using Tango.Synchronization;
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SQLite;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;

namespace Tango.Synchronization.Local
{
    /// <summary>
    /// Represents an SQLite database adapter used for synchronization by <see cref="LocalDBComparer"/>.
    /// </summary>
    /// <seealso cref="Tango.Synchronization.ISqlDataBase" />
    public class SQLiteDataBase : ILocalDataBase
    {
        private SQLiteConnection _connection;

        /// <summary>
        /// Gets the database source URL/File.
        /// </summary>
        public String Source { get; private set; }

        /// <summary>
        /// Gets the database tables collection.
        /// </summary>
        public List<DataTable> Tables { get; private set; }

        /// <summary>
        /// Initializes a new instance of the <see cref="SQLiteDataBase"/> class.
        /// </summary>
        /// <param name="filePath">The file path.</param>
        public SQLiteDataBase(String filePath)
        {
            Source = filePath;

            _connection = new SQLiteConnection(String.Format("Data Source={0};Version=3;New={1};Compress=FALSE;",
                filePath,
                (File.Exists(filePath) ? "False" : "True")
                ));

            _connection.Open();
        }

        /// <summary>
        /// Loads the tables (Must be done before any synchronization).
        /// </summary>
        public void LoadTables()
        {
            Tables = new List<DataTable>();

            var command = _connection.CreateCommand();
            command.CommandText = "SELECT name FROM sqlite_master WHERE type = 'table'";
            var reader = command.ExecuteReader();

            while (reader.Read())
            {
                String name = reader.GetString(0);

                if (name != Constants.SEQUENCE_TABLE_NAME)
                {
                    Debug.WriteLine(name);
                    Tables.Add(LoadTable(name));
                }
            }
        }

        /// <summary>
        /// Loads the table.
        /// </summary>
        /// <param name="name">The name.</param>
        /// <returns></returns>
        private DataTable LoadTable(String name)
        {
            var tableCommand = _connection.CreateCommand();
            tableCommand.CommandText = "SELECT * FROM " + name;

            DataTable table = new DataTable(name);
            table.Load(tableCommand.ExecuteReader());

            var infoCommand = _connection.CreateCommand();
            infoCommand.CommandText = String.Format("PRAGMA table_info({0});", name);
            DataTable infoTable = new DataTable(name);
            infoTable.Load(infoCommand.ExecuteReader());

            table.ExtendedProperties.Add(Constants.TABLE_INFO, infoTable);

            for (int i = 0; i < table.Columns.Count; i++)
            {
                DataColumn column = table.Columns[i];
                column.ExtendedProperties.Add(Constants.COLUMN_TYPE, infoTable.Rows[i][Constants.COLUMN_TYPE]);
                column.ExtendedProperties.Add(Constants.IS_NOT_NULL, infoTable.Rows[i][Constants.IS_NOT_NULL]);
                column.ExtendedProperties.Add(Constants.DEFAULT_VALUE, infoTable.Rows[i][Constants.DEFAULT_VALUE]);
            }

            return table;
        }

        /// <summary>
        /// Clears the data base.
        /// </summary>
        public void ClearDataBase()
        {
            foreach (var table in Tables)
            {
                var dropCommand = _connection.CreateCommand();
                dropCommand.CommandText = String.Format("DELETE FROM {0};", table.TableName);
                dropCommand.ExecuteNonQuery();
            }
        }

        /// <summary>
        /// Clones a table from another database into this database.
        /// </summary>
        /// <param name="otherDB">The other database.</param>
        /// <param name="otherTable">The other table.</param>
        /// <returns></returns>
        public DataTable CloneTableFrom(ILocalDataBase otherDB, DataTable otherTable)
        {
            String cmd = String.Format("CREATE TABLE {0} (", otherTable.TableName);

            foreach (DataColumn column in otherTable.Columns)
            {
                cmd += String.Format("{0} {1} {2} {3} {4} {5}",
                    column.ColumnName,
                    column.GetSQLType(),
                    otherTable.PrimaryKey.Contains(column) ? "PRIMARY KEY" : null,
                    column.Unique ? "UNIQUE" : null,
                    column.IsNotNull() ? "NOT NULL" : null,
                    column.HasDefaultValue() ? ("DEFAULT " + column.GetDefaultValue()) : null)

                    + ", " + Environment.NewLine;
            }

            cmd += ");";

            cmd = cmd.Remove(cmd.LastIndexOf(","), 1);

            var createCommand = _connection.CreateCommand();
            createCommand.CommandText = cmd;
            createCommand.ExecuteNonQuery();

            var attacheCommand = _connection.CreateCommand();
            attacheCommand.CommandText = String.Format("ATTACH DATABASE '{0}' AS other;", otherDB.Source);
            attacheCommand.ExecuteNonQuery();

            var copyCommand = _connection.CreateCommand();
            copyCommand.CommandText = String.Format("INSERT INTO main.{0} SELECT * FROM {1}.{0};", otherTable.TableName, "other");
            copyCommand.ExecuteNonQuery();

            var detacheCommand = _connection.CreateCommand();
            detacheCommand.CommandText = "DETACH other;";
            detacheCommand.ExecuteNonQuery();

            var table = LoadTable(otherTable.TableName);
            Tables.Add(table);
            return table;
        }

        /// <summary>
        /// Replaces the table data with the data from another table.
        /// </summary>
        /// <param name="otherTable">The other table.</param>
        public void ReplaceTableData(ILocalDataBase otherDB, DataTable otherTable)
        {
            var dropCommand = _connection.CreateCommand();
            dropCommand.CommandText = String.Format("DELETE FROM {0};", otherTable.TableName);
            dropCommand.ExecuteNonQuery();

            var attacheCommand = _connection.CreateCommand();
            attacheCommand.CommandText = String.Format("ATTACH DATABASE '{0}' AS other;", otherDB.Source);
            attacheCommand.ExecuteNonQuery();

            var copyCommand = _connection.CreateCommand();
            copyCommand.CommandText = String.Format("INSERT INTO main.{0} SELECT * FROM {1}.{0};", otherTable.TableName, "other");
            copyCommand.ExecuteNonQuery();

            var detacheCommand = _connection.CreateCommand();
            detacheCommand.CommandText = "DETACH other;";
            detacheCommand.ExecuteNonQuery();
        }

        /// <summary>
        /// Gets the SQL command for <see cref="ReplaceTableData(ILocalDataBase, DataTable)"/>.
        /// </summary>
        /// <param name="otherDB"></param>
        /// <param name="otherTable">The other table.</param>
        /// <returns></returns>
        public string GetReplaceTableDataCommand(ILocalDataBase otherDB, DataTable otherTable)
        {
            String cmd = String.Format("DELETE FROM {0};", otherTable.TableName) + Environment.NewLine;
            cmd += String.Format("ATTACH DATABASE '{0}' AS other;", otherDB.Source) + Environment.NewLine;
            cmd += String.Format("INSERT INTO main.{0} SELECT * FROM {1}.{0};", otherTable.TableName, "other") + Environment.NewLine;
            cmd += "DETACH other;" + Environment.NewLine;
            return cmd;
        }

        /// <summary>
        /// Gets the SQL command for <see cref="CloneTableFrom(ILocalDataBase, DataTable)" />.
        /// </summary>
        /// <param name="otherDB">The other database.</param>
        /// <param name="otherTable">The other table.</param>
        /// <returns></returns>
        public String GetCloneTableFromCommand(ILocalDataBase otherDB, DataTable otherTable)
        {
            String cmd = String.Format("CREATE TABLE {0} (", otherTable.TableName);

            foreach (DataColumn column in otherTable.Columns)
            {
                cmd += String.Format("{0} {1} {2} {3} {4} {5}",
                    column.ColumnName,
                    column.GetSQLType(),
                    otherTable.PrimaryKey.Contains(column) ? "PRIMARY KEY" : null,
                    column.Unique ? "UNIQUE" : null,
                    column.IsNotNull() ? "NOT NULL" : null,
                    column.HasDefaultValue() ? ("DEFAULT " + column.GetDefaultValue()) : null)

                    + ", " + Environment.NewLine;
            }

            cmd += ");";

            cmd = cmd.Remove(cmd.LastIndexOf(","), 1);

            cmd += Environment.NewLine;

            cmd += String.Format("ATTACH DATABASE '{0}' AS other;", otherDB.Source);

            cmd += Environment.NewLine;

            cmd += String.Format("INSERT INTO main.{0} SELECT * FROM {1}.{0};", otherTable.TableName, "other");

            cmd += Environment.NewLine;

            cmd += "DETACH other;";

            return cmd;
        }

        /// <summary>
        /// Adds the specified column to the specified table.
        /// </summary>
        /// <param name="table">The table.</param>
        /// <param name="column">The column.</param>
        /// <returns></returns>
        public DataColumn AddColumn(DataTable table, DataColumn column)
        {
            var insertCommand = _connection.CreateCommand();
            insertCommand.CommandText = String.Format("ALTER TABLE {0} ADD COLUMN {1} {2} {3} {4} {5}",
                table.TableName,
                column.ColumnName,
                column.GetSQLType(),
                table.PrimaryKey.Contains(column) ? "PRIMARY KEY" : null,
                column.Unique ? "UNIQUE" : null,
                //column.IsNotNull() ? "NOT NULL" : null,
                column.HasDefaultValue() ? ("DEFAULT " + column.GetDefaultValue()) : null);


            insertCommand.ExecuteNonQuery();
            var t = LoadTable(table.TableName);
            var index = Tables.IndexOf(Tables.Single(x => x.TableName == table.TableName));
            Tables[index] = t;
            return t.Columns[column.ColumnName];
        }

        /// <summary>
        /// Gets the SQL command for <see cref="AddColumn(DataTable, DataColumn)" />.
        /// </summary>
        /// <param name="table">The table.</param>
        /// <param name="column">The column.</param>
        /// <returns></returns>
        public String GetAddColumnCommand(DataTable table, DataColumn column)
        {
            String cmd = String.Format("ALTER TABLE {0} ADD COLUMN {1} {2} {3} {4} {5}",
                table.TableName,
                column.ColumnName,
                column.GetSQLType(),
                table.PrimaryKey.Contains(column) ? "PRIMARY KEY" : null,
                column.Unique ? "UNIQUE" : null,
                //column.IsNotNull() ? "NOT NULL" : null,
                column.HasDefaultValue() ? ("DEFAULT " + column.GetDefaultValue()) : null);

            return cmd;
        }

        /// <summary>
        /// Adds the specified row to the specified table.
        /// </summary>
        /// <param name="table">The table.</param>
        /// <param name="row">The row.</param>
        public void AddRow(DataTable table, DataRow row)
        {
            var insertCommand = _connection.CreateCommand();

            List<String> values = new List<string>();

            for (int i = 0; i < row.ItemArray.Length; i++)
            {
                String value = row.ItemArray[i].ToString();

                double num = 0;

                if (row.ItemArray[i].GetType() == typeof(bool))
                {
                    value = ((bool)row.ItemArray[i]) ? 1.ToString() : 0.ToString();
                }

                if (row.ItemArray[i].GetType() == typeof(DateTime))
                {
                    value = ((DateTime)row.ItemArray[i]).ToSQLiteDateString();
                }

                if (!double.TryParse(value, out num))
                {
                    value = "'" + value + "'";
                }

                values.Add(value);
            }

            insertCommand.CommandText = String.Format("INSERT INTO {0} VALUES({1});", table.TableName, String.Join(",", values));
            insertCommand.ExecuteNonQuery();

            var desRow = table.NewRow();
            desRow.ItemArray = row.ItemArray.Clone() as object[];
        }

        /// <summary>
        /// Gets the SQL command for <see cref="AddRow(DataTable, DataRow)" />.
        /// </summary>
        /// <param name="table">The table.</param>
        /// <param name="row">The row.</param>
        /// <returns></returns>
        public String GetAddRowCommand(DataTable table, DataRow row)
        {
            List<String> values = new List<string>();

            for (int i = 0; i < row.ItemArray.Length; i++)
            {
                String value = row.ItemArray[i].ToString();

                double num = 0;

                if (row.ItemArray[i].GetType() == typeof(bool))
                {
                    value = ((bool)row.ItemArray[i]) ? 1.ToString() : 0.ToString();
                }

                if (row.ItemArray[i].GetType() == typeof(DateTime))
                {
                    value = ((DateTime)row.ItemArray[i]).ToSQLiteDateString();
                }

                if (!double.TryParse(value, out num))
                {
                    value = "'" + value + "'";
                }

                values.Add(value);
            }

            String cmd = String.Format("INSERT INTO {0} VALUES({1});", table.TableName, String.Join("," + Environment.NewLine, values));
            return cmd;
        }

        /// <summary>
        /// Updates the matching row by the row GUID.
        /// </summary>
        /// <param name="table">The table.</param>
        /// <param name="row">The row.</param>
        public void UpdateRow(DataTable table, DataRow row)
        {
            var updateCommand = _connection.CreateCommand();

            List<String> values = new List<string>();

            for (int i = 0; i < row.ItemArray.Length; i++)
            {
                String value = row.ItemArray[i].ToString();

                double num = 0;

                if (row.ItemArray[i].GetType() == typeof(bool))
                {
                    value = ((bool)row.ItemArray[i]) ? 1.ToString() : 0.ToString();
                }

                if (row.ItemArray[i].GetType() == typeof(DateTime))
                {
                    value = ((DateTime)row.ItemArray[i]).ToSQLiteDateString();
                }

                if (!double.TryParse(value, out num))
                {
                    value = "'" + value + "'";
                }

                values.Add(value);
            }

            String cmd = String.Format("UPDATE {0} SET ", table.TableName);

            String guid = String.Empty;

            for (int columnIndex = 0; columnIndex < table.Columns.Count; columnIndex++)
            {
                DataColumn column = table.Columns[columnIndex];
                if (column.ColumnName == Constants.ID)
                {
                    continue;
                }
                else if (column.ColumnName == Constants.GUID)
                {
                    guid = values[columnIndex];
                    continue;
                }

                cmd += String.Format("{0} = {1},{2}", column.ColumnName, values[columnIndex], Environment.NewLine);
            }

            cmd = cmd.Remove(cmd.LastIndexOf(","), 1);

            cmd += "WHERE" + Environment.NewLine;
            cmd += String.Format("{0} = {1};", Constants.GUID, guid);

            updateCommand.CommandText = cmd;
            updateCommand.ExecuteNonQuery();
            var desRow = table.NewRow();
            desRow.ItemArray = row.ItemArray.Clone() as object[];
        }

        /// <summary>
        /// Gets the SQL command for <see cref="UpdateRow(DataTable, DataRow)" />.
        /// </summary>
        /// <param name="table">The table.</param>
        /// <param name="row">The row.</param>
        /// <returns></returns>
        public String GetUpdateRowCommand(DataTable table, DataRow row)
        {
            List<String> values = new List<string>();

            for (int i = 0; i < row.ItemArray.Length; i++)
            {
                String value = row.ItemArray[i].ToString();

                double num = 0;

                if (row.ItemArray[i].GetType() == typeof(bool))
                {
                    value = ((bool)row.ItemArray[i]) ? 1.ToString() : 0.ToString();
                }

                if (row.ItemArray[i].GetType() == typeof(DateTime))
                {
                    value = ((DateTime)row.ItemArray[i]).ToSQLiteDateString();
                }

                if (!double.TryParse(value, out num))
                {
                    value = "'" + value + "'";
                }

                values.Add(value);
            }

            String cmd = String.Format("UPDATE {0} SET ", table.TableName);

            String guid = String.Empty;

            for (int columnIndex = 0; columnIndex < table.Columns.Count; columnIndex++)
            {
                DataColumn column = table.Columns[columnIndex];
                if (column.ColumnName == Constants.ID)
                {
                    continue;
                }
                else if (column.ColumnName == Constants.GUID)
                {
                    guid = values[columnIndex];
                    continue;
                }

                cmd += String.Format("{0} = {1},{2}", column.ColumnName, values[columnIndex], Environment.NewLine);
            }

            cmd = cmd.Remove(cmd.LastIndexOf(","), 1);

            cmd += "WHERE" + Environment.NewLine;
            cmd += String.Format("{0} = {1};", Constants.GUID, guid);

            return cmd;
        }

        /// <summary>
        /// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
        /// </summary>
        public void Dispose()
        {
            _connection.Close();
            _connection.Dispose();
            GC.Collect();

            DateTime startTime = DateTime.Now;

            while (startTime.AddSeconds(2) > DateTime.Now)
            {
                try
                {
                    using (FileStream stream = File.Open(Source, FileMode.Open, FileAccess.Read))
                    {
                        return;
                    }
                }
                catch (IOException)
                {
                    GC.Collect();
                    Thread.Sleep(200);
                }
            }
        }
    }
}