiteConnection(builder.ToString());

            connection.Open();



            executeSQL("create table if not exists sync_regions (id TEXT, localVersion INTEGER)");

            executeSQL("create table if not exists sync_history (lastUpdate INTEGER)");



            regionEnum = service.GetSyncRegions().List.GetEnumerator();

        }



        public SQLiteConnection Connection

        {

            get

            {

                return connection;

            }

        }



        public bool NextSyncStep(SyncLogger logger)

        {

            if (currentRegionIsComplete)

            {

                if (!regionEnum.MoveNext())

                {

                    return false;

                }

            }



            SyncRegion region = regionEnum.Current;

            string localVersion = queryLocalVersion(region.Id);



            logger.log(1, "Requesting updates for region '" + region.Id + "', localVersion = " + localVersion);



            SyncRegionUpdates updates;



           

            updates = service.GetSyncRegionUpdates(region.Id, localVersion);



            if (updates.Sql != null)

            {

                foreach (SyncRegionUpdate update in updates.Sql)

                {

                    executeUpdate(logger, update);

                }

            }



            updateLocalVersion(region.Id, updates.Version);

            currentRegionIsComplete = updates.Complete;





            logger.log(1, "    now at version " + updates.Version + " [complete=" + updates.Complete + "]");



            return true;

        }

        



        private int executeUpdate(SyncLogger logger, SyncRegionUpdate update)

        {

            logger.log(2, update.Statement);



            SQLiteCommand cmd = new SQLiteCommand(connection);

            cmd.CommandText = update.Statement;



            if (update.Executions == null)

            {

                return cmd.ExecuteNonQuery();

            }

            else

            {

                int rowsAffected = 0;

                foreach (ParameterSet set in update.Executions)

                {

                    logger.log(3, string.Join(",", set));



                    cmd.Parameters.Clear();

                    foreach (string param in set)

                    {

                        SQLiteParameter p = new SQLiteParameter();

                        p.Value = param;



                        cmd.Parameters.Add(p);

                    }

                    rowsAffected += cmd.ExecuteNonQuery();

                }

                return rowsAffected;

            }

        }



        private int executeSQL(String sql)

        {

            SQLiteCommand cmd = new SQLiteCommand(sql, connection);

            return cmd.ExecuteNonQuery();

        }



        private String queryLocalVersion(String regionId)

        {

            SQLiteCommand cmd = new SQLiteCommand(connection);

            cmd.CommandText = "select localVersion from sync_regions where id = :id";

            cmd.Parameters.Add(new SQLiteParameter("id", regionId));



            object result = cmd.ExecuteScalar();

            return result == null ? null : result.ToString();

        }



        private void updateLocalVersion(string regionId, string localVersion)

        {

            SQLiteCommand cmd = new SQLiteCommand(connection);

            cmd.CommandText = "update sync_regions set localVersion = :localVersion where id = :id";

            cmd.Parameters.Add(new SQLiteParameter("localVersion", localVersion));

            cmd.Parameters.Add(new SQLiteParameter("id", regionId));



            if(cmd.ExecuteNonQuery() == 0) {

                cmd = new SQLiteCommand(connection);

                cmd.CommandText = "insert into sync_regions (id, localVersion) values (:id, :localVersion)";

                cmd.Parameters.Add(new SQLiteParameter("id", regionId));

                cmd.Parameters.Add(new SQLiteParameter("localVersion", localVersion));

                cmd.ExecuteNonQuery();

            }

        }

    }  

}